The Time-Varying Link of Public Timber REITs with Private Timberland, Real Estate, and Financial Assets - Srijana Baral; Bin Mei (Forest Science, 2022)
We examined the relationship between public timber real estate investment trusts (REIT), private timberland, real estate, and financial asset returns using a multi-factor model and investigated the time-varying volatility of timber REITs under the state space framework. We first orthogonalized explanatory variables to obtain pure factors. Then we decomposed REIT volatility into S&P500, private-equity timberland, real estate, bond, and idiosyncratic risk components. Results reveal that timber REITs are positively sensitive to large-cap stocks and bonds. Volatility contributions of the large-cap stock factor are consistent and high whereas those of idiosyncratic risk factors decline over time. Private-equity timberland, real estate, and bonds exhibit negligible contribution to the volatility of timber REITs. We conclude that timber REIT characteristics change with time and the timber REIT market is not mature. Thus, the results contribute to our understanding of the risk and return features of public-equity timberland investments.

Ecoregional Variation of Crimean Pine ( Pinus nigra subspecies pallasiana [Lamb.] Holmboe) Stand Growth - Mehmet Seki; Oytun Emre Sakici (Forest Science, 2022)
Investigation and numerical determination of the effects of ecologically different regions on forest growth are important issues to be considered for sustainable forest management. In this study, differences in growth patterns of Crimean pine (Pinus nigra subsp. pallasiana [Lamb.] Holmboe) stands among the ecoregions located in the Kastamonu region of northwestern Turkey were investigated. For this purpose, stand-level growth models for dominant height, number of trees, basal area, and volume were fitted using the data from 274 sample plots and 293 stem analysis in even-aged, pure, and productive Crimean pine stands. The nonlinear extra sum of squares method and graphical examinations revealed that growth characteristics of these Crimean pine stands were affected by ecoregional differences. Ecoregion-based growth models, which are more flexible and have the ability to reflect the ecoregional differences in growth patterns, were found to be superior to regional models. Applying general models without any ecoregional classification resulted in biases of 5.3%, 23.1%, 5.5%, and 6.2% in the estimates of dominant height, number of trees, basal area, and volume of Crimean pine stands, respectively. The results showed that ecological differences must be considered in studies on forest growth modeling and forest management.

Productivity of Clonal Ilex paraguariensis Genotypes in a Semi-Hydroponic System Is Reduced by Shading - Natália Saudade de Aguiar; Mônica Moreno Gabira; Jéssica de Cássia Tomasi; Manoela Mendes Duarte; Leandro Marcolino Vieira; Osmir José Lavoranti; Ivar Wendling (Forest Science, 2022)
Yerba mate (Ilex paraguariensis A. St.-Hil.) is a South American tree cultivated in systems with or without shading at different intensities; however, there is no consensus about shading effect on leaf biomass production. Therefore, we evaluated yerba mate clones under different shading levels over one year to determine the influence of shading and genotype on biomass production. Two yerba mate genotypes (EC22 and EC40), cultivated in a semi-hydroponic system, were subjected to five shading levels (0%, 40%, 51%, 76%, and 82%) in a greenhouse. We determined total fresh biomass (branches and leaves) and fresh biomass of young and mature leaves on six harvests. Biomass production was influenced by harvest season, genotype, and shading levels. Spring and summer harvests provided higher biomass production than the other seasons. EC40 genotype produced higher total fresh and young leaf biomass than EC22. Although we observed differences among genotypes and harvest seasons, shading was the factor that most influenced biomass production. Total fresh biomass productivity was reduced 6.8 times between 0% and 82% shading for the EC40 genotype. Thus, we do not recommend high levels of shade, such as 76% and 82%, in this new yerba mate cultivation system.

A Comparison of Multivariate and Univariate Time Series Models Applied in Tree Sap Flux Analyses - Xiaowei Zhao; Ping Zhao; Liwei Zhu; Gaoyang Zhang (Forest Science, 2022)
Accurate model predictions of the tree sap flux in sapwood are critical for forestry water management, primarily due to data availability limitations. Time series models have been used in tree sap flux analyses since 2005. Classic autoregressive models such as the ARIMA (autoregressive integrated moving average), ARIMAX (ARIMA with exogenous variables), SARIMA (seasonal ARIMA) and SARIMAX (seasonal ARIMAX) models are designed and tested for two common exotic species (Eucalyptus citriodora Hook. f. and Acacia auriculaeformis A. Chun) in dry and wet seasons in South China. The performance of the models is assessed with a scoring system for integrating six statistical indices. The results show that taking both seasonal term and exogenous variables into account could improve day sap flux prediction accuracy.

United States Family Forest Owners’ Awareness of and Participation in Carbon Sequestration Programs: Initial Findings from the USDA Forest Service National Woodland Owner Survey - Emma M Sass; Jesse Caputo; Brett J Butler (Forest Science, 2022)
Family forest owners (FFOs) hold a plurality of forestland in the United States, and programs and markets exist that compensate landowners for sequestering and storing increased carbon through extended rotations, improved forest management, and increased forest cover. We used USDA Forest Service National Woodland Owner Survey (NWOS) data from 2018 to estimate the number of ownerships and their associated acreage that are enrolled, that are familiar but not enrolled, and that are unfamiliar with these programs, as well as differences in attributes among these groups. As of 2018, less than 0.1% (SE < 0.1%) of FFOs are enrolled in carbon sequestration programs, and collectively they hold an estimated 400,000 ha (SE = 100,000). FFOs who are enrolled have larger holdings, are more likely to participate in other programs, and are more concerned about climate change, among other characteristics. Most FFO holdings are too small to be viable in traditional carbon programs, although new and evolving programs might enable smaller landholdings to be feasible to enroll. Knowing the characteristics of ownerships that are enrolled or aware of programs will allow for more informed design and implementation; future monitoring will be important to identify trends as these programs become more widespread.

Modeling Individual Extended Attack Wildfire Suppression Expenditures in British Columbia - Robert MacMillan; Lili Sun; Stephen W Taylor (Forest Science, 2022)
We developed models of suppression expenditures for individual extended attack fires in British Columbia using parametric and nonparametric machine-learning (ML) methods. Our models revealed that suppression expenditures were significantly affected by a fire’s size, proximity to the wildland–urban interface (WUI) and populated places, a weather based fire severity index, and the amount of coniferous forest cover. We also found that inflation-adjusted individual fire suppression expenditures have increased over the 1981 to 2014 study period. The ML and parametric models had similar predictive performance: the ML models had somewhat lower root mean squared errors but not on mean average errors. Better specification of fire priority as well as resource constraints might improve future model performance.

Stochastic Dynamic Optimization for Forest Rotation with Uncertain Stumpage Prices - Yu-Kai Huang; Ranjit Bawa; Puneet Dwivedi; Dehai Zhao (Forest Science, 2022)
This study investigates the effect of uncertain stumpage prices on the optimal forest rotation decision and related profitability under various silvicultural scenarios. The study applies loblolly pine (Pinus taeda L.) growth and yield models with distinct silvicultural scenarios in the Piedmont and Upper Coastal Plain region of the southeastern United States. It then applies chance-constrained dynamic optimization to derive optimal rotation age and related profitability on per acre basis. The growth and yield models show that using a combination of herbicide and fertilizer silvicultural treatment leads to a higher timber yield and profit at a lower optimal rotation age than other treatment scenarios. Furthermore, the stochastic optimization model shows that low risk tolerance results in low returns. Within a particular risk tolerance level, silvicultural treatment options with higher standard deviations almost always produce higher returns. The findings of this article contribute to the literature on optimizing forest management when considering uncertain stumpage prices over time, given different risk tolerance levels.

Evaluating Trade-Offs between Using Regional and Site-Specific Allometric Models to Predict Growing Stock Volume of Subtropical Atlantic Forests - Laio Zimermann Oliveira; Alexander Christian Vibrans (Forest Science, 2022)
Choosing models to predict volume for individual trees is a relevant step in estimating growing stock volume. When large-area estimates are needed, models should ideally be constructed based on observations acquired across the population. However, due to multiple constraints, models are often constructed using samples collected at one or in a few sites. Therefore, this study aimed to evaluate trade-offs between using models based on a regional dataset (RD) and a model based on a local dataset (LD) and to assess the effects of such models on large-scale estimates of stem volume (V) per unit area. Regional and local V datasets and inventory data acquired throughout the subtropical Brazilian Atlantic Forest were employed. When used to predict V for trees of the RD (n = 1,192), the local model (LM), based on 419 tree observations, presented a mean systematic percentage error (MSPE) of +11%. In turn, when the regional model (RM) (n = 1,192) was used to predict V for trees of the LD (n = 419), it yielded an MSPE of –3%. The estimated mean V ha–1 using the LM was 9.4% greater than the estimated mean using the RM. Moreover, less precise estimates were attained using the LM.

Contribution of the Root Component to Soil Respiration in Oriental Beech Stands in Artvin, Turkey - Musa Akbas; Aydın Tufekcioglu (Forest Science, 2022)
Autotrophic (root) and heterotrophic respiration components respond differently to environmental variables, and each component behaves differently at different time scales, so it is necessary to partition total soil respiration into its components. The aims of this study were determine soil respiration and its root and heterotrophic components in beech stands, examine the relationship between respiration and biogeochemical factors, and assess seasonal variation in soil respiration. Trenching was applied to separate soil respiration components 6 months before measurements. Monthly soil respiration, temperature and moisture measurements, and seasonal soil and root sampling were carried out in Oriental beech (Fagus orientalis L.) stands located in Artvin Saçinka, Turkey from April 2018 to November 2018 and also (except soil sampling) from May 2019 to November 2019. The average contribution of root respiration and heterotrophic respiration to total soil respiration were 58.8% and 41.2%, respectively. Carbon and nitrogen dynamics explained variations of soil respiration with significant models. This study indicates that soil respiration and its components are associated with biogeochemical factors as well as environmental climatic conditions, and each component of respiration responds differently to changes in them.

Robinia pseudoacacia decline and fine root dynamics in a plantation chronosequence in the Yellow River Delta, China - Longmei Guo; Yuanxiang Pang; Banghua Cao; Zhaofei Fan; Peili Mao; Zexiu Li; Wei Liu; Pengfei Li (Forest Science, 2022)
Fine roots (<2 mm in diameter) play a significant role in tree growth and stand productivity. However, knowledge of fine root dynamics in saline alkali soil remains limited. Using sequential soil core and ingrowth core methods, we assessed the dynamics of aboveground biomass (AGB) and production (AGP), fine root biomass (FRB), production (FRP) and turnover (FRT), and soil properties (water content [SWC], salt content [SSC], pH and nutrients) in 2-, 18-, 32- and 42-year-old black locust (Robinia pseudoacacia L.) stands in the Yellow River Delta, China. Corresponding to the unimodal growth pattern in AGP, the AGB of black locust rapidly increased until age 32 and then slowed down. In contrast, across all depths, FRB and FRP took a unimodal pattern with a decrease in growth around age 32, and FRT continually decreased with stand age. SWC and soil nutrients increased with stand age, whereas SSC and pH decreased with stand age until age 32 and then increased. Based on the correlation analysis, we may presume that in addition to the age effect, the decline of black locust in AGP is most likely caused by SWC, SSC, and pH stresses through the dysfunction in nutrient absorption by fine roots.

Predicting Lumber Grade Occurrence and Volume in Sugar Maple and Yellow Birch Logs - Filip Havreljuk; Alexis Achim; David Pothier (Forest Science, 2022)
The North American temperate deciduous forests are an important source of hardwoods sought after by the appearance wood products industries. The purpose of this study was to model the relationships between log characteristics and sawn board attributes in sugar maple (Acer saccharum Marsh.) and yellow birch (Betula alleghaniensis Britt.). We harvested sixty-four sugar maple and thirty-two yellow birch trees from two locations in southern Quebec, Canada, which were then processed into 189 sawlogs and 2,236 boards. We developed statistical models linking log characteristics to the volume recovery of the various lumber grades and color specifications according to the National Hardwood Lumber Association rules. In both species, board grades were strongly related to log length, position of the log in the stem, and small-end diameter and decay of the log. Color classes were related to small-end diameter of the log and red heartwood diameter of the log at both ends for sugar maple, and to log length, diameter of the log at the small-end, and red heartwood diameter at the large-end of the log for yellow birch. These models outperformed a log classification used in practice for predicting lumber volume recovery from different log grades.

Corrigendum to: Predicting the Location of Maple Habitat under Warming Scenarios in Two Regions at the Northern Range in Canada - Pratiksha Jain; Siddhartha Khare; Jean-Daniel Sylvain; Raymond Patricia; Sergio Rossi (Forest Science, 2022)

Developing a Harvest Plan by Considering the Effects of Skidding Techniques on Forest Soil Using a Hybrid TOPSIS-Entropy Method - Çiğdem Özer Genç; Burak Arıcak (Forest Science, 2022)
The aim of this study was to evaluate skidding techniques, which result in minimal damage to the soil, depending on the slope and stand type. Thus, three skidding techniques with tractor for harvesting (suspended skidding [SS], using a skidding cone [SC], and cable-pulling [CP]) were used in six different study sites and the variations in soil properties were examined at three different slopes (0%–20%, 20%–33%, >33%), 2 different stand types (A, B), and 2 different soil depths (0–5 cm, 5–10 cm). Soil bulk density, soil organic matter, soil compaction, organic carbon (C), and total nitrogen (N) were determined. The Entropy and TOPSIS methods were used among the multiple-criteria decision-making methods for six different coniferous stands. With the combination of the Entropy and TOPSIS methods, we found that slope was an important factor in determining the preferred skidding technique. Suspended skidding was seen as the preferred method of skidding technique in the 0–20% slope group. For the 20%–33% slope group, the usability of the three methods varied depending on stand type and soil depth, whereas the technique using a skidding cone was found to be the preferred skidding technique in the > 33% slope group.

Estimated Erosion from Clearcut Timber Harvests in the Southeastern United States - Jonah A H Fielding; Brent S Hawks; W Michael Aust; M Chad Bolding; Scott M Barrett (Forest Science, 2022)
Timber harvests with inadequate forestry best management practices (BMPs) can accelerate soil erosion, which has been associated with reductions in water quality and site productivity. Previous studies affirm positive water quality effects accrued by harvesting with BMPs. However, few studies document erosion rates and masses associated with harvest and access network features (e.g., decks, roads, skid trails, stream crossings) across different southeastern regions. This research evaluated 109 recent harvests across eleven southeastern states and three topographically different regions (Coastal Plain, Piedmont, and Mountains). Descriptive statistics of erosion for harvests and access features were developed from USLE-Forest model estimates. Harvests and access network areas were used in conjunction with erosion averages to calculate total erosion masses. Across the southeast, combined network features averaged nearly 12% of total harvest area yet produced approximately 48% of total site erosion due to disproportionately higher erosion rates. Regional differences indicated that the Mountain region had an average overall erosion rate of 6.8 t/ac/yr, whereas the Piedmont and Coastal Plain sites had lower average erosion rates of 2.7 and 2.2 t/ac/yr, respectively. Results suggest that additional BMP implementation strategies may be beneficial for erosion control from roads, skid trails, and stream crossings, particularly in erosive landscapes.

Shortleaf Pine ( Pinus echinata ) Site Index Equation for the Cumberland Plateau, USA - John M Zobel; Martin R Schubert; Joshua J Granger (Forest Science, 2022)
Shortleaf pine site index on the Cumberland Plateau is one of the least studied silvics of the species. To obtain site index information, practitioners must use site index curves from outside the region. This research proposes a novel approach to using USDA Forest Service, Forest Inventory and Analysis data to develop a shortleaf pine site index equation specific to the Plateau. Shortleaf pine site trees (n = 410) were grown forward or backward until base age of 50 years, using site specific, mixed-model parameters. Over thirty height models were then fit using traditional methods and the algebraic difference approach (ADA). Fit and cross-validation statistics, along with examinations of model behavior, showed that a derivation of the Lundqvist-Korf model provided the best estimates. The model was rearranged to directly estimate site index, and a traditional site index graph is provided. Site index estimates had average validation results nearly four times better than the currently recommended site index curve developed off the Plateau. Forest practitioners now have access to improved site index estimation for restoring and managing shortleaf pine on the Cumberland Plateau.

Effects of 21 Years of Simulated Acidic Deposition on Tree Growth and Species Composition in an Aggrading Appalachian Hardwood Forest - Alexander Storm; Mary Beth Adams; Zachariah Fowler; Jamie L Schuler (Forest Science, 2022)
The long-term effects of soil acidification on the development of a young aggrading Appalachian forest were examined after 21 years of continuous treatment. Beginning with a clearcut harvest in 1997, annual ammonium sulfate (N+S) and ammonium sulfate with lime (N+S+LIME) treatments were aerially applied to a developing forest. The lime treatment was designed to counteract the acidification of the nitrogen and sulfur amendments. After 21 years, the N+S and N+S+LIME treatments had little impact on total woody biomass accumulation relative to the control. There were significant differences among species and treatment responses with respect to woody biomass accumulation, however. Biomass of Prunus pensylvanica was about twice as much as any other species in N+S and N+S+LIME treatments but was similar to Liriodendron tulipifera and Betula lenta on control areas. Treatment effects were not significant for average tree diameter or stem density, although both varied among the six tree species with the highest importance values. The importance value of P. pensylvanica decreased by almost half in the last 6 years due to mortality, but this was not associated with either the N+S or N+S+LIME treatments. The dynamic nature of this short-lived tree species is potentially masking any effects of the N+S or N+S+LIME treatments to date. Study Implications: We examined the long-term impact of nitrogen and sulfur additions with and without lime on forest stand development. After 21 years, the forest showed little change in aboveground woody biomass, although the distribution of biomass among species was affected by the treatments. Prunus pensylvanica (pin cherry) accumulated the greatest biomass on N+S and N+S+LIME treatments relative to the untreated areas. However, P. pensylvanica is a short-lived species, and our data show it is declining. It is unclear whether the treatments are having minimal impacts or they are being masked by the early dominance and subsequent mortality of P. pensylvanica.

An Inverse Growth Curve Representation of the Clutter-Jones Stand Survival Model - Mingliang Wang; Cristian R Montes; Bronson P Bullock; Dehai Zhao (Forest Science, 2022)
The Clutter-Jones (CJ) stand survival model has been widely used for the projection of the reduction in trees per unit area in a forest stand over time. To better understand this well-recognized model, we introduced a varying-parameter formulation as an alternative to its original difference equation form, where plot-specific effects are presented explicitly. This new parameterization turns out to be a type of Richards (generalized logistic) equation with its independent variable age log-transformed, which might be termed “log-Richards” (LR) and falls into the category of the generalized algebraic difference approach (GADA) models. Under the LR GADA representation, a half-reduction age, at which half of the trees in a stand die, may be examined to improve stand survival simulation. The new reformulation provides an inverse growth curve modeling viewpoint of stand survival over time. It may motivate one to derive new survival models directly from existing growth equations that allow for generating inverse growth curves, complementary to the commonly used differential equation method in developing stand mortality models. Study Implications: The Clutter-Jones stand survival model plays an important role in southern pine plantation management as a component of whole-stand modeling systems. This study introduces a varying-parameter formulation as an alternative to its original difference equation form, providing an inverse growth curve modeling viewpoint of stand survival over time.

Best Management Practices, Estimated Erosion, Residual Woody Debris, and Ground Cover Characteristics Following Biomass and Conventional Clearcut Harvests in Virginia’s Mountains - Austin M Garren; M Chad Bolding; Scott M Barrett; W Michael Aust; T Adam Coates (Forest Science, 2022)
Water quality best management practices (BMPs) developed for conventional forest harvests may be adequate for biomass harvests, yet quantitative data is lacking. This study compared estimated erosion, operational feature areas, BMP implementation rates, ground cover characteristics, and downed woody debris quantities following biomass and conventional harvests in the mountains of Virginia. Haul roads on biomass harvests had significantly higher estimated erosion rates (P = 0.064) and masses (P = 0.045) than conventional harvests, but conventional harvests had higher erosion contributions from skid trails (P = 0.089) and averaged more estimated erosion mass overall, despite being significantly smaller in size (P = 0.054). There was significantly less area in heavy slash (P = 0.076) and lower estimated mass of residual downed woody debris (P = 0.001) on biomass sites than conventional sites (10.98 and 27.95 tons/ac, respectively). Site-wide BMP implementation scores (P = 0.041), streamside management zones (SMZs) (P = 0.024), and skidding (P = 0.063) were significantly higher on biomass sites than conventional sites. BMP implementation scores were significant predictors of estimated erosion rates (P < 0.001, R2 = 59%), indicating that adequate levels of existing water quality BMPs are effective for erosion control on both conventional and biomass harvests.

Modeling Advance Oak Reproduction at Landscape Scale: The Relative Importance of Abiotic and Biotic Factors - Joshua W Rittenhouse; Laura P Leites (Forest Science, 2022)
Establishing advance oak reproduction in the understory of mature oak forests before an overstory removal is critical to regenerate mixed-oak forests (Quercus spp.). Many studies have been conducted at the stand scale; however, studies at landscape scale can be particularly useful to guide silvicultural management investments. We developed a model of advance reproduction abundance at landscape scale using inventory, climate, topography, and soils data from ninety-seven mixed-oak forests located in Pennsylvania, USA. A negative binomial model was used to predict the abundance of oak seedlings between 15.2 and 91.4 cm in height and with a root collar diameter of 0.64 to 1.9 cm (established oak seedlings). This model had a Nagelkerke’s pseudo R2 of 58%. Deviance partitioning methods indicate that climate and overstory influence explain similar proportions of total deviance, but climate contributes a higher proportion of nonoverlapping information (22% versus 18%). Overstory basal area of two common oak species were positively associated with seedling abundance, whereas biotic stressors were negatively correlated. Biotic stressors showed considerable overlap with information provided by climate and overstory influences. The results of this study provide a reference to guide silvicultural management at a landscape scale.

Constraint Shock in Diameter Distribution Models: The Cost of Ignoring Negative Bounds - Adrian N Goodwin (Forest Science, 2022)
Diameter distributions are invariably fitted with constrained zero or positive lower bounds to prevent negative diameters. Goodwin (2021) found that the bound for the 3-parameter Weibull could be negative for negatively skewed data, and that constraining it to zero reduced model accuracy. The loss of model accuracy due to a bound constraint is referred to here as constraint shock. This article shows that the 4-parameter Kumaraswamy and Johnson’s SB distributions can also have negative lower bounds and exhibit constraint shock. A 3-step parameter recovery method was used to fit these distributions to plots in unthinned mixed species eucalypt plantations and results were compared with the less flexible Weibull. Based on Kolmogorov-Smirnov statistics, mean and maximum constraint shock for the 4-parameter distributions were 19% and 62%, respectively, compared with 19% and 51% for the Weibull, which indicated that constraint shock was not affected by model flexibility. Constraint shock was largely avoided by truncating and normalizing distributions with negative bounds. This work introduces a paradigm shift in diameter distribution modelling and adds clarity to a field that has not previously recognized the existence of constraint shock. Study Implications: Constraint shock is the loss of accuracy incurred by constraining the negative lower bound of a distribution to a nonnegative value. For a plantation eucalypt dataset in which 83% of plot diameters were negatively skewed, maximum constraint shock was 62% for the Kumaraswamy and Johnson’s SB distributions, and 51% for the less flexible 3-parameter Weibull, based on Kolmogorov-Smirnov statistics. Using distribution expectations of kurtosis, skewness, maximum diameter, and minimum diameter—all independent of bound parameters—a tractable 3-step parameter recovery method is described for unconstrained, constrained, and truncated 3- and 4-parameter distributions. This work introduces a paradigm shift in the treatment of distribution bounds that will result in substantial model improvements for negatively skewed data.

Atlantic White-Cedar ( Chamaecyparis thyoides [L.] B.S.P.) Response Post-Hurricane Disturbance - Clayton W Hale; Joshua J Granger; Sandra B Correa; Janice L DuBien; Courtney M Siegert (Forest Science, 2022)
Atlantic white-cedar (Chamaecyparis thyoides [L.] B.S.P.) is considered critically imperiled across much of its range. This species occurs in freshwater swamps, rarely further inland than 160 km from the Atlantic or Gulf Coasts and is susceptible to several natural and anthropogenic disturbances (i.e., tropical cyclones, fire, saltwater inundation, overharvesting). As the frequency and intensity of tropical storms increase, understanding the regeneration of Atlantic white-cedar will be critical to its conservation. This study evaluated the regeneration of Atlantic white-cedar 14 years after Hurricane Katrina. All Atlantic white-cedar ≥2.5 cm at breast height were inventoried within an ~9 ha study area located within Grand Bay National Wildlife Refuge in Jackson County, Mississippi, USA. Additionally, the competing woody vegetation was surveyed. After Hurricane Katrina, the number of Atlantic white-cedar stems increased by 191%. This long-term study provides the first analysis of Atlantic white-cedar regeneration post–tropical cyclone disturbance within the Gulf Coast and allows conservationists a better understanding of the effects of tropical cyclone disturbance on this species.

Long-Term Effects of Crop Tree Release on Growth and Quality in White-Oak ( Quercus alba L.)-Dominated Stands - Philip J Vogel; John M Lhotka; Jeffrey W Stringer (Forest Science, 2022)
Crop tree release (CTR) can be an effective intermediate silvicultural treatment for culturing high-value stems in mixed hardwood stands. The lengthy rotation of hardwoods requires long-term evaluations if silvicultural treatment effectiveness is to be fully evaluated. Our study provides a 35-year evaluation of individual-tree and stand response to CTR imposed in small sawtimber-sized white-oak (Quercus alba L.)-dominated stands. The focus on white oak is justified based on the significant biologic and economic values of the species, and this study furthers our ability to optimize use of CTR as management tool for sustaining our oak resources. The replicated experiment included three treatment levels: 20 crop trees ac−1, 34 crop trees ac−1, and a control. Using a repeated-measures framework, we analyzed (1) how CTR affects growth and stem quality of white oak crop trees and (2) stand-level effects of CTR on basal area, stocking, and ingrowth. CTR increased crop tree diameter growth and proportion of crop trees reaching their maximum potential grade. However, crop tree diameter growth and proportion achieving maximum potential grade did not differ between the 20 and 34 crop trees ac−1 treatments. Finally, CTR stimulated stand-wide growth without altering the patterns of ingrowth density or species distributions.

Genetic Diversity in Successive Age Cohorts of Ilex paraguariensis in Southern Brazil - Larissa Bittencourt; Douglas Trautmann e Silva; Bruno Nascimento; Flavia Anan Saiki; Lilian Iara Bet Stedille; Newton Clóvis Freitas da Costa; Adelar Mantovani (Forest Science, 2022)
Ilex paraguariensis A. St. Hil. (yerba mate) is a native species widely consumed in southern Brazil, a region that presents a current scenario of forest fragmentation. The objective was to evaluate the genetic diversity, genetic structure, and gene flow among cohorts of I. paraguariensis in two forest remnants. Genetic analyses were conducted using microsatellite markers from leaves from adult (Ad), regenerating (Reg), and seed-derived (Se) populations in Santa Catarina (SC) (Chapecó’s National Forest [CCO]) and Rio Grande do Sul (RS) (Teixeira Soares’ Municipal Natural Park [PTS]). We found unique alleles in both populations, eleven in the CCO and eight in the PTS. There was no significant difference in genetic diversity indexes, whereas high and significant fixation indexes were observed (FCCO = 0.394; FPTS = 0.319). The proportion of genetic variation obtained between populations was lower (8%) than the proportion within populations (92%). The presence of significant genetic structure was verified in the cohorts of I. paraguariensis for two study areas. Moreover, all pairwise genetic divergence between Ad and Reg, and Ad and Se cohorts was significant, except for Ad versus Reg in PTS. Aiming to maintain diversity over generations, we recommend the conservation of remnants and expansion of connectivity between fragments.

Effects of Pre-Bunching Trees With a Tethered Feller-Buncher on Cable Logging Productivity and Costs: A Case Study in Southern Oregon - Woodam Chung; Brett Morrissette; Preston Green; Brennan Garrelts; Ben Leshchinsky; Francisca Belart; John Sessions; Jeff Wimer; John Garland (Forest Science, 2022)
Winch-assist or tethered logging technology is rapidly being adopted by the forest industry across the western United States to replace conventional and dangerous manual tree falling in cable logging areas. Although the safety benefits of the technology are widely acknowledged, the effects of tethered mechanized timber falling and pre-bunching on the subsequent cable yarding operations have not been thoroughly investigated. We conducted a field study in southern Oregon to compare manual versus mechanized timber falling side-by-side for their impacts on the productivity and costs of cable logging operations. Our study shows that the costs of mechanized timber falling were higher than manual falling owing to high costs of tether equipment, but the ability of the felling machine to pre-bunch trees into piles along designated skyline corridors made subsequent cable yarding operations significantly more efficient. The efficiency gained during yarding was sufficient not only to offset cost increase in felling but also to reduce the total production costs of felling and yarding operations by 32% compared with cable yarding after manual timber falling.

Change in Doctoral Dissertation Topics in Forest Resources from US Universities Over Four Decades - Robert G Wagner; Kristen M Bellisario; Ningning N Kong (Forest Science, 2022)
Changes in forest resources expertise from 1978 to 2017, as measured by annual number of doctoral dissertations published on twenty topics, were examined. Using the ProQuest Dissertations and Theses Global database, titles and abstracts from 11,530 dissertations produced by fifty-six universities in the United States were selected. Automated content analysis and latent Dirichlet allocation were used to identify the optimal number of topic groupings among 7,742 dissertations that met selection criteria. Substantial differences were found in the pattern of publication among the twenty topics over time. The number of dissertations related to forest growth and silviculture; tree seedling propagation, physiology, and regeneration; and forest soil nutrients, ecology, and management declined over the past two decades. Dissertations related to forest wildlife management, including terrestrial wildlife ecology and management; wildlife food and nutrition; and fish ecology and management also declined during the same period. The number of dissertations in the fields of forest policy, politics, and social science; forest modeling, biometrics, and statistics; wood science; forest vegetation ecology; and avian ecology increased during the four decades. Dissertations published in the fields of forest economics, and forest entomology and pathology, remained relatively stable. Study Implications: We found decreasing production of doctoral dissertations focused on applied forest and wildlife management topics in recent decades. Declining doctoral-level expertise in applied fields after the early 2000s suggest that there may be reduced capacity to address practical problems facing both forest and wildlife managers. This decline also suggests that finding university instructors qualified to teach more applied forest and wildlife courses may have been more difficult over the past decade and possibly into the future. Our analysis indicated that the increased number of dissertations in adjacent sciences supporting forest resources has substantially increased capacity in these areas.

Allometric Relationships for Predicting Aboveground Biomass, Sapwood, and Leaf Area of Two-Needle Piñon Pine ( Pinus edulis ) Amid Open-Grown Conditions in Central New Mexico - Cameron D McIntire; Andrew M Cunliffe; Fabio Boschetti; Marcy E Litvak (Forest Science, 2022)
Pinus edulis Engelm. is a short-stature, drought-tolerant tree species that is abundant in piñon-juniper woodlands throughout semiarid ecosystems of the American Southwest. P. edulis is a model species among ecophysiological disciplines, with considerable research focus given to hydraulic functioning and carbon partitioning relating to mechanisms of tree mortality. Many ecological studies require robust estimates of tree structural traits such as biomass, active sapwood area, and leaf area. We harvested twenty trees from Central New Mexico ranging in size from 1.3 to 22.7 cm root crown diameter (RCD) to derive allometric relationships from measurements of RCD, maximum height, canopy area (CA), aboveground biomass (AGB), sapwood area (AS), and leaf area (AL). Total foliar mass was measured from a subset of individuals and scaled to AL from estimates of leaf mass per area. We report a strong nonlinear relationship to AGB as a function of both RCD and height, whereas CA scaled linearly. Total AS expressed a power relationship with RCD. Both AS and CA exhibited strong linear relationships with AL (R2 = 0.99), whereas RCD increased nonlinearly with AL. We improve on current models by expanding the size range of sampled trees and supplement the existing literature for this species. Study Implications: Land managers need to better understand carbon and water dynamics in changing ecosystems to understand how those ecosystems can be sustainably used now and in the future. This study of two-needle pinon (Pinus edulis Engelm.) trees in New Mexico, USA, uses observations from unoccupied aerial vehicles, field measurements, and harvesting followed by laboratory analysis to develop allometric models for this widespread species. These models can be used to understand plant traits such biomass partitioning and sap flow, which in turn will help scientists and land managers better understand the ecosystem services provided by pinon pine across North America.

Douglas-fir Tree Mortality Caused by the Douglas-fir Beetle in Thinned and Unthinned Stands in Montana, USA - Nancy Sturdevant; Laurel Haavik; José F Negrón (Forest Science, 2022)
Bark beetles are casual agents of tree mortality, often affecting landscapes with diverse topography. The Douglas-fir beetle (Dendroctonus pseudotsugae Hopkins) (DFB) uses Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco), as its primary host. Populations often increase following disturbances such as defoliation, fires, or blowdowns and then transition into live healthy trees. Mitigating tree mortality where high mortality levels are incompatible with land manager objectives is of relevance. In this study, we compared mortality levels in eighteen thinned and twelve unthinned pure Douglas-fir stands in the Helena National Forest in Montana. Managed stands were thinned during the summers of 2014 and 2015 and tree mortality evaluated in 2017 and 2018. Douglas-fir beetle populations were at endemic levels in the study area, as represented by low observed tree mortality. Even under endemic populations, 3.6% of Douglas-firs > 12 in diameter at breast height (dbh) were killed in unthinned stands compared to 1.6% in thinned stands. Basal area of trees killed in unthinned stands was 5.4 (± 2.4) ft2/ac compared with 0.5 (± 0.3) ft2/ac in thinned stands. Although insect pressure was low, this study indicates that vegetation management could be a tool to mitigate DFB-caused tree mortality. Additional studies conducted under higher insect populations are needed. Study Implications: Douglas-fir beetle (DFB) can cause extensive mortality of Douglas-fir, particularly in dense stands of large-diameter trees with a high percentage of hosts. Vegetation management through silvicultural thinnings has been proposed as a long-term strategy to mitigate tree mortality from bark beetles. In this study, we compared tree mortality caused by DFB in thinned and unthinned Douglas-fir stands. Douglas-fir beetle populations were at low levels post-thinning and mortality levels were limited. Regardless, we observed increased mortality in denser, unthinned stands compared with thinned stands with lower tree density, suggesting that stand density reductions may mitigate DFB-caused tree mortality.

Quantifying the Value of Log Sorting Based on the Location of Timber Harvest Sites Across Wisconsin - Adam Wysocki; Shuva Gautam; Baburam Rijal; Paul Doruska; Kevin Burns (Forest Science, 2022)
It is generally understood that sorting logs based on grade generates maximum value for all stakeholders. However, the benefits of sorting logs may depend on the location of a timber sale and distances to manufacturing mills. The objective is to quantify the potential value of log sorting through scenario-based analysis in different areas with divergent forest and mill types. An optimization model was developed to allocate logs from the timber sale to the highest profit-yielding mills. Factors considered by the model included logging and transportation cost, timber sale tract-to-mill distances, mills’ acceptance criteria, and price at the mill gate. Four timber sales from across Wisconsin were selected for the study. Three scenarios were tested, with each scenario yielding different proportions of log sorts. The results showed that log sorting increased profit by up to $41.10 per cord in certain locations but was not profitable in other locations. Study Implications The methods proposed in this study can help foresters and landowners increase the value of harvested timber. Practitioners can use the proposed method to systematically assess the gain or loss in profit associated with log sorting at each timber sale. It also provides directives on the best mill for each log sort to be sent. The proposed method should be adopted to minimize underutilization of timber, especially in areas where profits are marginal.

Corrigendum to: Removal of Woody Debris from Logging Gaps Influences Soil Physical and Chemical Properties in the Short Term: A Case Study in Central Amazonia - Alex de Sousa Trindade; João Baptista Silva Ferraz; Daniel DeArmond (Forest Science, 2022)

Comment on Economic Contributions from Conserved Forests: Four Case Studies of the USDA Forest Service Forest Legacy Program by Murray et al. - Samuel J Radcliffe (Forest Science, 2022)

Reply to Comment on Economic Contributions from Conserved Forests: Four Case Studies of the USDA Forest Service Forest Legacy Program - Helena Murray; Paul Catanzaro; Marla Markowski-Lindsay; Brett J Butler; Henry Eichman (Forest Science, 2022)

Growth Response of Ponderosa Pine to Intensive Cultural Treatments Varies with Site Quality and Plantation Age - Jianwei Zhang; Kaelyn A Finley; David H Young; Gary O Fiddler; Christopher Looney (Forest Science, 2022)
Long-term forest experiments provide valuable knowledge in managing forests for productivity and other ecosystem services. California’s “Garden of Eden” experiment was established to determine growth potential of Pinus ponderosa plantations in response to intensive cultural treatments. We examined the 20-year growth-response of tree volume to intensive cultural treatments consisting of combinations of herbicide on competing vegetation (H), fertilization (F), and insecticide (I). We found that both H and F treatments synergistically increased tree growth at intermediate and lower-quality sites. Growth increased by 1.5–2.1 times with F, 2.1–2.5 times with H, and 2.3–3.8 times with HF treatments versus control (range = 39.3–109.2 m3 ha−1). Across the highest productive site, H and F effects on volume seemed additive at younger ages, but largely dissipated by age 20, with volume increasing by 1.6, 1.2, and 1.6 times relative to control in F, H, and HF treatments, respectively. However, 20-year mean annual increment was 21.7 m3 ha−1 yr−1 for the F treatment, the highest volume reported for ponderosa pine in California. The results underscore how site-specific cultural treatments, especially H and F, may widely enhance plantation productivity and boost stand development. Study Implications In Mediterranean climates, competing vegetation control is essential for ponderosa pine planation establishment and early growth, especially at intermediate and poor-quality sites. At higher-productivity sites, fertilization enhances stand growth and development, although fertilization’s beneficial effects on growth do not appear until canopy closure. Precommercial thinning in herbicide and fertilization treatments will not reduce overall stand growth 10 years postthinning. Intensively managed plantations appear to have a higher maximum stand density index compared to natural stands or unmanaged plantations. Therefore, these cultural treatments can be used to rapidly reforest areas after disturbances and subsequently promote larger trees on reforested landscapes.

Landowner Willingness to Accept Monetary Compensation for Managing Forests for Ecosystem Services in the Southern United States - Ram K Adhikari; Robert K Grala; Daniel R Petrolia; Stephen C Grado; Donald L Grebner; Anusha Shrestha (Forest Science, 2022)
Distributional specifications of the willingness-to-accept function affect the accuracy of welfare estimates when the contingent valuation model includes unsure responses. By exponentiating the bid variable, we implemented an improved methodological approach to estimate four discrete choice models reflecting treatment of unsure responses. Landowners required an average compensation of $93 acre−1 year−1 to participate in a 10-year conservation program. The probability of participation was positively influenced by payment amount, concern about wildlife habitat loss, contact frequency with the Natural Resources Conservation Service, and education level. Findings will help determine regional-level budgets for various conservation scenarios facilitating an increased production of ecosystem services. Study Implications Conservation agencies can decrease landowner uncertainty that arises from limited information about conservation programs and motivate landowners to enroll in a conservation program facilitating an increased production of ecosystem services by offering adequate monetary incentives. Conservation agencies can provide similar financial compensation for conservation of bottomland hardwoods and pine stands but will most likely need to offer greater compensation for the protection of forests prone from impacts by wildfires, hurricanes, and tornadoes. Available funding should be prioritized for conservation of critical habitats and freshwater sources vulnerable to land disturbances.

Recognizing Uncertainty in Forest Planning: A Decomposition Model for Large Landscapes - Irene De Pellegrin Llorente; Howard M Hoganson; Marcella A Windmuller-Campione (Forest Science, 2022)
Multiple ecological, economic, social, and political facets influence forest-planning decisions. Decision models have been widely used in forest management planning, but most are deterministic models. However, long-term forest planning problems are surrounded by potential uncertainties. To begin to account for uncertainty surrounding growth and yield under climate change conditions, a stochastic forest planning model was developed and tested. The intent of the model is to help identify potential current forest management actions that will perform well over a range of plausible climate change scenarios (futures). The stages of the model address how uncertainty about the future might unfold, with model solutions providing immediate management actions plus detailed contingency (recourse) plans for each future. The use of specialized decomposition methods of operations research has allowed for testing the model in a detailed and large application. Results from the case study showed that planning for an average deterministic case produces a misleading solution, underestimating the potential impact of climate change. On the other hand, only planning for a worst-case scenario ignores the potential value of management opportunities under other likely futures in which harvesting benefits could be greater. Overall, results advance our understanding of recognizing forest-wide uncertainty in forest management planning models. Study Implications Stand-level decisions often have forest-wide implications. Forest planning helps coordinate management of stands to address ecological, economic, and social aspects. Decision models are often used, but most assume all the information is known. However, long-term forest planning is surrounded by potential uncertainties, such as climate change. We developed a model to identify current forest management actions that will perform well over a range of plausible climate change scenarios instead of just one. The novelty lies in how we solve the problem. Breaking it into smaller subproblems allows us to include more stand-level details while still tackling a large problem.

The Effects of Rehabilitation Treatments on Landscape Function Within a Softwood Plantation After Fire: Implications for Catchment Management - Jiyu Liu; Matthew J Colloff; David Freudenberger (Forest Science, 2022)
There is global interest in enhancing the ecosystem services provided by landscapes and catchments dominated by plantation (monoculture) forestry. Partial reversion of plantations to locally native species (reforestation) is one option. However, the ecological outcomes of this kind of plantation reversion are poorly known. The partial reforestation of a pine plantation (Pinus radiata D. Don 1836) in the Australian Capital Territory with native species following a wildfire provides a rare case study of the environmental consequences of such a reversion. We estimated changes in landscape functionality by measuring indices of water infiltration, nutrient cycling, and soil surface stability across five landscape-scale treatments after the 2003 Lower Cotter Catchment bushfire: (1) natural regeneration of a native forest burned in 2003, (2) burned pine plantation replanted to pines, (3) burned plantation replanted to native trees and shrubs, (4) burned plantation allowed to naturally regenerate, and (5) forest roads rehabilitated by planting native trees and shrubs. At 14 years after the fire, we found that the regenerating native forest had the highest indices of water infiltration, nutrient cycling, and soil surface stability. The burned pine plantation that was replanted to pines in 2005 had indices of functionality that were higher than the burned plantation areas that were either allowed to naturally regenerate to native eucalypt forest or were planted with native forest species. These two types of native forest rehabilitation treatments had only minor differences in functionality. The rehabilitated closed roads were the least functional. We found that a pine plantation at the closed canopy stage can supply regulating services of water infiltration, nutrient cycling, and soil surface stability comparable to a native forest at a similar stage postfire; however, a significant limitation of the plantation was its low ecosystem resilience. It required massive soil disturbance to replant postfire and long-term maintenance of an extensive unpaved road network. The active or passive rehabilitation of native forest is justified to improve the natural resilience to wildfire. However, this rehabilitation of a native forest following use as a pine plantation is a multidecade process in this relatively low-rainfall environment. Study Implications The 2003 Canberra bushfire destroyed the entire pine plantation at Lower Cotter Catchment, a water catchment in Australian Capital Territory, but also provided an opportunity to examine and quantify changes in ecosystem functions with different restoration treatments. Landscape Function Analysis, including three indices (water infiltration, nutrient cycling, and soil surface stability), was used in this study. Findings suggest that both native eucalyptus forests and pine plantations recovered to relatively high levels of functionality within just 15 years after the bushfire, compared with all other restoration treatments, but plantations of Pinus radiata are not resilient to wildfire from a commercial perspective. These results help to justify the controversial decision to restore the majority of the catchment with native species in 2005. However, long-term monitoring is needed to determine how long it will take for the replanted and natural regeneration treatments to approach the functionality of the native forest.

Carbon Accumulation and Partitioning Above and Belowground under Coppiced and Replanted Eucalypt Plantations - Rodinei F Pegoraro; Ivo R Silva; Ivan F Souza; Roberto F Novais; Nairam F Barros; Sebastião Fonseca (Forest Science, 2022)
The extent to which the C sink strength of eucalypt plantations can be affected by coppicing or replanting remains unclear. To address this issue, we evaluated variations in C stocks under coppiced or replanted eucalypt stands formed by clones or seedlings. For each field assessment (0 [T0], 2.5, 3.5, 4.5, 5.5 and 7.0 years [at harvest]), tree biomass, litterfall, and soil C stocks (0–120 cm depth) were determined. At harvest, debarked stemwood productivity was similar under coppice or replanting, about 50.0 Mg C ha–1. Generally, coppiced stands favored subsoil C storage (40–100 cm), whereas replanted stands favored soil C accrual in topsoil (0–20 cm), depending on the genetic material. Relative to T0, soil C increased about 2.14, 1.91, and 1.84 Mg C ha–1 yr–1 under coppice, replanting with seedlings and clones, respectively. Coarse root biomass under these stands were about 17.3, 13.4, and 9.5 Mg C ha–1, respectively, equivalent to 50% of total harvest residues. Hence, inputs from coarse roots could represent a large contribution to soil C over multiple rotations under coppiced or replanted stands. Otherwise, short-term C losses can be high where stumps and coarse roots are harvested, especially following successive coppice cycles. Study Implications: Our findings have important implications for forest managers growing eucalypt plantations aiming to maximize C accumulation. Both coppiced and replanted stands can fix up to 50 Mg C ha−1 only in debarked stemwood over 7 years, with a comparatively higher C storage in coarse roots under coppice. Despite the increasing demand for forest residues in bioenergy production, harvesting stumps and coarse roots should be avoided, especially upon replanting eucalypt stands after successive coppice cycles.

Carbon and Nitrogen Dynamics in Mexican Management Forest: Simulation of Biomass Harvesting and C and N Amendments - Maria-Cristina Ordoñez; Leopoldo Galicia; Karla Valladares-Samperio (Forest Science, 2022)
Sustainable silvicultural management requires the maintenance of long-term ecosystem processes. We used the CENTURY model to simulate the impact of wood extraction and organic amendments on aboveground biomass, carbon (C) storage, and the availability of nitrogen (N) in the two dominant silvicultural methods in Mexico: the silvicultural development method (SDM) and irregular forest management (IFM). The values of the mean absolute percentage error for the SDM and IFM were 2.1% and 3.3% for C in aboveground biomass, 5.7% and 5.0% for soil organic carbon (SOC), and 14.9% and 21.6% for N, respectively. Simulation for the SDM (1967–2068) suggested a reduction of ~7% in C in soil, microbial biomass, and litter, 9% in aboveground biomass C, and ~20% in the mineral N available. For IFM, the simulation (2009–2019) suggested a reduction of 14% in the accumulation of aboveground biomass and 13% in the mineral N available. Simulation of the adoption of management practices suggested that N mineral availability would increase by 2%–3% without drastically reducing the SOC, improving aboveground biomass production by ~7%, in each management system. Study Implications In Mexico, current silvicultural management is causing alterations in the biological and chemical processes of the soil, but the future impacts on the production of forest wood and loss of fertility cannot be estimated by direct measurements. We simulated two silvicultural management alternatives with two rotation cycles and measured the response in terms of SOC, nitrogen availability, and aboveground biomass. The model shows that improving forest residue management by adding organic amendments to the soil would counteract changes in soil microbial activity, nitrogen availability, SOC, and aboveground biomass in the future. Managers should consider this information to reorient current crop residue management to achieve the objectives and the sustainability of forest management in Mexican temperate forests.

Co-Inoculation with Beneficial Soil Microorganisms Promoted Growth and Quality of Tabebuia rosea Seedlings - María Isabel Higuita-Aguirre; Walter Osorio-Vega; Juan D León-Peláez (Forest Science, 2022)
Poor seedling quality is a major limiting factor for the success of commercial afforestation and ecological restoration in the tropics. This is commonly due to poor nutrient availability of soil-based substrates used for seedling growth. Currently, the use of biofertilizers has gained attention as a biotechnological tool to overcome plant malnutrition and enhance seedling quality from the nursery. The aim of this study was to evaluate the effects of individual and combined inoculation with selected beneficial soil microorganisms on plant growth of Tabebuia rosea (Bertol.) Bertero ex A.DC. in the nursery stage. For this purpose, individual, dual, and triple inoculations were conducted with Rhizoglomus fasciculatum (arbuscular mycorrhizal fungus: AMF), Mortierella sp. (mineral-solubilizing fungus: MSF), and Azospirillum brasilense (plant growth-promoting bacteria: PGPB). After six months, the inoculation with PGPB significantly promoted plant growth over the uninoculated control. Dual inoculation with AMF+MSF and AMF+PGPB had lower but significant effects over the control. The results showed that biofertilization is an effective alternative to promote plant growth and quality of this species in the nursery and thus to produce better plants for forestry and ecological restoration in tropical areas.

Assessing the Economic Viability of the Mechanized Removal of Understory Beech during a Shelterwood Harvest - Josh Weyrens; Rene Germain (Forest Science, 2022)
Beech bark disease is a pathogenic complex that has been spreading throughout the American beech’s range since the 1800s. A litany of negative consequences have manifested from the infestation of this disease, many of which deteriorate the ecological functions of forestland. This case study sought to analyze the cost structure for removing a recalcitrant beech understory via mechanized shelterwood harvesting. High-resolution data regarding the day-to-day operation of harvesting equipment was collected using daily production journals. Interviews were conducted with the logging company owner and maintenance supervisor to gather additional information required to calculate machine costs, overhead, job specific costs, and trucking costs. The yield from this harvest was 527 metric tonnes of sawtimber and 4,893 tonnes of clean chips. The total harvesting cost equated to $4,651/ha, with the cost attributed to removing beech at $204/ha. Despite the additional cost of beech removal, the logger generated a total profit of $5,965 and a return on investment of 7.5%, allowing us to conclude that mechanized harvesting can be a viable beech removal strategy given the forest stocking and market conditions that are in place.

Single-Step Genomic Analysis Increases the Accuracy of Within-Family Selection in a Clonally Replicated Population of Pinus taeda L. - Trevor D Walker; W Patrick Cumbie; Fikret Isik (Forest Science, 2022)
The use of genomic markers in forest tree breeding is expected to improve the response to selection, especially within family. To evaluate the potential improvements from genotyping, we analyzed a large Pinus taeda L. clonal population (1,831 cloned individuals) tested in multiple environments. Of the total, 723 clones from five full-sib families were genotyped using 10,337 single-nucleotide polymorphism markers. Single-step models with genomic and pedigree-based relationships produced similar heritability estimates. Breeding value predictions were greatly improved with inclusion of genomic relationships, even when clonal replication was abundant. The improvement was limited to genotyped individuals and attributable to accounting for the Mendelian sampling effect. Reducing clonal replication by omitting data indicated that genotyping improved breeding values similar to clonal replication. Genomic selection predictive ability (masking phenotypes) was greater for stem straightness (0.68) than for growth traits (0.41 to 0.44). Predictive ability for a new full-sibling family was poorer than when full-sibling relationships were present between model training and validation sets. Species that are difficult to propagate clonally can use genotyping to improve within-family selection. Clonal testing combined with genotyping can produce breeding value accuracies adequate to graft selections directly into deployment orchards without progeny testing.

Spatial and Temporal Patterns in Carbon and Nitrogen Inputs by Net Precipitation in Atlantic Forest, Brazil - Vanessa Alves Mantovani; Marcela de Castro Nunes Santos Terra; Carlos Rogério de Mello; André Ferreira Rodrigues; Vinicius Augusto de Oliveira; Luiz Otávio Rodrigues Pinto (Forest Science, 2022)
Understanding both carbon and nitrogen temporal and spatial inputs by rainfall in tropical forests is critical for proper forest conservation and management and might ultimately elucidate how climate change might affect nutrient dynamics in forest ecosystems. This study aimed to quantify the net precipitation contribution to the Atlantic Forest’s total carbon (C) and total nitrogen (N), identifying potential differences between these inputs regarding temporal (seasonal and monthly) and spatial scales. Rainfall samples were collected before and after interacting with the forest canopy from May 2018 to April 2019. The rainfall was enriched after crossing the forest canopy. Significant differences were found for gross rainfall and net precipitation between annual carbon (104.13 kg ha−1 and 193.18 kg ha−1) and nitrogen (16.81 kg ha−1 and 36.95 kg ha−1) inputs, respectively. Moreover, there was seasonal variability in the C and N inputs with 75% occurring in the wet season. Overall, the spatial patterns revealed that the same locations had the highest inputs regardless of the analyzed period. The forest-rainfall interactions provide constant C and N inputs, especially in the wet season, and are fundamental for the maintenance of ecological processes.

Characterizing Stand and Biomass Tables from Diameter Distribution Models: A Case Study for Mixed-Hardwood Forests in Eastern Tennessee, USA - Sheng-I Yang; Quang V Cao; David T Shoch; Trisha Johnson (Forest Science, 2022)
Accurately assessing forest structure and productivity is critical to making timely management decisions and monitoring plant communities. This study aims to evaluate the prediction accuracy of site-level stand and biomass tables from the diameter distribution models. The efficacy of the single Weibull function and two finite mixture models was compared for six species groups on three mixed-hardwood sites in eastern Tennessee, USA. To evaluate model performance, two types of stand/biomass tables were generated. The first type was constructed from all species on a given site (site-specific), whereas the second type was built for a single species from all sites (species-specific). Results indicate that both types of stand and biomass tables were consistently well quantified by the two-component mixture model in terms of goodness of fit, parsimony, and robustness. The two-component mixture model better characterized the complex, multimodal diameter distributions than the single Weibull model, which underpredicted the upper portion of the distributions. The three-component model tends to overfit the data, which results in lower prediction accuracy. Among the three models examined, the two-Weibull mixture model is suggested to construct site-level stand/biomass tables, which provides more reliable and accurate predictions to assess forest structure and product class.

Implementation of Forestry Best Management Practices and Sediment Delivery in Three Regions of North Carolina and Virginia - Brent S Hawks; M Chad Bolding; W Michael Aust; Scott M Barrett; Erik Schilling; Celeste N Horton (Forest Science, 2022)
Forestry best management practices (BMPs) were created in response to the Clean Water Act of 1972 to protect water quality from nonpoint source pollutants such as sediment. The objectives of this study were to quantify the relationship between BMP implementation and sediment delivery on 58 recently harvested sites across three physiographic regions and five forest operational features. BMP implementation rates, erosion rates, sediment delivery ratios, and sediment masses were calculated at 183 silt fences functioning as sediment traps adjacent to streams in Virginia and North Carolina. Major access system features, including stream crossings, skid trails, and haul roads, typically delivered the greatest sediment mass to streams and had the highest sediment delivery ratios on a per feature basis. When accounting for sediment mass delivered and area in each feature, harvest area accounted for approximately 70% of sediment delivered to streams for all regions. Most features had proportionally higher erosion rates than sediment masses collected at silt fences, indicating that most erosion generated by forest operations is being trapped by either harvest areas or streamside management zones. For most features and regions, as BMP implementation increased, erosion rates and the sediment masses delivered to streams decreased.

Strip Clearcutting Drives Vegetation Diversity and Composition in the Moso Bamboo Forests - Yaxiong Zheng; Shaohui Fan; Fengying Guan; Wen Xia; Shumei Wang; Xiao Xiao (Forest Science, 2022)
Strip clearcutting of Moso bamboo forests in southern China has seen increasing interest as a way of reducing harvesting costs. Previous research has shown that cutting influences the overstory structure and drives changes in the microclimate and soil properties. However, the effects of strip cutting on understory vegetation diversity and composition remain unclear. To better understand the influence of cutting on the understory vegetation, this study compares sites under natural restoration after cut and uncut sites in the Moso bamboo forest. We selected plots that were cut in 2019 (C19) and 2017 (C17), as well as unharvested plots as controls (CK). The results showed that strip clearcutting increased the understory vegetation richness and diversity, and a significant difference (A = 0.23, P = 0.001) existed in the composition of the vegetation between the three treatments. Furthermore, the decrease of soil total phosphorus and total potassium content resulted in the difference in undergrowth vegetation distribution and composition between the uncut plots and the cut plots. Our results suggest that strip clearcutting may not be harmful to biodiversity on a local scale in the Moso bamboo forest.

Plasticity as a Link Between Spatially Explicit, Distance-Independent, and Whole-Stand Forest Growth Models - Oscar García (Forest Science, 2022)
Models at various levels of resolution are commonly used for both forest management and ecological research. They all have comparative advantages and disadvantages, making desirable a better understanding of the relationships between various approaches. Accounting for crown and root morphological plasticity in the limit where equilibrium among neighbors is reached (perfect plasticity) transforms spatial models into nonspatial, distance-independent versions. The links between spatial and nonspatial models obtained through a perfect plasticity assumption are more realistic than ignoring spatial structure by a mean field approximation. This article also reviews the connection between distance-independent models and size distributions and how distributions evolve over time and relate to whole-stand descriptions. In addition, some ways in which stand-level knowledge feeds back into detailed individual-tree formulations are demonstrated. This presentation is intended to be accessible to nonspecialists.

Response of Chinese Tallow ( Triadica sebifera ) and Coexisting Natives to Competition, Shade, and Flooding - Olaniyi O Ajala; Kathryn R Kidd; Brian P Oswald; Yuhui Weng; Jeremy P Stovall (Forest Science, 2022)
A greenhouse experiment was designed to determine the interactive effect of light, flooding, and competition on the growth and performance of Chinese tallow (Triadica sebifera [L.] Roxb.) and three tree species native to the southeastern United States: water tupelo (Nyssa aquatica L.), sugarberry (Celtis occidentalis L.), and green ash (Fraxinus pennsylvanica Marshall). The experiment used a factorial design that received two treatments: light (low irradiance or high irradiance) and flood (nonflooded and flooded) regimes. In the nonflooded and high irradiance treatment, changes in the growth (ground diameter, number of leaves, and total biomass) indicated that growth metrics of tallow were highest when growing with sugarberry and water tupelo but decreased when tallow was in competition with green ash. In contrast, competition with tallow reduced the height, net photosynthetic rate, stomatal conductance, and transpiration rate of water tupelo. The results showed that tallow had lower growth metrics when in competition with green ash at no apparent decrease in the growth of green ash except for growth rate. Our results suggest that tallow may be less competitive with certain native species and underplanting may be a possible opportunity for improving the success rates of native tree species establishment in areas prone to tallow invasion.

Effect of Biochar and Manual Vegetation Control on Early Growth and Survival of Planted Jack Pine ( Pinus banksiana Lamb.) Seedlings in Northern Minnesota - Robert A Slesak; Sara G Kelso; Marcella A Windmuller-Campione (Forest Science, 2022)
Survival of planted seedlings following a regeneration harvest can be challenging and early interventions through silvicultural treatments may be required for successful stand establishment. We tested the influence of soil amendment (biochar plus compost, compost-only, or control) and vegetation control (VC; applied either initially or annually for five years using brush saws) on the growth and survival of jack pine at three sites in northern Minnesota. Application of the biochar plus compost soil amendment increased seedling survival by 30% relative to the control in the first year, but there was no significant difference in survival among soil amendment treatments after five years. Both soil amendments increased diameter growth relative to the control (14% increase with biochar plus compost, 10% increase with compost only), with most of the biochar plus compost effect attributed to the compost. Annual VC increased diameter growth by 17% relative to initial VC, but overall effects on survival and growth were generally small relative to reported effects of VC via herbicide. The limited short-term influence of biochar and manual VC on growth and survival of jack pine indicates that these practices are likely not an effective means to increase jack pine establishment, but other benefits (e.g., increased carbon storage) may become apparent with time.

Perceptions of Log Truck Weight Regulations Among Loggers and Forest Industry in Georgia, USA - Joseph L Conrad (Forest Science, 2022)
Georgia and other southern states have far lower gross vehicle weight (GVW) limits for log trucks than other US regions and other countries. Low GVW limits result in high hauling costs and truck traffic. In 2020, including tolerances, five-axle log tractor-trailers were allowed 38,102 kg (84,000 lb) GVW in Georgia. Telephone surveys of 30 loggers and 32 forest industry representatives from the state of Georgia were conducted to measure perceptions of weight regulations and assess support for alternative weights and configurations. The four alternatives included five axles, 39,916 kg (88,000 lb); six axles, 41,277 kg (91,000 lb); six axles, 45,359 kg (100,000 lb); and seven axles, 45,359 kg (100,000 lb) GVW. The majority of loggers and forest industry representatives stated that GVW limits for log trucks were too low. The average preferred GVW limits were 39,621 kg (87,350 lb) and 40,545 kg (89,387 lb) for loggers and forest industry, respectively. Loggers and forest industry supported the five-axle 39,916 kg (88,000 lb) configuration whereas many loggers opposed both 45,359 kg (100,000 lb) configurations. Loggers, forest industry, and policymakers should work to modernize weight laws to reduce hauling costs, maintain or improve safety, and protect public infrastructure.

Hunter Concerns and Intention to Hunt in Forested Areas Affected by Wildlife Disease - Abigail Meeks; Neelam C Poudyal; Lisa I Muller; Chuck Yoest (Forest Science, 2022)
Deer hunting is a major forest-based recreation activity in the US South. However, the recent discovery of chronic wasting disease (CWD) threatens deer hunting in the region. Stakeholders are interested in understanding how hunters perceive the risk and change their hunting behavior. This study found a significant change in hunters’ concerns after the first deer season since the discovery of CWD in Tennessee, USA. Results also showed that hunters’ short- and long-term intentions to hunt deer in the region were positively related to previous experience of hunting in CWD-affected areas, beliefs in the effectiveness of herd reduction to control CWD, concerns regarding potential decline in deer quality and changes in hunting regulations due to CWD, and trust in wildlife agency action. Hunters who hunt on public land and were concerned with deer and human health risk were less likely to hunt in the CWD region. These results are useful in understanding hunter behavior in response to wildlife disease and identifying variables that may help project immediate as well as long-term change in hunting demand in affected regions.

Forest Sector Dependence and Economic Well-Being in Kentucky: An Econometric Analysis - Kamana Poudel; Thomas O Ochuodho (Forest Science, 2021)
Kentucky’s forest sector plays an important role in the state’s economic development through provision of market and nonmarket goods and services as well as the employment. The forest-dependent communities are socio-economically diverse with varying poverty rate levels. An aggregate state-level analysis of the forest sector and its contribution to communities’ well-being masks regional differences in how forest sector dependence is related to the economic well-being of dependent communities. In this research, we divided Kentucky into three regions based on county poverty rates and used common indicators of forest sector dependence and economic well-being to assess this relationship at regional level. We used panel data from 2010 to 2017 and ran fixed effects regression to assess this relationship. Results show that the relationship between secondary wood manufacturing, pulp and paper dependence and per capita income was negative in high-poverty counties whereas the relationship between pulp and paper dependence and per capita income was positive in medium-poverty counties. This reflects high structural difference in economies of medium-poverty counties relative to high-poverty counties. Most of the high-poverty counties are in rural areas with limited job opportunities. Policy interventions on capacity building and workforce training in high-poverty counties is necessary for sustained forest industries in these regions.

Eucalyptus grandis Response to Calcium Fertilization in Colombia - Zach S Grover; Rachel L Cook; Marcela Zapata; J Byron Urrego; Timothy J Albaugh; Ariel Zelaya; Tomasz Ozyhar; Rafael Rubilar; David R Carter; Otávio C Campoe (Forest Science, 2021)
Calcium (Ca) is a critical plant nutrient typically applied at the time of planting in intensive Eucalyptus plantations in South America. At two sites in Colombia, we examined (1) calcium source by comparing growth after application of 100 kg ha−1 elemental Ca as lime or as pelletized highly reactive calcium fertilizer (HRCF) compared to a no application control, and (2) Ca rate by applying 0, 100, 200, and 400 kg ha−1 elemental Ca as HRCF with the addition of nitrogen, phosphorus, potassium, sulfur, and boron (NPKSB). We assessed height, diameter, and volume after 12 and 24 months. There were no growth differences from Ca source at the 100 kg ha−1 rate. We found increased volume after 24 months at the “Popayan” site with 200 and 400 kg ha−1 Ca HRCF+NPKSB treatments (112 and 113 m3 ha−1, respectively) compared to control (92 m3 ha−1), a 22% increase. In contrast, volume did not differ after 24 months at the “Darien” site, ranging from 114 m3 ha−1 in the 0 kg ha−1 Ca HRCF+NPKSB treatment to 98 m3 ha−1 in the control. Differences in response are likely due to soil characteristics, such as organic matter, emphasizing the importance of identifying site-specific nutrient deficiencies.

Collection Age and Seed Mass Influence Germination and Seedling Growth in Midwestern White Spruce Accessions - Brian M Connolly (Forest Science, 2021)
Stored tree seed collections are essential resources for seedling production and conserving unique germplasm. As stored seeds age, however, seed viability and seedling vigor can decline. This study tests how age and seed mass correspond to germination dynamics and seedling vigor in four white spruce collections from the upper midwestern United States. Using two seedling growth experiments, this study demonstrates that white spruce seeds stored for >30 years have low seed viability and slower seedling growth rates compared with seeds from more recent (≤10 years) white spruce collections. Seed mass also predicted seedling growth rate regardless of collection age, suggesting larger seeds from older collections generate faster growing seedlings.

Modelling Maximum Stem Basal Area Growth Rates of Individual Trees of Eucalyptus pilularis Smith - P W West (Forest Science, 2021)
The growth rate of a tree at any time relates to its size and the level of competition exerted by its neighbors for the resources it needs for growth. This work describes the development of a model to predict the maximum growth rate in stem basal area of Eucalyptus pilularis Smith trees in native and plantation forests of subtropical eastern Australia. It shows maximum growth rates increasing with size until the tree reaches a stem diameter at breast height of 27 cm. Thereafter, maximum growth rates decline progressively as the tree grows larger. Physiological reasons that might describe this growth pattern are discussed. The maxima are shown to be independent of tree age, stand stocking density or average tree size, and the productive capacity of the site on which the forest is growing.

Covariance Generalized Linear Models: An Approach for Quantifying Uncertainty in Tree Stem Taper Modeling - Luan Demarco Fiorentin; Wagner Hugo Bonat; Allan Libanio Pelissari; Sebastião do Amaral Machado; Saulo Jorge Téo (Forest Science, 2021)
A natural dependence among diameters measured within-tree is expected in taper data due to the hierarchical structure. The aim of this paper was to introduce the covariance generalized linear model (CGLM) framework in the context of forest biometrics for Pinus taeda stem form modeling. The CGLMs are based on marginal specification, which requires a definition of the mean and covariance components. The tree stem mean profiles were modeled by a nonlinear segmented model. The covariance matrix was built considering four strategies of linear combinations of known matrices, which expressed the variance or correlations among observations. The first strategy modeled only the variance of the diameters over the stem as a function of covariates, the second modeled correlation among observations, the third was defined based on a random walk model, the fourth was based on a structure similar to a mixed-effect model with a marginal specification, and the fourth was a traditional mixed-effect model. Mean squared error and bias showed that the approaches were similar for describing the mean profile for fitting and validation dataset. However, uncertainties expressed by confidence intervals of the relative diameters were significant and related to the matrix covariance structures of the CGLMs.

Removal of Woody Debris from Logging Gaps Influences Soil Physical and Chemical Properties in the Short Term: A Case Study in Central Amazonia - Alex de Sousa Trindade; João Baptista Silva Ferraz; Daniel DeArmond (Forest Science, 2021)
Generally, woody residues generated from logging remain on site, although recently, forest managers have been harvesting this material for energy generation. We evaluated the impact on an Oxisol’s physical and chemical properties after removal of residues (coarse woody debris, CWD) from logging-created gaps. The logging operations occurred on private timberland in the Central Amazon. Eighteen months after creation of the gaps, soil samples were taken up to 150 cm depth in each treatment: mature undisturbed forest (FOR), gaps with residues retained on site (RET), and gaps with removal of large branches greater than 10 cm in diameter that were from logging (REM). Clay content, up to 20 cm depth, was higher in RET and REM soils than in FOR soils. Soil bulk density values increased progressively from areas of FOR to RET and REM at 0–5 cm. The highest carbon and nutrient contents were observed in the 0–5 and 5–10 cm soil layers of RET. In the 10–30 cm depth, the contents of all nutrients, except phosphorus, were higher in REM soils. According to these short-term results, it is not possible to affirm categorically that the removal of CWD has a negative impact on the nutrient status of soils in gaps created by logging operations.

Influence of Neighborhood Competition on Douglas-Fir Growth Is Not Altered by Local Environmental Conditions and Climate - Klaus J Puettmann; Lisa M Ganio; David Woodruff; Bryn Morgan (Forest Science, 2021)
To evaluate impacts of competitive conditions in tree neighborhoods on growth responses as influenced by moisture availability and local environmental conditions, we sampled 102 codominant 40- to 70-year-old coastal Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) in regions with relatively high and low moisture availability. We quantified local environmental conditions (topographic position index, heat load, and soil depth), and the annual basal area increment and climate moisture deficits during two growth periods: a five-year period prior to commercial thinning and years six to 10 after thinning. In both regions and growth periods, tree growth was higher for trees growing in local neighborhoods with lower competition. The density/growth relationships differed by region and by growth period in the moist regions, but they were not influenced by climate moisture deficit. Furthermore, including topographic position index, heat load, or soil depth did not improve model support. Our results highlight the importance of managing local competition and indicate that environmental factors such as soil depth, heat load, and topography may be less likely to warrant consideration when developing thinning prescriptions. This could allow foresters to accommodate other ecosystem services when designing density management treatments, at least within typical growing conditions.

Utilization of Urea or Polymer-Coated Urea in Florida Slash Pinestraw Production - Anna Osiecka; Patrick J Minogue; Dwight K Lauer (Forest Science, 2021)
Controlled-release fertilizers may improve productivity and mitigate environmental hazards in Southern pine plantations intensively managed for pinestraw harvesting. We examined the effects of pinestraw removal and fertilization with conventional and polymer-coated urea (PCU) on foliar, needlefall, and pinestraw nutrients and yields in a North Florida slash pine (Pinus elliottii Engelm.) plantation. Raking treatments (raked or nonraked) were applied annually in February 2014–2017. Fertilization treatments (PCU at 0, 28, 56, 140, or urea at 56 kg N ha−1 year−1) were applied annually in June 2014–2016. Four years of pinestraw removal did not affect needlefall mass or foliar and needlefall nutrient concentrations. The positive fertilization rate effect on pinestraw yield, needlefall mass, foliar, needlefall, and pinestraw total Kjeldahl nitrogen (TKN) and K concentrations, and on foliar and needlefall Ca concentrations increased in magnitude with subsequent applications. TKN, total P, and K concentrations were lower in needlefall and pinestraw relative to foliage by 65%–90%, whereas Ca concentrations were higher by 120%–180%. Three PCU applications at 140 N ha−1 year−1 increased three-year cumulative pinestraw yield over the control by 19% and TKN, K, Ca, and Mg removals by 49%, 86%, 24%, and 32%, respectively. Responses to PCU did not differ from urea.

Atmospheric Warming-Associated Phenological Earliness Does Not Increase the Length of Growing Season in Himalayan Trees - G C S Negi; Pradeep Singh; S P Singh (Forest Science, 2021)
We present phenological data for two time periods (1985–1987 and 2014–2016) on major tree species (Shorea robusta, Pinus roxburghii, Myrica esculenta, Quercus leucotrichophora, Rhododendron arboreum, Quercus floribunda, and Machilus duthiei) occurring along an altitudinal gradient of 300–2,200 m asl of Himalayan forests (a data-deficient region identified by the IPCC, 2007), and show that bud break and leafing in trees has advanced at 0.20 days/year, which is associated with a significant (P < 0.001) increase in atmospheric temperature (0.038°C/year) over the years in the study area. Also, the leaf drop period has advanced correspondingly (0.40 days/year); hence, the length of season (LOS) did not increase in these trees. This finding is contrary to the report of increase in LOS due to climatic warming from temperate latitudes of the world and satellite-based studies in Himalayan region. Arguably, phenomena such as bud break and leafing may not be captured by remote sensing, which is critical for determining the impact of climate change on the forest vegetation of the eco-sensitive Himalayan region. We suggest that this phenological earliness may alter forest structure and functioning and associated ecosystem services of these forests in the long run.

Economic Contributions from Conserved Forests: Four Case Studies of the USDA Forest Service Forest Legacy Program - Helena Murray; Paul Catanzaro; Marla Markowski-Lindsay; Brett J Butler; Henry Eichman (Forest Science, 2021)
Privately-owned forests provide important environmental, economic, and cultural benefits to the general public. Resulting impacts from landownership changes and conversion of working forests to other land uses threaten these benefits. The USDA Forest Service Forest Legacy Program (FLP) permanently protects threatened private forests that are of environmental, cultural, and economic importance to the greater public while keeping land ownership and forest management at the private or local level. FLP provides grants to state agencies to purchase conservation easements on private forestlands or, less frequently, acquisition by public agencies. We employed IMPLAN’s input-output model of the 2016 economy to estimate how land protected by FLP in four regions of the United States contributes to the economy. FLP land adds tens of millions of dollars of value annually and supports thousands of jobs in the four study areas and, due to the permanent protection of these lands, they will continue to do so in perpetuity. Nonfederal partners contributed 34%–60% of total project costs, highlighting the importance of land conservation to multiple stakeholders and the ability to leverage federal resources. The permanent nature of FLP protection provides long-term security for the economic and cultural benefits these lands provide.

Heat Stress Affects the Physiological and Biochemical Quality of Dalbergia nigra Seeds in vitro - Ingridh Medeiros Simões; Julcinara Oliveira Baptista; Thuanny Lins Monteiro Rosa; Tamyris de Mello; Caroline Palacio de Araujo; Paula Aparecida Muniz de Lima; Breno Benvindo dos Anjos; João Paulo Bestete de Oliveira; Marcos Vinicius Winckler Caldeira; Wagner Campos Otoni; Rodrigo Sobreira Alexandre; José Carlos Lopes (Forest Science, 2021)
The jacaranda of Bahia (Dalbergia nigra (Vell.) Allemão ex Benth) is an endemic tree of a Brazilian neotropical biodiversity hotspot and is of great ecological and economic interest. Given the threat of extinction due to timber overexploitation and climate change, the present study aimed to analyze the physiological and biochemical quality of D. nigra seeds exposed to heat stress. The seeds were sown in a test tube containing woody plant culture medium, kept in a biochemical oxygen demand chamber at 45°C for 0, 24, 48, 72, and 96 hours, and then maintained in the same chamber at 25°C for 30 days. Physiological analyses of moisture, electrical conductivity, germination speed index, normal and abnormal seedlings, seedling length, root length, hypocotyl length, collar diameter, seedling and root dry mass, and Dickson quality index revealed a drop in germination and vigor with prolonged heat stress, dropping from 95% to 0% between 0 and 96 hours. This was accompanied by a reduction in the content of carbohydrates, lipids, and proteins. Therefore, the vigor and quality of seedlings is negatively influenced by exposure to heat stress at 45°C.

Forest Fragmentation Slows the Decomposition of Coarse Woody Debris in a Subtropical Forest - Chunsheng Wu; Chunjie Shu; Zhijian Zhang; Yanyan Li; Yi Zhang; Yuanqiu Liu (Forest Science, 2021)
Forest fragmentation is increasing rapidly around the world, and edge effects caused by fragmented forests can influence ecosystem functions and ecological processes, including coarse woody debris (CWD) decomposition. Understanding the influencing mechanisms of edge effect on CWD decomposition is needed to assess the effects of forest fragmentation on carbon cycling and storage. We measured rates of mass loss of CWD of Cinnamomum camphora (L.) Presl. and Pinus taiwanensis Hayata over two years at two distances (0−5 m versus 60 m) from a forest edge at two altitudes (215 and 1,400 m a.s.l.), in a subtropical forest. In addition, we determined the microbial community of each CWD segment and the soil beneath via phospholipid fatty acids (PLFAs). Mass loss of CWD 60 m from the forest edge was 15% greater than that at the edge (0–5 m). Mass loss was positively correlated with the abundance of microbial and fauna community and moisture content of the decaying CWD. Distance from edge explained 17.4% of the total variation of the microbial abundance in CWD. The results indicate that the reduced abundance of microbial and fauna communities and moisture content at forest edges influenced rates of decomposition of CWD. Long-term experiments with more tree species and more forest types are needed to better assess edge effects generally.

Financial Returns for Biomass on Short-Rotation Loblolly Pine Plantations in the Southeastern United States - Andrew Trlica; Rachel L Cook; Timothy J Albaugh; Rajan Parajuli; David R Carter; Rafael A Rubilar (Forest Science, 2021)
Rising demand for renewable energy has created a potential market for biomass from short-rotation pine plantations in the southeastern United States. Site preparation, competition control, fertilization, and enhanced seedling genotypes offer the landowner several variables for managing productivity, but their combined effects on financial returns are unclear. This study estimated returns from a hypothetical 10-year biomass harvest in loblolly pine plantation using field studies in the Coastal Plain of North Carolina and the Virginia Piedmont testing combinations of tree genotype, planting density, and silviculture. Although enhanced varietal genotypes could yield more biomass, open-pollinated seedlings at 1,236–1,853 trees ha−1 under operational silviculture had the greatest returns at both sites, with mean whole-tree internal rates of return of 8.3%–9.9% assuming stumpage equal to current pulpwood prices. At a 5% discount rate, break-even whole-tree stumpage at the two sites in the optimal treatments was $8.72–$9.92 Mg−1, and break-even yield was 175–177 Mg ha−1 (roughly 18 Mg ha−1 yr−1 productivity), although stumpage and yield floors were higher if only stem biomass was treated as salable. Dedicated short-rotation loblolly biomass plantations in the region are more likely to be financially attractive when site establishment and maintenance costs are minimized.

Inter-Temporal Aggregation for Spatially Explicit Optimal Harvest Scheduling under Area Restrictions - Atsushi Yoshimoto; Patrick Asante (Forest Science, 2021)
We propose a new approach to solve inter-temporal unit aggregation issues under maximum opening size requirements using two models. The first model is based on Model I formulation with static harvest treatments for harvest activities. This model identifies periodic harvest activities using a set of constraints for inter-temporal aggregation. The second model is based on Model II formulation, which uses dynamic harvest treatments and incorporates periodic harvest activities directly into the model formulation. The proposed approach contributes to the literature on spatially constrained harvest scheduling problems as it allows a pattern of unit aggregation to change across multiple harvests over time, as inter-temporal aggregation under a maximum opening size requirement over period-specific duration. The main idea of the proposed approach for inter-temporal aggregation is to use a multiple layer scheme for a set of spatial constraints, which is adapted from a maximum flow specification in a spatial forest unit network and a sequential triangle connection to create fully connected feasible clusters. By dividing the planning horizon into period-specific durations for different spatial aggregation patterns, the models can complete inter-temporal spatial aggregation over the planning horizon under a maximum opening size requirement per duration.

Genetic Variation in Frost Tolerance, Uromycladium acaciae Rust Resistance, and Growth in an Acacia mearnsii Population - Julian Moreno Chan; Fikret Isik (Forest Science, 2021)
Genetic variation in frost tolerance, resistance to the rust fungus Uromycladium acaciae, growth, stem form, and gummosis were evaluated in 110 open-pollinated families of black wattle (Acacia mearnsii De Wild). Families were tested at six frost-prone sites in northern KwaZulu-Natal and southeastern Mpumalanga, South Africa. Frost-hardy provenances were susceptible to rust disease and had poor growth. Locally grown F1 seed sources that originated from cold-hardy Australian seed sources had better growth and were tolerant to rust, but at a cost of lower frost tolerance. Considerable genetic variation was observed between families within seed sources for frost damage (hfm2 = 0.77), rust incidence (hfm2 = 0.89), and height (hfm2 = 0.80). The corresponding narrow-sense heritabilities (hi2) were 0.30, 0.80, and 0.32. Genotype-by-environment interaction levels were low for most traits. Except for a strong genetic correlation between tree height and diameter (0.90), all the pairs of traits had weak to moderate genetic correlations. Recurrent selection will be successful in improving frost tolerance and rust incidence. However, the current population comprises limited germplasm that is both tolerant to frost and resistant to rust. Thus, we recommend infusing germplasm from known cold-hardy Australian provenances into the current population to increase genetic variation for frost tolerance, rust, and growth.

Genetic Variation and the Effect of Herbicide and Fertilization Treatments on Wood Quality Traits in Loblolly Pine - Daniel Gräns; Fikret Isik; Robert C Purnell; Ilona M Peszlen; Steven E McKeand (Forest Science, 2021)
The effect of silvicultural treatments (herbicide, fertilization, herbicide + fertilization) and the interactions with genetic effects were investigated for wood quality traits in a 16-year-old loblolly pine (Pinus taeda L.) genetic test established in southwest Georgia, USA. Fertilizer and herbicide treatment combinations were applied multiple times to main plots containing 25 open-pollinated families as sub plots. Significant differences among treatments were found for all traits. Squared acoustic velocity, used as a surrogate for wood stiffness, was higher in herbicide-only plots compared with other treatments. Wood density was considerably lower in fertilization plots. A large proportion of variance observed for wood quality traits was explained by additive genetic effects, with individual-tree heritabilities ranging from 0.78 (ring 7–16 section wood density) to 0.28 (ring 2–6 section wood density). Corresponding family-mean heritability values were well over 0.86. Genotype-by-treatment interactions were nonsignificant for all traits, indicating no need to match families to silvicultural treatments. Wood quality traits had weak genetic correlations with growth and stem quality traits (stem slenderness, sweep, and branch angle) with a range of −0.33 to 0.43, suggesting that recurrent selection on growth or stem quality traits would not adversely affect wood quality in loblolly pine.

Variations in Soil Organic Carbon Stocks under Different Land-Use Categories in Subtropical Ecosystems of Kashmir - Hamayun Shaheen; Shahzad Naseer Awan; Raja Waqar Ahmed Khan; A Rehman Khalid; Waqas Ahmed; Fazan Masood Chughtai (Forest Science, 2021)
Quantification of soil organic carbon (SOC) stocks in different land uses holds vital significance because of its implications regarding carbon sequestration as the largest terrestrial carbon pool. The current study was conducted to quantify and compare SOC stocks in forest land, agricultural land, and barren land-use categories in the subtropical ecosystems of the Himalayan foothills in Kashmir. Results showed the highest SOC value in the forest soil (75 ± 11.1 Mg C ha−1) followed by agricultural soil (58 ± 7.0 Mg C ha−1) and barren land (44 ± 6.5 Mg C ha−1). SOC stocks in different land uses showed broad variations with values as high as 106 ± 11.3 Mg C ha−1 (forest soils) and as low as 14.1 ± 7.1 Mg C ha−1 (barren land). The forest SOC values responded significantly to species composition with the highest values in Pinus roxburghii Sarg. pure stands as compared with broad leaved forests. Multivariate ordination analyses revealed that the variations in SOC stocks were significantly correlated with vegetation type, altitude, and soil bulk density. The study has identified anthropogenic disturbances as a major factor deteriorating local SOC stocks and recommends immediate soil restoration efforts to enhance the ecological significance of soils as vital regional carbon sinks.

Functional Diversity and Assembly Rules of Two Deciduous Seasonal Forests in Southeastern Brazil - Ludmila Aglai Silva; Fernando Valladares; Raquel Benavides; Omar Flores; Anne Priscila Dias Gonzaga (Forest Science, 2021)
Deciduous seasonal forests (DSFs) have a peculiar floristic composition, with species capable of surviving periods of high water deficit in a year. Our goal was to demonstrate that abiotic filters lead to the assembly of two DSF communities that have high floristic dissimilarity. For this, we characterized the environment of the areas and used the community-weighted mean (CWM), functional richness (FRic) and functional dispersion (FDis) indices for regional recognition of functional patterns. The local assessment of assembly rules was carried out using null models. We found differences in the FRic and FDis between the areas, which was attributed to the different floristic influences exercised on the communities. However, in both, the typical attributes of dry formations were dominant (CWM), indicating that, on the regional scale of study, the dry season acts as a filter in the composition of species in the communities. On a local scale, stochastic dispersion was identified as the most influential mechanism in the assembly of communities. We conclude that deterministic and stochastic processes act in the assembly of the studied communities, and the proportion of each of these depends on the scale, with abiotic filtration predominating on a regional scale and stochastic dispersion events on a local scale.

Volatility Decay and Diversification Role of Timberland as the Investment Horizon Lengthens - Weiyi Zhang; Bin Mei (Forest Science, 2021)
Under the mean-variance efficiency framework, we investigate the role of timberland asset in a mixed-asset portfolio in the United States. Starting from a single period (quarterly) view, we first reveal the crucial role of serial correlation in defining an asset’s financial performance. Accordingly, we modify return, volatility, and correlation for multiyear horizons to account for the nature of long-term investments. Our results show that, although timberland is persistent in all portfolios, private-equity timberland can be substituted by other liquid assets, including public-equity timberland, as the lengthening holding period substantially reduces their volatilities. We conclude that private-equity timberland is a risk diversifier regardless of the length of the investment horizon, whereas public-equity timberland becomes a suitable diversifier only for long-term investors with high risk tolerance.

Efficacy of Clonal Propagation in Andaman Padauk ( Pterocarpus dalbergioides ): Augmenting Conservation of an Endemic Ornamental Timber Species of Andaman & Nicobar Islands, India - Iyyappan Jaisankar; R Jayakumara Varadan; S Vijayakumar; Nitiprasad Namdeorao Jambhulkar; Bosco Augustine Jerard; Nabanita Ganguly; Muthu Rajkumar; Ezekiel Manasseh Moses; Putcha Simhachalam (Forest Science, 2021)
The population of Andaman padauk (Pterocarpus dalbergioides Roxb.), an endemic ornamental timber species, is fast depleting in the Andaman Islands. Afforestation through seedlings is hindered by low germination and high mortality rates. This study attempts to assess the efficacy of clonal propagation methods to hasten mass multiplication by trying out different combinations of growth hormones, concentration, and dipping duration in semi-hardwood stem cuttings and different combinations of growth hormone concentration and substrate in air layering. Dipping the cuttings in indole-3-butyric acid (IBA) 1,500 ppm for 24 hours and spraying the modified stem-cut layers with IBA 2,000 ppm and binding with top soil and decomposed coir dust turned out to be the best treatment combination for cutting and air layering, respectively. Among the considered factors, the concentration of growth hormone is crucial for cutting, as the performance is enhanced with concentration under a given growth hormone and dipping duration. Similarly, the substrate is crucial for air layering, as modified stem-cut air layers bound with top soil and decomposed coir dust not only achieve the best performance, but also catalyze IBA for further improvement when other substrates remain unresponsive. Successful outcome of both clonal propagation techniques gives hope for disseminating the species across the tropics at global level.

Six Decades of Growth and Yield and Financial Return in a Silviculture Experiment in Northern Hardwoods - Maeve C Draper; Robert E Froese (Forest Science, 2021)
The Cutting Methods Study at the Ford Forest in the Upper Peninsula of Michigan, USA, was established in 1956 and has been maintained continuously on a 10-year cycle. Methods consist of three diameter limits (DL; 13, 30, and 41 cm), single-tree selection to three residual basal area limits (STS; 11, 16, and 21 m2ha−1), and light improvement (LI) focused on improving tree grade. Long-term results show that the 41 cm DL produced the greatest managed forest value and cumulative sawlog production, followed by the STS to 11 m2ha−1 residual basal area. STS treatments and LI were uniformly superior at improving standing tree grade. In contrast, treatments that emphasize removal of large diameter trees while retaining moderate residual basal area (the 41 cm DL and 11 m2ha−1 STS) produced the largest harvest volumes of high-grade sawlogs, driving financial performance. Stand density has declined in all treatments except the 30 and 41 cm DL, where it has increased, and these two treatments have larger abundance of saplings and poles. Alternative partial cutting methods such as selection to lower residual basal areas and medium-intensity diameter-limit cuts thus may provide greater financial returns and higher average quality, and could have implications on regeneration and long-term sustainability.

Effects of Wood Ash Application on Tree Nutrition and Soil Dynamics in a Pinus taeda System - Leonardo Packer de Quadros; Henrique Almeida Santos Ducheiko; Shizuo Maeda; Stephen Arthur Prior; Eloá Moura Araújo; João Bosco Vasconcelos Gomes; Itamar Antonio Bognola; Marcia Toffani Simão Soares; Ederlan Magri; Cleiton Frigo; Alberto Kawasaki; Antônio Carlos Vargas Motta (Forest Science, 2021)
Many Brazilian forest industries use wood biomass as a sustainable energy source that generates a wood ash by-product. This residue is typically discarded in nearby planted forests. To evaluate the effects of wood ash rates on Pinus taeda L. growth, a study was established on a high clay soil in 2006. Five rates of wood ash (0, 10, 20, 40, and 80 T ha−1) were applied to a P. taeda system. Soil chemical properties were evaluated three times at different depths. Tree growth (i.e., height, diameter at breast height, and commercial volume) and nutrition (needle elemental composition) were determined. After 11 years, litter accumulation and soil mobilization (bioturbation) were also evaluated. Ash application did not affect tree growth/yield or litter accumulation. A small reduction in soil acidity and increased bases in the upper soil layer were observed two years after ash application; this effect reached deeper layers after six years but retreated to shallower depths at 11 years. A soil amount of 14.6 m3 ha−1 year−1 was relocated closer to the soil surface due to bioturbation by edaphic fauna. The application of wood ash to forest soils appears to be an ecologically sound alternative for disposal of this industrial by-product.

Detection and Quantification of Coarse Woody Debris in Natural Forest Stands Using Airborne LiDAR - Lukas R Jarron; Nicholas C Coops; William H MacKenzie; Pamela Dykstra (Forest Science, 2021)
Coarse woody debris (CWD) is a meaningful contributor to forest carbon cycles, wildlife habitat, and biodiversity and can influence wildfire behavior. Using airborne laser scanning (ALS), we map CWD across a range of natural forest stand types in north-central British Columbia, Canada, providing forest managers with spatially detailed information on the presence and volume of ground-level woody biomass. We describe a novel methodology that isolates CWD returns from large diameter logs (>30cm) using a refined grounding algorithm, a mixture of height and pulse-based filters and linear pattern recognition, to transform ALS returns into measurable, vectorized shapes. We then assess the accuracy of CWD detection at the individual log level and predict CWD volume at the plot level. We detected 64% of CWD logs and 79% of CWD volume within our plots. Increased elevation of CWD significantly aided detection (P = 0.04), whereas advanced stages of decay hindered detection (P = 0.04). ALS-predicted CWD volume totals were compared against field-measured CWD and displayed a strong correlation (R = 0.81), allowing us to expand the methodology to map CWD over a larger region. The expanded CWD volume map compared ALS volume predictions between stands and suggests greater volume in stands with older and more heterogeneous stand structure.

Spatiotemporal Invasion Severity of Chinese Tallow ( Triadica sebifera ) and Invasibility of Forest Types in Southern US Forestlands - Sunil Nepal; W Keith Moser; Zhaofei Fan (Forest Science, 2021)
Quantifying invasion severity of nonnative invasive plant species is vital for the development of appropriate mitigation and control measures. We examined more than 23,250 Forest Inventory and Analysis (FIA) plots from the southern coastal states of the United States to develop an alternative method to classify and map the invasion severity of Chinese tallow (Triadica sebifera). Remeasured FIA plot-level data were used to examine the spatiotemporal changes in the presence probability and cover percentage of tallow. Four invasion severity classes were identified by using the product of presence probability and cover percentage. Chinese tallow invasion severity increased over time with 90 and 123 counties being classified into the highest severity class for the first and second measurement, respectively. Further, the invasibility of major forest-type groups by severity class was examined using the product of the county-level mean presence probability and mean cover percentage of Chinese tallow as a proxy of invasibility. Longleaf/slash pine (Pinus palustris/P. elliottii) forests were highly resilient to the Chinese tallow invasion. In contrast, elm/ash/cottonwood (Ulmus spp./Fraxinus spp./Populus deltoides) and oak/gum/cypress (Quercus spp./Nyssa spp./Taxodium spp.) forest-type groups were vulnerable to invasion.

Delayed Tree Mortality After Prescribed Fires in Mixed Oak Forests in Northwestern Ohio - Scott R Abella; LaRae A Sprow; Timothy A Schetter (Forest Science, 2021)
Delayed tree mortality can contribute to variability in fire effects in forests, but its prevalence is not well understood in eastern North American oak forests where a management goal is using prescribed fire to shape forest density and composition. To assess potential delayed mortality after prescribed fires, we tracked the fates of 690 trees of four species in burned and 542 trees in unburned oak forests in northwestern Ohio, USA, and modeled survival using tree diameter and bole char. Delayed mortality, occurring 3–4 growing seasons after fire and in addition to initial mortality (1–2 growing seasons after fire), varied with species and tree diameter. Compared to initial mortality, delayed mortality resulted in eleven times more small-diameter (1–13 cm) red maple (Acer rubrum) dying after fire. White oak (Quercus alba), 1–25 cm in diameter, also incurred delayed mortality (five-times increase in dead trees). Neither sassafras (Sassafras albidum) nor black oak (Quercus velutina) displayed delayed mortality. Background tree mortality in unburned sites was minimal (0.4% per year across species). Logistic regression to model canopy survival selected only stem diameter for burned red maple trees, whereas both diameter and bole char related to survival in other species. Results suggest that (1) monitoring postfire tree mortality in oak forests should extend for at least four growing seasons to detect delayed mortality in some species, and that (2) single surface fires may eventually reduce encroaching red maple in oak forests more than initial postfire years indicate.

Longleaf Pine ( Pinus palustris Mill.) Branch Pruning by Prescribed Fire - John P McGuire; John S Kush; J Morgan Varner; Dwight K Lauer; J Ryan Mitchell (Forest Science, 2021)
Efforts to restore longleaf pine (Pinus palustris Mill.) in the southeastern US require substantial artificial regeneration. Once established, important questions remain about when to introduce fire. We investigated the impact of initial planting density on tree branching and how prescribed fire might interact with tree architecture and survival. A particular focus was on how prescribed fires could “prune” lower branches. Lower density plantings (897 trees ha−1) had more and larger live lower branches than higher density plantings (2,243 trees ha−1). Fire was effective in pruning lower branches regardless of season burned, but fire in the growing season was more effective at pruning. Branches up to a height of 1.5 to 2 m were killed by fire. Fire applied in August caused greater damage with more needles scorched and/or consumed and more stem char. Prescribed fire did not impact longleaf pine tree survival. In general, fire applied to longleaf pine facilitated pruning lower branches that affect long-term wood quality, an additional argument for its utility in restoration and management of these ecosystems.

Wood Volume of Eucalyptus Clones Established Under Different Spacings in the Brazilian Cerrado - Jéssica L André; Rodrigo de S Oliveira; Carlos R Sette; Acelino C Alfenas; Edival Ângelo V Zauza; Leandro de Siqueira; Evandro Novaes (Forest Science, 2021)
Eucalyptus plantations are expanding in Brazil to meet growing demands for wood-based products, such as pulp, paper, and bioenergy. New clones and silvicultural adjustments are needed with the advance of eucalypts to new regions within Brazil. This study’s objective was to evaluate the effect of variable spacing on the development of six Eucalyptus clones cultivated in the Cerrado region of Brazil. These clones were evaluated in a systematic design, with 23 spacing treatments and five biological replicates. Spacing per tree ranged from 1.20 m2 to 21 m2. At two, four, and six years after planting, diameter at breast height (DBH) and height of all trees were measured to estimate wood volume. Regression models were fitted for each trait (DBH, height, and wood volume) and showed that DBH growth was positively affected by spacing, especially at four and six years after planting (R2 > 0.58). Consequently, estimates of individual volume per tree also had a positive relationship with spacing. Total stand volume, on the other hand, was higher under densest spacings. The GG100 clone outperformed all other clones, with higher stand wood volume, especially under the densest spacings. The CCL55 clone is a promising genotype, especially under dense plantations.

Spatial Patterns of Canopy Disturbance and Shortleaf Pine in a Mixedwood Forest - J Davis Goode; Justin L Hart; Daniel C Dey; Scott J Torreano; Stacy L Clark (Forest Science, 2021)
The spatial structure of forest ecosystems is dominated by the horizontal and vertical distribution of trees and their attributes across space. Canopy disturbance is a primary regulator of forest spatial structure. Although the importance of tree spatial pattern is widely acknowledged as it affects important ecosystem processes such as regeneration and recruitment into the overstory, quantitative reference spatial conditions to inform silvicultural systems are lacking. This is especially true for mixedwood forests, defined as those that contain hardwoods and softwoods in the canopy. We used data from a preexisting network of plots in a complex-stage mixedwood stand to investigate the influence of canopy disturbance on stand and neighborhood-scale spatial patterns. We reconstructed canopy disturbance history and linked detected stand-wide and gap-scale disturbance events to establishment and spatial patterns of shortleaf pine. The majority of shortleaf pine establishment coincided with stand-wide or gap-scale disturbance. Shortleaf pine was clustered at the stand scale but was randomly distributed at the neighborhood scale (i.e. five tree clusters), which was a legacy of the historical disturbance regime. These results may be used to improve natural disturbance-based silvicultural systems to restore and maintain mixedwood forests for enhanced resilience and provisioning of ecosystem goods and services.

Near-Infrared Spectroscopy for Discrimination of Charcoal from Eucalyptus and Native Cerrado Species—Contribution to a Database for Forestry Supervision - Silvana Nisgoski; Thaís A P Gonçalves; Júlia Sonsin-Oliveira; Adriano W Ballarin; Graciela I B Muñiz (Forest Science, 2021)
The illegal charcoal trade is an internationally well-known forest crime. In Brazil, government agents try to control it using the document of forest origin (DOF). To confirm a load’s legality, the agents must compare it with the declared content of the DOF. However, to identify charcoal is difficult even for specialists in wood anatomy. Hence, new technologies would facilitate the agents’ work. Near-infrared spectroscopy (NIR) provides a rapid and precise response to differentiate carbonized species. Considering the rich Brazilian flora, NIR studies are still underdeveloped. Our work aimed to differentiate charcoals of seven eucalypts and 10 Cerrado species based on NIR analysis and to add information to a charcoal database. Data were collected with a spectrophotometer in reflectance mode. Partial least square regression with discriminant analysis (PLS-DA) and a linear discriminant analysis (LDA) was applied to confirm the performance and potential of NIR spectra to distinguish native Cerrado species from eucalyptus species. Wavenumbers from 4,000 to 6,000 cm−1 and transversal surface presented the best results. NIR had the potential to distinguish eucalypt charcoals from Cerrado species and in comparison to reference samples. NIR is a potential tool for forestry supervision to guarantee the sustainability of the charcoal supply in Brazil and countries with similar conditions.

Marcellus Shale Gas Boom and Forestry Employment: Evidence from West Virginia - Kathryn A Gazal; Kathleen G Arano (Forest Science, 2021)
Advancement in drilling technology has increased natural gas extraction activities from the Marcellus shale deposit resulting in a shale gas boom in many regions, including West Virginia. This boom has created a significant labor demand shock to local economies experiencing the boom. A number of studies have shown that a shale gas boom directly increases employment and the income of those working in the industry. However, the boom can also have an adverse impact on other sectors through the resource movement effect and intersector labor mobility, pulling workers away from a related sector like forestry. Thus, an econometric model of employment in the forestry sector was developed to investigate the impact of the Marcellus shale gas boom in West Virginia. There is evidence of a labor movement effect with forestry employment negatively affected by the Marcellus shale boom. Specifically, the overall marginal effect of the shale boom on forestry employment is approximately 435 fewer jobs. However, the extent of the decline is slightly moderated by a higher relative wage between gas and forestry, perhaps suggesting diminishing returns and overall slack in the local labor market.

Seedling Emergence of the Tree Legume Clathrotropis brunnea Amshoff, Endemic from a Colombian Tropical Rainforest - Andrés I Prato; L Felipe Daibes; Miguel A Pabón; Alvaro A Castaño; Carolina Santos-Heredia; Claudimar S Fior (Forest Science, 2021)
Seedling emergence is the main propagation method of forest species. Thus, we aimed to evaluate emergence aspects of the tree legume Clathrotropis brunnea Amshoff (sapán or blackheart sapán), a Fabaceae of high economic value endemic to the Colombian rainforest. We characterized the biometry of legumes and seeds and assessed seedling emergence in three experiments: (1) effect of fruit color and substrate, (2) seed conservation in storage, and (3) presoaking and seed position. Our results showed that seeds of green-yellow fruits have greater length and weight and a water content of up to 53%. Seedling emergence did not differ between green-yellow and dark-brown fruits but did differ with substrate type; nearly 80% of seedlings emerged in the sand substrate (S1), but only 62% emerged in the mixed substrate (S3). Fresh sapán seeds are nondormant, showing a recalcitrant behavior in which seedling emergence decreased after storage in all tested conditions. Both seed-sowing positions allowed an emergence of >80% with a small benefit of the hilum downward, regardless of presoaking treatments. However, these differences did not affect seedling height or biomass after emergence. Our results provide basic knowledge on production of tropical seedlings, seeking species conservation, and use in restoration projects.

Growth and Wood Quality Traits in a Dipteryx alata Vog. (Fabaceae) Progeny and Provenance Test - T S Santos; K Martins; A V Aguiar; M J Baptista Filho; J R Menucelli; R F P Faria; R D Moura; J A R Machado; E L Longui (Forest Science, 2021)
Dipteryx alata Vog. presents an excellent economic potential because of its multiple uses. However, it is currently threatened as a result of the degradation of the biome in which it occurs, the Brazilian Cerrado. Therefore, our goal was to provide subsidies for future breeding and ex situ conservation programs of D. alata. We evaluated genetic variation in growth, stem form, and wood quality traits in a progeny and provenance test planted in a random complete block design. The traits were measured in 37-year-old trees. Significant effect for provenance was obtained for all evaluated traits except bifurcation, but progeny effect was significant only for acoustic wave velocity (AWV). The estimates of individual narrow sense heritability were of low magnitude for all traits except AWV (0.24 ± 0.09). Eleven groups were formed based on Mahalanobis genetic distance with 83.1% of progenies allocated to one group. Dipteryx alata has genetic variability between progenies and provenances that can be explored to obtain genetic gain, especially for AWV. We also recommend the use of multi-trait selection index to obtain gains for both growth and wood quality traits. Controlled pollination between individuals from different progeny groups would increase variability in next generation breeding.

Predicting the Location of Maple Habitat Under Warming Scenarios in Two Regions at the Northern Range in Canada - Pratiksha Jain; Siddhartha Khare; Jean-Daniel Sylvain; Patricia Raymond; Sergio Rossi (Forest Science, 2021)
Acer saccharum and Acer rubrum, two main maple species in North America, will be affected by ongoing global warming. Several studies predict a southern limit contraction but limited northward expansion of maple distribution for the future. We aimed to understand the main drivers of current maple distribution to quantify potential changes to maple habitat in this context. We identified the local conditions of maple stands and assessed the potential changes under warming scenarios. We selected two regions in Quebec, Canada, at the northern distribution of the species and applied probability distribution function and principal component analysis to identify the factors explaining the occurrence of maple compared with other forest species, croplands, and grasslands. Maple habitat was estimated under warming scenarios up to 2°C. We observed a lower density of maple stands in the north (7.76%), compared to the south (33.01%). Warming increased maple stands by 3.54 and 1.45% in the northernmost and southernmost regions, respectively, with the highest increases being estimated at the initial warming (+1.0°C). We conclude that maple of northern regions can benefit from local warming if precipitation does not become limiting. These changes could increase the potential for the regional maple industry and forest management.

A Performance Analysis of Sawmills in Oregon from 2003 to 2017 - Changyou Sun; Kate C Marcille; Jean M Daniels (Forest Science, 2021)
The number of mills and employees in Oregon’s sawmill sector has continuously declined from 2003 to 2017, but the amount of lumber produced has stabilized in recent years. In this study, the performance of individual sawmills is evaluated by applying data envelopment analysis on a unique dataset for 146 mills over four survey years of 2003, 2008, 2013, and 2017. The scale efficiency of these mills is generally high, but their overall technical efficiency is only 85%. In 2017, the most efficient mills as a group used 14% fewer employees, processed 18% more sawlogs, and produced 32% more lumber than an average mill in Oregon. Across the four survey years, productivity growth over time is small at only 0.14% per year, and most of the growth can be attributed to changes in technology. The catch-up effect by individual mills is actually negative at −0.07% per year. These findings reveal that the growth of production efficiency in Oregon’s sawmill sector has been slow, and the direction for future improvement relies on better management of operations and resources by individual mills.

Preliminary Evidence that Intraspecific Competition Increases Size of Restoration-Planted Pitch and Shortleaf Pines in a Mixed-Hardwood Clearcut in the Southern Appalachians - W Henry McNab (Forest Science, 2021)
Oak-pine (Quercus L. - Pinus L.) forest communities on low ridges in the southern Appalachian Mountains are losing diversity as mature pitch (P. rigida Mill.) and shortleaf (P. echinata Mill.) pines die and do not regenerate under a hardwood canopy. Restoration of biodiversity by planting pine seedlings is well known, but little is known regarding whether the configuration of planted seedlings affects growth and subsequent size (diameter at breast height, dbh) as trees age. The purpose of this study was to test the hypothesis that pines growing in groups of two or more trees respond with increased growth (expressed by dbh) to intraspecific competition with other pines compared to single trees subjected only to interspecific competition with surrounding hardwoods. For 13-year-old pitch and shortleaf pines, trees were larger in dbh when occurring in groups than trees occurring singly. Regression indicated that intraspecific competition accounted for 16% of the dbh variation of pitch pine and 29% for shortleaf pine. This study originated from chance observations in a small study of pine restoration. If a designed study confirms these results, resource managers could restore biodiversity with reduced site disturbance and establishment costs by planting pine seedlings in small groups rather than rows.

Evaluating Long-Term Seedling Growth Across Densities Using Nelder Plots and the Forest Vegetation Simulator (FVS) in the Black Hills, South Dakota, USA - Wade T Tinkham; Mike A Battaglia; Chad M Hoffman (Forest Science, 2021)
Small-tree development affects future stand dynamics and dictates many ecological processes within a site. Accurately representing this critical component of stand development is important for evaluating treatment alternatives from fuel hazard reduction to harvest scheduling. As with all forest growth, competition with other vegetation is known to regulate small-tree growth dynamics. This study uses three Nelder plots with 45 years of ponderosa pine growth to understand competition effects on seedling growth and evaluate the Forest Vegetation Simulator (FVS) Central Rockies (CR) variant’s ability to represent these dynamics. Removal of herbaceous competition before planting increased tree diameters by 50–135% and height by 35–75% across a planting density gradient at age 12. However, by age 45, the effect of herbaceous competition on tree size was no longer evident. Instead, trees at the lowest planting density had diameters 2.5–3 times larger than the most densely grown trees. Forest Vegetation Simulator (FVS) simulations underpredicted diameter at breast height (dbh) by 35–50% and 0–35% for 12 and 45-year-old trees, respectively. There was an underprediction bias of 15–20% for heights at age 12 and overpredictions of 5–10% at age 45. Continuous underprediction of dbh will affect the reliability of modeled fuel treatment longevity and sustainable harvest scheduling.

Third Year Survival, Growth, and Water Relations of West Gulf Coastal Plain Pines in East Texas - Jamie M Hooker; Brian P Oswald; Jeremy P Stovall; Yuhui Weng; Hans M Williams; Jason Grogan (Forest Science, 2021)
West Gulf Coastal Plain provenance loblolly (Pinus taeda L.), longleaf (Pinus palustris Mill.), shortleaf (Pinus echinata Mill.), and slash pines (Pinus elliottii Engelm.) were planted in December 2015 on three east Texas sites to compare initial growth and survival. Three years after planting, survival ranged from 26.4% to 76.4%. Damage by Texas leafcutter ants (Atta texana) caused significant mortality on one site, and feral hog (Sus scrofa) herbivory and uprooting greatly affected survival at two other sites. Tree heights were greater in loblolly and slash pine than in shortleaf and longleaf pine, whereas diameters were greater in loblolly than in slash, shortleaf, and longleaf. Height and survival rates were greater in Shelby County and were lowest in Cherokee County. Midday leaf-level water potentials were most negative for shortleaf and loblolly pines and varied across the three sites. Tree heights were significantly but weakly (R = −0.23) correlated to leaf-level water potentials.

Public Preferences for Longleaf Pine Restoration Programs in the Southeastern United States - Sydney Oluoch; Pankaj Lal; Bernabas Wolde; Andres Susaeta; Josè R Soto; Meghann Smith; Damian C Adams (Forest Science, 2021)
Longleaf pine (LLP) (Pinus palustris Mill.) is well known for its role in supporting healthy ecosystems in the southeastern (SE) United States (US). The decline of LLP forest ecosystems has led to a consensus among stakeholders that restoration efforts are needed. However, there is still a lack of robust understanding of the utilization of nonmarket ecosystem services of LLP forests. These challenges have presented major barriers to landowner acceptance of subsidized LLP restoration programs. Understanding the tradeoffs between forest ecosystem services is critical to restoring LLP in the SE US. This study employs the best-worst choice (BWC) method to assess public preferences toward hypothetical LLP restoration programs that consider ecosystem services such as recreation, timber production, carbon sequestration, water yield, and wildlife diversity. We surveyed a representative sample of n = 953 respondents from Alabama, Mississippi, Georgia, and Florida, and results showed that residents in all four states are willing to pay for LLP restoration, with the highest average willingness to pay (WTP) for forest recreation ($20.39), followed by red-cockaded woodpecker (RCW) conservation ($13.37) and carbon sequestration ($13.32). This research provides important public preference information on ecosystem services that is critical in forming sustainable LLP restoration programs.

Tree-level Growth of Four Oak Species in a Bottomland Hardwood Plantation: Implications for Silvicultural Treatments - Shaik M Hossain; Matthew G Olson; Mohammad Bataineh (Forest Science, 2021)
A 41-year-old bottomland hardwood plantation experiment located in southeastern Arkansas was revisited in 2017 to evaluate basal area increment (BAI) of four oak species [cherrybark oak (Quercus pagoda Raf.), swamp chestnut oak (Q. michauxii Nutt.), Nuttall oak (Q. texana Buckl.), and water oak (Q. nigra L.)] planted in monoculture in relation with species, spacing, thinning, and neighborhood competition. Species had a significant effect on BAI (P = 0.04), with cherrybark oak and Nuttall oak demonstrating the greatest (21.5 ± 2.5 cm2 year−1) and lowest (12.7 ± 2.9 cm2 year−1) growth rates, respectively, whereas BAI declined significantly with increasing competition (P = 0.03). However, rates of growth decline with competition did not differ between species (P > 0.05 for competition × species term), and thinning and spacing treatments had no effect on BAI (P > 0.05). We recommend that repetitive thinning, rather than a single thinning, would be appropriate to maintain a positive impact on oak growth. Managing stand density would not only provide opportunities for improving timber production, but also would enhance ecological benefits (e.g., wildlife habitat) through diversification of structure within monoculture plantations.

The Wrapper Model for Multiobjective Forest Monitoring Systems - Francis A Roesch; Todd A Schroeder (Forest Science, 2021)
Large multiobjective forest monitoring efforts such as the USDA’s Forest Inventory and Analysis Program and other National Forest Inventory (NFI) systems are usually described to the public in terms of the relationship of their sample designs to the land base of interest. Sometimes the third dimension of time is included in the description of the sample design. Additionally, there is a tendency to favor descriptions that arguably support design-based views of the used estimation systems. The accompanying justification usually relies on an assumption that design-based estimators are “objective,” whereas model-based estimators are “subjective.” This article posits that this argument misses the mark because design-based estimation begins with the assumption that a probability sample exists and that the sample observations have been obtained without error. In most large sampling efforts, it is known that violations of the sample design not only might, but will, occur. Additionally, some objectives in a multiobjective inventory require estimation of attributes of tangentially related populations. Here we unify estimation methods into an overall theoretical framework, or “wrapper” model, that allows for the recognition, acknowledgement, and accounting for nonsampling errors and imperfect sample frames into estimation systems capable of combining all observations available to analysts of these large inventory systems.

Prediction of Freeze Damage and Minimum Winter Temperature of the Seed Source of Loblolly Pine Seedlings Using Hyperspectral Imaging - Yuzhen Lu; Trevor D Walker; Juan J Acosta; Sierra Young; Piyush Pandey; Austin J Heine; Kitt G Payn (Forest Science, 2021)
The most important climatic variable influencing growth and survival of loblolly pine is the yearly average minimum winter temperature (MWT) at the seed source origin, and it is used to guide the transfer of improved seed lots throughout the species’ distribution. This study presents a novel approach for the assessment of freeze-induced damage and prediction of MWT at seed source origin of loblolly pine seedlings using hyperspectral imaging. A population comprising 98 seed lots representing a wide range of MWT at seed source origin was subjected to an artificial freeze event. The visual assessment of freeze damage and MWT were evaluated at the family level and modeled with hyperspectral image data combined with chemometric techniques. Hyperspectral scanning of the seedlings was conducted prior to the freeze event and on four occasions periodically after the freeze. A significant relationship (R2 = 0.33; p < .001) between freeze damage and MWT was observed. Prediction accuracies of freeze damage and MWT based on hyperspectral data varied among seedling portions (full-length, top, middle, and bottom portion of aboveground material) and scanning dates. Models based on the top portion were the most predictive of both freeze damage and MWT. The highest prediction accuracy of MWT [RPD (ratio of prediction to deviation) = 2.12, R2 = 0.78] was achieved using hyperspectral data obtained prior to the freeze event. Adoption of this assessment method would greatly facilitate the characterization and deployment of well-adapted loblolly pine families across the landscape.

Postharvest Bee Diversity is High but Declines Rapidly with Stand Age in Regenerating Douglas-Fir Forest - James W Rivers; Matthew G Betts (Forest Science, 2021)
Concerns about long-term pollinator declines have made assessing bee communities a priority in nonagricultural ecosystems, including managed forests. We assessed wild bee communities in Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) stands one to 15 years after clearcut harvest in western Oregon, USA, testing the hypothesis that bee diversity would be high initially and then decline with time-dependent reductions in floral resources. We captured 2,009 individual bees that represented 67 distinct species/morphospecies in 20 genera and five families. Asymptotic estimators of bee diversity representing Shannon and Simpson diversity were greater in communities during the second half of the early seral period, indicating older early seral stands were less diverse and contained more common and dominant bee species. In addition, observed species richness and bee abundance peaked at approximately three years postharvest and declined thereafter by 20% and 30% per year, respectively. Because floral resources declined in concert with reductions in bee diversity as stands aged, food appears to be a key driver of forest bee communities. Our results indicate that postharvest Douglas-fir stands supported a diversity of bees, including important crop pollinators, but their value to bees was restricted to a relatively short window at the beginning of the early seral period.

Provenance and Family Variation in Biomass Potential of Loblolly Pine in the Piedmont of North Carolina - Jessica A Maynor; Fikret Isik; Trevor D Walker; Ross W Whetten; Austin J Heine; Kitt G Payn; Steven E McKeand (Forest Science, 2021)
Considerable genetic differences in loblolly pine (Pinus taeda L.) exist for growth, stem form, and wood quality traits that influence biomass/biofuel production. By planting genetically superior trees with desirable biomass/biofuel traits, it is possible to substantially increase the amount of biomass and potential sawtimber trees produced from plantations. Ten of the fastest growing loblolly pine families from two provenances, Atlantic Coastal Plain and Piedmont, were tested for their biomass potential in North Carolina on a Piedmont site. At this northern Piedmont site at age six years, there were no provenance differences for biomass production or for trees with sawtimber potential. Variation in volume and sawtimber potential was significant at the family level. For biomass plantations, risks can be mitigated because of shorter rotation length, allowing for a higher-risk seed lot to capture greater gains in terms of volume. For a longer-rotation sawtimber stand, a more conservative family deployment strategy should be considered to maintain stem quality at the end of the rotation. Understanding the different seed source families and harvest regimes is essential to ensure profitable returns from pine plantations.

Assessing the Benefits and Economic Feasibility of Stand Improvement for Central Hardwood Forests - Yangyang Wang; Wu Ma; Lenny D Farlee; Elizabeth A Jackson; Guofan Shao; Thomas Ochuodho; Jingjing Liang; Mo Zhou (Forest Science, 2021)
Stand improvement (SI) has been widely accepted as an effective forest management tool. Yet most studies on its economic feasibility for nonindustrial private forest (NIPF) landowners are outdated and focus on the single stand level. The objective of this study was to conduct an economic assessment of SI’s effects and feasibility in hardwood stands for a case study in the White River Basin in Indiana. It is shown that SI could make these forests more productive and sustainable than the prevalent “hands-off” practice by enhancing the timber value of the residual stand (TV), generating regular timber income, and to some degree, reversing the decline in oak dominance. On average, a 25% increment in the TV could be achieved. Although costly for some NIPFs, once combined with voluntary financial incentive programs, SI could meet landowners’ demands for low-cost, high-return investment options. In particular, participation in the Environmental Quality Incentive Program could, on average, increase the net present value of timber income from thinning activities by nearly $1,600 per hectare over the course of 30 years. The spatial analysis revealed that there existed considerable spatial heterogeneity in SI benefits and impacts, suggesting that public incentive programs should be spatially targeted to achieve greater efficiency.

Effects of Sample Plot Size and Prediction Models on Diameter Distribution Recovery - Josh B Bankston; Charles O Sabatia; Krishna P Poudel (Forest Science, 2021)
Distribution of tree diameters in a stand is characterized using models that predict diameter moments and/or percentiles in conjunction with a mathematical system to recover the parameters of an assumed statistical distribution. Studies have compared Weibull diameter distribution recovery systems but arrived at different conclusions regarding the best approach for recovering a stand’s diameter distribution from predicted stand-level statistics. We assessed the effects of sample plot size and diameter moments/percentiles prediction models on the accuracy of three approaches used in recovering Weibull distribution parameters—method of moments, percentile method, and moments-percentile hybrid method. Data from five plot sizes, four of which were virtually created from existing larger plots, from unthinned loblolly pine (Pinus taeda) plantations, were used to fit moments/percentile prediction models and to evaluate the accuracy of the diameter distribution recovered using three approaches. Both plot size and prediction model form affected the accuracy of the recovery approaches as indicated by the changes in their ranking from one plot size to another for the same model form. The method of moments approach ranked best when the evaluation error index did not account for tree stumpage value, but the moments-percentile hybrid approach ranked best when stumpage value was considered.

Composition and Structure of Reproduction in Group Selection Openings after 20 Years in a Southern Appalachian Mixed-Hardwood Forest - W Henry McNab; Theodore M Oprean (Forest Science, 2021)
Following harvests by even-aged methods in mixed-hardwood forests, desirable oak (Quercus spp. L.) reproduction can be quickly overtopped by shade-intolerant pioneer species. In a long-term, operational-scale study of uneven-aged management by group selection, we inventoried 10- and 20-year-old reproduction following two harvest entries in a mature, dry-mesic southern Appalachian upland hardwood stand. Our study objectives included evaluating the species composition and structure of reproduction in relation to opening size (0.05 ha to 0.41 ha), position in openings (center or edge), uneven-aged diameter structure, and evidence supporting the delayed oak dominance hypothesis. Opening size had no effect on reproduction from either entry. After 10 years (but not 20) yellow-poplar (Liriodendron tulipifera L.) stem density and basal area were greater in opening centers; oaks were greater at edges. Position did not affect red maple (Acer rubrum L.) or other tolerant species. Diversity significantly increased between 10 and 20 years, suggesting evidence supporting the delayed oak dominance hypothesis. Early results from this study suggest that small openings can be used to regenerate desirable midtolerant and intolerant species in Appalachian mixed-hardwood stands on intermediate quality sites where uneven-aged stand structure is important for timber management and other goals such as visual appearance and early successional habitat.

Potential Recolonization Benefits of Retention Forestry Practices - Craig Loehle; Kevin A Solarik; Daniel U Greene; Laura Six; Darren J H Sleep (Forest Science, 2021)
Tree retention after forest harvest is often used to enhance biodiversity in forests that are otherwise managed using even-aged systems. It remains unclear to what extent scattered trees and residual patches (i.e., retained structures) actually facilitate recolonization of species in logged areas. For assessing recolonization benefits, it is necessary to consider both survival in retained structures postharvest and recolonization in cleared areas. We conducted a literature review to assess recolonization responses of birds, mammals, reptiles, amphibians, vascular plants, invertebrates, lichens/bryophytes, and mycorrhizal fungi. The clearest benefits of retention were for poorly dispersing plants. Seed dispersal type may be a key life-history trait relative to effectiveness of recolonization, with animal-dispersed seeds having the greatest dispersal range. We found that lichens/bryophytes are likely not dispersal limited (with possible exceptions) but are slow growing and require the development of moist microsite conditions. Significant literature gaps exist for amphibians, nonvolant invertebrates, and mycorrhizal fungi. Overall, recolonization success postharvest is taxon specific, where the benefits of implementing retention systems will depend on the region and species within that region. Species that require a long growth period (some lichens) or are poor dispersers (some herbaceous species) may benefit more from the creation of forest reserves than from retention practices.

Assessing Tree Mortality Probability in Harvested Hardwood Stands Using Long-Term Forest Inventory Data - Thomas J Brandeis; Consuelo Brandeis (Forest Science, 2021)
Partial harvesting (here defined as removal of ≤50% of preharvest volume) is the predominant silvicultural scheme applied to hardwood forest types in the eastern United States. Future stand conditions are largely reliant on trees retained after harvest, so their mortality because of harvesting activity damage should be minimized or taken into account when planning. We quantify partially harvested stand characteristics and postharvest mortality using data from 32,057 forested conditions, 366,953 trees with a diameter at breast height (dbh) ≥ 2.5 cm, of which 4,469 trees were cut and used in partially harvested stands. On average 23.3% of stand volume was selectively harvested with an additional 2.5% of volume lost to harvesting-caused mortality. Of the trees killed by logging activity in harvested stands, 90.7% were under 28 cm dbh. The likelihood of mortality was 1.31 times higher (95% CI of 1.20 to 1.44) for trees retained in stands that had undergone partial harvesting than for trees growing in unharvested stands. Commercial species had lower odds of mortality (0.88 times) in harvested stands than noncommercial species. Residual trees in harvested stands on private lands had a higher probability of mortality (1.23 times) than those on harvested public lands.

US Import Demand for Softwood Plywood: A Cointegration Approach - Noel Perceval Assogba; Daowei Zhang (Forest Science, 2021)
In this article, we present a model and estimates of US import demand for softwood plywood from Brazil, Canada, Chile, and China using a cointegration framework. We find evidence of long-run cointegration for time series variables in US import demand functions from Brazil, Canada, and China but not from Chile. The short-run own price elasticity estimates of US import demand from Brazil, Canada, Chile, and China are at –0.53, –0.80, –0.82, and –0.91, respectively. The estimates of long-run price elasticity suggest that US import demand for softwood plywood from the three countries is more sensitive to softwood plywood price change.

Forest Ownership, Management, and Water Production in Longleaf Pine Forests: A Stochastic Frontier Analysis - Andres Susaeta; Janaki Alavalapati (Forest Science, 2021)
This study employed stochastic frontier analysis to determine the effects of forest ownership and management on the technical efficiency of water production from longleaf pine forests in the southern United States. Data at the forest-plot level were obtained from the Forest Inventory Analysis, climatic models, and water supply relationships. Results showed that the provision of water was inefficient and significantly different between public and private ownership. Longleaf pine forests under public ownership were modestly more efficient (2.2%–1.5%) in the production of water than private longleaf pine forests. Forest management had a negative impact on the efficiency in water production for privately and publicly owned longleaf pine forests. If 1 hectare of longleaf pine supplied on average 5,000 cubic meters of water per year, the production of water on public and private lands would be reduced to 4,960 and 4,800 cubic meters per year, respectively, with forest management. Efficiency in water supply was found to decline over time in both types of forest ownership.

Predicting Logging Residue Volumes in Alaska - Erik C Berg; Eric A Simmons; Todd A Morgan; Stanley J Zarnoch (Forest Science, 2021)
Alaska forest managers seek information on how timber harvesting practices change the creation of postharvest woody residues. To predict residue volumes, researchers investigated how residue ratios—growing-stock residue volume per mill-delivered volume—related to readily available data on logging site and tree attributes in Alaska. Residue ratios were not related to logging site-level variables but were related to individual tree variables with predictive models. Ratios varied widely by tree species and were predicted to increase with larger stump height and larger small-end used diameters and decline exponentially with increasing diameter breast height (dbh) to approximately 25 inches. Ratios were then predicted to increase progressively in larger dbh trees. Results from this study update previous findings in other US Northwest states and can be used to produce or improve residue prediction tools for Alaska land managers.

Understanding the Resilience of Sal and Teak Forests to Climate Variability Using NDVI and EVI Time Series - Maneesh Kumar Patasaraiya; Rinku Moni Devi; Bhaskar Sinha; Jigyasa Bisaria; Sameer Saran; Rajeev Jaiswal (Forest Science, 2021)
This study attempts to understand the climatic resilience of two forest types of central India—that is, Tectona grandis (Teak) forest of Satpura Tiger Reserve and Shorea robusta (Sal) forest of Kanha Tiger Reserve—using normalized difference vegetation index (NDVI), enhanced vegetation index (EVI) extracted from MODIS, and climate variable data sets at highest spatial and temporal scales. Teak and Sal forests within the core area of the selected tiger reserves represent the least anthropogenic disturbances, and therefore, the observed changes in NDVI and EVI over the past 16 years could be analyzed in the context of climate change. The correlation analysis between climatic variables (minimum temperature, maximum temperature, mean temperature, and total annual rainfall) and forest response indicators (NDVI/EVI) at seasonal and annual scales revealed that Teak and Sal forests are more sensitive to change in past temperature as compared with rainfall. Also, the changes in NDVI and EVI of Sal forest are correlated more to minimum temperature, and that of Teak forest to maximum temperature. The analysis of sapling girth class of Sal and Teak further revealed that Sal as compared with Teak is more affected because of the changing climate variables of the recent past. The findings of the study will help manage forests more efficiently in the context of changing climate.

Avian Breeding Season Diversity and Community Composition in Camden White Gum and Slash Pine Plantations - Elizabeth J Messick; Christopher E Comer; Michael A Blazier; T Bently Wigley (Forest Science, 2021)
In the southern United States, some landowners have established plantations of eucalyptus (Eucalyptus spp.) and are managing them on short rotations (<15 years) to provide wood for fiber and other potential uses. Establishment of short-rotation woody crops dominated by nonnative species has implications for resident fauna in the United States that are largely unknown. We compared avifauna abundance, diversity, and community composition in newly established Camden white gum (Eucalyptus benthamii) plantations with slash pine (Pinus elliottii) plantations of the same age and height (one to two and six to seven years old, respectively) in southwestern Louisiana, USA. Species richness, diversity, and community composition in newly established eucalyptus plantations and six- to seven-year-old pines were similar. More birds were observed, and bird detections varied less in eucalyptus plantations. Indigo buntings (Passerina cyanea) and other shrub-associated species were detected more often in eucalyptus stands. In contrast, species that inhabit herbaceous-dominated communities, such as eastern meadowlarks (Sturnella magna), or that were associated with a dense graminoid community (e.g., Bachman’s sparrow [Peucaea aestivalis]) were detected less often in eucalyptus. Overall, breeding bird communities in eucalyptus plantations one to two years postestablishment differed little from plantations dominated by slash pine.

Overstory Retention and Stock Type Impact Survival and Growth of Underplanted Shortleaf Pine Beneath a Hardwood Canopy - David K Schnake; Scott D Roberts; John L Willis; John D Kushla; Ian A Munn (Forest Science, 2021)
This study was established to evaluate underplanting as a method of reestablishing a shortleaf pine (Pinus echinata Mill.) component to a dry upland hardwood stand in the Piedmont region of the southeastern United States. Replicated treatment plots were harvested to retain four levels (approximately 0, 3, 7, and 10 m2 of basal area per hectare) of residual overstory density. One-year-old containerized seedlings with both smaller (93.4 cm3) and larger (113.1 cm3) plugs and bareroot seedlings were underplanted beneath the residual overstory treatments. After five growing seasons, seedling survival averaged 61% and was not meaningfully affected by residual overstory density. Seedling height growth ranged from 1.42 m to 2.61 m and was inversely related to residual overstory density. Containerized seedlings with larger plugs had the highest survival (77.4%) and best height growth (2.11 m), followed by containerized seedlings with smaller plugs (64.3%, 1.76 m) and bareroot seedlings (40.2%, 1.85 m). The results of this study indicated that underplanting containerized seedlings, particularly those with higher plug volume and greater plug depth, was a suitable option for reestablishing shortleaf pine on drier, hardwood dominated upland sites in the Piedmont. However, even low levels of overstory retention suppressed seedling height growth after a few years.

Effects of Korean Pine Basal Area in Mixed Broadleaved–Korean Pine Forest Stands on Its Natural Regeneration in Northeast China - Xiaowen Ge; Jiaojun Zhu; Deliang Lu; Chunyu Zhu; Pingzhen Gao; Xiaoyan Yang (Forest Science, 2021)
Understanding the natural regeneration of Korean pine (Pinus koraiensis Sieb. et Zucc.) in mixed broadleaved–Korean pine (MBK) forests is crucial for MBK forest conservation and secondary deciduous broadleaved forest restoration. We hypothesized the ratio of Korean pine basal area (RKp) in MBK stands affected its natural regeneration. Regeneration censuses, including the height, root collar diameter, age, and growth stages (younger seedling, older seedling, smaller sapling, and taller sapling) of Korean pine, were conducted in northeast China. Results indicated the stem density and age composition of younger seedlings were positively correlated with RKp, whereas those of the saplings were negatively correlated with RKp. In the stands with lower RKp (<80% in Lesser Khingan Mountains [LKM]; <40% in Lushuihe Forestry Bureau [LFB]), individuals in all growth stages regenerated well with an age span of 65 yr. However, the regeneration of taller saplings was severely inhibited with increasing RKp (LKM: RKp ≥ 80%; LFB: RKp ≥ 40%). In summary, RKp significantly affected the natural regeneration of Korean pine in MBK forests. The basal-area thresholds limiting regeneration were found to be 80% in LKM stands and 40% in LFB stands. These basal-area thresholds provided evidence of why the zonal climax was MBK forests rather than pure Korean pine forests.

A Blind Spot in the Use of the Weibull Function for Modeling Diameter Distributions - Adrian Norman Goodwin (Forest Science, 2021)
Diameter distribution models based on probability density functions are integral to many forest growth and yield systems, where they are used to estimate product volumes within diameter classes. The three-parameter Weibull function with a constrained nonnegative lower bound is commonly used because of its flexibility and ease of fitting. This study compared Weibull and reverse Weibull functions with and without a lower bound constraint and left-hand truncation, across three large unthinned plantation cohorts in which 81% of plots had negatively skewed diameter distributions. Near-optimal lower bounds for the unconstrained Weibull function were negative for negatively skewed data, and the left-truncated Weibull using these bounds was 14.2% more accurate than the constrained Weibull, based on the Kolmogorov-Smirnov statistic. The truncated reverse Weibull fit dominant tree distributions 23.7% more accurately than the constrained Weibull, based on a mean absolute difference statistic. This work indicates that a blind spot may have developed in plantation growth modeling systems deploying constrained Weibull functions, and that left-truncation of unconstrained functions could substantially improve model accuracy for negatively skewed distributions.

Economic Depreciation of In-Woods Forestry Equipment in the US South - T Eric McConnell (Forest Science, 2021)
Forestry machines sold at auctions across the southern United States covering the years 2005 to 2019 (n = 640) were compiled into three equipment categories—rubber-tired feller bunchers, grapple skidders, and trailer-mounted loaders—with inflationary effects removed. The data were discounted by a reliability function derived from a two-parameter Weibull distribution, which defined the probability of future operability at machine hours h and a wrecking value based on each machine’s specified worth as scrap. These adjusted salvage values were then transformed using the Box-Cox normal method. Age affected all fellers and certain manufacturers of skidders and loaders. A significant annual use effect was revealed for fellers and skidders. Interactions of age and use with horsepower revealed that machine size influenced buyers’ feller and skidder purchasing decisions. Manufacturer intercept and slope shifters pointed to potential brand recognition by buyers. Perceived quality differences between manufacturers, however, were not revealed. Depreciation occurred at ever-increasing rates over machine lifetime.

A Strategic Forest Management Model for Optimizing Timber Yield and Carbon Sequestration - Marc-André Carle; Sophie D’Amours; Riadh Azouzi; Mikael Rönnqvist (Forest Science, 2021)
Strategic forest management planning models designed to maintain existing carbon stocks and maximize capacity for future sequestration can help identify underused opportunities to increase carbon stocks without diminishing other forest products. This study proposed a carbon stock unit that allows summing up the stocks in the different forest pools even if the decomposition far exceeds the planning horizon. This unit is used to integrate the methods and algorithms from the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3) model into a wood supply model. The resulting model could be used to predict changes in carbon stocks, transfers between carbon pools, and greenhouse gas emissions that would result from every forest management activity. We tailored this model to meet different strategies: maximizing carbon storage in the forest, maximizing high-sustained timber yield, and achieving the dual objectives of yield and carbon storage. A range of management scenarios were simulated using the data of a 485,000 hectares mixed-wood forest in Quebec, Canada. Our results demonstrate that, with the reduction in the harvest rates, the increase in the ecosystem carbon storage is insufficient to offset the carbon losses associated with the increase in the harvest rates.

Corrigendum to Introduction: 2017 National Silviculture Workshop: Forest Management Policy, Forest Restoration, Disturbance Resilience, Climate Adaptation (Forest Science, 2021)

Erratum to: Modeling Relations between Compacted and Uncompacted Crown Ratio for the Northern United States - James A Westfall; Megan B E Westfall; KaDonna C Randolph (Forest Science, 2021)

Corrigendum to Developing Methods for Truck Route Selection and Cost Modeling in Steeper Topographies (Forest Science, 2021)

An Empirical Evaluation of the Impact of Collaboration on the Pace and Scale of National Forest Management in Idaho - Chelsea Pennick McIver; Dennis R Becker (Forest Science, 2021)
It has been posited that US national forest administration is undergoing a governance transition characterized by an increase in the involvement and influence of non-state actors. One example of this new form of national forest governance is the use of multi-stakeholder collaborative efforts for planning and implementing projects. This has raised normative and positive questions about the value and effectiveness of such efforts and how they compare with more traditional public involvement and planning processes. This study attempts to address the latter questions by analyzing project-level planning and implementation data while comparing collaborative and traditional projects on a suite of metrics related to pace, scale, complexity, and legal outcomes. We used administrative data from the USDA Forest Service to conduct a quantitative analysis of projects over a 14-year period. We found that collaboratively developed projects were larger and more complex than traditional projects and were associated with greater planning efficiency. This analysis responds to the need to systematically assess the impact of collaborative governance and contributes to existing theories of governance, organizational learning, and policy implementation.

A Taper Equation for Loblolly Pine Using Penalized Spline Regression - Mauricio Zapata-Cuartas; Bronson P Bullock; Cristian R Montes (Forest Science, 2021)
Stem profile needs to be modeled with an accurate taper equation to produce reliable tree volume assessments. We propose a semiparametric method where few a priori functional form assumptions or parametric specification are required. We compared the diameter and volume predictions of a penalized spline regression (P-spline), P-spline extended with an additive dbh-class variable, and six alternative parametric taper equations including single, segmented, and variable-exponent equation forms. We used taper data from 147 loblolly pine (Pinus taeda L.) trees to fit the models and make comparisons. Here we show that the extended P-spline outperforms the parametric taper equations when used to predict outside bark diameter in the lower portion of the stem, up to 40% of the tree height where the more valuable wood products (62% of the total outside bark volume) are located. For volume, both P-spline models perform equal or better than the best parametric model, with taper calibration, which could result in possible savings on inventory costs by not requiring an additional measurement. Our findings suggest that assuming a priori fixed form in taper models imposes restrictions that fail to explain the tree form adequately compared with the proposed P-spline.

Genetic Parameters and Genotype-by-Environment Interactions in Regional Progeny Tests of Pinus taeda L. in the Southern USA - Edwin Lauer; Andrew Sims; Steven McKeand; Fikret Isik (Forest Science, 2021)
Genetic parameters were estimated using a five-series multienvironment trial of Pinus taeda L. in the southern USA. There were 324 half-sib families planted in five test series across 37 locations. A set of six variance/covariance matrices for the genotype-by-environment (G × E) effect for tree height and diameter were compared on the basis of model fit. In single-series analysis, extended factor analytical models provided generally superior model fit to simpler models for both traits; however, in the combined-series analysis, diameter was optimally modeled using simpler variance/covariance structures. A three-way compound term for modeling G × E interactions among and within series yielded substantial improvements in terms of model fit and standard errors of predictions. Heritability of family means ranged between 0.63 and 0.90 for both height and diameter. Average additive genetic correlations among sites were 0.70 and 0.61 for height and diameter, respectively, suggesting the presence of some G × E interaction. Pairs of sites with the lowest additive genetic correlations were located at opposite ends of the latitude range. Latent factor regression revealed a small number of parents with large factor scores that changed ranks significantly between southern and northern environments.

Development of Redwood Regeneration after Conifer Partial Harvest and Hardwood Management - John-Pascal Berrill; Lynn A Webb; Kristy L DeYoung; Christa M Dagley; Christopher G Bodle; Sean M Simpson (Forest Science, 2021)
Harvesting of commercial conifer species from conifer-hardwood mixtures can leave residual stands dominated by hardwoods. Removing unwanted hardwoods by cutting or herbicide makes growing space available to residual trees and regeneration and can restore conifer dominance. Forest managers of north coastal California need guidance on how such treatments affect subsequent growth of planted redwoods (Sequoia sempervirens [D. Don.] Endl.) or natural regeneration, as well as proliferation of undesirable species. Our observational study reconstructed growth of 108 regenerating redwoods in 26 treated stands. Residual stand density was the main driver of height and diameter growth in the new cohort of redwoods, irrespective of whether hardwoods were cut or received herbicide frill treatment (prevents resprouting). At lower residual stand densities, there were higher densities of natural regeneration (ingrowth) of conifers and hardwoods, which affected diameter at breast height (dbh) growth of regenerating redwoods. After heavier cutting of hardwoods, this ingrowth comprised a greater proportion of unwanted hardwood regeneration. Therefore, frill treatment is recommended when the objective of management is to reduce hardwood stocking and regeneration. Combining partial harvesting of conifers with cutting or frill treatment of hardwood is another option that reduces stand density to promote height and dbh growth of regenerating redwoods.

Contrasting Competitor and Predator Responses to a Short-Lived Southern Pine Beetle Outbreak: A Case Study - Stephen R Clarke; Jessica Hartshorn (Forest Science, 2021)
The southern pine beetle (SPB) Dendroctonus frontalis Zimmermann, is the most important insect pest of pines in the southeastern United States, with outbreaks often resulting in thousands of hectares of pine mortality. Natural enemies and competitors have been cited as significant regulators of SPB populations and, therefore, outbreaks. A recent outbreak on the Homochitto National Forest (NF) in Mississippi provided an opportunity to undertake a case study comparing population fluctuations of SPB, its major predator Thanasimus dubius, and its competitors, Ips bark beetles. Trap catches of all three were tracked through the course of the outbreak on the Homochitto NF as well as in two other forests with low or no SPB activity. The number of predators collected initially increased on the Homochitto NF in response to the SPB outbreak, but their impact on reducing infestation numbers was unclear. Numbers of Ips trapped were similar across all three forests, indicating that other factors were regulating SPB populations. The outbreak only lasted a single year, and its brevity likely limited the availability of host resources for natural enemy and competitor populations. Additional studies are warranted to explore the mechanisms affecting the extent and duration of SPB outbreaks, such as active forest management.

A Direct Measure of Stand Density Based on Stand Growth - Thomas J Dean; Anthony W D’Amato; Brian J Palik; Mike A Battaglia; Constance A Harrington (Forest Science, 2021)
Standardizing gross volume increment on periodic height increment of the dominant trees is a means of minimizing the effects of site quality and age in growth–growing-stock relations; however, volume increment per height increment contains more information than just a normalization method for fitting growth models. This study builds on previous work suggesting that the cumulative sum of the ratios between individual-tree volume increment and height increment may be a direct measure of stand density. We used data from several levels of growing-stock studies for Douglas-fir, ponderosa pine, and red pine to explore this hypothesis. Regression analysis indicated that the sum of the ratios is proportional to(Dqx⋅N), the underlying equation form of Reineke’s stand density index. Stem growth is a function of canopy dynamics, and additional analyses showed that volume added per unit of height growth was also related to canopy architecture, increasing with decreasing live-crown ratio and increasing foliage density. The linkages between growth, canopy architecture, intermediary canopy dynamics, and (Dqx⋅N) support the hypothesis that the sum of the tree ratios between volume increment and height increment is a direct measure of site occupancy due to its association between growth and corresponding resource use.

Improved Equations for the Density Management Diagram Isolines of Ponderosa Pine Stands - Woongsoon Jang; Martin W Ritchie; Jianwei Zhang (Forest Science, 2021)
This study was conducted to improve estimation of concomitant variables for implementation of a stand density management diagram (SDMD) for ponderosa pine (Pinus ponderosa Laws.) in northern California and Oregon. In traditional SDMD, isolines for variables such as stand volume are presented in such a way that uncertainty with estimation is not available. We developed the new top height and stand volume equations, as well as aboveground biomass and percent canopy cover, for building isolines in the SDMD using high-quality data collected from well-managed even-aged stands. The data were selected from the USDA Forest Service’s Pacific Southwest Research Station database. A total of 829 observations (from 113 plots across 15 sites in Oregon and California) were used for model construction. In addition, covariance-variance structures of all of the estimated parameters were provided so that users can evaluate the uncertainty associated with predictions. The model validation results indicated that the predictions made from fixed-effects model forms performed better than the current volume equation of SDMD, as well as those from mixed-effects model forms using the population average effect. The proposed equations provide enhanced predictions and additional useful information about managed ponderosa pine stands, including their uncertainty.

Accurate Estimation of Commercial Volume in Tropical Forests - Robson Borges de Lima; Ervan Rutishauser; José Antônio Aleixo da Silva; Marcelino Carneiro Guedes; Bruno Herault; Cinthia Pereira de Oliveira; Perseu da Silva Aparício; Eleneide Doff Sotta; Diego Armando Silva da Silva; Rinaldo Luiz Caraciolo Ferreira (Forest Science, 2021)
Accurate estimates of commercial volume in tropical forests are key for the implementation of sustainable forest management plans. Because of the lack of local or generic volumetric equations, most forest managers and forestry services are still using traditional expansion factors (i.e., multiplication of the diameter by a given value) to estimate the volume of commercial tree species in the Amazon. Volumetric models were developed through a unique data set of 1,264 fallen trees fully measured in 150 sample plots located across a broad range of forests in Amapá, Brazil. Forest-specific volumetric models were developed and compared with a generic (i.e., across all forests) model and with published equations developed elsewhere in the Amazon. The generic equation performed well in all forest types and allowed precise predictions. The most efficient sampling design to develop volumetric models consists of measuring approximately 50 trees across four different size classes representing the whole population. The form factors (FF) developed locally generated substantial bias but performed better than the traditional FF (0.7). Overall, our results suggest that it is possible to develop accurate generic models to estimate commercial timber volume, and this study can serve as a guideline for forest managers or scientists interested in calibrating volumetric models in a cost-efficient way.

Sugar Maple, Red Maple, and Yellow Birch Growth and Mortality in Even-Aged Adirondack Northern Hardwoods - Ralph D Nyland; Eddie Bevilacqua; David A Ruff; Diane H Kiernan (Forest Science, 2021)
Tree diameter growth models for northern hardwoods commonly used large data sets representing a composite of stands with varying management histories, structural characteristics, and age distributions. Yet common predictor variables like diameter can show differences in growth patterns for stands with different age structures and management histories. To address that, we modeled growth and mortality for sugar maple, red maple, and yellow birch in thinned even-aged Adirondack northern hardwoods. Findings indicate that change in diameter depends on initial diameter for sugar maple, with the rate decreasing exponentially from the largest size class to the smallest. Initial diameter did not prove significant with red maple and yellow birch in these thinned stands, perhaps because of the limited sample of trees of small diameter. Stand relative density and time since treatment affected growth for all three species. Those variables also proved significant for predicting mortality of sugar maple. Analyses revealed fewer losses of sugar and red maples among the larger diameter classes, but no relationship with diameter for yellow birch. Plot relative density did not affect mortality with red maple, but time after thinning had a significant effect on survival of all species.

Mixture of Triclopyr and Imazapyr More Effective than Triclopyr Alone for Hardwood Forest Stand Improvement - Mark A Turner; William D Gulsby; Craig A Harper (Forest Science, 2021)
Treatment of individual trees in hardwood stands typically is conducted with herbicides that have no soil activity, such as triclopyr. However, triclopyr is not effective on some tree species. Applying a mixture of triclopyr and imazapyr would broaden the spectrum of species controlled, but nontarget mortality may be problematic as imazapyr may affect other trees through soil activity. We applied herbicide via girdle-and-spray as part of a forest stand improvement treatment in four upland hardwood stands in the Upper Coastal Plain of Alabama. We compared effects of using triclopyr alone with a mixture of triclopyr and imazapyr 18 months posttreatment. Only one untreated sweetgum (Liquidambar styraciflua) out of 440 trees was killed in the stands treated with the herbicide mixture (0.5 percent nontarget mortality rate). Nontarget mortality did not differ between treatments. However, the herbicide mixture controlled hickory (Carya spp.) and sourwood (Oxydendrum arboreum) better than triclopyr alone, with 56 percent of hickory treated with triclopyr still alive 18 months later, compared with 0 percent of hickory treated with the mixture. Our results indicate a mixture of triclopyr and imazapyr provides better control than triclopyr alone, and there is minimal risk to nontarget tree species in hardwood stands when used according to label recommendations.

Model Predictions of Postwildfire Woody Fuel Succession and Fire Behavior Are Sensitive to Fuel Dynamics Parameters - Maureen C Kennedy; Morris C Johnson; Sarah C Harrison (Forest Science, 2021)
Computer models used to predict forest and fuels dynamics and wildfire behavior inform decisionmaking in contexts such as postdisturbance management. It is imperative to understand possible uncertainty in model predictions. We evaluated sensitivity of the Fire and Fuels Extension to the Forest Vegetation Simulator predictions to parameters that determine dynamics of standing dead trees (snags) and surface woody fuels. Predicted peak coarse and fine woody fuels were not sensitive to the decomposition rate of snags but were sensitive to decomposition rate of surface fuels regardless of initial snag density. Predictions of coarse woody fuel were sensitive to the snag fall rate when there was a higher initial density of snags. Fire behavior predictions were most sensitive to whether stylized fuel models or modeled fuels were used in calculations. When modeled fuels were used, fire behavior predictions were sensitive to the decomposition rate of surface fuels. Although this analysis does not inform the accuracy of model predictions, it does show where there is potential uncertainty in predictions of woody fuels succession and associated fire behavior. It is likely that any model that predicts postdisturbance fuel succession will also be sensitive to parameters that control snag dynamics and fuel decomposition.

Corrigendum to Effects of Arbuscular Mycorrhiza Fungi on the Growth Characteristics, Root Morphology, and Ion Distribution of Pyrus betulaefolia Bunge under Saline-Alkaline Stress (Forest Science, 2021)

Corrigendum to Sliding Stability of Cable-Assisted Tracked Equipment on Steep Slopes (Forest Science, 2021)

Erratum: An Agent-Based Model of Heterogeneous Forest Landowner Decision-making - Jesse D Henderson; Robert C Abt (Forest Science, 2021)

Antidumping Duty Investigations and Decisions in the Global Forest Products Industry - Xufang Zhang; Changyou Sun; Jason Gordon; Cheng Li; Ian A Munn (Forest Science, 2020)
Special tariffs have been increasingly adopted to protect domestic industries from potential injury caused by unfair international trade. In this study, a multinomial logit model is employed to examine the patterns and determinants of antidumping duty investigations in the global forest products industry. From 1995 to 2015, a total of 372 relevant cases are identified. The number of firms and the inclusion of unions as a petitioner generally improve the probability of an affirmative decision. The characteristics of petition countries have shown more impacts on the decisions than those of target countries. Developing countries have initiated a larger number of antidumping duty investigations in the global forest products industry, and furthermore, they are more inclined to adopt antidumping duties than developed countries. Countries with abundant forest resources and more forest products trade are more likely to make an affirmative decision. These findings will provide helpful information to industrial firms and government agencies in dealing with the challenges of global competition. Study Implications The findings reveal that getting more stakeholders involved in an antidumping duty investigation will increase the probability of trade intervention. The economic status in petition countries is the primary determinant of the decisions from antidumping duty investigations in the global forest products industry. Developing countries not only have initiated a large number of antidumping duty investigations in the forest products industry but also have been more inclined to adopt antidumping duties. Antidumping duty investigations offer an opportunity to countries with abundant forest resources and extensive forest products trade in case of unfair international competition.

Modeling Self-Thinning Patterns in Loblolly Pine with Provenance and Family Effects - Trevor D Walker; Bronson P Bullock; Benjamin C Smith; Steven E McKeand (Forest Science, 2020)
Size-density trajectories and self-thinning boundary lines were modeled for two diverse provenances of Pinus taeda L. and five open-pollinated families within each provenance. The data used come from a single site with replicated 64-tree block plots measured through age 25 years. The effects of provenance and family were tested using linear and nonlinear mixed-effects self-thinning models. The drought-hardy Lost Pines of Texas provenance displayed a greater predicted carrying capacity (almost 200 more trees per hectare at reference diameter 25.4 cm) and had a more abrupt approach to the self-thinning line than the widely planted Atlantic Coastal Plain provenance. However, the growth rate of the Lost Pines of Texas provenance was considerably slower and stem form was unacceptable for timber production. Families from the Atlantic Coastal Plain differed in their maximum stand density index predictions (from 1,118 to 1,282 trees per hectare at the reference diameter), suggesting there is an opportunity for artificial selection to change maximum stand density index in this breeding population of loblolly pine. A novel method for predicting the self-thinning boundary line using random effects inherent to the experimental design is presented and recommended for repeated measures data. Experimental design considerations for evaluating genetic differences in self-thinning are discussed. Study Implications Genetic improvement of growth rate in forest trees has resulted in large gains in plantation productivity, but the effect on carrying capacity has not been addressed. This study indicated that artificial selection on tolerance to competition in the widely planted Atlantic Coastal Plain provenance of loblolly pine can potentially increase harvest yield without sacrificing growth rate. The drought-hardy Lost Pines of Texas provenance displayed greater carrying capacity but had poor stem form and slow growth. The Lost Pines provenance may be attractive for aboveground carbon sequestration, since it sustained substantially more biomass because of greater maximum stand density and denser wood.

Long-Term Timber Contracts in the Southeastern United States: Updating the Primer Valuation Framework - Hector I Restrepo; Bin Mei; Bronson P Bullock (Forest Science, 2020)
Timberland ownership has drastically changed in the United States since the 1980s, driven by the divestitures of vertically integrated forest products companies. Having sold their timberland, forest products companies have exposed themselves more to the risk of raw material supply. To hedge against this risk, forest products companies usually use long-term timber contracts (LTTC). The objective of this article is to update the valuation framework for LTTCs proposed by Shaffer (1984) by including alternative option price models and refining the estimates of some key economic variables. In particular, conditional volatility from the generalized autoregressive conditional heteroscedasticity model and quasi-conditional volatility from rolling estimation windows, in addition to simple standard deviation, are used for the volatility estimates in the option pricing models. Contrary to the previous result by Shaffer (1984), our analysis suggests that LTTCs that were once profitable for forest products companies in the 1980s are no longer so under current market conditions. This is primarily because both timber price volatility and the risk-free interest rates have declined significantly. Thus, to be better off, forest products companies need to either lower the administration and management costs of those LTTCs or rely more on the open market for timber procurement. Study Implications: Forest products companies have traditionally relied on long-term timber contracts (LTTC) negotiated with forest landowners to mitigate the risk of raw material supply. The value of these LTTCs highly depends on the economic context. This research provides some insights into the valuation of LTTCs in the southeastern United States. Forest products companies can use this updated framework to aid their decisionmaking in timber procurement.

Community Classification of Piñon-Juniper Vegetation in the Four Corners Region, USA - Gennaro Falco; Kristen M Waring (Forest Science, 2020)
Piñon-juniper is one of the most common vegetation types in the Four Corners states of the western United States (Arizona, Colorado, New Mexico, and Utah). Because of its high degree of community heterogeneity across the landscape, development of a more detailed and statistically supported classification system for piñon-juniper has been requested by regional land managers. We used a USDA Forest Service Forest Inventory and Analysis (FIA) data set from the Four Corners states to develop a statistics-based classification system for piñon-juniper vegetation. Cluster analysis was used to group piñon-juniper FIA data into community classes. Classification and regression tree analysis was then used to develop a model for predicting piñon-juniper community types. To determine which variables contributed most to classifying piñon-juniper FIA data, a random forest analysis was conducted. Results from these analyses support a six-class piñon-juniper community-type model within the Four Corners states. Using the classification tree, membership of FIA piñon-juniper communities can be accurately predicted (r2 = 0.81) using only relative overstory species abundance. Our dominance-based classification system was useful in classifying piñon-juniper community types and could be used in the field to identify broad community types and complement more refined tools available for stand-scale decisionmaking. Study Implications: Piñon-juniper vegetation communities commonly occur in the Four Corners region of the United States. We used a regional data set to develop a statistically based classification system for piñon-juniper communities. We found support for a dominance-based approach supporting initial classification into six community classes. Classes were based on different overstory species dominance patterns, stand structural characteristics (stand density index, basal area [square meters per hectare], trees per hectare, and stand age), and precipitation patterns (mean annual precipitation and monsoonal index) (Table S2). Community type can be predicted using relative overstory abundance to help managers prioritize regional areas (~6,000 acres [2,428 hectares]) for management and predict responses based on precipitation patterns, current understory tree regeneration, and plant community abundance. This system could lead to better planning documents and management decisions on a regional scale to complement more refined tools available for stand-scale management such as plant associations and detailed soil maps.

Tree-Related Microhabitats: A Comparison of Managed and Unmanaged Oriental Beech–Dominated Forests in Northern Iran - Kiomars Sefidi; Carolyn A Copenheaver (Forest Science, 2020)
Tree-related microhabitats (TreMs) provide ecological niches in features for a variety of species in forests and are suitable indicators of biodiversity for certain taxa. The study objective was to compare the abundance and occurrence of TreMs in managed versus unmanaged Oriental beech (Fagus orientalis Lipsky) forests of northern Iran to quantify the effect of forest management on biodiversity indicators. We inventoried 3,954 trees to identify the number of trees with TreMs and quantify the occurrence of different types of TreMs. Managed forests averaged 25 trees with TreMs per hectare, and unmanaged forests averaged 41 trees with TreMs per hectare. In both forests, larger-diameter trees (≥50 centimeters diameter at breast height [dbh]) had more TreMs than smaller-diameter trees. TreMs were found on trees larger than a minimum size (32 centimeters dbh) and were more common on trees in poor health, as indicated by vitality class. According to our findings, managed forests have a lower diversity of TreMs than unmanaged forests. However, if management plans in deciduous forests include the retention of large-diameter trees during harvesting events, it is possible to balance providing TreMs within the forest while maintaining growth of economically valuable timber. Study Implications Forest biodiversity is time and labor intensive to quantify, and researchers have begun using tree-related microhabitats (TreMs) as a proxy for biodiversity. This study found TreMs occurred at lower abundances but had a similar occurrence of TreM groupings (cavities, injuries and wounds, deformation/growth form, and epiphytes) in managed Oriental beech (Fagus orientalis Lipsky) forests compared with unmanaged Oriental beech forests. Managed hardwood stands provided 25 TreMs per hectare, which is similar to numbers recommended for managing for biodiversity, and thus it may be possible to promote TreM creation and retention as an opportunity to increase forest biodiversity while also managing forests for timber production. Abundance of TreMs was associated with large-diameter trees and low-vitality trees (poor health). In deciduous forests managed for timber production, the retention of large-diameter trees is likely to align more closely with other management objectives than the retention of trees in poor health.

Burn Severity Effects on Sediment and Nutrient Exports from Southeastern Forests Using Simulated Rainfall - Kipling Klimas; Patrick Hiesl; Donald Hagan; Dara Park (Forest Science, 2020)
Burn severity, commonly assessed as the amount of fuel consumed during fire, is an indicator of postfire sediment yield and erosion. This study examined the effect of burn severity on sediment and nutrient response in three different fire-adapted forest types of the Southeast. Soil and litter samples were experimentally burned to achieve increasing levels of fuel consumption. Simulated rainfall was applied to burned litter samples collected from pine, hardwood, and mixed hardwood-pine forests in the Clemson Experimental Forest. Runoff and leachate samples were collected and analyzed for sediment yield (kilograms per hectare) and total suspended solids (grams per liter); both runoff and leachate samples were analyzed for ammonium (NH4–), nitrate (NO3–), and orthophosphate (PO43–). Sediment yield and total suspended solids increased at only the highest burn severity treatment in all three forest types, with pine litter samples yielding significantly greater sediment in surface runoff than both mixed and hardwood samples. Burn treatment did not readily affect soluble nutrient concentrations in either runoff or leachate, but the data suggest that high-severity burning increases the availability of PO43– bound to sediment. This study suggests that high-severity burn patches function as sediment sources, but overall sediment and nutrient response to burning was minimal. Study Implications This study suggests that low-to-moderate burn severity, in terms of litter removal, is not an important indicator of sediment and nutrient exports from southeastern forests; precipitation in the immediate aftermath of fire (<48 hours) is not an effective transport mechanism for biologically available macronutrients; and that even at the highest burn severity treatment, sediment yield was relatively low.

Estimating Forest Productivity Using Site Characteristics, Multipoint Measures, and a Nonparametric Approach - Halli Hemingway; Mark Kimsey (Forest Science, 2020)
Understanding the productivity of forestland is essential in sustainable management of forest ecosystems. The most common measure of site productivity is breast height–age site index (BHASI). BHASI has limitations as a productivity measure and can compound error in predictive models. We explored the accuracy of productivity predictions using an alternative productivity measure (10-meter site index) and a nonparametric approach. An orthogonal sampling design ensured samples were collected across the range of conditions known to influence Douglas-fir (Pseudotsuga menziesii var. glauca) height-growth rates. Using climate, soil, and topographic data along with 10-meter site index measurements, we compared five possible models to estimate forest productivity. Model parameters, performance, and predictions were compared. Twelve validation sites were used to test the accuracy of model predictions. Model performance was significantly improved when smoothing span values were optimized and elevation was added as a predictor. A four-predictor nonparametric model with a bias-corrected Akaike information criterion–optimized smoothing span value produced the most accurate results and was used to produce forest productivity maps for the study area. The low resolution of currently available climatic data and the complex nature of the study area landscape necessitate a topographic variable for accurate productivity predictions. Study Implications Defining and understanding forest productivity is of interest to a wide variety of natural resource professionals including ecologists, climate change experts, forest biometricians, and forest managers. A new method of defining forest productivity using multipoint height-age pairs at 10 and 20 meters and calculated growth rates combined with an appropriate landscape-scale stratification and a nonparametric approach provides accurate productivity estimates. This method is more widely applicable and more precise for specific locations than previous productivity estimation methods. Better productivity and tree growth information will provide more accurate estimates of future forest condition and structure.

Quality and Intensity of Light in the In Vitro Development of Microstumps of Eucalyptus urophylla in a Photoautotrophic System - Natane A Miranda; Aloisio Xavier; Wagner C Otoni; Ricardo Gallo; Kellen C Gatti; Luciana C de Moura; Denys M S C Souza; Joane H Maggioni; Suellen S de O Santos (Forest Science, 2020)
The quality and quantity of light are important factors in controlling in vitro plant growth in photoautotrophic systems. The aim of this study was to evaluate the influence of light quality (fluorescent, white, red, blue, red/blue, and distant red) on microstumps of a Eucalyptus urophylla clone in an in vitro photoautotrophic system, as well as the intensity of fluorescent light (60, 85, 100, and 140 μmol m–2 s–1) in the growth and production of microcutting. The number of shoots and microcutting, the size of the largest shoot, the stomatal density, chlorophyll, and carotenoid content were analyzed. Light quality altered plant growth, and fluorescent light intensity did not affect the microstumps’ production during the evaluation period. In white light-emitting diode (LED) light, there was higher production of carotenoids, with a lower initial production of microcuttings. A smaller number of shoots were obtained in blue LED. In general, the different qualities and light intensities tested allowed for the growth of the Eucalyptus urophylla clone grown in vitro, making it possible to obtain microcuttings under photoautotrophic cultivation. Study Implications In vitro propagation is a stressful process for plants and has limitations for commercial-scale Eucalyptus production. Fluorescent lamps, closed containers, and high sucrose concentrations are traditionally used. To reduce costs and improve production, the use of efficient light sources and photoautotrophic cultivation systems become alternatives. This study investigated the influence of light on the in vitro growth of a Eucalyptus clone in a photoautotrophic system. The quality was more important than the intensity of light. Foresters will be able to indicate the use of LEDs (light-emitting diodes) as a replacement for fluorescent lamps. This approach is useful in enhancing micropropagation techniques.

Nondestructive Tree Stem and Crown Volume Allometry in Hybrid Poplar Plantations Derived from Terrestrial Laser Scanning - Francesco Chianucci; Nicola Puletti; Mirko Grotti; Carlotta Ferrara; Achille Giorcelli; Domenico Coaloa; Clara Tattoni (Forest Science, 2020)
Accurate and frequently updated tree volume estimates are required for poplar plantations, which are characterized by fast growth rate and short rotation. In this study, we tested the potential of terrestrial laser scanning (TLS) as a reliable method for developing nondestructive tree volume allometries in poplar plantations. The trial was conducted in Italy, where 4- to 10-year-old hybrid plantations were sampled to develop tree crown volume allometry in leaf-on conditions, tree stem volume, and height-diameter allometries in leaf-off conditions. We tested one-entry models based on diameter and two-entry models based on both diameter and height. Model performance was assessed by residual analysis. Results indicate that TLS can provide accurate models of tree stem and crown volume, with percentage of root-mean-square error of about 20 percent and 15 percent, respectively. The inclusion of height does not bring relevant improvement in the models, so that only diameter can be used to predict tree stem and crown volume. The TLS-measured stem volume estimates agreed with an available formula derived from harvesting. We concluded that TLS is a reliable method for developing nondestructive volume allometries in poplar plantations and holds great potential to enhance conventional tree inventory and monitoring. Study Implications: Terrestrial laser scanning (TLS) is a technique that allows nondestructive measurement of the three-dimensional structure of a tree with high precision and low cost. The ability of TLS to measure both tree crown volume and tree position can be effective to test optimal spacing requirements and also to test innovative schemes such as mixed or polycyclic poplar plantations. The spatially explicit nature of TLS measurements allows better integration with different remotely sensed sensors, which can be used in combination with TLS, enabling a multiscale assessment of poplar plantation structure with different levels of detail, enhancing conventional tree inventory and supporting effective management strategies.

Effects of Native Tree Planting on Soil Recovery in Tropical Montane Cloud Forests - Jorge Mendoza-Vega; Victor M Ku-Quej; Ingmar Messing; Juan Carlos Pérez-Jiménez (Forest Science, 2020)
The tropical montane cloud forest is one of the most biodiverse ecosystems on Earth and is one of the areas most threatened by anthropogenic disturbance. This study assessed the temporal impact on soil properties (organic carbon, total nitrogen, cation exchange capacity, bulk density) following establishment of native tree species in two degraded tropical montane cloud forest areas with different soil types and land-use intensities in south-east Mexico. In Pueblo Nuevo, Chiapas, Pinus chiapensis and Alnus spp. were established at two sites with humic Nitisols with low and moderate disturbance levels, respectively. In Xalapa, Veracruz, plum pine (Podocarpus matudae), American hornbeam (Carpinus caroliniana), Oaxaca walnut (Juglans pyriformis Liebm.), and sweetgum (Liquidambar styraciflua) were established on a grassland-covered humic Andosol with a high level of disturbance. After 16 years, soil properties had generally improved, although in the initial years after planting, the values declined, indicating a possible negative impact because of disturbance during tree establishment. Land-use intensity prior to tree establishment influenced the level of recovery in soil properties. The Pueblo Nuevo sites, with low to moderate disturbance levels, regained soil quality faster than the highly disturbed Xalapa site, despite better initial soil quality in the latter.

Old-Field Longleaf Pine ( Pinus palustris Mill.) Long-Term Growth and Yield Response to Midrotation Fertilization - David C Clabo; E David Dickens; David J Moorhead (Forest Science, 2020)
Longleaf pine (Pinus palustris Mill.) is frequently planted on former agricultural fields throughout the southeastern United States. Limited information is available on the long-term growth and yield as well as stem quality of longleaf pine growing on these sites with and without midrotation fertilization. The objectives of this study were (1) to determine the growth rates, wood yields, and stem quality of old-field longleaf pine and (2) to quantify growth improvements provided by midrotation fertilization. Study sites were established on former agricultural fields in Screven and Tift County, Georgia in unthinned longleaf pine stands planted during December 1986. Three treatments including a control, single full dose, and split dose of nitrogen, phosphorus, and potassium were applied prior to thinning. Assessments of diameter at breast height, height growth, volume, green weight, and basal area at both sites were conducted at ages 21, 23, 27, 30, and 32. After 32 years, results indicated no statistically significant improvements of any growth parameters compared to the control in relation to midrotation fertilization treatments, and stem defects occurred in approximately 29–35 percent of trees. The fast growth rate and low nutrient demand of longleaf pine on these sites obviate the need for midrotation fertilization.

Thinning and Burning Effects on Long-Term Litter Accumulation and Function in Young Ponderosa Pine Forests - Matt Busse; Ross Gerrard (Forest Science, 2020)
We measured forest-floor accumulation in ponderosa pine forests of central Oregon and asked whether selected ecological functions of the organic layer were altered by thinning and repeated burning. Experimental treatments included three thinning methods applied in 1989 (stem only, whole tree, no thin—control) in factorial combination with prescribed burning (spring 1991 and repeated in 2002; no burn—control). Forest-floor depth and mass were measured every 4–6 years from 1991 to 2015. Without fire, there was little temporal change in depth or mass for thinned (270 trees ha−1) and control (560–615 trees ha−1) treatments, indicating balanced litterfall and decay rates across these stand densities. Each burn consumed 50–70 percent of the forest floor, yet unlike thinning, postfire accumulation rates were fairly rapid, with forest-floor depth matching preburn levels within 15–20 years. Few differences in forest-floor function (litter decay, carbon storage, physical barrier restricting plant emergence, erosion protection) resulted from thinning or burning after 25 years. An exception was the loss of approximately 300 kg N ha−1 because of repeated burning, or approximately 13 percent of the total site N. This study documents long-term forest-floor development and suggests that common silvicultural practices pose few risks to organic layer functions in these forests. Study Implications: Mechanical thinning and prescribed fire are among the most widespread management practices used to restore forests in the western US to healthy, firewise conditions. We evaluated their effects on the long-term development of litter and duff layers, which serve dual roles as essential components of soil health and as fuel for potential wildfire. Our study showed that thinning and burning provided effective fuel reduction and resulted in no adverse effects to soil quality in dry ponderosa pine forests of central Oregon. Repeated burning reduced the site carbon and nitrogen pools approximately 9–13 percent, which is small compared to C located in tree biomass and N in mineral soil. Litter accumulation after burning was rapid, and we recommend burning on at least a 15–20-year cycle to limit its build-up.

Correspondence between Breeding Values of the Same Pinus taeda L. Genotypes from Clonal Trials and Half-Sib Seedling Progeny Trials - Mohammad Nasir Shalizi; Salvador Alejandro Gezan; Steven E McKeand; Joshua R Sherrill; W Patrick Cumbie; Ross W Whetten; Fikret Isik (Forest Science, 2020)
The correspondence between breeding values of 65 loblolly pine (Pinus taeda L.) genotypes from clonal genetic tests and half-sib seedling progeny tests was studied in the southern United States. The two experiments were established separately, 10 years apart. Additive genetic variance estimates from clonal tests were larger compared with the estimates from the half-sib progeny tests, regardless of the covariance structure used in the statistical models and the traits. However, clone-mean and half-sib family-mean heritability estimates were comparable for all traits, ranging between 0.88 and 0.99. Based on the independent analysis, the correlation between the breeding values of the same genotypes from two propagule types was moderate (0.59) for tree height and stem volume. The combined analysis resulted in a strong genetic correlation (>0.93) between the breeding values of two propagule types. Herein the large discrepancy is mainly the outcome of different data analytical approaches. Conclusively, selecting genotypes for deployment based on clonal testing may not be optimal, but forest tree breeders can use the results from clonal tests to make some informed decisions.

Population and Stand-Level Inference in Forest Inventory with Penalized Splines - Steen Magnussen; Anne-Sophie Stelzer; Gerald Kändler (Forest Science, 2020)
Penalized splines have potential to decrease estimates of variance in forest inventories with a design-based population-level inference, and a model-based domain-level inference by decreasing the likelihood of a model misspecification. We provide examples with second-order (B2) B-splines and radial basis (RB) functions as extensions to a linear working model (WM). Bias was not prominent, yet greater with B2 and in particular with RB than with WM, and decreased with sample size. Important reductions in the variance of a population mean were achieved with both B2 and RB, but at the domain-level only with RB. The proposed regression estimator of variance generated estimates of variance being slightly smaller than the observed variance. A consistent and larger underestimation was seen with the popular difference estimator of variance. Study Implications: Forest inventories supported by light detection and range (LiDAR) data require—in the estimation phase—a model for linking LiDAR metrics to attributes of interest. Formulating a parametric model can be a challenge and unsatisfactory if the goodness of fit varies across the range of the attribute of interest. A semiparametric model provides more flexibility and lessens the chance of a model misspecification, albeit with the potential of overfitting. A penalty directed at reducing overfitting is required. A flexible semiparametric model is potentially also better suited for applications to small areas like stands than a parametric model. We demonstrate that important reductions in variance are indeed possible, but also that they depend on the form of the nonparametric part of the chosen model and the level of inference (population versus domains). With regard to practical application, reliable estimates of forest attributes at stand-level are of special interest within the scope of forest-management planning, as silvicultural treatments are always stand-oriented, at least with small-scale forestry under Central European conditions, and stand-related volume (basal area, tree density) belongs to the set of relevant parameters for management decisions regarding harvest and regeneration measures.

Carbon Mineralization and Inorganic Nitrogen Pools under Terminalia chebula Retz.-Based Agroforestry System in Himalayan Foothills, India - Amit Kumar; Gopal Krishna Dwivedi; Salil Tewari; Jai Paul; Rahul Anand; Narendra Kumar; Parmanand Kumar; Hukum Singh; Rajesh Kaushal (Forest Science, 2020)
Soil organic matter is major terrestrial pool for soil organic carbon (C) and nitrogen (N), and their decomposition is sensitive to vegetation and climate change. Integrated nutrient management (INM) deals with the combined application of chemical fertilizers and organic manures for nutritional requirement of crops and avoid the adverse effect of long-term application of chemical fertilizer on crop production and their sustainability. The present study was carried out to investigate the influence of different nutrient sources on soil C mineralization and inorganic N pools in a Terminalia chebula Retz, based on a agroforestry system. The results showed that the highest CO2 evolution was recorded in 100 percent INM and minimum in farmyard manure treatment after 120 days of incubation. Inorganic N was higher under the agroforestry system than under the open system. Among the different nutrient sources, the highest inorganic N was recorded in a 100 percent INM nutrient source and minimal in wheat straw treatment. The yield of turmeric was higher under the T. chebula-based agroforestry system (20.87 t ha–1) than under the open system (19.27 t ha–1). Results suggest that agroforestry systems using the INM approach can enhance C mineralization and inorganic N concentration with improved crop productivity in the Himalayan foothills. Study Implications: Fertilizer has been used since ancient times, and if well managed it can be an asset, promoting sustainable agriculture and increasing crop production, particularly for smallholder farmers in the Himalayan region of India. We compared fertilizer application practices under an agroforestry system in a representative Himalayan region of India. The majority of farmers in the region of the Himalayan foothills having marginal land and they are not able to produce optimum food grains for their requirement. However, their demands are increasing day by day, so to fulfill their demand, they have to adopt agroforestry. Agroforestry may be fulfilling their demand in terms of food, fuel, fodder, and other intangible benefits. Moreover, to increase the production under agroforestry, we have to apply organic and inorganic fertilizer in the soil either as the sole application or as a combination of these fertilizers. The application of these fertilizers will improve the productivity and fertility of land, especially carbon mineralization and inorganic nitrogen. These two soil properties are important to study because these are limiting to land productivity. In addition, efforts to improve integrated nutrient management in the Himalayan region of India would strengthen farmers’ incomes by strengthening land fertility and productivity. The rapid increase in human population over the last century is putting a massive pressure on existing resources, namely soil and water, resulting in environmental degradation in some regions around the world. As productive land becomes scarce, marginalized farmers are pushed into fragile croplands and forest lands unsuitable for modern agriculture which, in turn, is vulnerable, to degradation. If the present trend in population growth persists, pasture and forest lands will be further reduced (Satterthwaite et al. 2010). At this stage, the value of growing trees becomes more significant, and participation in tree planting schemes should be encouraged. However, this option is most feasible when combined with agriculture. As a result, agroforestry is an important management strategy that not only helps to meet the world food requirements but also helps to protect soil from degradation (Ram et al. 2017) and can enhance soil organic matter levels by adding the quantity of above- and below-ground organic matter inputs to soils (Nair et al. 2009, Marone et al. 2017).

Comparison of Volumes Estimated from Breast Height and Stump Diameters: Application to Tectona grandis Data - Onyekachi Chukwu; Friday N Ogana; Juliet U Nwatu (Forest Science, 2020)
Models estimating tree volume from stump diameter are important forest-management tools when volume estimation is needed postharvest, and dbh values are unavailable, for example the incidence of timber trespass. However, the use of stump diameter as the only independent variable for predicting tree volume has been limited. Therefore, in this article, stump diameter was used to estimate stem volume of Tectona grandis Linn. f, and this was compared with volume estimated from diameter at breast height. Five functions were considered each for the two stem diameters: simple linear, semilogarithmic, zero-intercept, power, and growth. Model assessment was based on least values of the root mean square error and Akaike information criterion. The results showed that the growth model had the best overall performance for both sets of volume models. A paired-sample t-test was used to compare volume estimated by stump diameter and volume estimated by diameter at breast height at 5 percent significance level. The results showed that there were no significant differences (P = .087) between timber volumes estimated from both stem diameters. Therefore, both diameters can be used interchangeably for modeling tree volume.

Evaluating Restoration Treatment Effectiveness through a Comparison of Residual Composition, Structure, and Spatial Pattern with Historical Reference Sites - Miles E LeFevre; Derek J Churchill; Andrew J Larson; Sean M A Jeronimo; Jamie Bass; Jerry F Franklin; Van R Kane (Forest Science, 2020)
Forest-restoration efforts are increasing in the western United States in response to realized and expected changes in climate and disturbance regimes. Managers are challenged to find practical and defensible targets to shift forest composition, structure, and spatial pattern to a more resistant and resilient state. The Northeast Washington Forest Vision 2020 project on the Colville National Forest presented an opportunity to map and use previously uncaptured mesic stand-level historical reference conditions to a large restoration project. We reconstructed historical forest conditions in 12 plots across a range of plant-association groups and mapped five restoration treatment units after implementation. We evaluated treatment effectiveness both in terms of meeting the prescriptions’ stated objectives and by similarity to observed reference conditions using metrics of density, species composition, clump-size patterns, and open-space patterns. We found that dry plant associations were historically dominated by distributed clumps of large shade-intolerant trees, whereas cold mesic plant associations were structured as a gap-matrix spatial pattern. Treatments were effective at meeting prescribed density and species-composition targets, but generally resulted in stands that were overly uniform or clumped compared to historical reference conditions.

Pollination Bag Type Has a Significant Impact on Cone Survival in Mass Production of Controlled Pollinated Seeds in Loblolly Pine - Austin J Heine; Trevor D Walker; Steven E McKeand; Jackson B Jett; Fikret Isik (Forest Science, 2020)
Since 2009, deployment of full-sib families of loblolly pine (Pinus taeda L.) has gained prominence in the southeastern United States. To produce full-sib seed, a pollination bag is used to isolate female strobili from outside pollen contamination, and a known pollen is applied at the time of maximum female strobilus receptivity. The goal of this study was to compare prototype pollination bags made by PBS International to the industry standard kraft paper pollination bag with and without a support wire for female strobili survival and to assess their efficiency for mass production of controlled cross loblolly pine seed. A multiyear study compared 13 pollination bag types at more than nine seed orchard sites across the southeastern United States. There were significant differences among bag types for conelet survival at the time of bag removal that persisted until cone harvest 18 months later. Female strobili bagged in prototype PBS-I2 were over three times more likely to survive to cone harvest than strobili inside the traditional kraft pollination bag. Two of the PBS bag types had the highest estimated filled seed per bag. One PBS bag was faster to install and remove than the kraft paper bag with a support wire.

Modeling Early Responses of Loblolly Pine Growth to Thinning in the Western Gulf Coastal Plain Region - Y H Weng; J Grogan; D W Coble (Forest Science, 2020)
Growth response to thinning has long been a research topic of interest in forest science. This study presents the first 3–4 years of response of loblolly pine (Pinus taeda L.) growth to thinning at different intensities. Data were collected from the East Texas Pine Research Project’s region-wide loblolly pine thinning study, which covers a wide variety of stand conditions. Four treatments, light, moderate, and heavy thinning, respectively having 370, 555, and 740 residual trees per hectare after thinning, and an unthinned control, were included. Individual tree diameter at breast height (dbh) and total height were recorded annually for the first 3–4 years after thinning. Results indicate significant differences between treatments in dbh growth in each year after thinning, as well as for all years combined. Each thinning treatment had significantly greater dbh growth than the control in the first growing season with this positive response being more evident in the case of the heavier thinning or at the later years post-thinning. Conversely, the thinning effect on tree height growth was initially negligibly negative, then becoming positive after 2–4 years, with the heavier thinning becoming positive sooner. Tree size class, assigned based on prethinning dbh, had a significant effect on both dbh and height growth responses. Compared to the control, small trees had a greater response both in dbh and in height growth than the medium and large trees over the measurement period. At the stand level, the heavier thinning had significantly less stand basal area per hectare, but the difference in stand basal area per hectare between the thinned and the unthinned plots decreased with years post-thinning. Results from this study can improve our understanding in thinning effects and help forest managers make accurate decisions on silvicultural regimes.

Hierarchical Effects of Tamarix aphylla Afforestation in a Sand Dune Environment on Vegetation Structure and Plant Diversity - Ofir Katz; Ilan Stavi (Forest Science, 2020)
One method of controlling dune encroachment is afforestation, which may result in biodiversity loss because of habitat change and adverse effects of trees on ecosystem functioning. We carried out a study on the effects of planting discrete areas with Tamarix aphylla (L.) Karsten trees, over 50 years ago, in a semiarid dunefield in the northern Negev, Israel. We surveyed the vegetation and sampled litter and soil in five microhabitats formed by this afforestation scheme. Afforestation had spatially and functionally hierarchical effects on vegetation and plant diversity. The strongest effect was associated with land-use change, showing reduced species richness (by 30–50 percent) and litter production following afforestation. The second strongest effect was associated with salt accumulation in T. aphylla leaves and litter, which increases soil salinity under T. aphylla canopies by 4–5, forming “salinity islands,” and leading to over 30 percent decrease in plant cover and aboveground biomass. The assumed effect of trees in blocking solar irradiance and wind was observed only outside canopies and had a weak impact on plant cover. Therefore, afforestation can increase plant diversity at the regional scale, but at the local (microhabitat) scale it has an overall adverse effect on measured ecosystem functions.

Relating Stocking and Density for Natural Regeneration of Conifers in Northern California - Martin W Ritchie (Forest Science, 2020)
Natural regeneration cannot be effectively evaluated by tree density because of spatial heterogeneity typically observed. A proper interpretation of natural regeneration will consider some evaluation of area stocked. However, stocking estimates for natural regeneration are plot-size-dependent. Stocking at the 1-milacre scale is not generally comparable to that on a 4-milacre scale unless a generalized relation with stand density can be established. A generalized relation was first suggested to hold in a paper by Lynch and Schumacher (1941), but this has not been confirmed in subsequent studies. The Lynch and Schumacher hypothesis of a generalized regeneration density-stocking relation across plot size was tested using observations on 60 stands. Results were consistent with Lynch and Schumacher (1941). With evidence of a well-defined relation for plots ranging from 1 to 10 milacres, it appears possible to approximate, for ponderosa pine and associated species, the natural regeneration stocking percentage for a range of stocking standards based solely on observations of regeneration density. Confidence intervals were derived for a range of stocking standards in English units from 1 to 10 milacre and for metric units from 0.0005 hectares to 0.0040 hectares.

Evaluation of Ground Plane Detection for Estimating Breast Height in Stereo Images - Lucas A Wells; Woodam Chung (Forest Science, 2020)
Diameter at breast height is a standard method for characterizing trees and ultimately forests over large geographical scales. Expressing the cross-section of a tree stem with a diameter measurement has inherent errors, as stems are not perfect conical frustums. Diameter suffices as an approximation, since methods for the exact cross-sectional area of a stem are infeasible in practice. There are other primary sources of error in diameter at breast height measurements: diameter measurement error and breast height measurement error. This paper addresses the latter in the context of an automated measurement system using 3D photography. We consider breast height estimation a fundamental component in such systems, as errors in measurement height can precipitate significant errors in stand-level attribute estimation as diameter changes along the height of the stem because of taper. We evaluate the efficacy of breast height estimation using stereo photogrammetry by fitting a planar surface to the ground and elevating the plane to breast height. Results from a validation test on 560 observations show that breast height can be estimated with a root mean squared error of 10.20 cm within 10 m from the camera and 13.36 cm within 20 m from the camera on flat terrain in varying levels of stem density. Study Implications Increasing the level of automation in forest operations is one approach to address workforce attrition and safety issues in the industry. Automated tree measurement and mapping systems present an opportunity to reduce operational costs by providing machine operators with necessary information to carry out silvicultural prescriptions and eliminate the need for individual tree marking in certain situations. In order to maintain trust between landowners and harvesting contractors, it is imperative that automatic measurement systems are rigorously tested to determine that measurement accuracy is within acceptable limits. Breast height measurement error is often overlooked as a source of error in estimating diameter at breast height. However, accurate breast height estimation is a necessary prerequisite for reliable, consistent, and precise diameter at breast height measurement. The capacity of machine vision systems to automate forest inventory and monitoring tasks is increasing and can help managers achieve sustainable forestry objectives on more acres in less time.

Spatio-Temporal Modeling and Competition Dynamics in Forest Tillage Experiments on Early Growth of Eucalyptus grandis L. - Pablo González Barrios; Alejandra Borges; José Terra; Mario Pérez Bidegain; Lucía Gutiérrez (Forest Science, 2020)
Forest tillage experiments regularly use long-term evaluations of large plots creating temporal and/or spatial correlations among observations. Not modeling these correlations could compromise treatment comparisons. The aim of this study was to evaluate the effect of modeling spatio-temporal (ST) variability in forest tillage experiments. We used different strategies that incorporate spatial and/or temporal correlations in the evaluation of tillage intensity effect in initial Eucalyptus growth as well as evaluate the effect of intraplot mortality and competition dynamics. Three tillage intensities in two contrasting soil conditions were compared for tree height and wood volume. Additionally, we compared the use of three individual growth curves for plant height to evaluate the time needed to reach 2 m in height (T2m). We modeled the spatial correlation of T2m using mixed models. In both sites, ST models were superior for plant height and wood volume per hectare, whereas for individual-tree wood volume, temporal models were superior. Pit planting always had a lower performance than disk harrowing and subsoiler, which behaved similarly. The competition dynamics within the plot because of tree mortality was affected by treatments and site. Modeling ST variability is key to improving treatment comparisons in forest experiments.

Estimating Price Dynamics in the Aftermath of Forest Disturbances: The Biscuit Fire in Southwest Oregon - Jun Zhai; Olli-Pekka Kuusela (Forest Science, 2020)
Catastrophic forest disturbances, such as wildfires, insect outbreaks, and hurricanes, have become more frequent in recent decades. Such disturbances can create supply disruptions in regional timber markets, with potentially significant short-run and long-run price effects. We review the time-series intervention models that have been used to analyze the impacts of forest disturbances. We apply the intervention models to investigate the market effects of the Biscuit Fire that burned nearly 500,000 acres (202,000 hectares) of forest land in southwest Oregon in 2002, thus creating an unexpected supply shock in the regional timber markets. Most of the burned area was located on federal lands. Although almost two billion board feet were available for harvesting by some estimates, the salvage logging on public lands after the Biscuit Fire amounted to 60 million board feet by the end of 2005. We use a univariate and reduced-form model to estimate the effect of the Biscuit Fire on regional Douglas-fir log markets. We find that the fire did not cause immediate price effects; however, we detect positive effects during the salvage logging period in some of the markets, whereas a negative long-run effect has persisted since the salvage logging period was completed.

Corrigendum to: The Systems Analysis in Forest Resources Sponsored Content (Forest Science, 2020)

The 17th Symposium on Systems Analysis in Forest Resources: An Introduction and Synthesis - Sándor F Tóth (Forest Science, 2020)
The 17th Symposium on Systems Analysis in Forest Resources was held in Suquamish, Washington, United States on August 27–30, 2017. The goal of this international meeting was to bring together operations researchers, remote sensing scientists, and the government to facilitate the exchange and implementation of systems science in forestry and conservation. The essay that follows is a summary of the outcome of the Symposium, as well as an introduction to the eight research articles that were selected for publication in this Special Issue. Each of the papers was presented at the Symposium and has undergone rigorous peer review. The papers represent a broad disciplinary scope within system analysis ranging from forest economics and management science to remote sensing. The problems addressed within these disciplines also vary, from wildfire mitigation, supply-chain optimization, bioenergy logistics, and participatory forest planning to fuel assessment. The technical tools the authors applied to these problems are equally diverse: game theory, dynamic programming, stochastic optimization, multiobjective decision theory, structure-from-motion, and airborne laser scanning.

Effects of Chinese Privet on Bees and Their Vertical Distribution in Riparian Forests - Michael D Ulyshen; Scott Horn; James L Hanula (Forest Science, 2020)
Chinese privet (Ligustrum sinense Lour.), is known to negatively affect biodiversity near the ground in invaded forests by forming thick layers of non-native vegetation in the midstory. Whether these effects extend above the shrub layer into the canopy remains unclear. We sought to test this question by using flight-intercept traps (clear plastic panels attached to a white bucket) to sample bees at three heights (0.5, 5, and 15 m) in plots in which L. sinense had or had not been experimentally eliminated. Privet removal (i.e., restoration) resulted in significantly higher bee abundance, richness, and diversity than in invaded sites, but this effect was only observed at 0.5 m. In restored plots, bee diversity was generally higher at 5 and 15 m than near the forest floor, but there were no differences between traps at 5 and 15 m. Our findings show that bees will benefit from the removal of invasive shrubs near the forest floor but not in the canopy. Why bee diversity is higher in the canopy than near the ground in temperate deciduous forests remains unknown. Study Implications Chinese privet is recognized as one of the most problematic plants invading southeastern US forests where it has strong negative effects on native plant and insect diversity near the forest floor. This study tested the impacts of privet removal on the diversity of bees at three heights to determine whether the effects of removing privet extend into the canopies of temperate deciduous forests. The findings indicate that management activities aimed at eliminating Chinese privet will greatly increase bee activity near the forest floor but will not immediately impact bee numbers in the canopy.

Seed Adaptive Traits of Fagus sylvatica Populations in Northeastern Greece - Georgios Varsamis; Theodora Merou; Ioannis Takos; Chrisovalantis Malesios; Apostolos Manolis; Aristotelis C Papageorgiou (Forest Science, 2020)
Fagus sylvatica in Europe is expected to be severely affected by the ongoing climate change. In this article, seed adaptive traits, in terms of morphology and germination, of F. sylvatica populations of different postglacial lineage and intrapopulation genetic diversity were evaluated. Eight plots from two geographical provenances, Evros and Drama, were selected. Provenance shaped both morphology and germination patterns, but the effect was more pronounced on germination. Seeds from Drama were larger and heavier than those from Evros but exhibited a higher degree of dormancy and slower germination. High among-plots variability on morphology and germination was also observed, especially in Evros. This higher variability was consistent with the higher level of genetic diversity observed at genomic and chloroplast DNA markers at small or larger spatial scales from previous published studies on the same plots. Results suggested the existence of different seed adaptation strategies, mainly between provenances, as a result of possible adaptation to different environmental conditions, whereas a possible influence of a generally complex pattern of admixture between different beech subspecies and postglacial lineages could not be excluded.

A Method for Reconstructing the Past Soil Temperature Based on Tree-Ring Widths - Shuai Yuan; Yonghong Zheng; Yongdong Qi; Fanxi Kong; Dan Wang; Fangfang Zhang (Forest Science, 2020)
Soil temperature can affect tree growth and is one of the most important types of basic data for forest cultivation and management. To obtain a long-term time series of soil temperatures, we explored the utility of dendroclimatology in a subtropical area of China. In this study, the relations between tree-ring-width chronologies and climate factors were explored by correlation analysis. The results indicated that the limiting climatic factors for the radial growth of Huangshan pine were elevation-specific. Further investigation found that chronology at high elevations was significantly correlated with soil temperature. Then, we described a reconstruction of the soil temperatures of the Dabie Mountains area using the tree-ring width chronology from 1869 to 2015 and showed that the reconstruction explained 42.9 percent of the instrumental soil temperature variation in the common years. We found that the 1970s and 2000s were the coldest and warmest decades since 1884, respectively. The results of the reconstruction method for describing past soil temperatures can provide a reference for other subtropical forests. Furthermore, the results of our research also have a certain significance for guiding policymaking related to forest cultivation and management.

Towards Spatially Explicit Quantification of Pre- and Postfire Fuels and Fuel Consumption from Traditional and Point Cloud Measurements - Andrew T Hudak; Akira Kato; Benjamin C Bright; E Louise Loudermilk; Christie Hawley; Joseph C Restaino; Roger D Ottmar; Gabriel A Prata; Carlos Cabo; Susan J Prichard; Eric M Rowell; David R Weise (Forest Science, 2020)
Methods to accurately estimate spatially explicit fuel consumption are needed because consumption relates directly to fire behavior, effects, and smoke emissions. Our objective was to quantify sparkleberry (Vaccinium arboretum Marshall) shrub fuels before and after six experimental prescribed fires at Fort Jackson in South Carolina. We used a novel approach to characterize shrubs non-destructively from three-dimensional (3D) point cloud data collected with a terrestrial laser scanner. The point cloud data were reduced to 0.001 m–3 voxels that were either occupied to indicate fuel presence or empty to indicate fuel absence. The density of occupied voxels was related significantly by a logarithmic function to 3D fuel bulk density samples that were destructively harvested (adjusted R2 = .32, P < .0001). Based on our findings, a survey-grade Global Navigation Satellite System may be necessary to accurately associate 3D point cloud data to 3D fuel bulk density measurements destructively collected in small (submeter) shrub plots. A recommendation for future research is to accurately geolocate and quantify the occupied volume of entire shrubs as 3D objects that can be used to train models to map shrub fuel bulk density from point cloud data binned to occupied 3D voxels.

A Discussion of Vintage Optimization Models in Forest Economics - Adriana Piazza (Forest Science, 2020)
Optimal forest harvesting is a problem that dates back many centuries. Modern forest-management needs models taking into account the relatively long rotation, the multiaged structure, the age-dependent timber content of trees, and the multiple services forests provide. Approaches to characterize the optimal management policy range from models that represent the forest by a unique state variable that can usually be solved analytically (i.e., models that consider forests composed by a unique even-aged stand or allow a uneven aged forest but only consider its total biomass), to much more sophisticated linear and integer programming harvest scheduling models. In this survey, we focus on dynamic optimization problems where the forest is represented with an age-class structure. These models present richer dynamics than one-variable models while preserving their analytic tractability to some extent.

Forest Road Status Assessment Using Airborne Laser Scanning - Katalin Waga; Piotr Tompalski; Nicholas C Coops; Joanne C White; Michael A Wulder; Jukka Malinen; Timo Tokola (Forest Science, 2020)
Forest roads allow access for silvicultural operations, harvesting, recreational activities, wildlife management, and fire suppression. In British Columbia, Canada, roads that are no longer required must be deactivated (temporarily, semipermanently, or permanently) in order to minimize the impact on the overall forested ecosystem. However, the remoteness and size of the road network present challenges for monitoring. Our aim was to examine the utility of airborne laser scanning data to assess the status and quality of forest roads across 52,000 hectares of coastal forest in British Columbia. Within the forest estate, roads can be active or deactivated, or have an unknown status. We classified road segments based on the vegetation growth on the road surface, and edges, by classifying the height distribution of airborne laser scanning returns within each road segment into four groups: no vegetation, minor vegetation, dense understory vegetation, and dense overstory vegetation. Validation indicated that 73 percent of roads were classified correctly when compared to independent field observations. The majority were classified as active roads with no vegetation or deactivated with dense vegetation. The approach presented herein can aid forest managers in verifying the status of the roads in their management area, especially in remote areas where field assessments are costly and time-consuming.

Bi-Level Participatory Forest Management Planning Supported by Pareto Frontier Visualization - S Marques; V A Bushenkov; A V Lotov; M Marto; J G Borges (Forest Science, 2020)
This research addresses the problem of forested landscape management planning in contexts characterized by multiple ecosystem services and multiple stakeholders. A new methodology for participatory landscape-level forest management is proposed. Specifically, a bilevel representation is used, whereas models of subsystems are used for constructing an integrated model of the master problem. Participatory workshops and interactive visualization of the Pareto frontier are used to support the solution of the multi-objective optimization upper- and lower-level problems. The visualization is implemented by a technique—Interactive Decision Maps—that displays interactively the Pareto frontier in the form of decision maps, that is, collections of the objectives’ tradeoff curves. Since the upper-level problem may be characterized by a large number of decision variables, we compare the Pareto frontier generated by the Interactive Decision Maps technique with the Pareto frontier generated by a decomposition approach that builds from the Pareto frontiers of the lower-level subproblems. The approach supports further the negotiation between upper- and lower-level goals. Results are discussed for a large-scale application in a forested landscape in northwest Portugal.

A Structured Framework for Adaptive Management: Bridging Theory and Practice in the Olympic Experimental State Forest - Teodora V Minkova; Jennifer S Arnold (Forest Science, 2020)
Adaptive management is a systematic approach to learning from outcomes to improve management. Although its virtues are commonly praised, it has been implemented infrequently in natural resource management because of the challenges of developing a feasible process that can be sustained over time. Our analysis of regional experiences from private, state, and federal lands in the Pacific Northwest (United States and Canada) finds that the questions addressed by private organizations tend to be more specific, associated with a narrower scope of uncertainties, and addressed in a shorter time frame with limited stakeholder involvement. On publicly managed lands, questions tend to be more complex and open-ended, usually driven by their mandate for multiple use and high level of stakeholder engagement. We present a structured adaptive management framework that translates theory into action by describing an implementation process and organizational structure, explicitly linking learning to management planning and implementation, and integrating the technical and social aspects of adaptive management. Forest managers and policymakers can customize our example according to their mandate and management objectives. The framework is particularly relevant to land management for multiple uses, where the uncertainties are abundant and complex, and the decisionmakers increasingly use mathematical modeling to inform their decisions.

Managing Fragmented Fire-Threatened Landscapes with Spatial Externalities - Christopher J Lauer; Claire A Montgomery; Thomas G Dietterich (Forest Science, 2020)
Accounting for externalities generated by fire spread is necessary for managing fire risk on landscapes with multiple owners. In this paper, we determine the optimal management of a synthetic landscape parameterized to represent the ecological conditions of Douglas-fir (Pseudotsuga menziesii) plantations in southwest Oregon. The problem is formulated as a dynamic game, where each agent maximizes their own objective without considering the welfare of the other agents. We demonstrate a method for incorporating spatial information and externalities into a dynamic optimization process. A machine-learning technique, approximate dynamic programming, is applied to determine the optimal timing and location of fuel treatments and timber harvests for each agent. The value functions we estimate explicitly account for the spatial interactions that generate fire risk. They provide a way to model the expected benefits, costs, and externalities associated with management actions that have uncertain consequences in multiple locations. The method we demonstrate is applied to analyze the effect of landscape fragmentation on landowner welfare and ecological outcomes.

Developing Methods for Truck Route Selection and Cost Modeling in Steeper Topographies - D Fjeld; M Rönnqvist; P Flisberg (Forest Science, 2020)
Payment tariffs for logging truck transport in Nordic countries are typically based on the loaded transport distance. Local tariffs often provide a good representation of the mean cost, however, as variation in topography and the transport environment increases; loaded distance alone represents the actual cost poorly. In addition, routes with increasing curvature also constitute more frequent braking and acceleration cycles. Moreover, driving in such topographical environments during the winter raises additional safety and operator stress issues. This study examines the situation in Norway where logging truck routes often start in mountainous regions. It tests the applicability of a route-generation system developed in Sweden and determines if it can be adopted in Norway. The case study is based on 30 detailed routes from each country, reported and analyzed by their respective transport managers. Based on typical local tariffs, the results show the route-specific variation in costs and profit margins associated with the varying transport environments. A framework for classifying transport environments is proposed as a basis for tariff agreements that better represent the actual transport cost. This increases fairness and supports economic sustainability for transporters.

Optimal Design of a Forest-Based Biomass Supply Chain Based on the Decision maker’s Viewpoint Towards Risk - Shaghaygh Akhtari; Taraneh Sowlati; Verena C Griess (Forest Science, 2020)
Economic viability is one of the main considerations in bioenergy and biofuel projects and is impacted by uncertainty in biomass availability, cost, and quality, and bioenergy and biofuel demand and prices. One important aspect of decisionmaking under uncertainty is the viewpoint of the decision maker towards risk, which is overlooked in the biomass supply chain management literature. In this paper, we address this gap by evaluating alternative supply chain designs taking into account uncertain future conditions resulting from changes in biomass availability and cost, and bioproduct and energy prices. Three decision rules, maximax, minimax regret, and maximin, representing, respectively, optimistic, opportunistic, and pessimistic perspectives, are used for evaluation. It is assumed that the decision maker has knowledge about the potential future events, but the likelihood of their occurrence is unknown. According to the results of the case study, investment in bioenergy and biofuel conversion facilities was recommended based on optimistic and opportunistic viewpoints. Production of both bienergy and biofuels would not be profitable under pessimistic conditions. Therefore, investment in only bienergy facilities was prescribed under pessimistic conditions.

Long-Duration Soil Heating Resulting from Forest Floor Duff Smoldering in Longleaf Pine Ecosystems - Jesse K Kreye; J Morgan Varner; Leda N Kobziar (Forest Science, 2020)
Prescribed fire is commonly used in southeastern US forests and is being more widely applied in fire-prone ecosystems elsewhere. Research on direct effects of burning has focused on aboveground impacts to plants with less attention to belowground effects. We measured soil heating during experimental burns in longleaf pine sandhill and flatwoods ecosystems in the southeastern US. Soil heating was minimal in frequently burned sites. Where fire had been excluded for several decades, however, we detected substantial soil heating sustained for considerable durations. Long-duration heating was most prominent where accumulated forest floor duff (Oe and Oa organic horizons) was deepest, particularly at the base of mature pines in long-unburned sites. Temperatures potentially lethal to plant tissues (≥60°C) were sustained for several hours as deep as 10 cm near pines in flatwoods sites. Sustained temperatures ≥300°C, when impacts to soil nutrients can occur, were observed for up to 35 min at mineral soil surfaces. Patterns of heating were similar in long-unburned sandhill sites; however, temperatures were generally lower and durations more brief. Heat transfer resulting from smoldering in forest floor duff deserves further attention to predict mineral soil heating, forecast fire effects, and inform restoration efforts in fire-prone ecosystems.

Changes in Deadwood and Understory Vegetation 12 Years after Partial and Clearcut Harvesting in Mixedwood Stands of Western Quebec, Canada - Kobra Maleki; Benoit Lafleur; Brian D Harvey; Marc J Mazerolle; Nicole J Fenton (Forest Science, 2020)
Ecosystem management promotes the integration of knowledge of natural ecosystem dynamics into forest-management planning and practices, and provides a useful framework for understanding and mitigating the impacts of timber harvesting on biodiversity and ecosystem functions. Understory vegetation and deadwood are involved in many ecosystem functions including nutrient and carbon, and tree-regeneration dynamics. The study objective was to compare the 12-year post-treatment effects on forest floor attributes of two intensities of partial harvesting (gap harvesting [62 percent basal area retention; BAR] and diameter-limit harvesting [35 percent BAR]) to clearcutting (10 percent BAR). We quantified the standing and downed deadwood abundance and the understory plant community composition in mixed, northern temperate forests, in western Québec, Canada. Our results suggest that moderate-intensity gap harvesting can best preserve a standing deadwood stem density and a diameter structure comparable to unmanaged stands. Downed deadwood abundance of all diameter classes was not altered, 12 years following the gap harvesting. Finally, understory plant communities in the gap treatment were more similar to those of unmanaged stands than those in diameter-limit and clearcutting treatments. These results illustrate the importance of tree retention levels for the maintenance of deadwood and understory plant species associated with closed-canopy or old-growth forests.

A Multipoint Felled-Tree Validation of Height–Age Modeled Growth Rates - Halli Hemingway; Mark Kimsey (Forest Science, 2020)
Accurate measures of forest site productivity are essential for forest-management planning. The most common measure of site productivity is breast height–age site index (BHASI)—the expected height at a reference age. Error from including early growth in productivity estimates and limited applicability of any one BHASI model warrant development of alternative methods. Exploring alternatives may only be necessary if regional BHASI models are not accurately predicting growth rates. We compared modeled height growth rates for Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca) to felled-tree measurements to evaluate relative performance of a regional BHASI model. An orthogonal sampling design ensured samples were collected across a range of site factors known to influence Douglas-fir growth rates. Growth rates for each 10 m section were calculated and compared to BHASI modeled growth rates. The regional BHASI model underpredicted growth rates from breast height to 30 m. Observed growth rates from 10 to 30 m accounted for the majority of underprediction relative to BHASI modeled growth rates. An alternative multipoint method of defining site productivity is described. More research comparing BHASI and alternative methods is needed, given the growth rate error associated with one-point site productivity assessment.

Nutrient Removals by Pinestraw Harvesting in Slash Pine Plantations in Florida - Anna Osiecka; Patrick J Minogue; Masato Miwa; Dwight K Lauer (Forest Science, 2020)
Pinestraw harvesting is an important industry in the southeastern United States. There is a need to understand how fertilization can be used efficiently to sustain or increase long-term pinestraw yields and avoid adverse environmental consequences. The effects of fertilization on needlefall nutrient concentrations, pinestraw yields, and nutrient removals on soils with contrasting soil nutrient sorption potential (Entisol vs. Ultisol) were compared using two midrotation slash pine plantations in North Florida. Diammonium phosphate was applied at 0, 144, 430, or 718 kg ha–1 in the spring of 2009 and 2010. Pinestraw was harvested annually in 2009–12. Needlefall mass, pinestraw yields, total Kjeldahl nitrogen concentrations in needlefall and pinestraw, and total Kjeldahl nitrogen, P, K, Ca, and Mg removals increased with fertilization. Diammonium phosphate at 718 kg ha–1 year–1 increased pinestraw yield over the control by 37 and 35 percent 2 years after the second fertilization, and by 11 percent (from 21.5 to 23.8 Mg ha–1) and 12 percent (from 25.0 to 28.1 Mg ha–1) over the 4-year control totals, at Entisol and Ultisol sites, respectively. Differences between sites were larger than fertilization response for most variables. Yields, nutrient concentrations, and removals were higher at the more fertile Ultisol than Entisol and, at both sites, higher than most reported in the literature.

Projecting Stand Survival and Basal Area Based on a Self-Thinning Model for Chinese Fir Plantations - Xiongqing Zhang; Quang V Cao; Hanchen Wang; Aiguo Duan; Jianguo Zhang (Forest Science, 2020)
The self-thinning rule has played a critical role in controlling stand stocking and modeling stand development in forest stands. Chinese fir (Cunninghamia lanceolata) is a native and fast-growing tree species used for timber production and is widely grown in southern China. Effective management of this important tree species requires accurate and reasonable predictions of stand growth and survival. Remeasured data from 48 plots distributed in Fujian, Jiangxi, Guangxi, and Sichuan provinces were used to develop models to predict stand survival and basal area based on the self-thinning trajectories. These trajectories were constructed using a self-thinning slope of –1.605, as suggested by Reineke (1933) (Method 1), and the slopes estimated either from two groups of sites (Method 2) or from climate variables (Method 3). Results indicated that the stand growth and survival models using Method 3 performed best, followed by Method 2 and Method 1. In addition, stand growth and survival curves predicted from Method 3 were more similar in shape to those from the observed values, as compared with Method 1. Overall, the models based on the self-thinning lines using climate-sensitive slopes provided reasonable predictions of the stand development dynamics. Therefore, these results facilitate modeling of the relation between stand growth/survival and self-thinning under climate change.

Spatial Patterns in Baseflow Mean Response Time across a Watershed in the Loess Plateau: Linkage with Land-Use Types - Xu-dong Huang; Dong Wang; Pei-pei Han; Wen-chuan Wang; Qing-jie Li; Xiao-li Zhang; Ming-wei Ma; Bao-jian Li; Shi-jie Han (Forest Science, 2020)
Understanding the relation between land-use types and baseflow mean response time (BMRT) is important to explore the response mechanism of baseflow processes in watersheds. BMRT was determined using an instantaneous unit hydrograph. The instantaneous unit hydrograph parameters were estimated by autocorrelation functions. The relative importance of land-use types in determining BMRT dynamics was assessed by hydrological model and partial least-squares regression. Our study suggests greater effects of urban area on BMRT than the effects of forest and agricultural land. This may be because the urban interception impervious area may impede baseflow generation over a short timescale. The effects of agricultural land are greater than those of forest in areas with steeper hillslopes, but lower than those of the forest in areas with more plains, reflecting the varied ability of forest and agricultural lands with different topography to hinder overland flow. Variations of BMRT are strongly linked to land use in the watershed. Overall, our study provides insight into the BMRT and dominant factors of land-use types in watersheds, planning of sustainable water resource use, and ecological protection in watersheds.

An Empirical Examination of Dominant Height Projection Accuracy Using Difference Equation Models - Mingliang Wang; Cristian R Montes; Bronson P Bullock; Dehai Zhao (Forest Science, 2020)
Site index models developed using the difference equation method, otherwise known as the algebraic difference approach (ADA) along with its generalization (GADA), play an important role in forest growth and yield modeling for operational use. Their projection accuracy tends to be reduced over increasing time intervals, a common modeling phenomenon not yet well understood. In this study, dominant height projections given one single prior observation using three (G)ADA models were examined in relation to pairwise height correlations on an empirical dataset consisting of height remeasurements taken on permanent plots of a second-rotation loblolly pine (Pinus taeda L.) plantation experimental study. The results indicated that the decline in projection accuracy in terms of RMSE or Rp2 (analogical to the coefficient of determination R2) with increasing time intervals is closely associated with the weakening correlations imbedded in distant height remeasurements. The squared coefficient of correlation (ρ2) between paired heights can be set as an upper bound of Rp2 in (G)ADA model prediction of heights conditional on prior observations. An examination of correlation over time interval will be informative of how projection accuracy is likely to change and what the maximal Rp2 might be for any potential (G)ADA model to be developed.

Midstory Removal Facilitates Growth but Reduces Competitiveness of Oak Reproduction Prior to and after Shelterwood Establishment Cutting - Zachary J Hackworth; John M Lhotka; Jeffrey W Stringer (Forest Science, 2020)
This study examined the influence of midstory removal applied 9 years prior to a shelterwood establishment cut on survival, growth, and competitive status of black oak (Quercus velutina Lam.), white oak (Quercus alba L.), and an oak competitor, red maple (Acer rubrum L.), immediately before and at 6 years following shelterwood cutting on intermediate productivity sites in the Central Hardwood Forest Region. We also examined height and density distributions of the regenerating cohort to quantify seedling establishment and to elucidate relative oak competitiveness at each time period. Although oak seedlings were taller 9 years after midstory removal than in undisturbed controls, the midstory removal treatment reduced the frequency of free-to-grow oaks (relative to understory competitors) and increased the size of red maple and relative density of large competitors. Height growth of all three species following establishment cutting was increased by prior midstory removal and dependent on seedling competitive position immediately before shelterwood establishment. Additionally, we observed increased seedling densities 6 years following shelterwood establishment cutting and greater white oak seedling establishment when midstory removal preceded the shelterwood treatment.

Bidens pilosa Extract Effects on Pine Wilt: Causal Agents and Their Natural Enemies - Satoshi Taba; Koichiro Ashikaga; Tsuyoshi Oohama; Atsushi Ajitomi; Chouji Kiyuna; Misa Kinjo; Ken-Taro Sekine (Forest Science, 2020)
We investigated the nematicidal and insecticidal activities of the aqueous extract from Bidens pilosa var. radiata on pine-wood nematode (Bursaphelenchus xylophilus) and Japanese pine sawyer (Monochamus alternatus) larvae and adults, the causal agent and vector of pine wilt, respectively. The aqueous extract killed the pine-wood nematode, adults, and larvae of the vector in vitro at all concentrations tested, and the effect decreased significantly with increasing extract dilution. Repellent activity was observed on the nematode and the vector adults as well, although the activity decreased with time in case of the vector. Furthermore, the aqueous extract of B. pilosa effectively promoted approximately 3.0–9.0 mm of hyphal growth in Beauveria spp., when compared with the control treatment. A minor insecticidal effect was also observed on two species of click beetle (Cryptalaus larvatus pini and Paracalais berus), which are natural predators of the Japanese pine-sawyer larvae. Pesticidal and repellent activities of the aqueous extract observed on several organisms related to pine wilt suggest that a multifactorial approach may effectively control this devastating disease.

Establishment and Early Development of Even-Age Shortleaf Pine–Hardwood Mixtures Using Artificially Regenerated Shortleaf Pine and Various Site Preparation and Release Treatments - David C Clabo; Wayne K Clatterbuck (Forest Science, 2020)
Shortleaf pine (Pinus echinata)–hardwood mixtures were once a common forest type on upland sites throughout the southeastern United States. These forest types have declined throughout much of shortleaf pine’s native range. Information on restoring shortleaf pine–hardwood types when a shortleaf pine seed source is not present is lacking. The objectives of this study were to investigate the effects of four site-preparation and release treatments (control, burn, herbicide, and herbicide and burn) on the development of even-aged mixtures of planted shortleaf pine and natural hardwoods located on the Highland Rim physiographic province of Tennessee, USA. Three years after study establishment, statistical differences among treatments occurred for shortleaf pine survival and basal diameter. Survival was greatest in the herbicide-only treatment. Height and basal diameter growth were greatest in the herbicide and burn treatment. Stem densities were greater in treatments that did not include a herbicide release than those where herbicide was used alone or combined with prescribed burning. The herbicide and burn treatment had the greatest potential after 3 years for developing into a balanced, mixed shortleaf pine–hardwood stand, whereas most treatments had an influx of exotic, invasive species such as Chinese privet (Ligustrum sinense) and callery pear (Pyrus calleryana).

Forest Restoration Potential in a Deforested Mountain Area: An Ecosociological Approach towards Sustainability - Stefan Zerbe; Lorenzo Pieretti; Susanne Elsen; Zezva Asanidze; Iveri Asanidze; Levan Mumladze (Forest Science, 2020)
Forest degradation worldwide stimulates efforts to restore forests. In particular, in mountain areas, where livestock agriculture and grazing have led to deforestation and a strong decrease in forest ecosystem services over centuries, it is necessary to develop sustainable strategies for the restoration of multifunctional forest ecosystems. We investigate the case study of the Javakheti Highland in the Southern Caucasus (Georgia), which is largely deforested because of long-lasting agricultural land use. We take into consideration the natural potential of forest development, the multifacetted potential of forest use, and those stakeholders directly and indirectly, respectively, involved in forest restoration. We show that neither the natural ecological site factors nor the potential of forest use, considering traditional and modern use, pose a limitation on forest restoration. Traditional ecological knowledge is still present, however hardly activated nowadays. However, social, cultural, and political obstacles have to be addressed for the development of a sustainable forest-management policy, which is rooted in the local communities. Environmental policy favoring forest development in Javakheti Highland should integrate national forest development policy with the perception, requirements, and traditions of local people.

Plant Water Stress and Soil Depletion in Variable-Density, Red Alder/Western Hemlock Coastal Oregon Plantations - Elizabeth C Cole; Michael Newton (Forest Science, 2020)
Riparian ecosystems provide critical habitat and functions while being some of the most productive areas in forests. Both conifers and hardwoods contribute to maintenance of habitat and function. To determine the impact of water stress on growth of red alder (Alnus rubra Bong.) and western hemlock (Tsuga heterophylla [Raf.] Sarg.), we installed Nelder type 1a combined with replacement series plots on three Oregon Coast Range sites. Densities ranged from 988 to 85,400 trees/hectare, with ratios (hemlock:alder) of 100:0, 75:25, 50:50, 25:75, and 0:100. In the first 4 years after planting, alder used water in the growing season at greater depths earlier than western hemlock. Higher densities resulted in greater water stress later in the growing season in weeded areas (maintained by herbicide applications), but stress was similar across densities in unweeded areas. Water stress at early ages was correlated with decreased size 14 or 24 years after planting for both species, but these correlations were confounded with other effects of density. Increasing water availability in areas with low summer precipitation could enhance growth of red alder and western hemlock, even in highly productive riparian areas.

Short- and Long-Term Results of Alternative Silviculture in Peatland Black Spruce in Minnesota, USA - Brian D Anderson; Marcella A Windmuller-Campione; Matthew B Russell; Brian J Palik; Douglas N Kastendick (Forest Science, 2020)
Across the boreal forest in North America, the black spruce (Picea mariana) cover type is ecologically and economically important, occupying roughly 10 percent of Minnesota’s, USA 17.4 million acres (7.0 million hectares) of forestland. Traditionally managed through clearcut regeneration harvests, alternative silvicultural systems are being increasingly used in Canada. Here, we examine the 10- and 57-year effects of six silvicultural treatments (clearcut strips, clearcut patches, thinning, group selection, single-tree selection, shelterwood) on stand structure and dynamics in lowland black spruce. Treatments were installed in 1948 in northern Minnesota, and remeasured and re-treated 10 years later. A subset of the clearcut strips, clearcut patches, and shelterwood treatments were remeasured in 2017. After 10 years, diameter growth of residual stems varied by treatment, with the shelterwood experiencing the greatest growth, and basal area increased in all but the shelterwood treatment. Over the long term, the shelterwood exhibited larger diameters and heights and greater crown ratios, basal area, structural complexity, and compositional diversity than the clearcuts. Our results suggest that managers may consider using a shelterwood instead of traditional large clearcuts to achieve increased structural and compositional diversity, particularly when eastern spruce dwarf mistletoe (Arceuthobium pusillum) does not necessitate a traditional clearcut.

Optimal Continuous Cover Forest Management with a Lower Bound Constraint on Dead Wood - Janne Rämö; Aino Assmuth; Olli Tahvonen (Forest Science, 2020)
We analyze economically optimal continuous cover forestry with dead wood as a biodiversity indicator. We study mixed-species stands consisting of Norway spruce (Picea abies [L.] Karst.), birch (Betula pendula Roth.), and other broadleaves (e.g., oak [Quercus sp.], maple [Acer sp.]). The analysis is based on an economic description of continuous cover forest management using an empirically estimated size-structured transition matrix model. We use size-specific decomposition rates for dead wood, with the lower limit on total dead wood volume varying between 0 and 40 m3 ha–1. The optimization problem is solved in its general dynamic form using gradient-based interior point methods. Increasing the dead wood volume requirement affects total stand density only slightly, but increases stand heterogeneity as other broadleaves are grown in higher numbers. In addition, increasing the dead wood requirement has only a minor effect on the total felled volume, but harvests shift from timber harvests to biodiversity fellings to maintain the required dead wood volume. In the optimal steady state with a high dead wood requirement, two harvesting cohorts emerge: one for timber harvests and the other for biodiversity fellings. Increasing the dead wood requirement decreases steady-state net timber income by up to 30 percent compared to the unconstrained solution.

Evaluating Regeneration in Heterobasidion Root Disease Infested Stands in the Lake States - Michael C Demchik; Monique L Sakalidis; Michael Hillstrom; Kyoko Scanlon; Trevor A Adams; Katherine R Minnix (Forest Science, 2020)
Heterobasidion root disease (HRD) infection is becoming increasingly common in red pine plantations of the Lake States. Although stump treatment can reduce rates of overland transmission, infested stands continue to experience expansion of mortality pockets. Natural regeneration into HRD mortality pockets can assist with revegetation. The objective of this study was to determine what tree species naturally regenerate in red pine plantations impacted by HRD in Wisconsin and Michigan. We visited 49 pockets (in 31 stands) in Wisconsin and Michigan that had existing confirmed HRD infections during the fall of 2017. We surveyed the regeneration in the pocket and measured the species and basal area of overstory trees 10 m from the expanding edge of the pocket. Overall, pockets were regenerating with desirable species, some of which are susceptible to HRD. Additionally, woody invasive species were present in 39 percent of the pockets. We expect these pockets to generally fill with desirable species of regeneration, although long-term successful regeneration by susceptible species such as pines may be limited.

Alternative Silvicultural Approaches to Managing Jack Pine Plantations for Endangered Species Habitat and Forest Products - Daphna Gadoth-Goodman; David E Rothstein (Forest Science, 2020)
Since the early 1980s, ca 1,550 hectares (3,800 ac) of high-density jack pine (Pinus banksiana) plantations have been established annually in northern Lower Michigan to serve as habitat for the federally endangered Kirtland’s warbler (KW; Setophaga kirtlandii). Because these plantations do not appear capable of producing merchantable sawlogs by their planned 50-year harvest age, we investigated the potential to implement reduced rotation lengths in these stands to produce biomass and/or pulpwood. We used space-for-time substitution to assess biomass and volume accrual over time, using our own locally derived allometric biomass equations. The predicted optimal rotation age for biomass was 20 years, and the predicted optimal rotation age for pulpwood volume was 28 years. We compared the total land area required for management under these rotation scenarios to continue establishing 1,550 hectares (3,800 ac) of KW habitat annually. Management on the current 50-year cycle requires ca 77,500 hectares (191,500 ac). Management for pulpwood would reduce this to ca 43,400 hectares (107,250 ac), and management for biomass would require ca 31,000 hectares (76,600 ac). Our results suggest that rotation lengths in these plantations could be substantially reduced, allowing for reductions in the total land area dedicated to warbler habitat, allowing for diversification of management at the landscape scale.

Simulating the Effectiveness of Improvement Cuts and Commercial Thinning to Enhance Fire Resistance in West Coast Dry Mixed Conifer Forests - Theresa B Jain; Jeremy S Fried; Sara M Loreno (Forest Science, 2020)
Nine multipurpose silvicultural treatments, formulated as a synthesis of recently implemented prescriptions offered by forest managers, were simulated to evaluate their effectiveness at enhancing fire resistance. The Forest Vegetation Simulator was applied, within the BioSum Framework, on over 3,000 Forest Inventory and Analysis plots representing 5 million hectares of dry mixed conifer forests in eastern Washington and Oregon and California’s Sierra Nevada Mountains. We developed a composite fire-resistance score based on four fuel modification principals and metrics: fuel strata gap, canopy bulk density, proportion of basal area in resistant species, and predicted tree survival. The trajectories of stands with and without treatment were compared to evaluate effectiveness immediately post-treatment, and over the three decades that followed. Seventy percent of these forests could be effectively treated in the short term by at least one prescription. Pretreatment forest condition, particularly fire-resistant species abundance, strongly influenced short-term treatment success, and the post-treatment stand dynamics that limit treatment longevity. Treatment effectiveness endured only 10 or 20 years, depending on fire-resistant species abundance, owing to growing space for crown expansion generated by treatment plus regeneration and release and growth of understory tree strata.

Effects of Density Control and Fertilization on Log Wood Quality from a Douglas-fir Stand in Western Oregon, USA - Rapeepan Kantavichai; Eric C Turnblom; Eini C Lowell (Forest Science, 2020)
This study aimed to investigate the effects of juvenile spacing (precommercial thinning), thinning, and fertilization on Douglas-fir butt log (first 4.9 m) and second log (4.9–10 m) quality attributes: juvenile wood percentage, heartwood percentage, rings per inch, specific gravity, and modulus of elasticity. A 41-year-old, 36.6 m site index Douglas-fir stand in western Oregon, USA was selected as the first stand to explore. Nine common silviculture pathway treatments of juvenile spacing, thinning, and fertilization were applied to independent 0.404-hectare plots. Ninety-nine trees were felled and disks cut at five heights along the stem. Wood properties were measured and calculated from the disks for log quality attributes. There was no effect of silvicultural treatments on log heartwood percentage, but significant effects on other log quality attributes were observed. Juvenile wood percentage and rings per inch declined with stand density control and fertilization treatment. Responses to thinning and fertilization in log specific gravity depend on juvenile spacing. Also, thinning and juvenile spacing were shown to have impacts on log modulus of elasticity.

Assessment of Disturbances across Forest Inventory Plots in the Southeastern United States for the Period 1995–2018 - Santosh K Ojha; Kozma Naka; Luben D Dimov (Forest Science, 2020)
Disturbances of varying frequency and intensity shape the species composition, stand structure, and functions of forests. This study assessed the frequency and distribution of disturbances caused by eight agents (insects, diseases, fire, animals, weather, other vegetation, human, and unknown) in the forests of the southeastern United States from 1995 to 2018. We used data from 88,722 inventory measurements of 33,531 plots from the USDA Forest Inventory and Analysis database to assess disturbance among different forest types and to different canopy strata. Disturbances were detected in approximately 14 percent of the plots, located mostly in pine-dominated forest types. Fire was the most frequent disturbance agent (occurring 6 percent of the time), followed by weather and animal agents. The agents that caused the highest mortality rate during the period for saplings were silvicultural treatments (8.6 percent), other vegetation (5.6 percent), and fire (4.4 percent), whereas for trees they were silvicultural treatments (9.8 percent), weather (1.9 percent) and insects (1.7 percent). The forest type that appeared to have been most affected by disturbances was longleaf–slash pine of the Coastal Plain. These results are useful for understanding the spatiotemporal distribution of disturbance events in different southeastern forest types and locations and for guiding forest management activities to mitigate potential impacts.

An Assessment of Soil Compaction after Logging Operations in Central Amazonia - Daniel DeArmond; João B S Ferraz; Fabiano Emmert; Adriano José Nogueira Lima; Niro Higuchi (Forest Science, 2020)
In the forests of the Amazon Basin, there are still few studies on soil compaction caused by logging activities. This study evaluated an operation located on the property of a timber company in Central Amazonia, which uses harvesting techniques based on the harvesting system developed by the Centre for Agricultural Research in Suriname. The timber-extraction method employed by the timber company consists of three activities: (1) skid trail construction with a track-type tractor, (2) log winching with a winch attached to the tractor, and (3) log skidding with a rubber-tired skidder. Soil bulk density and soil penetration resistance were quantified to 20 cm in depth. After a single tractor ingress and egress for trail construction, the soil incurred an increased root growth-limiting bulk density and penetration resistance. However, log winching did not cause significant soil compaction. The conclusions of the study were: (1) the greatest impact from this harvesting system came from the skid trail construction, (2) the technique of log winching limited forest floor compaction and disturbance that damages forest regeneration, and (3) log skidding during dry soil conditions limited increases in compaction and track formation.

Resilience or Vulnerability of the Rear-Edge Distributions of Pinus halepensis and Pinus pinaster Plantations Versus that of Natural Populations, under Climate-Change Scenarios - E Silvério; J Duque-Lazo; R M Navarro-Cerrillo; F Pereña; G Palacios-Rodríguez (Forest Science, 2020)
It is predicted that changes in climate will lead to episodes of large forest decline and mortality. Therefore, the distributions of forest plantations and natural stands might already be facing such impacts. We selected the most arid zone of south-eastern Europe (eastern Andalusia) to assess how the distributions of Pinus halepensis Miller. and Pinus pinaster Aiton forest plantations and natural stands cope with climate change and to determine whether natural or planted distributions would be more stable under future climate-change scenarios. We used presence-point locations from natural distributions, obtained from the third Spanish National Forest Inventory, to develop ensemble species distribution models. The forecast predicted a slight increase in the potential distribution of both species by 2040, with a subsequent drastic decrease until 2099. Pinus halepensis had larger current and future potential distributions than P. pinaster but a slightly greater decrease with time in the potential distribution than that of P. pinaster. On the other hand, the natural and planted distributions of P. halepensis were more vulnerable to future climate change scenarios than those of P. pinaster. Natural populations will likely be more resilient to climate change than planted populations.

Consulting Forester Timber Sale Practices in the US South - Patrick M Grove; Joseph L Conrad; Thomas G Harris; Joseph Dahlen (Forest Science, 2020)
Private timber sale transactions are vital to the forest products industry in the US South. Consulting foresters often assist private landowners in administering timber sales, and their decisions and practices have a major impact on landowner compensation, satisfaction, and market efficiency. This study used a mixed-mode survey of consulting foresters in 11 southern states to examine contract terms, timber sale practices, and market conditions on private sales. Responses were received from 430 consultants, resulting in a 37 percent response rate. Final harvests are primarily offered to bidders, whereas thinnings are more likely to have timber prices negotiated. Pay-as-cut payment terms are typical for thinnings, but less common in the Mountains where lump sum is relatively more common. Well under 50 percent of firms from the Coastal Plain and Piedmont conduct presale inventories on thinnings, whereas nearly two-thirds of firms in the Mountains use inventories on these types of harvests. Fewer than 25 percent of responding foresters suggested that restrictive quotas reduced landowner revenue on pay-as-cut timber sales. Consulting firms reporting that sawtimber quotas were never a problem in their area reported at least two more sawtimber outlets than those concerned about restrictive mill quotas.

Abiotic and Biotic Factors Affecting Loblolly Pine Health in the Southeastern United States - David R Coyle; Brittany F Barnes; Kier D Klepzig; Frank H Koch; Lawrence A Morris; John T Nowak; William J Otrosina; William D Smith; Kamal J K Gandhi (Forest Science, 2020)
Southern pine forests are important fiber and wood sources, and critical to local, regional, and national economies in the United States. Recently, certain areas of southern pine forests, especially those dominated by loblolly pine (Pinus taeda), have been reported to exhibit abnormally high levels of tree dieback and mortality. However, causal agents either have not been well defined or are controversial in their impacts on tree health. We assessed various abiotic (e.g., slope, aspect, soil characteristics) and biotic (e.g., tree species, stand characteristics, presence of root fungi) factors in 37 healthy (asymptomatic) and unhealthy (symptomatic) sites to elucidate specific factors affecting loblolly pine health in Alabama and Georgia. Soil nutrient content did not differ statistically between healthy and unhealthy sites, but manganese contents were slightly greater, and nitrogen and carbon contents were slightly lower in healthy sites. Unhealthy sites did have a higher silt content than did healthy sites. Pine stems and basal area were greater on unhealthy than on healthy sites, whereas opposite trends were observed for the incidence of stem cankers and mechanical damage. An increased incidence of the root fungal pathogen Heterobasidion irregulare, the causal agent of Heterobasidion root disease, was found on unhealthy sites, but incidence of Leptographium spp. did not differ between the two site types. Thus, soil attributes, stand structure, and management history seem to be the most critical factors affecting loblolly pine health, at least at the local level. Further, some of these factors may be improved through appropriate silvicultural techniques, emphasizing the importance of silviculture in maintaining pine health throughout the southern region.

Moving Forward - Scott D Roberts (Forest Science, 2020)

Modulation of Morpho-Physiological Responses in Populus deltoides by Elevated Carbon Dioxide and Temperature - Santosh Kumar Yadav; Hukum Singh; Raman Nautiyal; Harish Singh Ginwal; Shamim Akhtar Ansari; Santan Barthwal (Forest Science, 2020)
Rising atmospheric carbon dioxide (CO2) and temperature alter gene-expression arrays commensurate with physio-morphological changes, resulting in issues of adaptation, growth patterns, and productivity of terrestrial vegetation. An experiment was conducted to investigate the adaptive response of Populus deltoides clone G48 to the combined effect of elevated CO2 and temperature inside open-top chambers. The elevated CO2 and temperature acted as environmental cues to help express upregulated/downregulated genes involved in important metabolic pathways. As a result, P. deltoides exposed to the elevated CO2 and temperature developed adaptation to undo the effect by enhancing gaseous exchange, transpiration, and carbon assimilation and partitioning as observed on 180 days after treatment. The elevated conditions significantly enhanced stomatal density and size on adaxial/abaxial leaf surfaces, chlorophyll b that augmented photosynthesis, stomatal conductance, transpiration, and internal CO2, but decreased instantaneous and intrinsic water-use efficiency. These stimulated biomass accumulation in root, stem, and leaves. Hence, the elevated conditions of CO2 and temperature operate at the gene-expression level that acts pleiotropically for reinforcement of photosynthetic apparatus, morphological amendment for accelerated gaseous exchange, and finally growth and biomass improvement, supporting adaptive plasticity of clonal planting stock of the species to future climatic change and global warming.

Insight into the Productivity, Cost and Soil Impacts of Cable-assisted Harvester-forwarder Thinning in Western Oregon - Preston Q Green; Woodam Chung; Ben Leshchinsky; Francisca Belart; John Sessions; Stephen A Fitzgerald; Jeffrey A Wimer; Tamara Cushing; John J Garland (Forest Science, 2020)
Cable-assisted (or tethered) mechanized harvesting has recently been introduced to the Pacific Northwest of the United States, and is rapidly being adopted by the forest industry. However, potential environmental impacts, productivity and cost of the new harvesting systems have not been well-assessed. This study aims to examine the effects of cable assistance on soil compaction, system productivity and cost through a field-based experiment. A harvester-forwarder system was used to thin a harvest unit on dry soils in western Oregon, with and without cable-assistance. We conducted a detailed time study during operations and collected soil measurements before and after machine passes. Machine productivity ranged from 28.75 to 92.36 m3 per scheduled machine hour, with resulting unit costs for untethered and tethered systems ranging from $13.19 to $18.13/m3. Our results showed reduced soil impacts in both extent and degree of soil compaction when cable assistance was employed. The reduced extent of soil impacts is attributed to a reduction in track wander owing to the operative tensions of the tether cable, and the smaller increase in soil density appears to be attributed to combined effects of initially denser soil conditions and reduced shear displacement as a result of cable-assistance.

Nitrogen Availability Decreases the Severity of Snow Storm Damage in a Temperate Forest - Christopher A Walter; Mark B Burnham; Mary Beth Adams; Brenden E McNeil; Lindsay N Deel; William T Peterjohn (Forest Science, 2020)
Storms are among the greatest natural disturbances in temperate forests, and increased nitrogen (N) availability is thought to increase storm damage. However, the extent to which N availability increases damage from snowfall is less clear. To test how N availability might affect the susceptibility of trees to snow damage in a temperate forest, we took advantage of an opportunistic storm and surveyed damage in fertilized and unfertilized stands, and across a native N availability gradient. In response to a severe, early season snow storm—a consequence of Superstorm Sandy—the percentages of both basal area and stems damaged were lower in a fertilized watershed than in an unfertilized watershed. Across the native N availability gradient, the percentage of basal area damaged by snow decreased with higher soil N. The effects of N availability on damage were also affected by tree species. Our results suggest that N availability decreases damage from snow storms, contrary to our hypotheses drawn from broader studies. Understanding the relation between storm damage and N availability is important, considering the global increase in N deposition, and since severe storms are likely to become more prevalent with climate change.

Structural Changes on Pulpwood Market in the US South: Wood Pellets Investments and Price Dynamics - Bruno Kanieski da Silva; Frederick W Cubbage; Robert C Abt (Forest Science, 2019)
We investigated the impact of wood pellet mills on pulpwood price structure in the US South. Rather than focusing exclusively on price elasticities, we progress by examining how wood pellet production has affected the spatial transmission of pulpwood prices. Pairwise price ratios were modeled using smooth transition regression to identify changes in the cointegration (linkage) between markets over time. A logistic model was fitted to estimate market linkages as a function of market distances, industry concentration, and capacity of pellet wood production. Results show that the US South is not composed of market clusters, but each market pair has a particular relation. Distance and wood pellet production capacity are the only factors driving market linkages; the pulp and paper industries did not affect market structure changes. Our research suggests spatial price transmission varies over time, and pellet mills have caused a structural change in the pulpwood prices in the US South.

Factors Associated with Establishment and Growth of Pinus coulteri and Pinus sabiniana in California’s Central Coast Bioregion - Thomas Seth Davis; Miranda D Redmond; Nathaniel E Foote; William Miller (Forest Science, 2019)
Forest inventory indicated recent decline in a P. coulteri population at its northern extent but live stems in sympatric P. sabiniana increased. Patterns of cone production, localized factors associated with regeneration, relations between wildfire and tree age distributions, and correlations between climate, seedling establishment, and tree growth were analyzed as potential mechanisms underlying unequal demographics between the two species. Four findings emerged: (1) P. sabiniana had a higher frequency of open cones at the time of observation, but cone production was size-biased, and cone production rates were similar for both species; (2) P. sabiniana seedlings were associated with a higher proportion of bare ground cover and westerly aspects, whereas establishment of P. coulteri seedlings was correlated with warm growing seasons and high vapor-pressure deficits, and seedlings occurred on northernly aspects; (3) age distributions of stands inside and outside a wildfire perimeter did not differ for either species, but annual growth increments of P. coulteri were greater within the fire perimeter; and (4) P. coulteri was even-aged, establishment was episodic, and occurred approximately 10 years post-wildfire. In contrast, the age distribution of P. sabiniana was highly variable, consistent with continuous recruitment, and establishment was not correlated with a climate signal.

Economic Contributions of North Carolina, United States, Forest-Sector Foreign Exports: An Export-Chain Perspective - T Eric Mcconnell; Clayton B Altizer (Forest Science, 2019)
North Carolina forest-sector foreign exports were quantified by applying an origin-of-production methodology that awarded the state a portion of national export value corresponding to its share of a US forest industry. A US$1.945 billion North Carolina forest export chain (FEC) was identified, producing forest industries, wholesalers, transporters, and port authorities. Contributions of the FEC were determined from a social accounting matrix in terms of output, value added, and employment. Port value multipliers were then calculated to provide context to the FEC’s contributions. Direct contributions were US$602.989 million of value added and 6,870 jobs based upon FEC activities of US$1.945 billion. Total FEC contributions were US$1.439 billion of value added and 16,640 jobs on sales across North Carolina of US$3.494 billion. The output and value-added port value multipliers indicated each US$1.000 million of FEC output and value added generated an additional US$800,000 and US$1.386 million in other industries, respectively, before leaving the state to purchase imported inputs. Each 1,000 FEC-dependent jobs supported an average of 1,420 jobs elsewhere in North Carolina’s economy. Information such as this provides policymakers an improved scope of the contributions driven by exporting to foreign markets.

Tree Strata Structure in an Ecotone among the Amazon Forest Types: A Comparative Study - Aline Canetti; Evaldo Muñoz Braz; Patrícia Póvoa de Mattos; Afonso Figueiredo Filho; Renato Olivir Basso (Forest Science, 2019)
This work aimed to describe the structural dynamics of the Transitional Amazonian Forest and to evaluate whether the most abundant tree species present a structural pattern. As it is an ecotone composed of two forest types, a high composition complexity is expected. Forest analysis occurred with six 100 percent inventories data considering all trees with diameter at breast height ≥15.7 in., totalizing over 13 000 ac. The study areas were compared in terms of tree density, number of species, and importance value of the most abundant species. The Morisita index and the cluster analysis tested the forests similarity. We also evaluated the importance value of species in the upper and middle strata. Differences between study areas were detected regarding tree density and number of species. However, the forests presented more than 75 percent similarity and were grouped in three structural clusters. Some species showed alternations of dominance in the middle and upper strata. Although the forest is an ecotone, the trees had a structural pattern, where the same species dominate large areas, allowing us to apply the results on a huge scale.

Increased Individual Tree Growth Maintains Stand Volume Growth after B-Level Thinning and Crop-Tree Management in Mature Oak Stands - Jeffrey S Ward; Jessica Wikle (Forest Science, 2019)
Six study areas were established in 80–125-year-old upland oak stands on average sites to compare stand and individual tree growth response following two active treatments (B-level thinning, crop tree) with an unmanaged control. Initial stocking of 104 percent was reduced to 62 percent and 60 percent on the B-level and crop-tree-management plots, respectively. Approximately 7,200 board feet per acre (International ¼) were harvested on the actively managed plots with upland oaks accounting for 81 percent of pre- and 86 percent of residual stand. Eleven-year diameter and volume growth of oak sawtimber trees was greater on actively managed plots. Growth response increased with degree of release and was maintained for the length of the study. Because of the increased individual tree growth of oaks in response to release, stand volume growth of oak sawtimber did not differ between treatments. In contrast to an 11-year decline of poletimber stocking on unmanaged plots, poletimber stocking increased on managed plots as diameter growth increased in response to partial release. This may increase difficulty of regenerating oak in the future. For those mature red oak stands where traditional regeneration prescriptions will not be implemented or will be delayed, commercial harvests can be conducted without compromising stand volume growth of oak.

Molecular and Pathogenic Characteristics of Paecilomyces formosus, a New Causal Agent of Oak Tree Dieback in Iran - Mohammad Sabernasab; Samad Jamali; Alireza Marefat; Saeed Abbasi (Forest Science, 2019)
Oak dieback is one of the most important diseases that presently affects the Kermanshah oak forests (West Iran). During the period from 2013 to 2015, oak trees exhibiting branch dieback were sampled, and fungal colonies resembling those of the Paecilomyces sp. were obtained from diseased tissues. Based on morphology, physiology, and phylogeny of the internal transcribed spacer rDNA, all isolates were identified as Paecilomyces formosus. Pathogenicity tests in vivo were made on 2-year-old seedlings, potted Q. brantii plants, and excised branch sections under controlled conditions. Inoculated seedlings produced characteristic symptoms, and subsequent pathogen recovery confirmed pathogenicity. We determined these to be thermophilic fungi, which may be related to warming and drought. This is the first report of Paecilomyces formosus as the causal agent of Q. brantii dieback in Iran and the world.

Laurel (Litsea glaucescens Kunth) Regeneration in the Presence of Disturbance Events: A Case Study - Ramón Razo-Zárate; Laura Berenice Retama-Cázares; Rodrigo Rodríguez-Laguna; Abraham Palacios-Romero; Joel Meza-Rangel; Juan Capulín-Grande; Pablo Irving Fragoso-López; Hermann Jesús Cortés-Blobaum (Forest Science, 2019)
A study was carried out in an Abies religiosa Kunth Schltdl. et Cham forest of the community of San Antonio Tecocomulco Tres Cabezas, Municipality of Singuilucan, Hidalgo, to evaluate the resprouting ability of laurel (Litsea glaucescens Kunth) in response to controlled burning treatments and removal of entire stems. The number of laurel bushes, shoots, and mean plant height were evaluated, and three treatments were applied: controlled surface burn; all sprouts cut from the base; and control treatment. Nine weeks after the treatments were applied, the plants in the stem removal treatment remained alive (100 percent), and the appearance of shoots with a mean height of 4.8 cm increased by 18 percent, whereas in the controlled burning treatment, the number of live plants and shoots decreased by 38.2 and 71.5 percent, respectively, with a mean height of 1.1 cm. In the control, the number of bushes remained at 100 percent, and shoots increased by 9.9 percent with a mean bush height of 7.6 cm. This indicates that although surface forest fires tend to affect laurel, surviving plants tend to emit more vigorous shoots, whereas stem removal in laurel bushes generates more shoots

Subregional Timber Supply Projections with Chip-n-Saw Stumpage: Implications for Southern Stumpage Markets - Rajan Parajuli; Shaun Tanger; Robert Abt; Fred Cubbage (Forest Science, 2019)
Softwood chip-n-saw (CNS), an intermediate stumpage product between sawtimber and pulpwood, has become a mainstay in southern timber markets in recent years. Most of the previous studies in southern timber markets primarily focused on pulpwood and sawtimber markets, and often overlooked CNS as a standalone timber product. Using the Subregional Timber Supply model, this study examines the dynamics of sawtimber- and pulpwood-dominated softwood stumpage markets with growing CNS markets in the US South. Results suggest that South-wide CNS inventory increases over the short run but begins to decrease by 2024, which leads to CNS prices rising over the years. The projected trends vary widely from one wood basket to another. This study provides additional nuance to future prospects of southern timber markets.

Effect of Prescribed Fire on Timber Volume and Grade in the Hoosier National Forest - Shannon Stanis; Jan Wiedenbeck; Mike R Saunders (Forest Science, 2019)
Low-intensity surface fire is prescribed in eastern North American hardwood stands prior to overstory harvest in order to improve regeneration and recruitment of oak and other fire-tolerant and fire-adapted species. However, this use of prescribed fire potentially can reduce timber value. We inventoried overstory trees (>10 in. diameter at breast height) in 54 oak-dominated stands with varied prescribed fire histories and aspects in southern Indiana. We then documented the extent of prescribed fire damage (i.e., wounds) to overstory trees and quantified both the relative stand volume of timber loss and the proportion of trees that had tree grade reductions because of prescribed fire. Generally, as a stand received more prescribed fires, more trees were scarred, the relative volume lost increased, and a higher proportion of trees declined in grade. Overall, burned stands experienced less than 10 percent sawtimber volume loss, regardless of the number of prescribed fires and aspect. Less than 3 percent of trees, study-wide, had reduced grade because of prescribed fire. Grade and volume reductions varied by species, however. Our results suggest that prescribed fire has a minor economic impact on standing timber, particularly when timber is harvested within two decades of the first fire.

Bee Communities across Gap, Edge, and Closed-Canopy Microsites in Forest Stands with Group Selection Openings - Hannah L Mullally; David S Buckley; James A Fordyce; Beverly Collins; Charles Kwit (Forest Science, 2019)
As insect pollinator populations continue to decline, it is essential to understand the impacts of anthropogenic activities, including forest management, on pollinator communities. Although multiple studies have shown that clearcutting is beneficial for bees, other less intense, selective silvicultural methods that result in disproportionate increases in edge habitat within stands are less well understood. We investigated bee community characteristics across microsites (center of cut, edge of cut, and closed-canopy forest) in three mixed-mesophytic forest stands subjected to group selection cuttings. Results revealed bee communities in the center of cuts and their edges to differ from those in forest microsites, and their diversity measures were higher than in forest microsites. Within-stand edge microsites did not differ from their cut centers in terms of their communities or their diversity. Finally, center of cut and edge microsites combined, and forest microsites, were characterized by different indicator species, thereby exemplifying differences between these two microsite groupings. These results suggest that group selection harvests support differing communities of bees across microsites and sustain a wide range of bee species, and that edges within these forest stands behaved more like extensions of canopy gap openings despite differences in forest physiognomy.

Photosynthesis and Survival of Young Carpotroche brasiliensis Endl. (Achariaceae) Plants Subjected to Flooding - Laize Queiroz-Alves; Adrielle Leal; Ândrea Carla Dalmolin; Bruce Schaffer; Marcelo Schramm Mielke (Forest Science, 2019)
Carpotroche brasiliensis is a native tree of the Brazilian Atlantic Forest with potential economic value for cultivation in agroforestry systems. We conducted an experiment to determine the photosynthetic and survival responses of young C. brasiliensis plants to electrochemical changes in flooded soils as an indication of their flood tolerance and potential for cultivation in flood-prone areas. Soil flooding decreases the reduction–oxidation potential (redox) potential (Eh), pH, and electrical conductivity (Ec) of the soil, with subsequent recovery of the pH and Ec. Decreases in Eh negatively affect net photosynthesis (A). In flooded soil, decreased A was associated with decreased stomatal conductance (gs) and after 21 days was also associated with decreases in the instantaneous carboxylation efficiency (A/Ci) and potential quantum yield of photosystem II (Fv/Fm). Although flooded C. brasiliensis seedlings developed morphological structures known to increase flood tolerance, this was not enough to prevent severe signs of flooding stress. After 21 days of flooding, flooded plants were unflooded, and 17 days after plants were removed from flood, 90 percent of the unflooded plants died. Our results demonstrate that young plants of C. brasiliensis are suitable for planting in agroforestry systems only in areas with well-drained soils.

Within-Patch Structures Influence Small Mammal Abundance in Managed Forests of Northern California, USA - Steven M Gray; Gary J Roloff; Andrew J Dennhardt; Brian P Dotters; Thomas T Engstrom (Forest Science, 2019)
We evaluated how forest type, vegetation structure in trapping webs, and proximate forest types influenced localized (~6.35 hectares) abundances for commonly captured small mammals in northern California, USA. We trapped from May to August of 2011–13 in 69 forest patches that represented: (1) clearcuts (3–5 years postharvest), (2) 10–20 year-old conifer plantations, (3) rotation-aged conifer stands, and (4) Watercourse and Lake Protection Zones. We captured 11 species; four in sufficient numbers for regression modeling. Our average abundance estimates for the study were 4.57 (standard error [SE] = 0.43), 0.32 (SE = 0.11), 0.90 (SE = 0.30), and 0.25 (SE = 0.09) individuals per web location (~0.75 hectares) for Peromyscus spp., Neotoma spp., California ground squirrels, and Allen’s chipmunks. We found that web-level ground cover (shrubs and grass), downed wood, and types of forests containing our trapping webs best described small mammal abundances, whereas proximate forest types were not important. Our results indicated that retaining localized structures in the form of understory shrub cover and downed wood positively influences small mammal abundance in intensively managed forests of northern California.