Associations between Forest Fire and Mexican Spotted Owls - Jeffrey S. Jenness; Paul Beier; Joseph L. Ganey (Forest Science, 2004)
In 1993, the US Fish and Wildlife Service listed the Mexican spotted owl (Strix occidentalis lucida) as threatened, in part because of the rising threat to its habitat from stand-replacing wildfires. In 1997, we surveyed 33 owl sites that, in the previous four years, had burned at various levels ranging from light controlled burns to stand-replacing fires. We compared owl occupancy and reproduction in these burned sites to 31 unburned owl sites with similar habitat and topography. Although unburned sites showed higher proportions of both occupancy and reproduction, the negative relationship observed between recent fire occurrence and owl occupancy rank was statistically weak (Test for Marginal Homogeneity, P = 0.110). Owls tended not to be present where pure pine stands (Pinus spp.) comprised a large proportion (38–85%) of burned sites, but no other factors relating to habitat or fire severity had a significant, biologically interpretable influence on occupancy rank. We suspect that relatively low-intensity ground fires, including most prescribed fires, probably have little or no short-term impact on Mexican spotted owl presence or reproduction, but we have no data on long-term effects of fire. We recommend proactive fuels-management treatments in areas not currently occupied by owls as a means of reducing fire risk in areas occupied by owls. Within areas occupied by owls, judicious treatments may be appropriate after case-by-case evaluations of potential benefits and risks within those sites. FOR. SCI. 50(6):765–772.

Effects of Fertilization with Dolomite Lime+PK or Wood Ash on Root Distribution and Morphology in a Norway Spruce Stand in Southwest Sweden - Hooshang Majdi; Claes-Göran Viebke (Forest Science, 2004)
Pelleted wood ash (A) or crushed dolomite lime with added potassium and phosphorous (CaMgPK) was applied to plots in a 60-yr-old Norway spruce stand in Southwest Sweden. Eight years later, we measured the effect of these treatments on a number of root parameters, including root biomass and distribution (in different diameter classes), root length density (cm cm-3 soil), specific root length (SRL, m g-1 DM), and number of mycorrhizal root tips. Layers sampled included the humus layer and the upper 30 cm of the mineral soil. The total fine root (0–1 mm) biomass in the mineral soil layer was lower in the A plots than the control plots, and the fine root (1–2 mm) systems were shallower in the A plots compared to both the control and CaMgPK plots. SRL was higher in the humus layer in both the CaMgPK and A plots than in the controls, and higher in the CaMgPK than in the A plots. The number of mycorrhizal root tips was also higher in the treated plots than in the controls, with the highest numbers being found in CaMgPK plots. Based on our results, we conclude that both the CaMgPK and ash treatments resulted in changes in root morphology and, therefore, presumably increased the capacity for nutrient uptake. FOR. SCI. 50(6):802–809.

Forest Change Detection Applying Landsat Thematic Mapper Difference Features: A Comparison of Different Classifiers in Boreal Forest Conditions - Jukka Heikkonen; Jari Varjo (Forest Science, 2004)
This article addresses the problem of detecting forest changes via multitemporal Landsat Thematic Mapper (TM) imagery. A stand-level classification approach is selected, where, for each stand, a total of 35 statistical differences is extracted from Landsat TM images. Three forest stand-changeclasses are considered: 1) no change, 2) moderate change, and 3) considerable change. The classification results are reported by using the following classifiers: K-nearest-neighbor, Maximum Likelihood classifier with Gaussian- and Kernel-based class probability density estimation, Classificationand Regression Trees, Multilayer Perceptron (MLP) early stop committee, and the MLP with weight decay training. Two Bayesian learning methods for MLP are also used: The Evidence Framework of MacKay, and Hybrid Monte Carlo (HMC) method following Neal. The best overall correct classificationresult (88.1%) is obtained by MLP trained with HMC and the Automatic Relevance Detection approach, but the variation of the performance of the classifiers is rather small. FOR. SCI. 50(5):579–588.

Public Values for Biodiversity Conservation Policies in the Oregon Coast Range - Brian Garber-Yonts; Joe Kerkvliet; Rebecca Johnson (Forest Science, 2004)
This study uses a choice experiment framework to estimate Oregonians' willingness to pay (WTP) for changes in levels of biodiversity protection under different conservation programs in the Oregon Coast Range. We present biodiversity policy as an amalgam of four different conservationprograms: salmon and aquatic habitat conservation, forest age-class management, endangered species protection, and large-scale conservation reserves. The results indicate substantial support for biodiversity protection, but significant differences in WTP across programs. Oregonians indicatethe highest WTP for increasing the amount of forest devoted to achieving old-growth characteristics. On average, respondents indicate an annual household WTP of $380 to increase old-growth forests from 5% to 35% of the age-class distribution. Conversely, WTP for increasingconservation reserves peaks at $45 annually to double the current level to 20% of the landscape, whereas WTP is negative for any increase over 32%. We also find resistance to any change in conservation policy, which substantially offsets WTP for increases in all four conservationprograms. FOR. SCI. 50(5):589–602.

Simulating the Effect of Landscape Size and Age Structure on Cavity Tree Density Using a Resampling Technique - Zhaofei Fan; Stephen S. Lee; Stephen R. Shifley; Frank R. Thompson III; David R. Larsen (Forest Science, 2004)
Cavity-tree density (CTD) is an important indicator of habitat quality for cavity-dependent wildlife. However, the abundance of cavities and cavity trees can vary dramatically, even among trees or stands with similar attributes. This uncertainty can make it difficult to expand stand-levelestimates of cavity abundance to large landscapes, although it is often desirable to do so. This limits the utility of CTD as a measure of habitat quality. We use a resampling method (statistical bootstrap) to construct a set of regression models to predict CTD based on landscape age structureand landscape size. The estimated regression coefficients are highly variable (in terms of the adjusted R2 and root mean square error) for landscapes <100 ha, but the models perform well for larger landscapes. We test the regression models using an independent data set from theMissouri Ozark Forest Ecosystem Project (MOFEP) and find that the mean relative error (RE) when predicting CTD for landscapes between 300 and 4,000 ha is less than 10%. Both the size (in hectares) of the landscape and the stand age-class components affect RE; but RE decreases with increasinglandscape size in a consistent and quantifiable manner. For Ozark landscapes ≥100 ha, knowledge of the proportion of the area in the seedling/sapling, pole, sawtimber, and old-growth age classes can be used to readily estimate the number of cavity trees and how that number will change ifthe landscape age structure is altered. FOR. SCI. 50(5):603–609.

Climate and Productivity of Major Conifer Species in the Interior of British Columbia, Canada - Gordon D. Nigh; Cheng C. Ying; Hong Qian (Forest Science, 2004)
Lodgepole pine (Pinus contorta var. latifolia Engelm. ex S. Wats.), interior spruce (including Picea glauca (Moench) Voss, P. engelmannii Parry ex. Engelm., P. glauca×engelmannii), and interior Douglas-fir (Pseudotsuga menziesiivar. glauca (Beissn.) Franco) are the most important commercial species in the interior of British Columbia. We develop statistical models to predict site index (a measure of site productivity) from climate for these species. Using data from 193 climate stations, we first developedmodels that predict mean annual temperature, mean temperature of the warmest and coldest months, number of frost-free days, and frost-free period from latitude, longitude, and elevation. With these models and the Parameter-elevation Regressions on Independent Slopes Model (used to predictmean annual and mean summer precipitation), we predict 10 climate attributes for site index plots of lodgepole pine, interior spruce, and interior Douglas-fir. These attributes are then used in regression models to estimate site index. The models allow us to investigate the current relationshipbetween climate (particularly temperature and precipitation) and site productivity for these species. The productivity for all the species studied increased as temperature increased, with lodgepole pine exhibiting the greatest response. The productivity of lodgepole pine and interior Douglas-firalso increased with increasing precipitation, with interior Douglas-fir having a greater response than lodgepole pine. We discuss the application of the models in relation to the impact of climate change on site productivity. FOR. SCI. 50(5):659–671.

A Genetic Algorithm Approach to Tree Bucking Optimization - Veli-Pekka Kivinen (Forest Science, 2004)
Tree bucking on modern cut-to-length harvesters is controlled by two types of matrices. The price matrix provides the bucking computer with information on how to prioritize various log grades and diameter-length combinations within the same grade, while the demand matrix specifies the desired proportion for each combination. The traditional approach has been to apply the samematrix set to all stands to be harvested within the same planning period, although the stand structure and the characteristics of trees may vary markedly from stand to stand. The purpose of this research was to test the hypothesis that controlling bucking matrices prior to harvesting would improve bucking results at the forest level. The search for stand-specific price matrices was based on a genetic algorithm (GA) that, given a desired overall log distribution and the stem profiles of all the trees in each stand, optimizes, in a parallel manner, the price matrix of a given log grade for each stand involved in the process. The mutation rate and the degree of elitism had the greatest effect on the performance of the developed GA system. In 10 test runs with the same parameter set, the fitness value of the poorest solution (price matrix string) was 98.2% of that of the best solution. The simulations with the bucking simulator, however, indicate that precontrol of price matrices does not improve the fit between the overall demand matrix and the global output matrix even if the log prices are adjusted according to stem data without estimation errors. FOR. SCI. 50(5):696–710.

Surrogate Pheromone Plumes in Three Forest Trunk Spaces: Composite Statistics and Case Studies - Harold W. Thistle; Holly Peterson; Gene Allwine; Brian Lamb; Tara Strand; Edward H. Holsten; Patrick J. Shea (Forest Science, 2004)
An atmospheric tracer gas was used as a pheromone surrogate to study near-field canopy dispersion within the trunk space. The objective is to improve guidance for forest managers deploying bark beetle antiaggregation pheromone sources to protect high-value forest stands. Data are shownfrom field studies in three forest canopies (oak-hickory, Quercus-Carya; lodgepole pine, Pinus contorta Dougl. ex Loud.; and ponderosa pine, Pinus ponderosa Dougl. ex Laws.) and include over 13,000 chemical tracer samples compiled into half-hour dispersion fields arounda point source. Maximum normalized concentrations (χ/Q) at each arc distance for each sampling period were of similar order at 5 m from the tracer source in the three canopies, although the differences in maximum χ/Q between canopies increased with distance from thesource. Plume dilution was highest in this study in the more open ponderosa pine canopy. A high-frequency tracer gas analyzer was also deployed to ascertain the structure of the gas plumes at 1 Hz. The high-frequency tracer data showed that the 30-minute average mean plumes are compositesof narrow filamentous plumes. The near-field plumes in each canopy were strongly affected by changes in atmospheric stability, as wander range and meander frequency increased after the morning transition to an unstable boundary layer. FOR. SCI. 50(5):610–625.

Effect of Selfing on Various Economic Traits in Pinus radiata and Some Implications for Breeding Strategy - S. Kumar (Forest Science, 2004)
Selfed and outcrossed progenies of 41 Pinus radiata plus trees were obtained from two separate studies to evaluate the effect of inbreeding on economic traits such as diameter, bole straightness, branching, wood density, and Dothistroma infection at the selection age and at theharvest age. The possibility of using selfed families for estimation of genetic parameters and future breeding was investigated. For diameter, inbreeding depression (ID) varied between 13 and 17% at different ages across different sites. An ID of about 13% and −3.0%was obtained for straightness and wood density, respectively. For Dothistroma, the pattern of ID at different ages was not consistent across different environments. There was generally a close agreement, for all traits except diameter, between estimates of narrow-sense heritability obtainedfrom selfed and outcrossed progenies. Estimated correlations between predicted breeding values at different ages were higher for selfed families compared to outcrossed families, indicating that early selection would be more effective among selfed families than among outcrossed families. Forall traits except diameter growth, ranking of parents on selfed performance was highly correlated with outcrossed performance at the selection age. This study showed that selection on selfs (even after culling of less vigorous individuals at the nursery stage) would not be effective for diametergrowth, but it might be a reasonably good strategy for form traits, Dothistroma resistance, and wood density. FOR. SCI. 50(5):571–578.

Corrections (Forest Science, 2004)

Book Reviews: Forests in a Market Economy - Daowei Zhang (Forest Science, 2004)
Those of us who teach senior undergraduate and graduate level forest economics courses have often been frustrated with the fact that there is no good textbook for these courses. The publication of this book may ease some of the frustration. Moreover, as the book title implies, it can serve as a background and research guide for forest economists in studying the role of forests in a market economy.

Book Reviews: Conserving Forest Biodiversity: A Comprehensive Multiscaled Approach - John W. Groninger (Forest Science, 2004)
Landscape-level management, driven by conservation objectives, will undoubtedly continue to play a role in natural resource decisionmaking for the foreseeable future. A fundamental justification for landscape management is that reliance on designated protected areas and reserves alone is inadequate for the maintenance of forest biological diversity. According to the authors, management practices on unreserved, commodity-producing lands (referred to throughout this book as “the matrix”) will determine the success or failure of efforts to maintain forest biological conservation and forest health. This book makes the case for management at several scales to achieve these objectives within large, contiguous forest systems.

Aesthetic Impacts of Disturbances on Selected Boreal Forested Shorelines - Len M. Hunt; Wolfgang Haider (Forest Science, 2004)
This article investigates the aesthetic impacts of anthropogenic and fire disturbances on forested shorelines for most coniferous forest types of the boreal forest. The novel use of the psychophysical landscape-perception approach to near-vista-view shoreline settings makes this application unique. Evaluations of aesthetic quality by laypeople show that severe fire and clearcut-logging disturbances make the forested shorelines much less attractive when compared to undisturbed sites. The analysis also provides a detailed examination of the relationships between undisturbed and logged sites by investigating the relationship between reserve width (i.e., the amount of land that separates the shoreline from logging activities) and aesthetic quality. A regression model of aesthetic evaluations demonstrates that aesthetics is positively related to undisturbed sites, to reserve width, and to the slope of the land. An interaction term of the reserve width and slope of the land is negative, which suggests that the reserve width necessary to mitigate the effects of logging on flat lands is smaller than the reserve width needed to mitigate logging on steeper lands. The model can also be used for predictive purposes such as estimating a reserve width that may be necessary to mitigate all visual effects of logging on shoreline sites. FOR. SCI. 50(5):729–738.

A Generalized Methodology for Developing Whole-Stand Survival Models - Charles E. Rose; Michael L. Clutter; Barry D. Shiver; Daniel B. Hall; Bruce Borders (Forest Science, 2004)
A large source of variability in yield predictions is due to estimation of future surviving trees per unit area. Previous whole-stand survival modeling efforts have concentrated on modeling the empirical survival curve. Modeling hazard functions, an approach to survival analysis commonly used in fields such as medicine and sociology, can be applicable to plantation survival estimation. We offer a generalized method for deriving whole-stand survival models that are capable of modeling complex underlying hazard functions. We use our knowledge of the empirical hazard function to limit our selection to appropriate functions. Integrating selected functions results in initial condition difference equations that, when fitted to our data, provide biologically reasonable whole-stand survival predictions and adequately represent the underlying hazard function. Our method is relatively easy to implement and can model a whole-stand survival curve with a complex underlying hazard function. FOR. SCI. 50(5):686–695.

Predicting Parameters of a Weibull Function for Modeling Diameter Distribution - Quang V. Cao (Forest Science, 2004)
The Weibull function has been widely used to characterize diameter distributions in a forest stand. Methods have been developed to predict the Weibull parameters, either directly or indirectly, from stand age, density, and dominant height. In this study, four existing methods and twonew methods of obtaining the Weibull parameters were evaluated using data from a loblolly pine (Pinus taeda L.) plantation. While both new methods performed well, one of them produced consistently better goodness-of-fit statistics than those from the existing methods. FOR. SCI. 50(5):682–685.

Some Theory for the Application of the Moving Average Estimator in Forest Surveys - Devin S. Johnson; Michael S. Williams (Forest Science, 2004)
The Forest Inventory and Analysis (FIA) and National Resources Inventory programs are two examples of large-scale survey programs that are in the process of moving from periodic surveys, where data for an area are collected once every 10–15 years, to annual surveys, where a smallersample of the data is collected every year. Each yearly sample can be referred to as a panel, and yearly estimates can be made with the data in each panel. With the change from periodic to annual surveys, there has been a substantial amount of discussion related to combining the data fromthe individual panels into a single estimator with an acceptably small mean square error. Numerous methods, each with certain advantages and disadvantages, have been proposed and tested. Testing with FIA data suggests that, in terms of mean square error, the equally weighted moving averageestimator is often as good as or better than other estimators when making estimates for individual counties or small groups of counties. This favorable performance is due to the relatively small sample sizes in these situations. One area of research that has not been addressed is the performanceof the moving average estimator when the sampling design deviates from its original protocol. Factors that cannot be controlled, such as weather, budgets, and politics, can alter the original sampling design. The purpose of this article is to propose and derive estimators that accommodatethese factors and give some guidelines on how to handle these situations when they occur. FOR. SCI. 50(5):672–681.

Sustainability of Timber Supply Considering the Risk of Wildfire - Glen W. Armstrong (Forest Science, 2004)
The boreal mixedwood forest of Alberta, Canada is an important timber-producing region subject to highly variable annual disturbance by wildfire. Existing timber supply models do not adequately capture the variation in annual area burned. This article presents a procedure to evaluatethe joint effects of harvest levels and wildfire on the sustainability of timber harvest. A Monte Carlo simulation model is developed that incorporates timber harvesting, forest fires, and replanning. The output of the model consists of projected distributions of sustainable harvest levelsgenerated by a linear programming-based timber supply model in response to specified harvest volumes and randomly generated burn areas. Because of the highly variable nature of the fire regime, it is difficult or impossible to set a harvest level that is perpetually sustainable with completecertainty. An alternative definition of sustainability is developed incorporating probabilities and time. At any point in time, a harvest level is considered sustainable if the probability of the harvest level exceeding the annual allowable cut is less than an acceptable level. FOR. SCI. 50(5):626–639.

Small-Mammal Relationships with Down Wood and Antelope Bitterbrush in Ponderosa Pine Forests of Central Oregon - Troy G. Smith; Chris C. Maguire (Forest Science, 2004)
The influence of down wood on fire behavior in ponderosa pine (Pinus ponderosa) forests in central Oregon is much understood. However, little is known about down-wood affiliations with wildlife in this area. Antelope bitterbrush (Purshia tridentata) contributes to wildfires, nitrogen fixation, and the food web, yet its influence on small-mammal populations remains poorly defined. In this study, population density, survival, and reproductive status of yellow-pine chipmunks (Tamias amoenus), golden-mantled ground squirrels (Spermophilus lateralis), and deer mice (Peromyscus maniculatus) are estimated under three down-wood and shrub-cover conditions in ponderosa pine/antelope bitterbrush forests of Oregon. The odds for golden-mantled ground squirrel survival are 4.2 times greater on units with high (x¯ = 117.8 m3/ha) versus low down-wood volume (x¯ = 15.8 m3/ha), and each 35.1-m3/ha increase in down wood coincides with a 10% increase in ground squirrel density. Yellow-pine chipmunk densities are 57% higher on units with high (x¯ = 31.2%) versus low total shrub cover (x¯ = 9.2%), and 4.4 and 2.3% increases in total shrub and live bitterbrush cover, respectively, coincide with 10% increases in chipmunk density. Deer mouse populations are little affected by down-wood volume or shrub cover. Study results suggest that management activities influencing down wood or bitterbrush will likely affect the composition of small-mammal communities through population changes in one or more small-mammal species. FOR. SCI. 50(5):711–728.

Modeling the Likelihood of Crown Fire Occurrence in Conifer Forest Stands - Miguel G. Cruz; Martin E. Alexander; Ronald H. Wakimoto (Forest Science, 2004)
The unknowns in wildland fire phenomenology lead to a simplified empirical model approach for predicting the onset of crown fires in live coniferous forests on level terrain. Model parameterization is based on a data set (n = 71) generated from conducting outdoor experimentalfires covering a significant portion of the spectrum of burning conditions associated with the initiation of crown fires. A logistic model is developed to predict the likelihood of crown fire occurrence based on three fire environment variables, namely the 10-m open wind speed, fuel stratagap (equivalent to live crown base height in some stands), estimated moisture content of fine dead fuels, and one fire-behavior descriptor–surface fuel consumption. The model correctly predicts 85% of the cases in the data set used in its development, and the receiver operatingcharacteristic statistic is 0.94. The model is evaluated for its sensitivity to its inputs, and its behavior is compared with other models used in decision support systems to operationally predict crown fire initiation. The results of a limited test of the model against two independent experimentalfire data sets for distinctly different fuel complexes is encouraging. FOR. SCI. 50(5):640–658.

Note—Foliage-Sapwood Area Equations for Balsam Fir Require Local Validation - Daniel W. Gilmore; Robert S. Seymour (Forest Science, 2004)
The foliage-sapwood area relationship (AL/AS) for balsam fir has been described in three separate studies with no less than four regression model forms. While there are clear differences in predicted AL values between the studies, it is not apparent if these differences are an artifact of the regression model form used or caused by regional differences in the AL/AS relationship. We extracted published AL and AS values from the literature to statistically determine the best model form to describe the AL/AS relationship. Using this model form, we then explicitly tested for regional differences in the AL/AS relationship. We found that a linear model using natural logarithmic transformations best satisfied the assumptions of least squares regression in describing the AL/AS relationship. Based on the published data, there may be regional differences in the AL/AS relationship for balsam fir. FOR. SCI. 50(4):566–570.

A Cost-Efficient Approach to Selecting Forest Stands for Conserving Species: A Case Study from Northern Fennoscandia - Artti Juutinen; Erkki Mäntymaa; Mikko Mönkkönen; Juha Salmi (Forest Science, 2004)
We analyze cost-efficient conservation of boreal old-growth forests using three variants of the site selection framework. In all variants, the aim is to maximize biodiversity subject to a given resource constraint. Our benchmark, an integrated site selection model, takes into account both ecological and commercial values of the stands and defines a cost-efficient solution to conservation problems. The other two models are called the ecological and the penny-pincher models. The ecological model reflects current conservation practices and is based on ecological criteria. The penny-pincher model reflects an ad hoc preservation used earlier in many countries, which leads to selection of the stands having the lowest commercial value irrespective of their ecological features. Using Finnish data on forest dwelling species and commercial values of the stands, we demonstrate that the integrated model leads to 9–19% higher conservation cost-efficiency than the other two models. We also show that the xeric forest type may be underrepresented in the current old-growth forest preservation network in this region. FOR. SCI. 50(4):527–539.

Long-Term Soil Responses to Site Preparation Burning in the Southern Appalachians - Jennifer D. Knoepp; James M. Vose; Wayne T. Swank (Forest Science, 2004)
The mixed oak–pine ecosystems in the southern Appalachians are in decline because of a combination of drought and southern pine-beetle infestation. A commonly applied prescription for restoration of these degraded sites has been to fell all vegetation, allow it to dry, and conduct a site-preparation burn. However, there is little information on the mid- and long-term influences of this prescription on nutrient cycling. The fell-and-burn treatment was applied to three mixed oak–pine stands in the Nantahala National Forest in western North Carolina. Each stand had an untreated control area. Our objective was to determine the effects of this treatment on soil nutrient availability and potential nutrient loss. Exchangeable soil cations, pH, total carbon (C), and total nitrogen (N) were measured before and periodically for 5 years after treatment. Nitrogen transformations and nutrient availability in soil solution and in a stream draining one site were measured before and periodically for 3 years after burning. Exchangeable calcium and magnesium concentrations, soil pH, and N availability increased after treatment. There was no treatment effect on total soil C or N. Nitrogen mineralization rates were greater on burned versus control plots in 50% of the posttreatment measurements. This treatment increased nutrient availability and, although a significant amount of total site N was lost, there were no adverse effects on total soil nutrients or water quality. FOR. SCI. 50(4):540–550.

Short-Term Forecasting Models for the Finnish Forest Sector: Lumber Exports and Sawlog Demand - Lauri Hetemäki; Riitta Hänninen; Anne Toppinen (Forest Science, 2004)
Due to liberalization of capital and currency markets, globalization of the forest industry, and developments in information technology and logistics, the world's forest product markets have become more interrelated, and they react ever more quickly to changes in macroeconomic conditions. Thus, short-term analysis and forecasting of forest product markets have also become more important. This article explains the framework for the system of short-term forecasting of the Finnish forest sector (MESU) using a case study. We present models and forecasts for short-term changes in the lumber import demand in Germany, how this affects forecasts for Finnish lumber exports, and in turn, how these exports affect forecasts for sawlog demand in Finland. Univariate and multivariate time series models are estimated using quarterly data from 1980:1 to 1996:4, and forecasts are computed for 1997:1 to 1998:4. Results show that the MESU system can be a helpful tool for forecasting short-term changes in the Finnish forest sector. FOR. SCI. 50(4):461–472.

Relative Growth Trend as an Early Selection Parameter in a Douglas-Fir Provenance Test - Rafael Zas; Esther Merlo; Raquel Díaz; Josefa Fernández-López (Forest Science, 2004)
Height data from 89 Douglas-fir provenances planted at seven sites in northern Spain were used to explore and discuss the utility of the relative height growth trend as an early selection parameter. Total height was measured at each site at different ages between 2 and 18 years after planting. A modification of the joint regression analysis was used to analyze and interpret the provenance × age interaction at each site. The analyses of variance showed a significant provenance × age interaction in five out of the seven sites. Most of this interaction at these sites was explained by the linear relation over years between the provenance mean height at each site and the overall site mean height. The relative growth trend was defined as the slope of these linear relations for each provenance and was considered as a temporal stability parameter. Both the high genetic variability and the biological significance of this parameter suggest its applicability in early selection. A strong linear relationship was observed between this growth parameter and the initial provenance mean height at all sites where provenance × age interaction was significant except one. This relationship indicates that the differences between provenances at an early stage will hold up and be amplified in future measurements, and then there is a relative security of early selection. One site showed no significant relation between the relative growth trend and the initial performance. At this site, rank changes among measurements are likely to be more frequent, and early selection becomes harder. The use of the relative growth trend as an early selection parameter in these sites improves the early selection efficiency. The results suggest that the relative growth trend can help in both the early selection and the evaluation of the early selection efficiency. FOR. SCI. 50(4):518–526.

Area-Independent Sampling for Total Basal Area - James W. Flewelling; Kim Iles (Forest Science, 2004)
An unbiased direct estimator of total basal area for a stand is presented; stand area need not be known. Sampling can use horizontal point samples or fixed-area plots distributed on a regular grid or randomly selected. The sample space extends beyond the stand boundary. The estimator for basal area makes no distinction between plots whose centers are interior to the stand boundary and plots whose centers are outside. Only trees within the stand boundary are tallied. For horizontal point sampling, the estimator is the product of the sample tree count, the basal area factor, and the area per grid point, with the latter being derived from grid spacing. This method avoids the complexities associated with most other estimators designed to minimize or eliminate edge bias. The proposed method may require more sample points to achieve the same level of precision as competing estimators. FOR. SCI. 50(4):512–517.

Forest and Rangeland Ecosystem Condition Indicators: Identifying National Areas of Opportunity Using Data Envelopment Analysis - John Hof; Curtis Flather; Tony Baltic; Rudy King (Forest Science, 2004)
This article reports the methodology and results of a data envelopment analysis (DEA) that attempts to identify areas in the country where there is maximum potential for improving the forest and rangeland condition, based on 12 indicator variables. This analysis differs from previous DEA studies in that the primary variables are measures of human activity and indicators of forest and rangeland condition in place of the traditional economic inputs (costs) and outputs. It also involves a different (ecological) production process than traditional DEA analyses, and a statistical preanalysis is developed and applied to homogenize the large and highly diverse landscape where this ecological production process takes place for the purposes of the DEA. It is concluded that, based on this analysis, there are opportunities to improve the forest and rangeland condition without reducing the amount of human activity, but not over large areas, only for some indicators, and typically not for a large number of indicators in the same place. This means that large-scale improvements in environmental condition across many indicators may often not come about without a reduction in human activity. FOR. SCI. 50(4):473–494.

Softwood Lumber Products in the United States: Substitutes, Complements, or Unrelated? - Rao V. Nagubadi; Daowei Zhang; Jeffrey P. Prestemon; David N. Wear (Forest Science, 2004)
This study addresses an important dimension concerning the softwood lumber trade dispute between United States and Canada–substitutability among imported and domestically produced species. We employ the restricted translog subcost function approach to study this issue based on the monthly data of US softwood products consumption and prices between Jan. 1989 and July 2001. The results show that the spruce-pine-fir lumber species group, mainly imported from Canada, is largely unrelated to domestically produced treated southern yellow pine, Douglas-fir, and other species groups, but is a substitute to untreated southern yellow pine and engineered wood products. Furthermore, untreated southern yellow pine is facing more severe competition from structural panels rather than from the imported Canadian spruce-pine-fir group. FOR. SCI. 50(4):416–426.

Forest Parameters Estimation in a European Mediterranean Landscape Using Remotely Sensed Data - George Mallinis; Nikos Koutsias; Apostolos Makras; Michael Karteris (Forest Science, 2004)
Satellite remote sensing provides new possibilities and challenges to forest managers for monitoring and managing forest ecosystems. The value/use of high-resolution satellite data of Landsat Thematic Mapper (TM) to estimate tree density, basal area, basal volume, and forest biomass was investigated under an operational perspective in a spatially heterogeneous Mediterranean landscape in northern Greece. Digital classification using Fisher's linear discriminant functions produced an overall accuracy of 82%. A series of multispectral transformations were also performed, and the derivative synthetic channels were used along with the original ones as explanatory variables in the model developed. The forest stand parameters that were investigated in the study presented a similar but weak correlation with the Landsat-5 TM spectral channels. Among them, TM4 and TM7 presented the highest correlation with forest stand parameters, while the integration of the derivative synthetic channels increased the correlation coefficients and resulted in statistically significant predictive models. FOR. SCI. 50(4):450–460.

A Walkthrough Solution to the Boundary Overlap Problem - Mark J. Ducey; Jeffrey H. Gove; Harry T. Valentine (Forest Science, 2004)
Existing methods for eliminating bias due to boundary overlap suffer some disadvantages in practical use, including the need to work outside the tract, restrictions on the kinds of boundaries to which they are applicable, and the possibility of significantly increased variance as a price for unbiasedness. We propose a new walkthrough method for reducing boundary overlap bias that diminishes or eliminates the need to work outside the tract and accommodates irregular boundaries easily. Under typical conditions, the walkthrough method eliminates the boundary overlap bias associated with most objects near the border and reduces it for the remaining objects. The walkthrough method is object-centered in conception and implementation, but the measurements required are simple. The walkthrough method complements existing methods for correcting boundary overlap bias and should prove especially helpful when conditions make existing methods difficult or impossible to use. FOR. SCI. 50(4):427–435.

Fusion of Small-Footprint Lidar and Multispectral Data to Estimate Plot- Level Volume and Biomass in Deciduous and Pine Forests in Virginia, USA - Sorin C. Popescu; Randolph H. Wynne; John A. Scrivani (Forest Science, 2004)
The principal study objective was to explore the feasibility of using small-footprint lidar data and multispectral imagery to estimate forest volume and biomass on small (0.017-ha) plots. In addition, the spatial dependency of residuals between ground-measured and lidar-estimated variables was investigated. The lidar data set was acquired over deciduous and pine stands in the southeastern United States. Individual trees were identified on the lidar-derived canopy height model by local maximum focal filtering with both square and circular windows of variable size. The size of the dynamically varying window was based on the height of the canopy and the taxonomic group as derived from coregistered multispectral optical data. Lidar-measured parameters at an individual tree level (height, crown diameter) were used with regression models and cross validation to estimate plot-level field inventory data, including volume, biomass, basal area, and diameter at breast height (dbh). Maximum R2 values for estimating biomass were 0.32 for deciduous trees (RMSE 44 Mg/ha) and 0.82 for pines (RMSE 29 Mg/ha). When estimating volume, maximum R2 values for deciduous trees were 0.39 (RMSE 52.84 m3/ha) and 0.83 for pines (RMSE 47.9 m3/ha). Calculation of Moran's I coefficient for each regression model revealed a lack of significant autocorellation of the residuals at 0.05 level. Both model fit and prediction for volume and biomass models for deciduous and pine plots indicated that the circular window shape is more appropriate to locate individual trees with lidar. Using the fused data set, lidar and optical imagery, as opposed to using lidar data alone, always improved biomass and volume estimates for pines and in some cases for deciduous plots as well. FOR. SCI. 50(4):551–565.

Market Dynamics and Optimal Timber Salvage After a Natural Catastrophe - Jeffrey P. Prestemon; Thomas P. Holmes (Forest Science, 2004)
Forest-based natural catastrophes are regular features of timber production in the United States, especially from hurricanes, fires, and insect and disease outbreaks. These catastrophes affect timber prices and result in economic transfers. We develop a model of timber market dynamics after such a catastrophe that shows how timber salvage affects the welfare of different market groups and quantifies the impacts of salvage on product markets. A theoretical framework is developed that explores how government spending to mitigate economic losses through salvage is related to the costs of intervention. Using empirical price and quantity parameters derived for Hurricane Hugo as an example, we simulate how alternative levels of salvage would have affected southern pine timber prices and economic surplus. Results show that for this large-scale disturbance, the economic surplus generated by salvage averaged $6.25 million for each percentage change in the volume of salvaged timber up to the observed salvage rate (∼16%). Consumers benefited by an average of $5.4 million for each percent of the damaged timber that was salvaged, producers of salvaged timber benefited by $6.4 million for each percent salvaged, and producers of undamaged timber lost an average of $5.6 million for each percent salvaged. Sawtimber salvage yielded welfare benefits for each cubic meter averaging more than four times those generated by pulpwood. These results therefore have implications for strategic salvage planning following catastrophic damage to forests. FOR. SCI. 50(4):495–511.

Tree Size Distribution Functions of Four Boreal Forest Types for Biomass Mapping - Wenjun Chen (Forest Science, 2004)
To accurately map forest biomass, which is essential for many socioeconomic and environmental studies, reliable information of tree size distribution within a stand is needed. Using measurements at 87 stands of trembling aspen (Populous tremuloides Michx.), jack pine (Pinus banksiana Lamb.), black spruce (Picea mariana [Mill.] BSP.), and mixed forests along a 1,000-km boreal forest transect in western Canada, we investigated three methods for estimating tree size distribution: parameter prediction method for diameter-frequency distribution (PPM-Nk/N), PPM for diameter-basal area distribution (PPM-Bk/B), and parameter recovery method for diameter-frequency distribution (PRM). For diameter-frequency distribution estimation, the PPM-Nk/N and the PRM were more accurate than PPM-Bk/B. For biomass estimation, the PPM-Bk/B and the PRM were found to have mean estimation errors <3% and root mean square errors <10%, relative to the “true” values given by summation overall trees, but the PPM-Nk/N didn't perform as well. Three distribution functions (i.e., the Weibull, the Johnson's SB, and the lognormal) were used for each method but were found to make little difference in method performance. An additional test indicated that the PPM-Bk/B and the PRM performed equally well for a balsam fir (Abies balsamea [L.] Mill) stand in eastern Canada. FOR. SCI. 50(4):436–449.

Juvenile Versus Mature Wood: A New Concept, Orthogonal to Corewood Versus Outerwood, with Special Reference to Pinus radiata and P. taeda - Rowland D. Burdon; R. Paul Kibblewhite; John C. F. Walker; Robert A. Megraw; Robert Evans; David J. Cown (Forest Science, 2004)
Wood properties vary within stems of trees according to genera, species, and individuals. Such variation is largely systematic and is very pronounced in many pines, notably Pinus radiata and P. taeda. While gradual transitions predominate, there are practical needs for categorizing wood, in cutting stems to log lengths, followed by sorting and segregation for processing. Even radial segregation of wood is often possible. In such pines, there are strong, widely recognized progressions, in various wood properties, from pith to bark. Based largely on variation in density, the first few rings from the pith are widely termed juvenile wood, which intergrades outward into wood termed mature wood. Alternative terminology used for this radial progression has been from corewood into outerwood. Critical examination shows the juvenile versus mature wood terminology to be inadequate, on two counts: (1) various other wood properties, some of which can be important, show substantial axial variation at equal ring number from the pith; (2) this categorization based solely on radial variation does not fit the well-established botanical concept of maturation. However, this axial variation closely parallels the vertical variation in shoot morphology and the onset of reproduction that reflect maturation. This argues for a two-dimensional characterization of wood properties: juvenility versus maturity for the progression up the stem, and corewood versus outerwood for the radial progression from the pith to bark. FOR. SCI. 50(4):399–415.

Spatial Relationship of Biomass and Species Distribution in an Old-Growth Pseudotsuga-Tsuga Forest - Jiquan Chen; Bo Song; Mark Rudnicki; Melinda Moeur; Ken Bible; Malcolm North; Dave C. Shaw; Jerry F. Franklin; Dave M. Braun (Forest Science, 2004)
Old-growth forests are known for their complex and variable structure and function. In a 12-ha plot (300 m × 400 m) of an old-growth Douglas-fir forest within the T. T. Munger Research Natural Area in southern Washington, we mapped and recorded live/dead condition, species, and diameter at breast height to address the following objectives: (1) to quantify the contribution of overstory species to various elements of aboveground biomass (AGB), density, and basal area, (2) to detect and delineate spatial patchiness of AGB using geostatisitcs, and (3) to explore spatial relationships between AGB patch patterns and forest structure and composition. Published biometric equations for the coniferous biome of the region were applied to compute AGB and its components of each individual stem. A program was developed to randomly locate 500 circular plots within the 12-ha plot that sampled the average biomass component of interest on a per hectare basis so that the discrete point patterns of trees were statistically transformed to continuous variables. The forest structure and composition of low, mediate, and high biomass patches were then analyzed. Biomass distribution of the six major species across the stand were clearly different and scale- dependent. The average patch size of the AGB based on semivariance analysis for Tsuga heterophylla, Abies amabilis, A. grandis, Pseudotsuga menziesii, Thuja plicata, and Taxus brevifolia were 57.3, 81.7, 37, 114.6, 38.7, and 51.8 m, respectively. High biomass patches were characterized by high proportions of T. heterophylla and T. plicata depending on spatial locations across the stand. Low AGB patches had high densities of A. amabilis and T. brevifolia. We presented several potential mechanisms for relating spatial distribution of species and biomass, including competition, invasion and extinction, disturbance, and stand dynamics. Clearly, future studies should be developed to examine the details of how each process alters the spatial patterns of tree species with sound experimental designs and long-term monitoring processes at multiple scales. FOR. SCI. 50(3):364–375.

Crown Cover Is Correlated with Relative Density, Tree Slenderness, and Tree Height in Lodgepole Pine - Mark Rudnicki; Uldis Silins; Victor J. Lieffers (Forest Science, 2004)
The objective of this study was to investigate the relationship between tree height, bole slenderness, and relative density with crown shyness (crown interstitial space) in even-aged lodgepole pine. In 10 lodgepole pine stands in Alberta, Canada, ranging in height from 5.6 to 22.1 m, 9–23 triangular plots were established. A plot consisted of three trees that formed the corners of the triangle; all plots were at theoretical crown closure. Within each triangle, the percentage crown closure (% CC) was related to the mean height, slenderness coefficient (SC, tree height/diameter), and relative density (RD) of the trees that defined the triangle. Within the stands less than 12 m in height, % CC was positively correlated with RD. Within most of the stands greater than 15 m, % CC was negatively correlated to SC. Mean % CC declined with increasing stand height. Results suggest that RD is strongly related to % CC in short stands but as trees grow in height, biomechanical issues related to stem form (i.e., SC) probably play a large role in determining the amount of canopy coverage. We suggest that taller trees with high SC are more flexible, resulting in intense crown collisions, crown abrasion, and crown shyness. FOR. SCI. 50(3):356–363.

Three-Dimensional Canopy Structure of an Old-Growth Douglas-Fir Forest - Bo Song; Jiquan Chen; Janet Silbernagel (Forest Science, 2004)
In this study, the structurally heterogeneous canopy of a 12-ha plot in an old-growth Douglas-fir forest was analyzed using three-dimensional (3-D) canopy modeling, geographic information system (GIS), and spatial statistics. Using this approach, we were able to depict how species composition and spatial distribution affect the 3-D structure of canopies. We were also able to slice the canopy and calculate the canopy coverage at various heights, and therefore were able to calculate the cumulative canopy volume at individual crown bases. Information generated by GIS allowed us to calculate how much area canopies or canopy openings occupy. Total canopy volume (243,641 m3/ha) was dominated by western hemlocks (67.1%) and Douglas-firs (23.7%) in this plot. Western hemlocks and Douglas-firs also dominated the canopy coverage, with 65.7% and 25.5% average coverage, respectively. Average total canopy coverage was 84.3% with variations between 78.7% and 89.9% among the 12 1-ha subplots, implying that 15.7% of the stand consisted of canopy openings. Coverage of the canopy projection changed greatly from the lower to the upper canopy layers, with the maximum at about 20 m high. We also examined spatial relationships among groups of trees at different heights and at various scales using bivariate Ripley's K analysis. We found that different species of the understory layer showed different spatial relationships relative to the overstory canopy layer. Likewise the same species in the understory layer showed different spatial relationships when the overstory species differed. This approach provided a useful tool for characterizing 3-D forest canopies, and the results will be very helpful for examining leaf distribution, understory light environment, understory vegetation, and microclimate. FOR. SCI. 50(3):376–386.

The Distribution of Free Space and Its Relation to Canopy Composition at Six Forest Sites - Roman Dial; Benjamin Bloodworth; Andrew Lee; Patrick Boyne; Jeffrey Heys (Forest Science, 2004)
Forest canopy free space, element density (clutter), and the distribution and relative abundance of coarse canopy elements were measured at six sites: two boreal (south-central Alaska), two temperate (Washington State and Victoria, Australia), and two tropical (Pacific Costa Rica and Malaysian Borneo). Great clutter, high relative abundance of dead elements, and shallow understory characterized boreal canopies. Presence of dead elements and deep understory characterized temperate sites, sharing clutter profiles that differed in magnitude but not shape from each other. Few dead elements, little obvious zonation, and constant, mid-canopy clutter characterized tropical sites. The neotropical site showed a clear overstory, while the paleotropical site did not. The results motivate three hypotheses: (1) forest canopies of similar latitude and climate have similar structure; (2) canopy zones form cohesive, repeatable structures as “understory” (near-ground nondominant vegetation bounding small free-spaces), “overstory” (high, dominant foliage bounding small free-spaces), “bole zone” (mid-canopy boles bounding the largest free spaces), and “dead zone” (unique to conifer sites and typified by dead elements and upwardly narrowing free-spaces above bole zone); and (3) Australian and paleotropical canopies, regions rich in vertebrate gliders, are an order of magnitude more open (less cluttered) than neotropical and North American canopies, regions poor in gliders. FOR. SCI. 50(3):312–325.

Development of Canopy Structure in Pseudotsuga menziesii Forests in the Southern Washington Cascades - Robert Van Pelt; Nalini M. Nadkarni (Forest Science, 2004)
We quantified stand-level structural diversity in eight stands of temperate coniferous forests that ranged in age from 50 to 950 years in the southern Washington Cascade Range. Stands were chosen based on the dominance, or former dominance in the case of the oldest stands, of Pseudotsuga menziesii. In addition, to avoid confusing patterns of structural development, only stands that had a single disturbance of origin were used. Within each stand, randomly located transects were laid out that were proportional in size to the dominant tree height. Tree heights and diameters ranged up to 90 m and 309 cm, respectively. A total of 5,737 trees among the 32 transects were mapped and measured for height, diameter, crown height, and four crown radii. The structure of the canopy in the younger stands is a simple, fairly even monolayer. This contrasts with the older stands, which have a very complex, highly diffuse canopy with extreme variability in both horizontal and vertical dimensions. The stands with the highest structural complexity were between 500 and 650 years old and retained from 17 to 76 Pseudotsuga stems/ha. Our oldest site had only one living Pseudotsuga/ha. Mean diameter of just the Pseudotsuga trees was less than 55 cm for stands less than 200 years and over 180 cm for the most complex old-growth stands. One measure of stand structural diversity, the standard deviation of dbh, ranged from less than 25 (stands less than 200 years) to values greater than 50 (most complex old-growth sites). A similar relationship exists when using the standard deviation of height. Large snags and logs important for wildlife were present only in the old-growth stands and were abundant in the most structurally diverse stands. FOR. SCI. 50(3):326–341.

Old-Growth Forest Canopy Structure and Its Relationship to Throughfall Interception - Nalini M. Nadkarni; Mark M. Sumera (Forest Science, 2004)
Structural elements of the forest canopy such as foliage, branches, and epiphytes intercept, retain, and regulate inputs of matter and energy to the forest floor in spatially variable ways. Most studies of forest structure-function have analyzed relationships between canopy structure and the spatial distribution of inputs at the forest stand level. Few studies have focused on within-canopy spatial scales or identified the functional roles of particular structural components. Our objective was to quantitatively assess the amount of canopy structural material to a critical functional attribute: canopy interception of rainfall. We investigated forest canopy structure with a novel technique, “vertical canopy cylinder transects,” that uses access from a construction crane in an old-growth coniferous forest in Washington State. We characterized the diversity and composition of forest structural elements (tree foliage and branches by species, epiphytes by functional group) and found the majority of the foliage and epiphytes concentrated in the upper- to mid-canopy, with some vertical stratification of the epiphyte functional groups. We also quantified one aspect of forest function, the volume and variability of throughfall interception. We documented a strong relationship between the amount of structural elements and rainfall interception (R2 = 0.79). This approach of quantifying three-dimensional canopy structure at particular locations had higher predictive ability for throughfall volume than previous approaches that were not able to gain direct access to canopy components. FOR. SCI. 50(3):290–298.

Importance of Foliar Nitrogen Concentration to Predict Forest Productivity in the Mid-Atlantic Region - Yude Pan; John Hom; Jennifer Jenkins; Richard Birdsey (Forest Science, 2004)
To assess what difference it might make to include spatially defined estimates of foliar nitrogen in the regional application of a forest ecosystem model (PnET-II), we composed model predictions of wood production from extensive ground-based forest inventory analysis data across the Mid-Atlantic region. Spatial variation in foliar N concentration was assigned based on a correlation with mean July temperature for deciduous forests and with latitude for coniferous forests. Although the slight variation observed in foliar N in conifers had little effect on predicted wood production, large differences in N concentration in deciduous trees increased agreement with field surveys by 12–59% in individual states and by 17% across the region. The validation revealed the need to develop regional foliar N concentration equations that represent the spatial variations of N concentration in deciduous forests to improve PnET-II's predictions. FOR. SCI. 50(3):279–289.

Introduction to Special Issue on Canopy Research - Edwin J. Green (Forest Science, 2004)

Structural Phenology of the Leaf Community in the Canopy of a Liriodendron tulipifera L. Forest in Maryland, USA - Geoffrey G. Parker; Donna J. Tibbs (Forest Science, 2004)
We measured the vertical dynamics of leaf area in a tall, tulip poplar (Liriodendron tulipifera)-dominated, deciduous forest on the Maryland coastal plain over three growing seasons (one intensively) using nondestructive, ground-based observations. Leaf area index (LAI) and leaf area density (LAD) were calculated by vertical level, time, and species; the time-integrated duration of leaf display (leaf area extent, LAE) was estimated by species and vertical level. In this stand LAI rises rapidly in the spring, declines slightly during the growing season, and then rapidly in the fall. In the intensively studied year, total LAI peaked at 7.1 m2m-2 LAE was 1259 m2m-2day, and the length of the canopy season (time from half-maximum LAI at leaf-out to the half-maximum at decline) was 191 days. The maximum growing season LAI, the date of leaf emergence, and the LAE differed among years, ranging 0.61 m2m-2, 14 days, and 261 m2m-2day, respectively. However, the timing of leaf fall was more consistent, ranging only 6 days. Each species differs in its height distribution, density, and timing of foliar display. In the canopy, leaf number, area, and duration are the bases of species importance; these differ substantially by species from typical importance values derived from stem-based attributes (density, basal area, biomass). FOR. SCI. 50(3):387-397.

Exploring the Relationships Among Canopy Structure, Stand Productivity, and Biodiversity of Temperate Forest Ecosystems - Hiroaki T. Ishii; Shin-ichi Tanabe; Tsutom Hiura (Forest Science, 2004)
Impacts of human activity on forest ecosystems are most pronounced in the temperate region. Simplification of stand structure has resulted in diminished ecosystem function and biodiversity decline, raising much debate over future management policies. Ecosystem functions and biodiversity may be enhanced by managing forests for increased structural complexity. However, processes that determine relationships among structural complexity, ecosystem functions, and biodiversity of forest ecosystems remain unclear. In this review, we present examples of studies conducted at two canopy research facilities located in different types of temperate forest to illustrate that structural complexity of forest canopies enhances stand productivity and biodiversity: (1) development of structurally complex canopies comprising various tree species enhances stand productivity by promoting complementary resource utilization among species through spatial, physiological, and temporal differentiation; and (2) development of complex canopy structure enhances biodiversity of canopy-dwelling organisms by creating a resource-rich habitat. These ecological observations stress the importance of including three-dimensional structural attributes of forest canopies in management plans and silvicultural prescriptions that aim to maintain ecosystem functions and biodiversity. FOR. SCI. 50(3):342–355.

Forest Stand Structure and Pattern of Old-Growth Western Hemlock/Douglas-Fir and Mixed-Conifer Forests - Malcolm North; Jiquan Chen; Brian Oakley; Bo Song; Mark Rudnicki; Andrew Gray; Jim Innes (Forest Science, 2004)
With fire suppression, many western forests are expected to have fewer gaps and higher stem density of shade-tolerant species as light competition becomes a more significant influence on stand pattern and composition. We compared species composition, structure, spatial pattern, and environmental factors such as light and soil moisture between two old-growth forests: Pacific Northwest western hemlock/Douglas-fir at the Wind River Canopy Crane Research Facility exhibiting gap-phase replacement and southern Sierra Nevada mixed conifer at the Teakettle Experimental Forest after 135 years without a fire. We hypothesized that fire suppression at Teakettle would create a current tree composition and distribution more like Wind River where light is an important influence on stand dynamics. Wind River has nearly continuous canopy cover and a high foliage volume that severely reduces understory light and stratifies the canopy composition by shade tolerance. Large trees are regularly spaced from 0 to 15 m and shade-tolerant and intolerant species are “repelled.” In contrast, Teakettle's canopy cover is discontinuous, foliage volume is one-fifth that of Wind River, and understory light is 15 times higher. Trees at Teakettle are significantly clustered in groups containing a mix of shade-tolerant and -intolerant species, separated by large gaps. Although Teakettle's gaps have higher moisture and a thinner litter layer than tree groups, regeneration in gaps is scarce. Fire suppression has increased stem density at Teakettle but it has not filled in gaps, stratified the canopy by shade tolerance, or produced a composition consistent with patterns at Wind River. Teakettle's distinctly clustered stem distribution may result from a minimum canopy cover threshold needed for tree establishment. If high temperatures produced by direct sunlight inhibit stem patterns, traditional stand management that reduces canopy cover to release regeneration should be applied with caution in the southern Sierra Nevada. FOR. SCI. 50(3):299–311.

Book reviews: Ecology and Control of Introduced Plants - Christopher R. Webster (Forest Science, 2004)
Intentional and unintentional introductions of exotic organisms have become commonplace in our increasingly global society. While many of these introductions have been benign, others have significantly altered native ecosystems and posed insurmountable challenges to agriculture, forestry, and the conservation of biological diversity worldwide.

Book Reviews: Wildlife of Southern Forests: Habitat & Management - Debbie L. Miller (Forest Science, 2004)
Wildlife of Southern Forests: Habitat and Management consolidates within one volume a plethora of information concerning wildlife and wildlife management in southern forests. The intended audience, land managers, will appreciate the one-stop shopping for detailed biological information coupled with practical guidelines for habitat management on a broad scale. This book succeeds in providing a complete, up-to-date overview of most areas of ecology and management important to wildlife in southern forests. Experts from universities, federal agencies, and conservation organizations of the South well qualified to write on their chosen topics author individual chapters. Most of the book is devoted to providing detailed, current information on life history traits and management strategies of individual species or suites of species.

Local Modeling of Tree Growth by Geographically Weighted Regression - Lianjun Zhang; Haijin Shi (Forest Science, 2004)
The spatial heterogeneity of multivariate relationships between tree growth and diameter is explored using geographically weighted regression (GWR). GWR attempts to capture spatial variation by calibrating a multiple regression model fitted at each tree in a sample plot, weighting all neighboring trees by a function of distance from the subject tree. GWR produces a set of parameter estimates and model statistics (e.g., model R2) for each tree in the sample plot. It is evident that the GWR model not only predicts individual tree growth better than the traditional ordinary least-squares model, but also provides useful information on the nature of the growth variation caused by neighboring competitors and surrounding environmental factors. The parameter estimates and model statistics of the GWR model can be mapped using visualization tools, such as geographic information systems (GIS), to illustrate local spatial variation in the regression relationship under study. Consequently, the influence of microsite variation, competition status, growth potential, and the impacts of management activities on trees can be evaluated, tested, modeled, and readily visualized. GWR is a useful tool that provides much more information on spatial relationships to assist in model development and further our understanding of spatial processes. FOR. SCI. 50(2):225–244.

Projecting Diameter Growth in Tropical Trees: A New Modeling Approach - Martin Ricker; Rafael del Río (Forest Science, 2004)
An important and heretofore unresolved challenge in forestry has been how to project long-term tree growth (i.e., decades to hundreds of years) from short-term measurements (here 1 year) for trees that do not present annual growth rings in their trunk wood. Such a method is crucial in the lowland tropics, where few long-term growth measurements have been taken, and where frequently trees lack reliable annual growth rings because of the lack of winters or highly seasonal dry periods. The new piecewise linear (PL) growth model, developed in this article, relates logarithmic relative growth to trunk diameter. Having obtained the coefficients from piecewise linear regression, the long-term age-diameter curve is calculated, i.e., the expected average growth curve of a statistical population of individual trees. The model is applied to the following five tree species without annual growth rings from the tropical rainforest in Los Tuxtlas (Veracruz, Mexico): Aspidosperma megalocarpon, Cordia alliodora, Dialium guianense, Guarea grandifolia, and Persea schiedeana. Using the tools of multiple linear regression, the PL model is highly flexible to derive sigmoid, exponential, and over-exponential growth separately for different diameter segments. FOR. SCI. 50(2):213–224.

Improving Taper Equations of Loblolly Pine with Crown Dimensions in a Mixed-Effects Modeling Framework - Laura P. Leites; Andrew P. Robinson (Forest Science, 2004)
A mixed-effects modeling framework was applied to Max and Burkhart's (1976) (MB) taper equation for loblolly pine (Pinus taeda L.). The advantages of such a strategy over ordinary least squares were: (1) more accurate specification of the correlation structure of the data and (2) the ability to assess the potentially explainable variation at the tree level. Significant relationships were established between tree-level crown dimensions and parameter estimates. The study data comprised 197 plantation-grown loblolly pine trees of 10 different ages in Uruguay. Four versions of MB were evaluated: (1) the original equation, (2) the original equation fitted with mixed effects, and two adapted versions: (3) the first included crown variables and fixed effects, (4) the second included crown variables and mixed effects. The crown variables were tree-level crown length and crown length ratio. The best of the four competing equations included both of the crown variables as well as tree-level random effects, suggesting that some linear tree-level variability may yet be explained by variables not considered in this study. Testing on an independent validation data set did not show over-fitting problems. For prediction purposes, the equations with added crown variables were more precise but not less biased. FOR. SCI. 50(2):204–212.

Fine Root Carbon Allocation and Fates in Longleaf Pine Forests - Durwin C. Carter; Joseph J. Hendricks; Robert J. Mitchell; Stephen D. Pecot (Forest Science, 2004)
The patterns and mechanistic controls of fine root production and mortality in a 19-year-old longleaf pine (Pinus palustris Miller) plantation were assessed using minirhizotrons in a complete factorial design experiment that manipulated root carbon source and sink strengths. Carbon source strength to roots was manipulated through foliar scorching, carbon sink strength in roots was altered via nitrogen fertilization, and carbon transfer from roots to the soil organic matter pool was impacted using a general soil pesticide to distinguish between root mortality via herbivory and senescence. Fertilization significantly increased fine root nitrogen concentrations and mortality rates in the nonscorched plots across the last four sample intervals. Scorching significantly reduced fine root biomass. The influence of soil herbivores on fine root carbon allocation and fates could not be assessed in this study because the soil pesticide had no measurable effect on herbivorous nematode and insect larvae populations. The results of this study suggest that nitrogen increases fine root mortality via an increase in fine root carbon sink strength rather than a decrease in carbon allocation to fine roots. These findings support the constant allocation hypothesis regarding nitrogen controls on fine root carbon allocation and transfers in forest ecosystems. FOR. SCI. 50(2):177–187.

Comparison of Historical and Contemporary Forest Structure and Composition on Permanent Plots in Southwestern Ponderosa Pine Forests - Margaret M. Moore; David W. Huffman; Peter Z. Fulé; W. Wallace Covington; Joseph E. Crouse (Forest Science, 2004)
We compared historical (1909–1913) and contemporary (1997–1999) forest structure and composition on 15 permanent plots in ponderosa pine (Pinus ponderosa Dougl. ex Laws.) forests of Arizona and New Mexico. We used the same sampling methods as in the early 1900s and compared stand density, diameter distributions, species composition, and broad age classes from the two periods. Stand density (trees ≥9.14 cm dbh) significantly (P < 0.001) increased on plots from an average of 77.4 trees per plot (s = 49.9) at plot establishment in 1909–1913 to 519.1 trees per plot (s = 252.3) at remeasurement in 1997–1999. Basal area significantly (P < 0.001) increased from 8.0 m2 per plot (s = 3.5) to 28.5 m2 per plot (s = 10.1). Contemporary tree diameter distribution shifted toward smaller size classes as demonstrated by a significant (P = 0.001) decrease in quadratic mean diameter from 38.5 cm (s = 7.5) in 1909–1913 to 28.6 cm (s = 7.1) in 1997–1999. Broad age classes yielded an average of 61.5 (s = 49.5) residual live trees classified as “blackjack” ponderosa pine (P. ponderosa <150 years) and 13.3 (s = 11.9) “yellow pine” (P. ponderosa ≥150 years) in 1909–1913. In 1997–1999, 416 live trees (s = 229.6) were “blackjack” and 57.2 (s = 28.5) trees on average were “yellow pine.” Twelve of the 15 plots were not invaded by other tree species (remained pure ponderosa pine type), while composition shifted slightly on three plots toward more shade-tolerant and fire-intolerant species. Ninety-one percent of the historically (1909–1913 or older) mapped tree structures (live trees, snags, logs, stumps, etc.) were relocated, which suggested that the forest reconstruction field techniques are reliable within 10%. Dramatic increases in tree densities may represent an increased potential for bark beetle epidemics and stand replacing wildfire over large areas in the Southwest. FOR. SCI. 50(2):162–176.

Comparison of Annual Inventory Designs Using Forest Inventory and Analysis Data - Stanford L. Arner; James A. Westfall; Charles T. Scott (Forest Science, 2004)
Three annual inventory designs, a periodic design, and a periodic measurement with midcycle update design are compared using a population created from 14,754 remeasured Forest Inventory and Analysis plots. Two of the annual designs and the midcycle update design allow updating of plots not measured using sampling with partial replacement procedures. Comparisons are based on root mean square error and estimator bias determined for net volume (m3/hectare) and mean annual net volume change. For the annual designs, both individual year and moving average estimates are investigated. The latter are compared to both the population means of the most recent year used in the average and to population means covering the same period as the estimate. Among annual designs, a rotating panel design, in which an equal portion of the total sample is measured each year without remeasurement until the start of the next measurement cycle, produced the smallest root mean square error for estimates of mean net volume. For multiple-year comparisons, the rotating panel and periodic designs resulted in the smallest root mean square errors; for single-year comparisons, the periodic design resulted in the smallest root mean square error. For mean annual volume change, the smallest root mean square error was produced by the periodic design. Among annual designs, the rotating panel design resulted in the smallest root mean square error for multiple-year comparisons of volume change, while a design allowing annual updates of estimates using generalized least squares resulted in the smallest root mean square error for single-year comparisons. FOR. SCI. 50(2):188–203.

Relationship Between Territorial Male Golden-Winged Warblers in Managed Aspen Stands in Northern Wisconsin, USA - Amber M. Roth; Scott Lutz (Forest Science, 2004)
We compared territorial male Golden-winged Warbler (Vermivora chrysoptera) (GWWA) density and territory placement across four size classes [(1) seedling (<2.5 cm mean diameter at breast height (dbh)), (2) small sapling (3.0–6.0 cm dbh), (3) large sapling (7.0–11.5 cm dbh), (4) pole (12.5–17.0 cm dbh)] of aspen forests (Populus spp.) in northern Wisconsin. We surveyed four stands in each size class in May-June 2000 and observed the highest male density (0.55 males/ha) in the seedling size class. Male density for size classes 2–4 combined was 0.04 males/ha. Aspen sucker density was a good predictor of male density across size classes and thus may be a good indicator of habitat quality in aspen communities. Mean GWWA territory area was 0.82 ha (n = 12) in Size Class 1, 0.54 ha (n = 6) in Size Class 4, and 0.18 ha (n = 6) for Size Classes 2 and 3 combined. We found no relationship between male density and the amount of stand edge (km/ha), and territories did not consistently include the stand edge. Because GWWA are strongly associated with aspen seedling stem densities and this aspen stand size class is suitable to GWWAs for a relatively short period of time, we believe conservation will require managing aspen forests to ensure that habitat is always available. Clearcutting aspen forest is a practical strategy to create GWWA breeding cover in the Upper Great Lakes Region. FOR. SCI. 50(2):153–161.

An Assessment of the Impacts of Forest Management on Aboriginal Hunters: Evidence from Stated and Revealed Preference Data - Wiktor Adamowicz; Peter Boxall; Michel Haener; Yaoqi Zhang; Donna Dosman; Juanita Marois (Forest Science, 2004)
Assessing the impacts of forest harvesting activities on Aboriginal people and incorporating these considerations into forest management plans is one of the challenges facing Canadian forest managers. In this study, we model hunting behavior using stated and revealed preference data on subsistence use of wildlife resources. We use this framework to assess the impacts of forest management changes on Aboriginal people in northwestern Saskatchewan. Innovative approaches to data collection are employed to address challenges in obtaining data in these contexts. The econometric analysis combines the stated and revealed preference information to account for limitations in the revealed preference data. Monetary measures of welfare are examined, but we also assess resource compensation and zoning as mechanisms for addressing the impact of forest harvesting on subsistence wildlife use. The results also demonstrate the use of geographic information system information in linking forest management and Aboriginal resource use. FOR. SCI. 50(2):139–152.

Predicting Forest Attributes in Southeast Alaska Using Artificial Neural Networks - Simon A. Corne; Stephen J. Carver; William E. Kunin; Jack J. Lennon; Willem W. S. van van Hees (Forest Science, 2004)
Artificial neural network (ANN) methods are used to predict forest characteristics. The data source is the Southeast Alaska (SEAK) Grid Inventory, a ground survey compiled by the USDA Forest Service at several thousand sites. The main objective of this article is to predict characteristics at unsurveyed locations between grid sites. A secondary objective is to evaluate the relative performance of different ANNs. Data from the grid sites are used to train six ANNs: multilayer perceptron, fuzzy ARTMAP, probabilistic, generalized regression, radial basis function, and learning vector quantization. A classification and regression tree method is used for comparison. Topographic variables are used to construct models: latitude and longitude coordinates, elevation, slope, and aspect. The models classify three forest characteristics: crown closure, species land cover, and tree size/structure. Models are constructed using n-fold cross-validation. Predictive accuracy is calculated using a method that accounts for the influence of misclassification as well as measuring correct classifications. The probabilistic and generalized regression networks are found to be the most accurate. The predictions of the ANN models are compared with a classification of the Tongass national forest in southeast Alaska based on the interpretation of satellite imagery and are found to be of similar accuracy. FOR. SCI. 50(2):259–276.

Importance of Non-Stand-Replacing Fire for Development of Forest Structure in the Pacific Northwest, USA - Peter J. Weisberg (Forest Science, 2004)
Old-growth forests have been the subject of much political concern and forestry research in the 20th century. Evidence that many old-growth stands of the western Oregon Cascade Range have experienced multiple low- to moderate-severity fires has led to the hypothesis that such fires have sustained structural complexity in certain temperate coniferous forests. Multiple regression analysis was used to assess the role of historical non-stand-replacing fire for 90 mature and old forest sites on a 450-km2 landscape of mixed-severity fire regime in western Oregon. The occurrence of non-stand-replacing fire was inferred from the relative frequency of fire scars on Pseudotsuga menziesii. Results suggest that in the central western Cascades, the occurrence of non-stand-replacing fire has favored variability in tree diameter sizes, larger trees, and a greater component of shade-tolerant tree species, after accounting for the effects of elevation, slope aspect, and stand age. However, the fire scar variable explained a relatively small percentage of the variance not explained by these effects, with partial R2 values ranging from 0.05 to 0.16. A path analysis suggested that the effects of stand age on forest structure can be partitioned into direct effects (gap dynamics and successional processes in the absence of disturbance) and indirect effects (older stands have had more time to experience non-stand-replacing fire), with the indirect effects explaining a large component of forest structural attributes that are typically associated with the old-growth seral stage. While the cumulative and long-term effects of non-stand-replacing fire in this region are likely complex, it would seem prudent to include such disturbances as a key ecosystem process, where management practices seek to emulate natural disturbance regimes or facilitate the development of old-growth forest structures. FOR. SCI. 50(2):245–258.

Fuzzy Classification of Ecological Habitats from FIA Data - Lianjun Zhang; Chuangmin Liu; Craig J. Davis; Dale S. Solomon; Thomas B. Brann; Lawrence E. Caldwell (Forest Science, 2004)
Fuzzy c-mean classification (FCM), multi-layer perceptron neural network (MLP), fuzzy ARTMAP, and linear discriminant analysis (LDA) were used to classify Forest Inventory and Analysis (FIA) plots into six ecological habitats in the U.S. Northeast. Among the four classifiers, both FCM and MLP produced “soft” classifications based on fuzzy membership values. In contrast, fuzzy ARTMAP and LDA generated only “hard” classifications in which a plot is assigned to the dominant habitat class, based on binary logic, without considering any coexisting classes. The error matrix and several accuracy indices were calculated to assess the classification accuracy of the methods and to test the differences among the four classifiers. The classification accuracies of FCM and MLP were 98% and 97%, respectively, for overall classification, while fuzzy ARTMAP and LDA had an overall classification accuracy of 92% and 85%, respectively. The χ2 test showed that there was no significant difference between the FCM and MLP methods in classification accuracy. But they were significantly better than both fuzzy ARTMAP and LDA methods at a significant level of α = 0.05. This study showed that the fuzzy classifiers such as FCM and MLP were preferable in the classification of ecological habitats using FIA plots, especially for the classification of ambiguous plots with mixed overstory and understory species compositions. FOR. SCI. 50(1):117–127.

An Algorithm for Ensuring Compatibility Between Estimated Percentiles of Diameter Distribution and Measured Stand Variables - Lauri Mehtätalo (Forest Science, 2004)
It is difficult to formulate a diameter distribution model that is compatible with many stand variables. In previous studies, compatibility of diameter distribution has been ensured with the aid of calibration (adjustment) based on making small changes to the predicted frequencies of diameter classes. In these methods, the minimum and maximum diameters cannot be changed, and the measurement error of the stand variables is not taken into account. In this study, two calibration methods based on minimizing deviations from predicted percentiles were developed. Because minimum and maximum diameters were among the predicted percentiles, there were no problems in changing them in the calibration. In the first method, the measurement error of the stand variables was not taken into account. In the second method, in addition to deviations from predicted percentiles, deviations from the measured stand variables were allowed, and the measurement error was taken into account by weighting each term of the objective function inversely by its error variance. The methods were tested in a dataset of Finnish mixed coniferous forests. Both methods were found to be better than the reference method used because the minimum and maximum diameters could be changed. Even if the measurement error was large, the second method was still advantageous, while the other methods were of no use. FOR. SCI. 50(1):20–32.

2003 Subject and Author Index (Forest Science, 2004)

Basal Area Increment and Growth Efficiency as Functions of Canopy Dynamics and Stem Mechanics - Thomas J. Dean (Forest Science, 2004)
Crown and canopy structure correlate with growth efficiency and also determine stem size and taper as described by the uniform stress principle of stem formation. A regression model was derived from this principle that expresses basal area increment in terms of the amount and vertical distribution of leaf area and change in these variables during a growth period. This model was fit to data collected from five studies analyzing various effects of cultural practices, atmospheric deposition, and stand density on the growth of loblolly pine (Pinus taeda), slash pine (P. elliottii), or lodgepole pine (P. contorta). For both southern pines, the model was fit to individual-tree data and plot totals measured on 1- to 4-yr-old trees and from 12- to 20-yr-old trees. The model was also fit to data measured on approximately 90-yr-old lodgepole pine trees in northern Utah. The model explained an average of 85% of the variation in individual-tree basal area increment and an average of 86% of variation in gross basal area increment per hectare. By comparison, leaf area alone explained an average of 54% of the variation in the increment of individual-tree stem volume and an average of 50% of the gross increment in stem volume per hectare. The value of the exponent in the model implicates stem mechanics in stem growth, and fitted exponents were all within 7% of the exponent derived from the uniform stress model. Isolines of basal area increment and basal area growth efficiency based on fitted equations indicate that increments in the product of leaf area and height to center of leaf area must increase yearly for either basal area increment or growth efficiency to be constant with age. FOR. SCI. 50(1):106–116.

Stand Productivity and Development in Two Mixed-Species Spacing Trials in the Central Oregon Cascades - Sean M. Garber; Douglas A. Maguire (Forest Science, 2004)
Two mixed-species spacing trials were established in central Oregon to test the effects of species composition and initial spacing on stand growth, yield, and structural development. One trial was composed of Pinus contorta Dougl. ex Loud. and Pinus ponderosa Dougl. ex Laws. and the other Abies grandis (Dougl. ex D. Don) Lindl. and P. ponderosa. Spacing, species composition, and age all had large influences on standing volume and periodic annual growth. In both studies, standing volume and periodic annual increment decreased with increasing spacing. In mixed plots, the least shade tolerant species had the fastest early growth rates, while the more shade tolerant species had the slowest. Over time, initial differences in volume growth rates among plots of different species composition decreased. Relative yields in mixtures of P. contorta and P. ponderosa indicated no yield benefits. Mixtures of A. grandis and P. ponderosa, however, resulted in relative yield totals greater than one at all spacings. Spacing and species composition play an important role in stand production and development, and mixtures can yield similar if not more volume than pure stands of the higher yielding species at some spacings and stages of stand development. FOR. SCI. 50(1):92–105.

An Assessment of Canopy Stratification and Tree Species Diversity Following Clearcutting in Central Appalachian Hardwoods - Mark Benjamin Brashears; Mary Ann Fajvan; Thomas M. Schuler (Forest Science, 2004)
On high quality growing sites in West Virginia, shade intolerant tree species have increased in importance in third-generation forests following clearcutting. We investigated the effect of tree species canopy position on the Shannon-Weiner Diversity Index (H′), Pielou's evenness index (E), and species richness (S) using a chronosequence of 13 clearcuts. Two to 26 yr after clearcutting, tree species diversity significantly decreased from 2.07 to 1.83, and evenness decreased from 0.80 to 0.71 while species richness was maintained. As the number of years since harvesting increased, the importance value of oaks (Quercus L.), hickories (Carya Nutt.), American beech (Fagus grandifolia Ehrh.), sugar maple (Acer saccharum Marsh.), and black birch (Betula lenta L.) decreased while the importance of yellow-poplar (Liriodendron tulipifera L.) increased. In these mixed-species stands with stratified canopies, species importance in overstory versus understory canopy layers was the best indicator of competitive success during stem exclusion. Second-generation forests that had almost equal representation of overstory sugar maple and yellow-poplar prior to harvesting had 43% yellow-poplar and 13% sugar maple overstory importance 22–26 yr after harvest. Forty-five percent of the dominant crown class stems and 54% of the codominant class were yellow-poplar. While sugar maple was also an important (13%) overstory species overall, it had no dominant and few codominant stems and over 30% importance as overtopped trees and in the understory. As these stands progress through the stem exclusion stage, richness and measures of diversity may continue declining as yellow-poplar basal area increases. FOR. SCI. 50(1):54–64.

Optimal Harvest Strategy for Slash Pine Plantations: The Impact of Autocorrelated Prices for Multiple Products - Peichen Gong; Runsheng Yin (Forest Science, 2004)
Using the management regimes of slash pine plantations in Georgia as an example, this article examines the impact of serially correlated prices for multiple outputs on harvest decision and financial performance. A stochastic dynamic programming model is formulated to derive the optimal harvest strategy numerically. While the general rule remains to harvest when the observed stumpage prices are greater than the reservation prices, our results show that there exist multiple pairs of reservation prices at each stand age, and these reservation prices cannot be reduced to a single one. This is in contrast to cases where prices are independent over time. Intensive silvicultural practices (e.g., herbicide use and fertilization) can reduce the reservation price and the variance of the financial return, but push up the mean return of a plantation project. Simulations with alternative price processes reveal that ignoring price uncertainty or price autocorrelations results in lower expected level but greater variability of the financial return and thus reduces investments by risk-averse investors. FOR. SCI. 50(1):10–19.

2003 Contents (Forest Science, 2004)

Seasonal Photosynthesis in Fertilized and Nonfertilized Loblolly Pine - Christopher M. Gough; John R. Seiler; Kurt H. Johnsen; David Arthur Sampson (Forest Science, 2004)
Net photosynthesis (Pn) of loblolly pine (Pinus taeda L.) foliage was monitored monthly in 14 yr old stands under near-ambient conditions over an entire year in upper and lower crowns and in both nonfertilized stands and stands receiving nutrient amendments for six consecutive years. Air temperature, humidity, vapor pressure deficit (VPD), photosynthetic photon flux density (PPFD), and plant water potential were monitored concurrently with Pn. Foliar nitrogen (N) concentration was also monitored. The effect of fertilization on Pn was inconsistent and generally not significant. Rates were consistently higher in the upper crown compared to the lower crown primarily due to variable light intensity. Multiple linear regression analysis shows that PPFD and VPD explain between 56% and 64% of the variability in foliar Pń, depending on the treatment. Little or no correlation between foliar N concentration and Pn was found, despite greater N concentrations in fertilized foliage, suggesting that fertilization does not enhance the photosynthetic capacity of loblolly pine foliage over the long term. Substantial amounts of carbon were fixed on measurement days during the winter season, even after freezing nights. Predicted light response curves indicate that foliar photosynthetic capacities are similar year-round, and gross primary productivity estimates (GPP) indicate that over 20% of the annual carbon fixation occurred during the nongrowing season. FOR. SCI. 50(1):1–9.

Tree Size and Drought Affect Ponderosa Pine Physiological Response to Thinning and Burning Treatments - Kjerstin R. Skov; Thomas E. Kolb; Kimberly F. Wallin (Forest Science, 2004)
Thinning and burning treatments based on presettlement (prior to Euro-American settlement) stand conditions have been proposed for improving the vigor and growth of Pinus ponderosa. No study has examined effects of different levels of such thinning treatments on tree water, carbon, and nitrogen relations, or compared effects between postsettlement (trees established after Euro-American settlement) and presettlement (established before Euro-American settlement) trees. We investigated responses of presettlement and postsettlement trees to three levels of thinning and burning (unthinned/unburned control, light thinning/burning, heavy thinning/burning) over 2 yr that differed in precipitation in northern Arizona. Both thinning treatments consistently increased predawn water potential of both tree sizes compared with the control. Effects of thinning on leaf gas exchange varied between tree sizes and measurement times. Thinning increased net photosynthetic rate and stomatal conductance only when soil water availability was lowest, and increases were greater for postsettlement than presettlement trees. In contrast, thinning had no effect on foliar nitrogen concentration.Our results suggest greater positive effects of restoration thinning on tree water and carbon relations for postsettlement versus presettlement trees, and under drought versus nondrought conditions. Photosynthetic response to thinning in old trees may be constrained by physiological factors associated with large size such as low soil-to-leaf hydraulic conductance. FOR. SCI. 50(1):81–91.

A Model for Foliage and Branch Biomass Prediction for Intensively Managed Fast Growing Loblolly Pine - Yujia Zhang; Bruce E. Borders; Rodney E. Will; Hector De Los Santos Posadas (Forest Science, 2004)
Prediction models of foliage and branch biomass were derived based on the foliage distribution within the crown and the pipe model theory. Resulting models were fitted to data collected from intensively managed loblolly pine (Pinus taeda L.) plantations in the Lower Coastal Plain and Piedmont of Georgia. We found that diameter outside bark at the base of the live crown, crown height, and crown length are key predictors of foliage biomass. Together they produce reliable predictions of foliage and branch biomass for stands managed under a wide array of silvicultural treatments. The model indicates that an annual fertilization treatment significantly increased foliage and branch biomass in the Lower Coastal Plain. However, in the Piedmont, complete control of competing vegetation significantly increased foliage and branch biomass. A significant fertilization-age interaction for foliage and branch biomass was also detected in Piedmont stands. FOR. SCI. 50(1):65–80.

Population Growth, Urban Expansion, and Private Forestry in Western Oregon - Jeffrey D. Kline; David L. Azuma; Ralph J. Alig (Forest Science, 2004)
Private forestlands in the United States face increasing pressures from growing populations, resulting in greater numbers of people living in closer proximity to forests. What often is called the “wildland/urban interface” is characterized by expansion of residential and other developed land uses onto forested landscapes in a manner that threatens forestlands as productive socioeconomic and ecological resources. Prevailing hypotheses suggest that such forestlands can become less productive, because forest owners reduce investments in forest management. We develop empirical models describing forest stocking, thinning, harvest, and tree planting in western Oregon, as functions of stand and site characteristics, ownership, and building densities. We use the models to examine the potential impacts of population growth and urban expansion, as described by increasing building densities, on the likelihood that forest owners maintain forest stocking, precommercial thin, harvest, and plant trees following harvest. Empirical results support the general conclusion that population growth and urban expansion are correlated with reduced forest management and investment on private forestlands in western Oregon (USA). Results have potential implications for both economic outputs and ecological conditions, as well as for wildfire risks at the wildland/urban interface. FOR. SCI. 50(1):33–43.

Efficiency of Seedlings and Rooted Cuttings for Testing and Selection in Pinus taeda - Fikret Isik; Bailian Li; John Frampton; Barry Goldfarb (Forest Science, 2004)
Predicted genetic gains of polymix, cloned polymix, full-sib and cloned full-sib testing and selection options for a breeding population were estimated for Pinus taeda L. Heritabilities for volume from the clonal testing were considerably greater than the heritabilities from the seedling testing. Cloned options had higher expected genetic gains than seedling options, even after adjusting for their longer breeding cycles and higher cost of testing. This was mainly due to higher genetic gains from within-family selection of the cloned testing options. Adjusted genetic gain from within-family selection of polymix and cloned polymix were 0.27 and 0.36% per year, respectively. Increasing the number of ramets per clone did not increase the genetic gain, but gain was sensitive to the clone selection ratio within families. When the number of trees tested per family was fixed at 90 trees, all clone/ramet combinations gave greater within-family gains than the seedling option. A complementary breeding strategy consisting of polymix breeding for estimation of general combining ability and clonal selection from clonally replicated full-sib families appears to be more efficient for loblolly pine improvement than the currently used seedling-based testing system. For. Sci. 50(1):44–53.

Local Analysis of Tree Competition and Growth - Haijin Shi; Lianjun Zhang (Forest Science, 2003)
The relationships between the Local Indicator of Spatial Association (LISA) and traditional tree competition indices and individual tree growth were investigated. The results show that like most of the competition indices, LISA had moderate correlations with tree basal area growth. For predicting the tree basal area growth in a linear regression model, the local Gi performed better than many (73%) competition indices at a plot aggregation level and had higher explanatory power than most (91%) competition indices at an individual plot level. LISA also had linear and strong relationships with some traditional competition indices, such as the Lorimer index. The relationships were stronger (ρ >0.90) at an individual plot level than for all plots combined (ρ>0.75). More importantly, LISA could be statistically tested to identify local clusters of trees of similar or dissimilar sizes, even though there was no discernible pattern as summarized by a global statistic of spatial autocorrelation. These significant “hot spots” (clusters of trees of similar sizes) or “cold spots” (clusters of trees of dissimilar sizes) indicated subareas in a forest stand where the competition among trees may be more severe than the average. Therefore, LISA can replace the traditional competition indices for exploring the competitive status of neighboring trees, investigating the relationships between tree competition and growth, and estimating individual tree growth as a predictor variable in a forest growth simulator. The hot spots or cold spots identified by LISA provide useful information for the design of silvicultural and management treatments, such as selection thinning. Furthermore, LISA can be readily incorporated into visualization tools, such as a geographic information system (GIS), because it provides georeferenced information at a local level.

Examining the Interaction Between Geographic Scale and Ways of Knowing in Ecosystem Management: A Case Study of Place-Based Collaborative Planning - Antony S. Cheng; Steven E. Daniels (Forest Science, 2003)
This article examines the interaction between geographic scale and ways of knowing in the context of collaborative stakeholder participation in ecosystem analysis and management. The examination uses data from a qualitative comparative case study of two watershed councils in western Oregon. The results tentatively support the proposition that geographic scale can significantly affect individual stakeholder ways of knowing. For small-scale places, stakeholder ways of knowing tend to be particularistic and rely on diverse personal experiences and specific place features; for large-scale places, stakeholder ways of knowing tend to be aesthetic and rely primarily on recreational experiences and scientific analyses. However, the results also indicate that geographic scale combines with at least three factors to affect the development of shared ways of knowing: (1) tensions between experts and laypersons; (2) primacy of organizational representation in stakeholder interactions; and (3) discovery of common group identity based on long-term communication and shared on-the-ground experiences, such as field trips. This examination suggests that geographic scale in ecosystem management is likely an important factor affecting working relationships in a collaborative stakeholder participation process. These relationships, in turn, can affect the perceived credibility and legitimacy of outcomes.

The Importance of Place: Advances in Science and Application - Linda E. Kruger; Pamela J. Jakes (Forest Science, 2003)
The concept of place is introduced and an orientation to place literature is provided. Following the introduction, an overview is given of the papers in this special issue of Forest Science. The papers included in this issue were presented at the 2000 International Symposium on Society and Resource Management in Bellingham, Washington.

Applying Stochastic Multicriteria Acceptability Analysis to Forest Ecosystem Management with Both Cardinal and Ordinal Criteria - Jyrki Kangas; Joonas Hokkanen; Annika S. Kangas; Risto Lahdelma; Pekka Salminen (Forest Science, 2003)
Multicriteria decision analysis is applied to ecosystem management planning in a forest landscape. Ten alternative action plans were evaluated employing five criteria. For some criteria, cardinal measures with their associated uncertainties were obtained. For other criteria, only ordinal (ranking) information was available. The Stochastic Multicriteria Acceptability Analysis with Ordinal criteria (SMAA-O) method was used, as it accommodates both cardinal and ordinal data. This is the first application of SMAA methods to forest management. SMAA-O represents inaccurate or uncertain cardinal criteria measurements by a joint probability distribution. Ordinal data is converted into stochastic cardinal data by simulating mappings between ordinal and cardinal scales that preserve the given rankings. At the same time, the unknown or partly known preferences of the decision maker are simulated by choosing weights randomly from appropriate distributions. The main results of the analysis are “acceptability indices” that describe the variety of different weights that support an alternative for a given rank. The special characteristics of SMAA-O are best utilized in problems involving uncertainty and where both cardinal and ordinal data are to be employed. It also serves well as an analysis tool in interactive planning processes, especially when criteria weights are not known or they are difficult to assess.

Tests for Long-Run Relationships in Hardwood Lumber Prices - William G. Luppold; Jeffrey P. Prestemon (Forest Science, 2003)
Hardwood lumber prices are unique because of the large number of marketable species and variability of prices across species. Previous research showed that long-run fashion decisions regarding species selection may be influenced by price, so the interaction between fashion and species price may act to keep prices (hence, demand) of different hardwood species together in the long run. To test this hypothesis, we examined the joint lumber price behavior of six major hardwood species representing different appearance characteristics in the Appalachian hardwood region. Bivariate and multivariate price cointegration tests within lumber grades of these mainly nonstationary price series, conducted using a consistent vector error-correction rank and lag-order model selection procedure, revealed no stable long-run statistical relationships, rejecting the principal null hypothesis. Current relative price levels therefore cannot be used to infer future relative levels. Supplementary vector autoregressions of mostly differenced series, however, indicate that some interspecies price relationships exist. Such relationships, however, were mostly confined within appearance groups and only rarely across groups.

Sapling Diversity in Canopy Gaps in an Ecuadorian Rain Forest - D.Salvador-van Eysenrode; J. Bogaert; V. Zak-Mnacek; R. Ceulemans (Forest Science, 2003)
In a “terra firme” rain forest (Amazonian Ecuador) we quantified the species abundance distribution, gap size, gap isolation, sapling diversity, and gap community similarity for 24 initial gap communities. The pooled community distributions showed a log-series distribution, mainly because 2-D space was partitioned during the forest cycle's first stages, and randomness is accepted as influencing both species arrival and gap formation. Gap size interacted with species richness and evenness due to the low species abundances. The species composition in each gap was an almost unique set: on average, a gap shared <20% of its species with any other gap. A cluster analysis confirmed this observation: the first fusion occurred at a similarity level of 0.42, which related to <27% of common species. Despite this high intergap dissimilarity, association analysis showed that 33.7% of all pairwise gap comparisons represented a significant association, indicating that more species were in common than expected with random assumptions. A principal components analysis revealed three dimensions in the data; sapling diversity, community similarity, and gap size were found to be independent of gap isolation. The uniqueness of the communities in terms of sapling composition highlights the value of gaps for conservation.

Selection for Both Growth and Wood Properties in Hybrid Poplar Clones - Shu Yin Zhang; Qibin Yu; Gilles Chauret; Ahmed Koubaa (Forest Science, 2003)
To better understand the genetic control of growth and wood properties in hybrid poplar (Populus spp.), genetic relationships of selected wood properties with growth traits were examined in a 3-yr-old clonal trial located in Windsor and St-Ours, southern Quebec, Canada. In total, 371 trees from 21 hybrid poplar clones were sampled at the two locations. Clonal effects are stronger than growth traits effects on wood density and initial moisture content. The estimated clonal repeatability for wood density (0.92) and initial moisture content (0.80) across the two sites are thus considerably higher than for dbh (0.64) and tree height (0.72). Neither wood density nor mean fiber length were found to significantly correlate with growth traits. This suggests that in the hybrid poplar clones selection for growth traits will not result in a significant reduction in the wood quality traits. Selection for stem dry fiber weight appears to be an optimal selection strategy, as it will lead to the highest genetic gain in stem dry fiber yield, or maximum fiber production while wood density is improved.

Diversity in Ponderosa Pine Forest Structure Following Ecological Restoration Treatments - Amy E.M. Waltz; Peter Z. Fulé; W. Wallace Covington; Margaret M. Moore (Forest Science, 2003)
We tested the effectiveness of ponderosa pine forest restoration by comparing forest restoration treatments to untreated forest and to reconstructed forest structure in 1870 (date of Euro-American settlement) using an experimental block design at the Grand Canyon-Parashant National Monument in northwestern Arizona. Forest tree density averaged more than 20 times the historical tree density, and basal area was 4 to 6 times higher in contemporary forests than in historical forests. Restoration treatments consisted of thinning young trees to emulate the forest density, tree composition, and spatial distribution in 1870, followed by prescribed burning. Following restoration treatment, tree density was significantly reduced but remained 6 times higher than historical forests. Basal area in restored forests was still 2.5 times greater than reconstructed basal area values. Ponderosa pine dominance changed little from pretreatment data across the four blocks, averaging 60% of stems and 87% of the basal area prior to treatment and 56% of stems and 85% of the basal area following treatment. Ninety-eight percent of contemporary forest trees were less than 100 yr old prior to restoration treatment; this proportion was reduced to 82% following treatment. Restoration treatment also significantly reduced canopy cover and increased total tree regeneration. However, treatment effects on forest fuels were highly variable. Litter and duff fuel layers were significantly reduced by prescribed fire but woody debris increased. Overall forest structural diversity following treatment implies that fire behavior, wildlife habitats, and other ecological attributes will vary relatively widely in the future landscape.

Place Attachment and Context: Comparing a Park and a Trail Within - Roger L. Moore; David Scott (Forest Science, 2003)
A number of recent studies have focused on place attachment, defined as the extent to which a person values or identifies with a particular setting. Some studies suggest that place attachment includes an emotional/symbolic “place identity” dimension and a functional “place dependence” dimension. One aspect of place attachment that has not been explored empirically is the extent to which people become attached to a specific site versus its larger setting. The main purpose of this study was to examine users' place attachment to a large metropolitan park versus their place attachment to a particular trail located within that same park. The study sample was comprised of 438 recreational users of a paved trail located in a large regional park near Cleveland, Ohio. Major findings include: (1) Frequency of use was positively related to both park and trail attachment. (2) Levels of trail attachment varied across different trail activities, but levels of park attachment did not. (3) The most powerful predictor of both park attachment and trail attachment was personal commitment to the activity that users were pursuing. (4) –Unlike previous research, factor analyses indicated that both park and trail attachment were unidimensional rather than comprised of place identity and dependence dimensions. Implications for management and research are discussed.

Incorporating the Natural Landscape Within an Assessment of Community Attachment - Julie K. Clark; Taylor V. Stein (Forest Science, 2003)
An ecosystem approach to managing public natural areas requires that land planners and managers thoroughly understand the stakeholders who live within these ecosystems and are emotionally connected to the lands. Building on previous research conducted on community attachment, place attachment, and sense of place, this article explores how local stakeholders in two areas of Florida identify with and account for the natural landscape within their sense of community. To better capture the physical-natural landscape element currently unaccounted for in community attachment research, researchers explored how stakeholders identified with their communities and examined their attitudes and behaviors regarding local public natural areas. Results show the physical-natural landscape is an important part of how stakeholders identify with their community. Stakeholders who frequently visit surrounding public natural areas and identify these areas as an important part of why they live in the area are likely to identify more with the physical-natural landscape of their community than the social-cultural elements of their community. Determining how stakeholders identify with their community (natural landscape or social elements), offers public land managers a better understanding of the role the areas they manage play in local stakeholders' daily lives, and how to best communicate with those stakeholders.

The Politics of Place: Understanding Meaning, Common Ground, and Political Difference on the Rocky Mountain Front - Laurie Yung; Wayne A. Freimund; Jill M. Belsky (Forest Science, 2003)
A major challenge of forest policy and management is effectively understanding different people's viewpoints on natural resource use and conservation, and how those viewpoints contribute to conflict and conflict resolution. In response to this challenge, the concept of place is gaining currency in natural resource research. The study of place promises an integrative approach to understanding people's relationships with particular areas. Realizing the potential of place research to inform forest policy and management means conceptualizing place as an arena of shared and contested meanings. A politics of place is attentive to different and potentially conflicting meanings, and how senses of place may be connected to larger political struggles. This study examines people's images, values, and interests with respect to the Rocky Mountain Front in Montana. In this case study, discourse about placenames provided a window into the politics of place. Results illustrate the ways in which place meanings are connected to people's ideas about property, conservation, and governance. Knowledge of the politics of place can inform forest policy and management and contribute to a more sophisticated understanding of natural resource conflict and the potential effectiveness of decision-making processes.

The Measurement of Place Attachment: Validity and Generalizability of a Psychometric Approach - Daniel R. Williams; Jerry J. Vaske (Forest Science, 2003)
To enhance land managers' ability to address deeper landscape meanings and place-specific symbolic values in natural resource decision making, this study evaluated the psychometric properties of a place attachment measure designed to capture the extent of emotions and feelings people have for places. Building on previous measurement efforts, this study examined the validity and generalizability of place attachment across measurement items, places, and dimensions (place dependence and place identity) of attachment. Colorado State University students (n = 65) rated four forest-based recreation sites on two dimensions of place attachment. In addition, data from a sample of University of Illinois students (n = 380) and visitors to Shenandoah National Park (n = 2005) and Mt. Rogers National Recreation Area (n = 369) were analyzed and compared to the Colorado sample. Confirmatory factor analysis of these four data sets demonstrated that subjects distinguish between two dimensions of attachment and assign different levels of attachment to the different areas. Generalizability analysis of the Colorado data provided additional evidence for the two-dimensional structure and suggested that each attachment dimension can be reliably measured with as few as four questionnaire items. Convergent validity was supported through analyses of the relationships between the place attachment measures and both behavioral and psychological variables predicted to be related to place attachment.

Sense of Place and Forest Science: Toward a Program of Quantitative Research - Richard C. Stedman (Forest Science, 2003)
Sense of place is rich in theory, but quantitative research approaches often fail to reflect this richness. This schism between theory and application not only impedes the development of theory, but also the ultimate utility of the concept for integration into resource management planning. Here, several fundamental points in sense of place theory that can readily be translated into testable hypotheses are identified, as are suggestions for how they may be reformulated into hypothesis language. Sense of place is composed of descriptive and evaluative components that are a function of landscape attributes, experience with the landscape. In turn, any of these elements may affect place-related behaviors.

Nantucket Pine Tip Moth Development and Population Dynamics: Influence of Nitrogen Fertilization and Vegetation Control - John T. Nowak; Timothy B. Harrington; C.Wayne Berisford (Forest Science, 2003)
It is commonly believed that Nantucket pine tip moth (Rhyacionia frustrana [Comstock]) feeding damage on loblolly pine (Pinus taeda L.) increases in relation to the intensity of silvicultural practices. Some studies have produced contrary or inconclusive data regarding this issue. This study was designed to examine the relationships between tree growth rates and tip moth development by enhancing growth with nitrogen (N) fertilizer and herbicide applications. The four treatments were N fertilizer, herbicide, herbicide+fertilizer, and untreated control. These treatments were monitored for tip moth damage levels, tip moth pupal numbers per pine shoot, insect population dynamics, and tree growth. Pine growth was significantly greater in the herbicide treatments than in the other treatments. There was a significant increase in diameter related to the fertilizer treatments, but no differences in tree height or volume were detected. Pupal weight was significantly lower in the herbicide treatment in the second year. Tip moth population fluctuations were greater in the herbicide treated plots than in the untreated control, and there were significant linear relationships between these fluctuations in the treatments versus percent parasitism, pupal weight, and diameter growth. This study shows that tip moth populations are not necessarily increased or decreased by intensive management practices, but can be less stable due to these practices.

Relationship Between Foliar δ13C and Hydraulic Pathway Length in Pinus palustris - Lisa J. Samuelson; Price C. McLemore; Greg L. Somers (Forest Science, 2003)
Because of the importance of hydraulic architecture in understanding physiological differences between small and large trees, we tested the hypothesis that foliar δ13C increased with aboveground flow-path length in longleaf pine (Pinus palustris Mill.) trees of varying age and size at two sites in the lower Coastal Plain. This species offered a unique opportunity to examine variability in foliar δ13C in relation to pathway length because of the open, well-mixed canopy in savanna-like stands and concentration of foliage in splayed tufts on branch ends. At both sites, models with total flow-path length (bole + branch) explained 78–81% of the variation in foliar δ13C, and a full model with separate slopes and intercepts for each tree was required. Branch flow-path length was highly correlated with foliar δ13C and the models accounted for 76–88% of the variation in foliar δ13C, and a reduced model with one slope was suitable for each site. Flow-path length was not as well correlated to foliar N concentration, specific leaf area or tuft leaf area. Greater δ13C enrichment with increasing flow-path length indicates the need for mechanistic studies to better understand the role of hydraulic resistance in controlling leaf-level physiology within the canopy and among different size longleaf pine trees.

Poverty and Employment in Forest-Dependent Counties - Peter Berck; Christopher Costello; Louise Fortmann; Sandra Hoffmann (Forest Science, 2003)
One of the most controversial aspects of federal and state policies aimed at protecting old-growth ecosystems is the potential effect of job losses on local economic conditions. A fundamental question for historically forest-dependent areas is whether these policies will result in local economic stagnation and enduring pockets of poverty. This study uses monthly, multicounty time series data to estimate a vector autoregressive model of the experience of northern California counties during the 1980s and 1990s. It examines the long-run impact of changes in timber-related employment on other employment and participation in major federal poverty programs. It finds that employment base-multiplier effects of timber employment on other county employment are small and state economic conditions rather than local employment conditions are the principal driver behind local poverty.

Above- and Belowground Competition from Longleaf Pine Plantations Limits Performance of Reintroduced Herbaceous Species - Timothy B. Harrington; Christa M. Dagley; M.Boyd Edwards (Forest Science, 2003)
Although overstory trees limit the abundance and species richness of herbaceous vegetation in longleaf pine (Pinus palustris Mill.) plantations, the responsible mechanisms are poorly understood because of confounding among limiting factors. In fall 1998, research was initiated to determine the separate effects of above- and belowground competition and needlefall from overstory pines on understory plant performance. Three 13- to 15-yr-old plantations near Aiken, SC, were thinned to 0, 25, 50, or 100% of nonthinned basal area (19.5 m2 ha-1). Combinations of trenching (to eliminate root competition) and needlefall were applied to areas within each plot, and containerized seedlings of 14 perennial herbaceous species and longleaf pine were planted within each. Overstory crown closure ranged from 0 to 81%, and soil water and available nitrogen varied consistently with pine stocking, trenching, or their combination. Cover of planted species decreased an average of 16.5 and 14.1% as a result of above- and belowground competition, respectively. Depending on species, needlefall effects were positive, negative, or negligible. Results indicate that understory restoration will be most successful when herbaceous species are established within canopy openings (0.1–0.2 ha) managed to minimize negative effects from above- and belowground competition and needlefall.

Risk-Aversion and the Short-Run Supply of Timber - Peichen Gong; Karl-Gustaf Löfgren (Forest Science, 2003)
This article examines the effect of risk-aversion on the short-run supply of timber, when the harvest revenue is invested in a portfolio of a riskless and a risky asset. Assuming that the future stumpage price and the rate of return on the risky asset are independent and normally distributed, it is shown that the effect of risk-aversion on the optimal harvesting behavior depends on the sign of a marginal variance function. This shows the effect of a marginal increase in the harvest volume on the variance of the future wealth, evaluated at the optimal harvest-investment decision under risk-neutral preferences. If the marginal variance is negative, then risk-aversion increases harvest in the first-period. If it equals zero, then only high degrees of risk-aversion affect (increase) the harvest. Finally, if the marginal variance is greater than zero, then high degrees of risk-aversion increase the harvest, whereas low degrees of risk-aversion have the opposite effect. The result has implications for the analysis of the harvesting behavior of any renewable resources.

Book Reviews: Decision Methods for Forest Resource Management - Glen W. Armstrong (Forest Science, 2003)
Decision Methods for Forest Resource Management is a book that describes several modeling approaches that natural resource managers use to help guide decisions. Nine of its 19 chapters are devoted to linear programming and its application to modeling even-aged and uneven-aged forest management. The book also covers goal programming, integer programming, CPM/PERT, dynamic programming, deterministic and stochastic simulation, Markov chains and decision processes, investment analysis, and econometric analysis and forecasting. The examples and the problems presented are relevant to forest management in today's environment. There is a strong emphasis on sustainability, environmental values (including biodiversity), and economics. The book is targeted at senior undergraduate students, graduate students, and professionals involved in natural resource management.

Book Reviews: Forest Products and Wood Science: An Introduction. 4th Edition - Myron W. Kelly (Forest Science, 2003)
This is the fourth edition of a book that first appeared more than 20 years ago and has been revised approximately every 7 years. This edition includes an additional author (Shmulsky) and the promotion of Bowyer to senior author. The overall quality has improved with each new edition and the current edition has reached another higher level of quality and content. This edition also has extended coverage of the composite wood panels that have attained market acceptance since the publication of the earlier editions.

The Effects of Exchange Rate Volatility on U.S. Forest Commodities Exports - Changyou Sun; Daowei Zhang (Forest Science, 2003)
This article addresses the impact of exchange rate volatility on U.S. exports of four forest commodities. Exchange rate volatility is measured by the standard deviation of the growth rate of real effective exchange rate of the U.S. dollar. The nonstationarity of individual time series is explicitly taken into account by employing multivariate cointegration analysis and error correction models. The results show that exchange rate volatility has a negative impact on U.S. exports in the long term, but short-term dynamics vary for different commodities. A stable currency policy in the long run helps promote U.S. exports of forest commodities, although some commodities may benefit from exchange rate volatility in the short term.

Growth Responses of Abies amabilis Advance Regeneration to Overstory Removal, Nitrogen Fertilization and Release From Vaccinium Competition - Barbara J. Hawkins; Jonathan A. Moran (Forest Science, 2003)
Abies amabilis advance regeneration may take several years to acclimate to overstory removal, and poor performance has been attributed to unfavorable microclimate, nutrient stress, and competition from ericaceous vegetation. Our objective was to examine potential factors limiting growth of advance regeneration of Abies amabilis on a montane site in coastal British Columbia. In 1996, 72 experimental plots were established at the Montane Alternative Silvicultural Systems site, Vancouver Island, to provide a design with 12 plots within each of 2 replicate blocks of 3 overstory removal treatments [clearcut (CC), shelterwood (SW), green tree retention (GT)]. Two plots within each replicate block were randomly allocated to each level of 3 nitrogen (N) treatments (0, 100, 250 kg ha-1, applied as urea) × 2 Vaccinium treatments (shoots present or removed).The three overstory removal treatments differed in the amount of solar radiation received beneath the canopy, in the order CC > GT > SW. Three to five growing seasons after treatment, advance regeneration in the GT and CC treatments exposed to >70% incoming solar radiation had the greatest height, stem diameter, and dry weight. N content, new N uptake (inferred from uptake of applied 15N), and allocation of uptake to new shoots were greatest in the CC followed by the GT and SW treatments. N fertilization had no effect on seedling growth. Removal of Vaccinium shoots increased stem diameter of advance regeneration, and increased new shoot dry weight in the GT treatment. Allocation of N to new shoots was greatest in advance regeneration from plots where Vaccinium was removed.

Light Transmittance Estimates in a Longleaf Pine Woodland - Michael A. Battaglia; Robert J. Mitchell; Paul P. Mou; Stephen D. Pecot (Forest Science, 2003)
While the importance of canopy structure in open woodlands and savannas on regulating the flow of energy and matter is well known, few studies have investigated how variation in overstory abundance influences canopy light transmission and the extent that estimates vary in their ability to characterize the light environment in these ecosystems. Canopy light transmittance (% photosynthetic photon flux density, or %PPFD) was measured with gallium arsenide phosphide (GaAsP) photodiodes and was monitored throughout the growing season in an open-canopy longleaf pine (Pinus palustris Mill.) woodland across an overstory abundance gradient. Several estimates of canopy light transmittance were also measured, including 10 minute averages of %PPFD under clear and overcast sky conditions during summer, fall, and winter, as well as light estimates derived from hemispherical photographs (gap fraction, GF: gap light index, GLI; and weighted canopy openness, WCO). Linear and curvilinear regression were used to analyze the relationship between (1) light measurements and canopy structure and (2) light estimates and growing-season % PPFD measured by light diodes. Of all light measurements in this study, ten-minute average % PPFD measurements during clear days were the most variable: only a small proportion in the 10-minute average of light reaching the understory was correlated to either overstory structure or growing-season canopy transmittance. While measures on overcast days improved the correlations, they tended to overestimate transmittance. Gap fraction (GF) and gap light index (GLI) were strongly correlated with % PPFD and overstory structure, and the relationship between GLI and % PPFD was improved by using a direct light setting of 60%. In addition to strong correlation, hemispherical photographic estimates of light fell along a 1:1 line with % growing-season PPFD; thus, estimates were relatively unbiased. Measures of light in this ecosystem need to incorporate the large spatial and temporal variation in light transmittance that is characteristic of this ecosystem if investigators are to understand the relationship between open-canopy woodlands and their light environments.

Spatial and Temporal Disturbance Characteristics of Oak-Dominated Old-Growth Stands in the Central Hardwood Forest Region - James S. Rentch; Mary Ann Fajvan; Ray R. Hicks (Forest Science, 2003)
Using a radial growth averaging technique, decadal-scale growth changes of 150- to 350-yr-old overstory oaks were used to identify canopy disturbance events in five old-growth stands, and canopy disturbance intervals were estimated using frequency analysis. Stem maps and tree-establishment and canopy-accession chronologies were then used to reconstruct the size of canopy openings. Between 1700 and 1990, median canopy disturbance interval was approximately 3 yr for each stand; larger disturbances involving two or more trees occurred about every 16 yr per stand. Based on age distribution of the oldest cohorts, three stands became established after a major disturbance, but the majority of multiple-tree disturbances were associated with gaps < 200 m2 in area. Historic disturbance frequency and size distribution of canopy gaps suggest that the oak components of these stands persisted by utilizing a variety of growth strategies appropriate to large and small openings. The absence of significant changes in overstory disturbance frequencies further suggests that increases in the level of understory competition are responsible for the present-day decline in oak dominance.

A 2-Opt Tabu Search Procedure for the Multiperiod Forest Harvesting Problem with Adjacency, Greenup, Old Growth, and Even Flow Constraints - Felipe Caro; Miguel Constantino; Isabel Martins; Andrés. Weintraub (Forest Science, 2003)
Because of environmental concerns, modern forest harvesting plans are being modified to address aesthetics and wildlife protection issues. In the literature, the most referenced are adjacency constraints with exclusion or “greenup” years. Also of interest are the concepts of old growth patch size and total old growth area restrictions. Typically, harvest blocks have been defined a priori. Recently, some have proposed a more complex approach in which basic cells are defined, and the decision-making process includes forming harvest blocks from these cells. This has been called ARM (Area Restriction Model). Until now, no successful exact method has been reported for large-scale ARM problems, leaving heuristics as a viable option. In this work we present a multiperiod harvest-scheduling ARM model with these spatial constraints. A tabu search procedure with 2-Opt moves (exchanging at most 2 units) was developed. For small size instances, the procedure found the optimal solution in most cases, and for a real-size problem an 8% optimality gap is provided.

Estimating the Cost of Land Base Changes Due to Wildfire Using Shadow Prices - Glen W. Armstrong; Steven G. Cumming (Forest Science, 2003)
Linear-programming-based timber harvest scheduling models produce shadow prices of constraints as a standard output. We present a method whereby the shadow prices of starting inventory constraints can be used to approximate the costs of land base changes, expressed in terms of the units of measure for the objective function in the timber supply model. We use this method to approximate the cost of forest fires, and compare these costs to a measure of the true cost. The approximation worked remarkably well over a large range of fire sizes, and alternative model formulations, for a study area in northeastern Alberta, Canada.

Acquisition of a Forest Estate: A Stochastic Optimization Approach for Financing and Management - Gunnar Rutegård; Lars Lönnstedt; Markku Kallio (Forest Science, 2003)
This article addresses the financing and managing problem of a private investor who considers purchasing a forest estate. The focus is on financing the investment, timing of harvesting, and financial and nonfinancial benefits over years succeeding an acquisition. We take into account uncertainty concerning future timber prices, real rate of interest, and rate of inflation. To aid in the solution of the problem, we propose a multistage stochastic optimization model. The total amount of loan available is assumed given, while alternative interest and repayment schedules are considered for loans. The model accounts for the initial state of the forest, growth, and allowable cutting. The objective function is the expected utility. In an illustrative example, the utility for a risk averse investor is based on income for consumption. Variations of this model demonstrate the use of decision aids. These concern valuation of a forest estate, initial age distribution of forest stands, timber price volatility, initial equity, time-varying preferences for consumption, and nonfinancial benefits.

Time Trends in Genetic Parameters for Height and Optimal Age for Parental Selection in Scots Pine - Gunnar Jansson; Bailian Li; Björn Hannrup (Forest Science, 2003)
Data used to estimate time trends in genetic parameters and the optimal age for parental selection were obtained from 13 Scots pine (Pinus sylvestris L.) progeny tests in southern Sweden. The final age at measurement was between 24 and 39 yr, corresponding to approximately half the rotation age in southern Sweden. Trees in each test have been measured for height 4–6 times, covering ages from 5 to 39 yr. Individual tree heritability for height averaged 0.16, and increased slightly over time, although there were differences among tests. The average additive coefficient of variation for height (CVA), which decreased with age, was 6.0% while the average nonadditive coefficient of variation (CVD) was 3.8% and did not show any significant trend over time. A model based on the natural logarithm of the ratio between the two ages at measurement was used to predict genetic age-age correlations. The efficiency of early selection was also examined, in an analysis considering total height at age 30 as the target trait. The optimal age for parental selection based on gain per unit time peaked at 11 yr, with a time lag for breeding of 10 yr. In the southern tests, the peak came some years earlier than in the northern tests. Selection efficiency based on present value with an interest rate of 5% showed the optimum at 11 yr.

What We May Have Is a Failure to Communicate*: Labeling Environmentally Certified Forest Products - Mario F. Teisl (Forest Science, 2003)
To develop an understanding of the performance of different eco-labels for certified forest products, we administered a mail survey to a nationally representative sample of U.S. residents. In the survey, respondents viewed different eco-labels and were asked to perform a series of tasks designed to measure the labels' communication performance. Results indicate that relatively detailed labels are more beneficial for consumers (and environmentally sensitive forest product manufacturers) than simpler eco-seals. Eco-seals are the least credible type of label and, in general, do not allow consumers an adequate basis for product differentiation. However, we also find evidence that marginal changes can significantly improve the performance of simple eco-seals. The results suggest that U.S. consumers value the environmental benefits created from more environmentally benign forestry. Thus, consumer-driven purchases could potentially support a future of environmentally benign forest management practices with less reliance on other policy alternatives. However, the results also suggest that the current state of forest product labeling, where firms can (voluntarily) label their products with simple eco-seals from a variety of certification organizations, is not the most effective labeling approach. Parties who are interested in the long-run success of these programs need to consider altering current labeling approaches.

The Influence of Forest and Stand Conditions on Spruce Budworm Defoliation in New Brunswick, Canada - Wayne E. MacKinnon; David A. MacLean (Forest Science, 2003)
The species composition of stands and surrounding forest have been suggested as important factors influencing the amount of spruce budworm (Choristoneura fumiferana [Clem.]) defoliation and, consequently, budworm-induced growth loss and mortality. We measured spruce budworm defoliation from 1989–1993 in 40 spruce (Picea sp.) and balsam fir (Abies balsamea [L.] Mill.) stands in north-central New Brunswick, Canada, and evaluated the influence of surrounding forest type (softwood, mixedwood), species group (balsam fir, spruce), and site quality (wet/nutrient poor, moist/nutrient rich) on defoliation. Surrounding forest type had a significant effect on the amount of defoliation in white spruce (Picea glauca [Moench] Voss) stands; stands in softwood forests sustained 11% more (P = 0.0485) defoliation than those in mixedwood. There was evidence that hardwood species have to be within, rather than surrounding, a spruce-fir stand to significantly influence defoliation. Site quality had a significant effect (P = 0.0039) on balsam fir defoliation, with stands on moist/rich sites sustaining 19% more defoliation than those on wet/poor sites. In softwood forest, white spruce stands sustained an average of 16% more defoliation than red-black spruce (Picea rubens Sarg.-Picea mariana [Mill.] B.S.P.) stands.

Book Reviews: The Potential of U.S. Forest Soils to Sequester Carbon and Mitigate the Greenhouse Effect - S. Jose (Forest Science, 2003)
In recent years, the growing realization that as much as 40–60% of the carbon in forest ecosystems is stored belowground has sparked a great deal of interest in exploring forest soil processes and their relation to carbon dynamics. Because of its slower turnover rates, soil organic carbon offers considerable potential to mitigate the increase in atmospheric carbon dioxide and alleviate the greenhouse effect. Through the publication of this book, the editors have done a remarkable job in bringing together the collective wisdom of 41 prominent soil scientists in analyzing the carbon sequestration potential of U.S. forest soils and the implications for policy decisions. This book is the third one in a series of books addressing the carbon sequestration potential of U.S. land use systems. The first two books examined the potential of crop and grazing lands and were published in 1999 and 2001, respectively.

Book Reviews: Applied Ecology and Natural Resource Management - M.A. Jenkins (Forest Science, 2003)
The incorporation of ecological information is probably the most critical step in making decisions about the management of natural resources. However, because of the complexity of both ecological information and its potential application to management prescriptions, it is also among the most difficult tasks facing resource managers. There has long existed a divide between researchers, who are often searching for generality among ecological relationships, and managers, who seek specific information about the systems they manage. For managers, bridging this divide is critical to preserving biological diversity, ensuring sustainability, and meeting the resource needs of an ever-expanding population. For researchers who are interested in applied ecology, bridging this divide is critical if their efforts are to move from the journal page to real world applications within the field of resource management.

Comparison of Neural Networks and Statistical Methods in Classification of Ecological Habitats Using FIA Data - Chuangmin Liu; Lianjun Zhang; Craig J. Davis; Dale S. Solomon; Thomas B. Brann; Lawrence E. Caldwell (Forest Science, 2003)
Two artificial neural networks (ANN) and three traditional statistical classification methods are used to classify Forest Inventory and Analysis (FIA) plots into six ecological habitats in the U.S. Northeast. Four variables (overstory and understory species composition, hardwood basal area percentage, and current FIA forest type) are identified from a list of available stand variables as the most important discriminating variables for habitat classification. The error matrix and accuracy indices are used to assess the classification accuracy of the models and to test the differences between the five classifiers. The ANN models (MLP and RBF) are superior to the traditional statistical methods such as linear discriminant analysis and minimum-distance classification. The classification accuracy of the ANN models is 90% or higher for overall classification, and exceeds 92% in five of the six habitat categories. The K-Nearest Neighbor (KNN) method classifies the six ecological habitats as accurately as the two neural network models. This study shows that the ANN models and KNN method have a great potential for the classification of ecological habitats using FIA data, due to their flexibility of modeling algorithms and robustness to the problems in FIA data such as non-Gaussian distributions, nonlinear relationships, outliers and noise in the data. For. Sci. 49(4):619–631.

A Mixed-Integer Formulation of the Minimum Patch Size Problem - Stephanie Rebain; Marc E. McDill (Forest Science, 2003)
Forest harvest scheduling models have addressed wildlife habitat concerns in a variety of ways. One way is through minimum patch size constraints specifying that a certain amount of the forest must consist of patches meeting both minimum size and minimum age requirements. Patch size requirements may be necessary because a forest with only small patches of mature habitat may not be able to support populations of some wildlife species. Maximum harvest opening size constraints, which are often imposed for legal or policy reasons, tend to divide forest habitat into small patches. Minimum patch size constraints may be able to help mitigate the negative impact of maximum harvest opening size restrictions. Patch size requirements have been considered elsewhere, but a mixed-integer linear programming (MILP) formulation has never been presented. This article presents such a formulation, which allows minimum patch size problems to be solved using the branch and bound algorithm available through commercial solver packages. An example problem is formulated, solved, and discussed. For. Sci. 49(4):608–618.

Modeling Tree Mortality Following Wildfire in the Southeastern Canadian Mixed-Wood Boreal Forest - Christelle Hély; Mike Flannigan; Yves Bergeron (Forest Science, 2003)
We modeled tree mortality three months after a wildfire in the mixed-wood boreal forest (Quebec, Canada) using data from 1963 trees in 36 stands burned under a wide range of fire behavior conditions during the 1997 Val Paradis fire. Stand composition influenced the char height: height of burn was lower in deciduous stands than mixed or coniferous stands. Analysis of species mortality rates revealed that Populus tremuloides Michx. was the least fire-resistant species, whereas Picea mariana Moench and Pinus banksiana Lamb. were the most resistant species. Efficient interactions for conifers exist between crown and cambial resistance to injury and fire behavior, as diameter at breast height (DBH), total tree height (TOTH), and mean bark thickness are characteristic variables throughout the fire behavior range. The best logistic regressions, relating probability of wildfire-induced mortality to morphology and fire variables, always entered char height (CH) at the first step of the stepwise procedure, followed by a morphological variable (DBH or TOTH). The Kappa coefficient used for model validations revealed that logistic regressions using morphologic and fire variables were very efficient as compared to logistic regressions based only on morphologic variables. Potential applications of these results by land managers are discussed. FOR. SCI. 49(4):566–576.

Developing a Well-Behaved Dynamic Site Equation Using a Modified Hossfeld IV Function Y 3 = ( axm )/( c + x m –1), a Simplified Mixed-Model and Scant Subalpine Fir Data - C.J. Cieszewski (Forest Science, 2003)
I developed a dynamic height growth model by using a simplified form of mixed effects modeling and subalpine fir (Abies lasiocarpa [Hook.] Nutt .) stem analysis data. The new dynamic equation uses directly heights at any age to predict consistent heights (e.g., y2 = f(t2, t1, y1) ⇔ y1 = f(t1, t2, y2)) and f(t3, t1, y1) = f(t3, t2, f(t2, t1, y1))), and therefore constitutes compatible site index and height models in one common equation. The parameters for the model were estimated by analysis of fixed and random effects with corrections for first- and second-order serial autocorrelation. The correction for second-order autocorrelation was necessary to assure the model's proper representation of the data and to remove a seeming cross-sectional autocorrelation across different sites/series. Estimating the errors in site indices as random effects eliminated the effects of stochastic predictive variables. The proposed model has outperformed all other base-age specific and base-age invariant models in both the fit to the data and in its behavior during extrapolations. It also outperforms the model (developed on amabilis fir data) that is currently, operationally used for subalpine fir. The new model's advantages are parsimony, mathematical tractability, base-age invariance, and greater consistency in curvatures of the generated height-age trajectories. FOR. SCI. 49(4):539–554.

Maximum Likelihood Estimation for Predicting the Probability of Obtaining Variable Shortleaf Pine Regeneration Densities - Thomas B. Lynch; Jean Nkouka; Michael M. Huebschmann; James M. Guldin (Forest Science, 2003)
A logistic equation is the basis for a model that predicts the probability of obtaining regeneration at specified densities. The density of regeneration (trees/ha) for which an estimate of probability is desired can be specified by means of independent variables in the model. When estimating parameters, the dependent variable is set to 1 if the regeneration density (trees/ha) on the plot is greater than the specified density (trees/ha), otherwise 0. Since it is desired to estimate parameters for a range of probability densities, traditional estimation techniques for logistic models cannot be used. Multiple regeneration densities require a multinomial distribution, for which maximum likelihood estimates are obtained. Counts of shortleaf pine regeneration taken 9-10 years after thinning on 182 plots established in naturally occurring shortleaf pine forests are used to estimate parameters. FOR. SCI. 49(4):577–584.

A Panel Data Analysis of Nonindustrial Private Roundwood Supply with Emphasis on the Price Elasticity - Torjus Folsland Bolkesjø; Birger Solberg (Forest Science, 2003)
This article presents an econometric analysis of the Norwegian nonindustrial private forest (NIPF) owners' short-term roundwood supply applying the conventional pooled Tobit model as well as the fixed effects (FE) Tobit model where unobserved individual heterogeneity are incorporated in the assumptions of the model. A panel consisting of 14,468 forest owners during the period 1989–1997 (except 1991) is used for the statistical testing. The results indicate that the current and lagged price, interest rate and various owner and property characteristics are relevant explanatory variables when evaluating factors affecting Norwegian NIPF owners' short-term roundwood supply. It is demonstrated that the econometric results differ quite substantially between the two models. Both the common interpretation of the results from pooled and FE models, the match to the theory of forest owner behavior, and the statistical measures suggest that panel data methods, like the FE model, are more suitable for short-run roundwood supply analysis than the conventional pooled model. Special attention is given to the price elasticity and its variability across regions and time. Based on the empirical results it is concluded that, among other factors, both the nature of the price data and the distribution of the price elasticity estimates are important to consider when comparing stumpage price elasticity estimates from different analysis. FOR. SCI. 49(4):530–538.

Impacts of Intensive Management on Black Walnut ( Juglans nigra L.) Growth and Bole Quality at Mid-Rotation - James R. Bohanek; John W. Groninger (Forest Science, 2003)
High value hardwood species, such as black walnut (Juglans nigra L.), are increasingly planted and intensively managed in the hopes of profitably producing high quality logs. Success or failure of silvicultural practices used to establish these plantations are commonly judged on the basis of early diameter growth response. However, it is generally not known whether treatments judged to be successful when the stand is young translate into mid- and late-rotation bole quality and, ultimately, log value. This study revisits a 35-yr-old experimental black walnut plantation in south-central Illinois (black walnut site index50 = 23m), to evaluate how initial planting density, interplanting with nitrogen-fixing black alder (Alnus glutinosa [L.] Gaertn.), postestablishment weed control, and time of thinning impacted the productivity and bole quality at mid-rotation. Postestablishment weed control conducted at age 6–7 yr did not impact walnut diameter at age 35, but incidence of frost cracks and grade defects in the butt log (lower 2.44 m) were 100% and 30% greater, respectively, on trees receiving the weed control treatment. Time of first thinning of the alder affected walnut quality in the upper log (second 2.44 m log). The higher planting density of walnut and alder reduced the number of defects by 31% in the upper log, but at the expense of stem diameter growth. At a walnut planting density of 7.9 × 7.9 m, interplanting black alder impacted neither walnut diameter growth nor bole quality. The early thinning treatment increased the number of defects on the upper log, but not the butt log. These results suggest that intensive management can have a complex and enduring impact on black walnut plantation growth and development, and elucidate the need for long-term assessment of silvicultural treatments where bole quality is an important component of stand value. For. Sci. 49(4):522–529.

The Influence of Fire Weather and Land Use on the Fire Activity of the Lake Abitibi Area, Eastern Canada - Patrick Lefort; Sylvie Gauthier; Yves Bergeron (Forest Science, 2003)
The fire history of two adjacent regions of the boreal forest, one characterized by logging (Ontario—510,000 ha) and the other by small scale agricultural activities (Quebec—140,000 ha), was studied before and after these regions were opened up to settlement in 1916. From a review of provincial forest fire records and the assessment of the age of fire-initiated forest stands, it appears that large but rare fires occurred during the presettlement period on both sides of the border. After 1916, due to slash and burn activities, the agricultural region (Que) had proportionally about twice the burned areas and ten times more fires than the forestry region (Ont). Despite differences in population density, road network, and land use, fire size class occurrence did not differ between landscapes over time. However, the occurrence of fires larger than 100 ha, considering three development phases (1916–1939; 1940–1969; 1970–1998), decreased in both regions from settlement to the present, particularly during the late phase (1970–1998) in the agricultural region. An analysis of fluctuations in the Canadian forest Fire Weather Index system (FWI), a rating of fire danger severity, showed major climatic stresses at the beginning of the century (1916–1924), followed by a decrease in the occurrence of extreme FWI values. Combined with the impact of climate, which affected the annual area burned and the number of large fires in both landscapes, the results suggest that the landscape fragmentation, the increase in the percentage of deciduous trees over time and/or effective fire detection by residents led to a decrease in the number of fires larger than 100 ha on the agricultural side for the late phase (1970–1998). FOR. SCI. 49(4):509–521.

Public Land Management and Quality of Life in Neighboring Communities—The Chugach National Forest Planning Experience - Patrick Reed; Gregory Brown (Forest Science, 2003)
Quality of life (QOL), by almost any definition, is important to people. We apply the concept to the relationship between rural communities and public land management. A 1999 study of residents in 12 communities neighboring the Chugach National Forest in Alaska was used during the revision of the Forest's land and resource management plan to assess the relationships between quality of life components and possible management activities being considered. Specifically, we addressed the following five questions: (1) What QOL components are most important to residents of the 14 neighboring local communities? (2) How satisfied are residents with the current status of the QOL components in their communities? (3) How do local respondent perceptions of QOL component importance compare with those of their peers nationwide? (4) If proposed forest management activities may adversely affect resident perceptions of QOL, what are the possible consequences to the communities? (5) How prepared are the communities to address any possible adverse consequences on their own? Our findings confirm that the Forest, probably not unlike other public land management units, has the ability to affect the quality of life of the communities neighboring it for better or for worse. However, the degree to which the communities' residents themselves are prepared for such change is equally significant. FOR. SCI. 49(4):479–498.

Book Reviews: Forest Policy for Private Forestry—Global and Regional Challenges - William R. Bentley (Forest Science, 2003)
This volume is a collection of the best papers presented during a 2001 international conference in Atlanta titled Global Initiatives and Public Policies: First International Conference on Private Forestry in the 21st Century. The papers are grouped in four sections, with the broadest views in the first and most detailed in the last two sections.

Market Participation and Willingness to Pay for Environmentally Certified Products - Kim Jensen; Paul M. Jakus; Burton English; Jamey Menard (Forest Science, 2003)
The purpose of this study is to ascertain (1) consumers' willingness to participate in a market for environmentally certified hardwood products, and (2) the ‘price premium’ consumers would be willing to pay for a certified oak shelving board. Further, we test how demographics influence market participation and the price premium. Results were obtained through a telephone survey of 811 Pennsylvania residents. Overall, 42.2% supported certification and were willing to pay higher prices for certified products, 45.5% supported certification but were not willing to pay higher prices, and 11.3% did not support certification regardless of costs. The profile of those most likely to participate in a certified wood product market includes nonhomeowners, female, college-educated, recyclers, and previous purchasers of environmentally labeled nonwood products. Among those supporting certification and willing to pay a premium, consumers were willing to pay $10.18 above the cost of an uncertified board ($28.80). For. Sci. 49(4):632–641.

Optimal Forest Taxation under Private and Social Amenity Valuation - Erkki Koskela; Markku Ollikainen (Forest Science, 2003)
This article analyzes the socially optimal forest taxation in the rotation framework when the government has a binding tax revenue requirement. In the Faustmann model, the optimal design of taxation consists of nondistortionary taxes, such as site productivity tax, site value tax, or profit tax. A combination of distortionary unit (or yield) tax and timber tax can also be used to collect the tax revenue in a nondistortionary way. In the Hartman model, with forest amenity services as a public good, the optimal design consists of a nondistortionary tax and a Pigouvian tax, which adjusts the private rotation age to the socially optimal one. Now only the site productivity tax is nondistortionary, while unit, yield, timber, site value, and profit taxes generally serve as corrective Pigouvian taxes. Finally, in the absence of a nondistortionary tax, if the marginal valuation of amenity services is nondecreasing with the age of forest stand, a combination of unit (or yield) and timber taxes can be used for both tax revenue collection and Pigouvian correction. FOR. SCI.49(4):596–607.

Efficiency and Merger Gains in the Danish Forestry Extension Service - Peter Bogetoft; Bo Jellesmark Thorsen; Niels Strange (Forest Science, 2003)
In Denmark, many small-scale forest owners are affiliated to local district offices of The Danish Forestry Extension Service. In this article, the efficiency of the different offices is evaluated using Data Envelopment Analysis (DEA). Furthermore, recent theoretical developments in DEA are used to assess the gains from a number of potential mergers and to decompose these gains into those from technological improvements, harmony effects, and scale effects. The results show that inefficiency is widespread and may in some cases be improved through mergers due to potential harmony gains and scale returns. However, the dominant part of the inefficiency is technical, and this suggests that improved learning and sharing of know-how or key resources across offices may improve efficiency. For. Sci. 49(4):585–595.

Clustering and Compactness in Reserve Site Selection: An Extension of the Biodiversity Management Area Selection Model - Douglas T. Fischer; Richard L. Church (Forest Science, 2003)
Over the last 15 yr, a number of formal mathematical models and heuristics have been developed for the purpose of selecting sites for biodiversity conservation. One of these models, the Biodiversity Management Area Selection (BMAS) model (Church et al. 1996a), places a major emphasis on protecting at least a certain area for each biodiversity element. Viewed spatially, solutions from this model tend to be a combination of isolated planning units and, sometimes, small clusters. One method to identify solutions with potentially less fragmentation is to add an objective to minimize the outside perimeter of selected areas. Outside perimeter only counts those edges of a planning unit that are not shared in common with another selected planning unit in a cluster, and, therefore, compact clustering is encouraged. This article presents a new math programming model that incorporates this perimeter objective into the BMAS model. We present an application using data from the USDA Forest Service-funded Sierra Nevada Ecosystem Project (Davis et al. 1996) and show that the model can be solved optimally by off-the-shelf software. Our tests indicate that the model can produce dramatic reductions in perimeter of the reserve system (increasing clustering and compactness) at the expense of relatively small decreases in performance against area and suitability measures. FOR. SCI. 49(4): 555–565.

Predicting the Spatial Distribution of Aspen Growth Potential in the Upper Great Lakes Region - Eric J. Gustafson; Sue M. Lietz; John L. Wright (Forest Science, 2003)
One way to increase aspen yields is to produce aspen on sites where aspen growth potential is highest. Aspen growth rates are typically predicted using site index, but this is impractical for landscape-level assessments. We tested the hypothesis that aspen growth can be predicted from site and climate variables and generated a model to map the spatial variability of aspen growth potential across the upper Great Lakes region. The model predicting aspen growth from climate and site characteristics performed nearly as well as the site index model. Sites currently growing aspen have a somewhat lower growth potential than do nonaspen upland sites. The mean growth potential of national forest sites is lower than on other ownerships, except in Michigan. Upland sites with the highest aspen growth potential had higher growth potential than sites currently growing aspen, suggesting that productivity could be increased by shifting the location of aspen production. Only 6.7% of the highest growth sites are located on national forests across the region. The spatially explicit nature of these results may facilitate cooperative planning to better optimize where aspen will be managed across a subregion to enhance regional productivity and to focus management where the potential for production is the greatest. FOR. SCI. 49(4):499–508.

Combining Remotely Sensed Optical and Radar Data in k NN-Estimation of Forest Variables - H. Holmström; J.E.S. Fransson (Forest Science, 2003)
The use of optical and radar data for estimation of forest variables has been investigated and evaluated by employing the k nearest neighbor (kNN) method. The investigation was performed at a test site located in the south of Sweden consisting mainly of Norway spruce and Scots pine forests with standwise stem volume in the range of 0–430 m3 ha-1. The kNN method imputes weighted reference plot variables to areas to be estimated (target areas), facilitating further use of data in forestry planning models. Remotely sensed multispectral optical data from the SPOT-4 XS satellite and radar data from the airborne CARABAS-II VHF SAR sensor were used, separately and combined, to define weights in the kNN algorithm. The weights were inversely proportional to the image feature distance between the reference plot and the target area. The distance metric was defined using regression models based on the image data sources. Positive impact on the accuracies of stem volume and age estimates was found by combining the two image data sources. Stem volume, at stand level, was estimated with a RMSE of 37 m3 ha-1 (22% of the true mean value) using the combination of optical and radar data, compared to 50 m3 ha-1 (30%) for the best single-sensor case in this study. In conclusion, the results indicate that the accuracy of forest variable estimations was substantially improved by using multisensor data. FOR. SCI. 49(3):409–418.

Special Commentary: The Future of Digital Remote Sensing for Production Forestry Organizations - James L. Smith; Michael Clutter; Brent Keefer; Zhenkui Ma (Forest Science, 2003)
It cannot honestly be stated that digital imagery is a standard instrument in the repertoire of the professional natural resource manager. However, we believe that the opportunity to change that situation is rapidly approaching because a nexus of technology and need has finally occurred. However, pragmatic issues remain. The key to the successful adoption of any new tool, including digital imagery, is not just having the need, but having the tool be useful, usable and available to the great mass of users, (i.e., those in the field in the case of our profession). No forester thinks twice about using an analog aerial photograph, and we need to create that same “ho-hum” status for digital imagery. FOR. SCI. 49(3):455–456.

Potential Improvements in the Characterization of Forest Canopy Gaps Caused by Windthrow Using Fine Spatial Resolution Multispectral Data: Comparing Hard and Soft Classification Techniques - Giles M. Foody; Robin G. Jackson; Christopher P. Quine (Forest Science, 2003)
Gaps often form in forest canopies due to windthrow and have important management and ecological implications. Remote sensing has considerable potential for the provision of information on gap properties but this has not been fully realized. This is largely due to the use of conventional (hard, one-pixel one-class) image analysis techniques and imagery with a relatively coarse spatial resolution. This article investigates the potential to extract information on gap properties from fine spatial resolution airborne thematic mapper imagery using soft classification techniques that allow image pixels to have multiple and partial class membership. It is shown that a standard hard maximum likelihood classification may be used to derive an accurate map of the land cover of a forested site (95.1%) from which gaps in a canopy of Sitka spruce were accurately identified (94.5%). The maximum likelihood classification was also softened by outputting probabilities of class membership for each pixel. Softening the classification increased the information on gap properties that could be extracted from the data. In particular, the accuracy with which key gap properties, such as gap area, perimeter length and shape, were estimated was higher in the outputs of the softened than hard classification. Thus, while strong correlations between the remotely sensed and ground data estimates of gap area (r ≥ 0.96) and perimeter (r ≥ 0.87), based on a sample of 36 gaps, were derived from all classifications, the accuracy with which gap properties were estimated was generally highest when a soft classification was used. For example, the use of a soft rather than hard classification resulted in the root mean square error in estimating gap area declining from 144.90 to 132.87 m2. Furthermore, the soft classification allowed the sharpness of the gap boundary to be estimated, enabling further gap properties to be inferred. In particular, the soft classification output enabled the direction of the wind event causing the initial damage to be estimated, and it may aid the definition of sites with a future risk of windthrow. FOR. SCI. 49(3):444–454.

Combining High-Resolution Aerial Photography with Gradient-Directed Transects to Guide Field Sampling and Forest Mapping in Mountainous Terrain - Holger Sandmann; Ken P. Lertzman (Forest Science, 2003)
Forest inventory and management relies on accurate maps of vegetation structure and composition. Creating such maps typically proceeds in two main stages: delineating stand boundaries on midscale aerial photography (≈1:15,000) followed by collection of reference data in field plots. Technical and logistical limitations arise with respect to the resolution of photography, the allocation of field plots, and the sequence of the stages. Here we present a novel approach for forest mapping that (1) places the mapping process as the last rather than the first stage; (2) concentrates sampling in areas with strong environmental gradients; and (3) uses large-scale, high-resolution aerial photography (≈1:2,000) to supplement field data and midscale airphotos. Our design builds on observations that plant communities in mountainous areas often exhibit strong correlations with environmental variables and that digital or hardcopy maps of these variables are becoming more widely available. In the first stage, 1:2,000 aerial photography is obtained via helicopter-mounted small-format cameras along flight lines that are located subjectively to follow significant environmental gradients. In the second stage, field plots are placed within airphoto transects to provide reference data of forest conditions. An integrated analysis of plot data and high-resolution photography provides the empirical basis for the development and calibration of an interpretation key. In the third stage, this key is applied to the delineation and classification of forested area on stereoscopic 1:15,000 aerial photography across the landscape of interest. We demonstrate this approach using a watershed in southwestern British Columbia and compare four probability-sampling designs with the gradient-directed approach proposed here using computer simulations. The results indicate that sampling along topographic gradients leads to a loss of accuracy with respect to estimation of distributional parameters. However, gradient-directed sampling is as likely as probability sampling to capture the full range of variability in forest conditions, with greatly improved logistics and cost-effectiveness. We conclude that our sampling design is a practical alternative for mapping projects in topographically complex landscapes. FOR. SCI. 49(3):429–443.

Estimation of Tree Height and Stem Volume on Plots Using Airborne Laser Scanning - Johan Holmgren; Mats Nilsson; Håkan Olsson (Forest Science, 2003)
Airborne laser scanning has the ability to measure the vertical and horizontal structure of forest vegetation. The aim of this study is to investigate how measures derived from laser scanning data can be used in regression models for estimation of basal-area-weighted mean tree height and stem volume on 10 m radius field plots. Influence of laser scan angle on tree height estimation and on crown coverage area estimation is also investigated. The study area was located in southern Sweden (lat. 58°30′N, long. 13°40′E). The dominating tree species were Norway spruce (Picea abies L. Karst .), Scots pine (Pinus sylvestris L.) and birch (Betula spp.). Linear regression functions (R2=0.89–0.91) used to predict basal-area-weighted mean tree height had a Root Mean Square Error (RMSE) of 1.45–1.56 m, corresponding to 10–11% of average height. Scanning angle was not significant for estimation of basal-area-weighted mean tree height. Two regression models were used for prediction of stem volume. The first model (R2 = 0.90), with laser derived mean height together with laser derived crown coverage area as predicting variables, gave RMSE of 37 m3 ha-1, corresponding to 22% of average stem volume. The second model (R2=0.82), with laser derived tree height together with laser derived stem number as predicting variables, gave RMSE of 43 m3 ha-1, corresponding to 26% of average stem volume. The results implies that airborne laser scanning, if combined with a field sample, has potential of retrieving information with high spatial resolution (10 m radius plot) about tree height and stem volume for a forest area. FOR. SCI. 49(3):419–428.

Hyperspectral Remote Sensing of Forest Condition: Estimating Chlorophyll Content in Tolerant Hardwoods - Paul H. Sampson; Pablo J. Zarco-Tejada; Gina H. Mohammed; John R. Miller; Thomas L. Noland (Forest Science, 2003)
To develop practical and objective measures of forest condition, the Bioindicators of Forest Sustainability Project has used a physiological, remote sensing approach that emphasizes identifying early warning measures of stress effects in forests. While stress indicators exist at the leaf level (e.g., chlorophyll fluorescence, pigment levels), developing reliable indicators at the canopy level is a challenge. Hyperspectral sensors, such as the Compact Airborne Spectrographic Imager (CASI), may be useful in remotely detecting vegetation stress effects. In this study, an inverse modeling approach demonstrated that the CASI could be used to map chlorophyll content (root mean square errors ranging from 12.6 to 13.0 mg/cm2) following different silvicultural treatments in a tolerant hardwood (sugar maple [Acer saccharum M.]) forest. This capability could be readily applied to operationally assessing forest physiological strain and in classifying forest condition based on chlorophyll content. A change analysis study was also conducted to evaluate chlorophyll estimation across seasons for a range of sites. The implications of these findings and recommendations for a prototype system to monitor forest condition are presented. FOR. SCI. 49(3):381–391.

Classification Accuracy for Stratification with Remotely Sensed Data - Raymond L. Czaplewski; Paul L. Patterson (Forest Science, 2003)
Tools are developed that help specify the classification accuracy required from remotely sensed data. These tools are applied during the planning stage of a sample survey that will use poststratification, prestratification with proportional allocation, or double sampling for stratification. Accuracy standards are developed in terms of an “error matrix,” which is familiar to remote sensing specialists. In addition, guidance is provided to determine when new remotely sensed classifications are needed to maintain acceptable levels of statistical precision with stratification. FOR. SCI. 49(3):402–408.

Comparing Two Area Estimation Techniques for Established Surveys Using Remotely Sensed and Ground Data - Michael S. Williams; Paul L. Patterson (Forest Science, 2003)
Estimates of the area of forest using remotely sensed and ground data can be derived using two distinctly different paradigms. The first, which will be referred to as the “tessellated population paradigm,” relies on the assumption that the area is divided into contiguous blocks that constitute an area frame. Inference is drawn using traditional finite population sampling methods. The other approach will be referred to as the point paradigm, which assumes that the sampling unit is a point on the ground. The estimators are derived assuming the number of ground plots in each remotely sensed category is random. The mechanisms that determine the variance of the estimators are different for both paradigms, with the variance of the point paradigm depending on the accuracy and size of each remotely sensed class, while the variance of the tessellated population paradigm depends predominantly on the fragmentation of the landscape in comparison with the size of the sampling unit. An analytical comparison of the estimators is not possible because of the difficulty associated with relating landscape fragmentation to the accuracy of the remotely sensed data. Thus, both estimators were tested by drawing samples from a series of artificial landscapes and satellite images using a plot configuration similar to the one used by the Forest Inventory and Analysis program of the United States. It is concluded that if the landscape is heavily fragmented and the accuracy is reasonably high, the point paradigm estimator is likely to have a smaller variance. The tessellated population estimators will usually have a smaller variance when the landscape has only a small degree of fragmentation. For the majority of the artificial populations studied, the estimator based on the tessellated population paradigm had the smallest variance. In situations where there would not be sufficient prior knowledge to determine which paradigm is superior or when the variance of both is expected to be about equal, the point paradigm is recommended because it is theoretically more tractable and easier to implement in the field. FOR. SCI. 49(3):392–401.

Satellite Change Detection of Forest Harvest Patterns on an Industrial Forest Landscape - Steven A. Sader; Matthew Bertrand; Emily Hoffhine Wilson (Forest Science, 2003)
Multiple dates of Landsat Thematic Mapper (TM) imagery were analyzed to compare a decade of forest harvest activity in northern Maine's industrial forest. Unsupervised clustering on three-date sequences of Normalized Difference Vegetation Index classified the harvest type and time period when change occurred. Problematic clusters were reclassified using the Normalized Difference Moisture Index, which improved the detection of light partial harvests. The procedure classified clearcuts and partial cuts in all time periods with at least 80% agreement with 250 reference sample points. Patch characteristics of the harvest areas revealed a shift from large clearcuts in the late 1980s and early 1990s to fewer and smaller clearcuts in the middle to late 1990s. By the late 1990s, large clearcuts (>40 ha) were eliminated, and partial cuts increased in size. Partial cuts affected more land area than did clearcuts in all time periods. Comparison of harvest patches between the two largest landowners in the study area revealed significant differences in the number and distance between clearcut harvest areas. The trends in decreasing clearcut harvesting practices over the past decade appear to have been influenced by forestry legislation, according to the results of this study and an independent report by the Maine Forest Service. The changing harvest patterns on the landscape were detectable on time-series satellite imagery. FOR. SCI. 49 (3):341–353.

Global Forest Cover Mapping for the United Nations Food and Agriculture Organization Forest Resources Assessment 2000 Program - Zhiliang Zhu; Eric Waller (Forest Science, 2003)
Many countries periodically produce national reports on the status and changes of forest resources, using statistical surveys and spatial mapping of remotely sensed data. At the global level, the Food and Agriculture Organization (FAO) of the United Nations has conducted a Forest Resources Assessment (FRA) program every 10 yr since 1980, producing statistics and analysis that give a global synopsis of forest resources in the world. For the year 2000 of the FRA program (FRA2000), a global forest cover map was produced to provide spatial context to the extensive survey. The forest cover map, produced at the U.S. Geological Survey (USGS) EROS Data Center (EDC), has five classes: closed forest, open or fragmented forest, other wooded land, other land cover, and water. The first two forested classes at the global scale were delineated using combinations of temporal compositing, modified mixture analysis, geographic stratification, and other classification techniques. The remaining three FAO classes were derived primarily from the USGS global land cover characteristics database (Loveland et al. 1999). Validated on the basis of existing reference data sets, the map is estimated to be 77% accurate for the first four classes (no reference data were available for water), and 86% accurate for the forest and nonforest classification. The final map will be published as an insert to the FAO FRA2000 report. FOR. SCI. 49(3):369–380.

Clustering Versus Regression Trees for Determining Ecological Land Units in the Southern California Mountains and Foothills - Janet Franklin (Forest Science, 2003)
A landscape stratification was required for simulation modeling of fire disturbance and succession in the mountains and foothills region of the Peninsular Ranges within San Diego County, California. Two quantitative approaches to mapping ecological land units (ELUs) were compared for a 3,878 km2 study area. These were: (a) clustering of climate overlain with key terrain variables; and (b) regression tree modeling of climate, geology, and terrain variables using a normalized difference vegetation index (NDVI), derived from a Landsat Thematic Mapper image, as the dependent variable. Terrain variables derived from a digital elevation model included slope gradient, cosine transformed slope aspect, potential solar insolation, and a topographic moisture index. For the simulation model ELUs were required that would stratify the landscape according to biomass (fuel) accumulation dynamics, related to site productivity, and probabilities of plant species establishment. Therefore, ELUs were defined using abiotic variables, and the resulting stratifications were evaluated by their ability to reduce within-class variance in the NDVI (as an index of biological productivity), and by comparing them to a map of existing vegetation. While the regression tree method resulted in classes that explained more variance in NDVI than classes resulting from unsupervised clustering, the difference was not large. In contrast, the unsupervised approach resulted in ecological land classes that were more strongly related to existing vegetation patterns. FOR. SCI. 49 (3):354–368.

Introduction to the Special Issue on Remote Sensing - Randolph Wynne (Forest Science, 2003)

Influence of Fusing Lidar and Multispectral Imagery on Remotely Sensed Estimates of Stand Density and Mean Tree Height in a Managed Loblolly Pine Plantation - John W. McCombs; Scott D. Roberts; David L. Evans (Forest Science, 2003)
Stereo aerial photography has long been used to measure tree density and height photogrammetrically. Recent attempts have been made to locate and measure trees automatically in high-resolution digital imagery. This study used small-footprint lidar (1.057 µm, 1 mrad divergence, 0.67 m footprint) and high-resolution (0.61 m) multispectral (550, 675, 700, and 800 nm) data sets to estimate stem counts and tree heights in 15-yr-old loblolly pine stands. A data fusion process was used to combine the datasets. Tree identification accuracy and mean height estimation derived from the separate and fused data sets were compared against field data. Tree identification was more accurate using spectral data (78.6% and 92.4%) than lidar data (64.7% and 87.3%) within the two planting densities, respectively. The fused dataset improved accuracy of tree identification over the single-dataset approaches (83.5% and 94.8%). Plot-level mean height of lidar-located trees provided the best estimates of mean field height (average difference = 0.15 m). Missed trees for all methods were shorter than mean field height by up to 3.03 m (fused data). These results indicate fusion of spectral and lidar data will likely improve estimates of mean tree height and stem density. Increased lidar posting density is identified as a key factor to improve tree recognition and measurement. FOR. SCI.49(3):457–466.

Photosynthesis and Growth in Seedlings of Five Forest Tree Species with Contrasting Leaf Anatomy Subjected to Supplemental UV-B Radiation - John H. Bassman; Gerald E. Edwards; Ronald Robberecht (Forest Science, 2003)
Seeds or cuttings of five forest tree species with contrasting leaf anatomies and shoot growth characteristics were cultivated under three different UV-B radiation regimes: ambient (7.5 kJ m-2 d-1 = 1×), two times ambient (2×), or three times ambient (3×) biologically effective UV-B radiation (UV-BBE) USA at the summer solstice, as calculated for Pullman, Washington. Experiments were conducted in glasshouses using a nonmodulated UV-B lamp system. Gas exchange was measured in recently mature leaves after six months of exposure. Photosynthetic rates were reduced by 2× and 3× treatments in Populus trichocarpa, and by the 3× regime for Pseudotsuga menziesii. Photosynthetic rates increased under the 2× treatment for Pseudotsuga menziesii and under the 3× treatment for Picea engelmannii. For Pinus ponderosa and Quercus rubra, photosynthetic rates were unchanged. Dark respiration increased under both 2× and 3× treatments for Picea engelmannii and by the 3× level in Quercus rubra, but was unaffected in the other species. Transpiration and stomatal conductance generally mirrored changes in photosynthesis. Water use efficiency increased for Pinus ponderosa (2× treatment) and Quercus rubra (2× and 3×), was reduced for Populus trichocarpa (2× & 3×), and remained unchanged in the other species. Enhanced UV-B radiation changed the shape of light response curves for all species. Quantum yields were unchanged for Pinus ponderosa, increased for Pseudotsuga menziesii (2×) and Picea engelmannii (2× and 3×) and were reduced in Populus trichocarpa (2×) and Quercus rubra (3×). Light compensation points were higher in the conifers (3×) and reduced in the angiosperms (2×). Chlorophylls were generally reduced by higher UV-B radiation in the conifers and for Populus trichocarpa (3×), but increased for Quercus rubra. Ultraviolet-absorbing compounds increased in the conifers and were unchanged in the angiosperms by enhanced UV-B radiation. Height growth increased (Pinus ponderosa, 3×; Quercus rubra, 2×), decreased (Picea engelmannii, 3×) or was unchanged (Pseudotsuga menziesii, Populus trichocarpa) by higher levels of UV-B radiation. Stem diameter and plant biomass were generally reduced, and shoot: root ratios increased for all species except Populus trichocarpa. Our results do not appear to support the hypothesis that inherent leaf anatomy or shoot growth pattern in these species directly determine the response of photosynthesis and growth to enhanced UV-B radiation. FOR SCI. 49(2):176–187.

Book Reviews: The Ecology and Silviculture of Oaks - W. Keith Moser (Forest Science, 2003)
In writing The Ecology and Silviculture of Oaks, Paul Johnson, Stephen Shifley, and Robert Rogers have performed a tremendous service to the forestry community, and the hardwood forestry community in particular. Although there have been several books on hardwoods and numerous symposia on oak ecology and management over the years, this volume provides a centralized, albeit expensive, explanation and reference to a significant body of information focusing on the various species of oaks. What was most informative and valuable to me, however, was how this book also presented a template for understanding the ecology and management of all shade-intolerant to mid-tolerant species.

Book Reviews: Forest Hydrology: An Introduction to Water and Forests - Richard C. Schultz; Kye-Han Lee (Forest Science, 2003)
In recent years, water resource issues concerning quality, quantity, and timing have been dominating natural resource management discussions around the world. Forest hydrology has historically been an important topic in forest management leading to some of the earliest forest research conducted in the United States. While there are a few textbooks on forest hydrology, there has always been a dilemma in what to include in such books. The hydrologic cycle may be briefly covered in ecology courses. However, without a significant introduction to water resources, most forestry and nonforestry students who enroll in a forest hydrology course do not have sufficient background in water resources to really understand the effect forests have on water quality, quantity and timing. A textbook for most forest hydrology courses should not only cover topics on forest impacts on water but also provide the basics of water properties, movement, and storage in the atmosphere, soil matrix, and surface water bodies. Putting both major topic areas in one manageable textbook requires trade-offs that do not dilute either subject area too much, but rather skillfully blend the two together. Mingteh Chang has done just that in writing this book.

An Integer Programming Model to Optimize Resource Allocation for Wildfire Containment - Geoffrey H. Donovan; Douglas B. Rideout (Forest Science, 2003)
Determining the specific mix of fire-fighting resources for a given fire is a necessary condition for identifying the minimum of the Cost Plus Net Value Change (C+NVC) function. Current wildland fire management models may not reliably do so. The problem of identifying the most efficient wildland fire organization is characterized mathematically using integer-programming techniques. This mathematical exposition is then solved using the LINGO optimization language. Sensitivity analysis is conducted on model inputs to demonstrate the flexibility of the model architecture. Further, the model is used to model budget constraints commonly faced by fire managers. FOR. SCI. 49(2):331–335.

Predicting External Branch Characteristics of Planted Silver Birch ( Betula pendula Roth.) on the Basis of Routine Stand and Tree Measurements - Harri Mäkinen; Risto Ojansuu; Pentti Niemistö (Forest Science, 2003)
The aim of this study was to develop simultaneous models for external branch characteristics along the stem that could be applied as a part of a growth simulation system. Data were collected from planted pure stands of silver birch (Betula pendula Roth.) growing on abandoned agricultural land and forest sites of different fertility, with different stand density and age. The data were used to develop generalized linear variance component models for (1) crown ratio, (2) self-pruning ratio, i.e., height of the lowest dead branch divided by the height of the crown base, (3) number of living branches along the stem, (4) total number of branches, (5) diameter of the thickest branch, (6) diameters of smaller branches, and (7) branch angle. The independent variables of the models were restricted to those measured in forest inventories and used for forest management planning purposes. Even though there was bias in predicting some of the branch characteristics in the independent evaluation data set of silver birch, the behavior of the models was logical. No major additional bias was found when the models were applied to downy birch (Betula pubescens Ehrh.). The models provide a framework for predicting the development of wood quality and the possibilities of using silvicultural treatments to control branch characteristics. FOR. SCI. 49(2):301–317.

Nutrient Concentrations and Contents, and their Relation to Stem Growth, of Intensively Managed Pinus taeda and Pinus elliottii Stands of Different Planting Densities - Greg A. Barron-Gafford; Rodney E. Will; E. Colter Burkes; Barry Shiver; Robert O. Teskey (Forest Science, 2003)
Foliar, stem, and fine root nitrogen (N), phosphorus (P), and potassium (K) concentrations were measured, and their contents calculated, to determine the relationship between nutrient acquisition and stem biomass increment on a stand basis in 4-yr-old pine plantations planted at different densities. The study examined stands of loblolly pine (Pinus taeda L.) and slash pine (Pinus elliottii Engelm.) in the lower Coastal Plain of the southeastern United States that were intensively managed (i.e., received bedded site preparation, a high level of fertilization, and nearly complete weed control). The stands were planted at densities of 740, 2, 220, and 3,700 trees ha-1 on three sites, each with a different soil type. Increases in stem biomass growth on a stand basis were not proportional to increases in stand density, indicating that competition for resources was limiting growth at the higher densities. Foliar N and P, stem wood N and K, and fine root N concentrations decreased with increased stand density. For loblolly pine, foliar N concentrations fell from 13.1 mg g-1 at 740 trees ha-1 to 10.9 mg g-1 at 3700 trees ha-1 (average of current-year and 1-yr-old foliage), the latter considered below a critical threshold concentration for maintaining high growth rates. Slash pine foliar N concentrations followed a similar pattern, decreasing from 11.2 to 9.1 mg g-1. In both species, foliar P and K concentrations remained above critical concentrations at all planting densities. Overall, foliar N concentration was negatively correlated to stem biomass increment on a stand basis (r = -0.57) whereas foliar N content of 1-yr-old foliage was positively correlated with stem biomass increment (r = 0.59). However, biomass of 1-yr-old foliage was better correlated to total stem biomass growth (r = 0.76) suggesting that amount of foliage, rather than its nutrient content, was a better estimator of growth. FOR. SCI. 49(2):291–300.

A Comparison of Compatible and Annual Growth Models - Norihisa Ochi; Quang V. Cao (Forest Science, 2003)
Compatible growth and yield models are desirable because they provide the same growth estimates regardless of length of growth periods. However, the compatibility constraints restrict the number of possible models. This restriction might be overcome by using models that predict annual stand growth based on periodic measurements. The advantages of this approach are (1) the flexibility allowed in building annual growth models without constraints, and (2) the step-invariance property maintained by these models. An annual growth model was developed in this study that predicts yield based on information from the previous year. For 162 plots from the Southwide Seed Source Study of loblolly pine (Pinus taeda L.), the annual growth model provided better predictions of stand survival, basal area, and volume than two compatible growth models. FOR. SCI. 49(2):285–290.

Genetic Variation in Nitrogen Uptake and Growth in Mycorrhizal and Nonmycorrhizal Picea abies (L.) Karst. Seedlings - Samuel Mari; Alena Jonsson; Roger Finlay; Tom Ericsson; Monika Kähr; Gösta Eriksson (Forest Science, 2003)
The purpose of this study was to estimate genetic variation in nitrogen uptake and growth of mycorrhizal and nonmycorrhizal seedlings from 30 open-pollinated families of Norway spruce (Picea abies), at two levels of nitrogen (N) supply. Six-week-old seedlings were transplanted into 1.7 L pots filled with pumice, and one-half of them was inoculated with the ectomycorrhizal symbiont Laccaria bicolor. A 2 × 2 factorial combination of the presence or absence of the fungus and two nitrogen concentrations (200 mg N/L and 25 mg N/L) was used during 2 wk of establishment. During the following 10 wk, no water or nutrients were supplied. At harvest (week 18) height, shoot and root dry weights, as well as the amount of nitrogen in the shoot and nitrogen acquisition capacity, were determined. There was a strong treatment effect, and most of the traits ranked in increasing order: low N, low N + Mycorrhiza, high N, high N + Mycorrhiza. With low N, plants with mycorrhiza had a shoot dry weight twice that of nonmycorrhizal plants. Significant differences among families were found for most traits in treatments without mycorrhiza, while mycorrhiza strongly reduced the number of significant family differences. The amount of nitrogen in the shoot and all biomass traits showed a significant family × mycorrhiza × nitrogen interaction. Of the two traits related to nitrogen uptake, shoot nitrogen amount showed strong genetic correlations with biomass traits in all treatments (rg within the range 0.92 to 0.99) whereas nitrogen acquisition capacity did not (rg within the range -0.53 to +0.23), which implies that the amount of nitrogen in the shoot is a better predictor of growth than nitrogen acquisition capacity. FOR. SCI. 49(2):258–267.

Simple Tests for Detecting Segregation of Major Genes with Phenotypic Data from a Diallel Mating - Wen Zeng; Bailian Li (Forest Science, 2003)
Three simple statistical tests (the Bartlett test, the log-ANOVA test, and the Fain test) were investigated for detecting the segregation of major genes controlling a quantitative trait in half-diallel mating populations. Eight experimental diallel progeny populations of loblolly pine (Pinus taeda L.) from a breeding program were analyzed to detect major gene segregation for 6 yr tree height. The results from three simple tests indicated that there could be major gene segregation for 6 yr height in three diallels. Data with different degrees of major and polygenic effects were simulated with the same mating and field experimental design for further evaluation of these simple tests. Statistical powers of detection were assessed for a major gene with two alleles plus the polygenic background of general combining ability (GCA) and specific combining ability (SCA) effects. The robustness of methods to the presence of half-sib relationships, a skewed phenotypic distribution, and unbalanced data were evaluated. The Bartlett test was the most powerful, but was sensitive to half-sib relationship and skewness. The log-ANOVA test was as powerful as the Bartlett test, but was robust to half-sib relationship and skewness. The Fain test was less powerful but less sensitive to skewness than the Bartlett test. The major gene effect (percent of total phenotypic variance) and dominance level of the major gene were the two most important factors affecting the power of detection. The power for the Bartlett and log-ANOVA test increased with the increment of polygenic heritability. The ratio of dominance to additive variance for polygenic inheritance had little effect on the power for the Bartlett and log-ANOVA tests. The log-ANOVA test is the most desired simple test for detecting major gene segregation in a diallel population with half-sib structures. Simple tests can be used to screen breeding populations for major genes affecting tree growth, and the information can be useful to speed up traditional tree breeding programs. FOR. SCI. 49(2):268–278.

Valuing Biodiversity, Aesthetics, and Job Losses Associated with Ecosystem Management Using Stated Preferences - Weihuan Xu; Bruce R. Lippke; John Perez-Garcia (Forest Science, 2003)
The study performs a joint estimation of the values for three important attributes of forest ecosystem management—biodiversity, aesthetics, and rural employment impacts using a choice-based, stated preference approach. It develops the marginal willingness-to-pay schedule for the three attributes for timber rural, other rural, and urban communities in Washington State. In contrast to the conventional wisdom in neoclassical economics, the public perceives job losses as losses of social welfare in this study. There are differences as well as similarities among the preferences of the three communities for the attributes of ecosystem management. The results show that the overall preferences of the timber rural and urban communities towards ecosystem management are substantially different, while the preferences of other rural community are not statistically significantly different from the other two communities. The estimated environmental and social values make it possible for policy makers and resource managers to compare and assess the trade-offs of different management plans. For example, with the biodiversity index level at 60, where an index of 50 relates current conditions, and rural forest-related job losses at 5,000, each household in urban communities in Washington State is willing to pay $31.44 annually for an additional unit of improvement of biodiversity, and $45.97 annually for avoiding an additional 1,000 rural job losses. The trade-off relationship for the given biodiversity and job loss levels suggests each household in urban communities each year is willing to trade 684 additional rural forest-related job losses with one unit of biodiversity improvement, ceteris paribus. Similar trade-off relationships for households in timber and other rural communities suggest each is willing to trade 598 and 388 additional rural forest-related job losses, respectively, with one unit of biodiversity improvement, ceteris paribus. The trade-off between aesthetics and job losses are 1,229, 452, and 686 additional jobs with one unit of aesthetics improvement for urban, timber, and other rural households, respectively. The trade-off relationships provide important information for improving the efficiency and equity of forest ecosystem management. FOR. SCI. 49(2):247–257.

Biomass Partitioning and Growth Efficiency of Intensively Managed Pinus taeda and Pinus elliottii Stands of Different Planting Densities - E. Colter Burkes; Rodney E. Will; Greg A. Barron-Gafford; Robert O. Teskey; Barry Shiver (Forest Science, 2003)
The effect of planting density (740, 2,220, 3,700, and 4,440 trees/ha-1) on growth efficiency and biomass partitioning was examined in intensively managed stands of 4-yr-old loblolly (Pinus taeda L.) and slash pine (Pinus elliottii Engelm.) stands on the Coastal Plain of southern Georgia. The primary objective of this study was to determine whether decreased partitioning of biomass to stem relative to other tree components limits stem biomass growth on a per hectare basis as stand density increases. Fourth growing season stem biomass production did not increase proportionally with planting density, indicating that stem biomass growth was limited at the higher stand densities. For both species, growth efficiency (stem biomass growth produced during the fourth growing season per unit of leaf biomass) was significantly lower for stands planted at 740 trees/ha-1 compared to the other stand densities. Similarly, the ratio of stem biomass growth: fine root biomass was significantly lower for the 740 trees/ha-1 stand. Within sites, planting density had no effect on the ratio of fine root biomass: leaf biomass for either species. Overall, these results indicate that partitioning to stem growth increased relative to foliage or fine roots as stand density increased. Therefore, the limitation in stem biomass growth on a per hectare basis that occurred as stand density increased was not due to changes in partitioning, but probably due to a limitation in net primary production. FOR. SCI. 47(2):224–234.

Comparison of Ground Sampling Methods for Estimating Canopy Cover - Michael S. Williams; Paul L. Patterson; H. Todd Mowrer (Forest Science, 2003)
Knowledge of the canopy structure is essential to improving our understanding of forest structure. While numerous sampling techniques have been developed to estimate attributes of the forest canopy, these require either additional measurements or a sampling design and measurement techniques that differ substantially from the ones that are used to estimate more traditional forest attributes, such as basal area, number of stems, or volume. The root of the problem is that the sample element for a design that estimates canopy attributes is the tree crown, whereas the sample element is the bole for a design that estimates an attribute such as basal area. For example, if a fixed-area plot is used to estimate basal area, canopy cover cannot be estimated using the same design because a portion of the plot invariably is covered by the crowns of trees whose boles lie outside the plot boundary and would not be included in the sample under the standard sampling design. In this study, a technique called “morphing” is used to model the trees outside the plot boundary. For the purpose of comparison, the morphing technique is used to estimate canopy cover using data from a circular fixed-area plot, and this technique is compared with both dot count and line intersect sampling using a simulation study and two small forest populations. For the study, the populations were sampled using circular fixed-area plots with radii ranging from ρ = 3.05–6.10 m (10–20 ft) and line lengths ranging from L = 3.05–22.9 m (10–75 ft). For both populations, the bias of the canopy cover estimator derived from the morphing technique was negligible. The estimator based on line intersect sampling is design-unbiased, but it generally had a much larger variance than the one based on the morphing technique. The dot count method consistently had the highest variance. FOR. SCI. 49(2):235–246.

Coarse Filter Ecosystem Management in a Nonequilibrating Forest - Glen W. Armstrong; Wiktor L. Adamowicz; James A. Beck; Steven G. Cumming; Fiona K.A. Schmiegelow (Forest Science, 2003)
The natural disturbance model of forest management is the basis of many of the sustainable forest management systems being proposed for the boreal forest of Canada. Wildfire is the dominant natural agent of disturbance in the boreal mixed-wood forest. The natural disturbance model assumes that timber harvesting systems emulating the annual area burned by natural fire, its spatial distribution, and the amount of residual material can be developed. It is further assumed that natural processes can be emulated closely enough to maintain forest biota at natural or near-natural population levels. This is a coarse filter approach to ecosystem management. In order to emulate the natural rate of disturbance, one needs to quantify it. The annual area burned in the study area, under natural conditions, is characterized as a random draw from a lognormal distribution. A modeling system comprised of an aspatial Monte Carlo simulation model and a linear programming based forest activity scheduling model was developed. The simulation model is used to develop 200 yr forecasts of probability distributions for habitat area of five vertebrate species under a stochastic wildfire regime. These probability distributions are used to construct habitat area constraints for use in an optimization model to help quantify the trade-offs between timber values and maintenance of the range of natural variability in the forest. The model is used to identify the trade-offs between forest harvesting, wildlife habitat, and the degree of similarity between the managed forest structure and the distribution of structures that could be generated by natural disturbance. FOR. SCI. 49(2):209–223.

Scaling Growth Relationships from Seedling Plots Using Similarity Analysis - Ralph L. Amateis; Mahadev Sharma; Harold E. Burkhart (Forest Science, 2003)
Data from a small-scale loblolly pine seedling experiment established at 1/16 scale to an operational study were used to develop height and diameter development models appropriate for either scale. An additional model was constructed that analytically relates stand development between the two scales and links the size of trees grown at small scale to operational scale counterparts. Results suggest that important stand characteristics associated with forest productivity develop similarly at the two scales. The models presented here can be used to evaluate the effects of stand density on tree growth at either scale and make inferences to operational scales from small-scale seedling studies. FOR. SCI. 49(2):188–195.

Guided Transect Sampling with a New Strategy for Second-Stage Guidance - Anna Ringvall (Forest Science, 2003)
Guided transect sampling (GTS) was recently proposed as a method for surveying sparse and geographically scattered populations if prior information with high spatial resolution is available. With this method, wide survey strips are, during a first stage, randomly selected in the area to be surveyed. In the second stage, the selected first-stage strips are subsampled with a survey line or survey strip based on the prior information. In this article, a new strategy for second-stage guidance is developed and evaluated in a simulation study. The suggested strategy uses an assumed model for the relationship between the prior information and the variable of interest to find an efficient design for selecting the second-stage transects. The performance of the suggested strategy is evaluated in terms of the variance obtained in different realizations of the assumed model. Results from the simulation study indicate that the suggested strategy is an efficient alternative to previously suggested strategies, if the correspondence between the model population and the real population is good. On the other hand, if the difference between the two populations is large, large variances were sometimes obtained. FOR. SCI. 49(2):169–175.

Selecting a Level of Conditioning for the Segmented Polynomial Taper Equation - Mahadev Sharma; Harold E. Burkhart (Forest Science, 2003)
Using tree data collected from loblolly pine thinning study plots, different levels of conditioning were examined for the segmented polynomial taper equation presented by Max and Burkhart (1976). An eight-parameter model with minimum constraints (diameter at the tip of a tree is zero and the adjacent functions are continuous at the join points) did not perform better than a six-parameter model with an additional smoothness constraint in terms of fit and predictive ability. The join points where the adjacent segments of a tree meet, the inflection points, were assumed known to further reduce the number of parameters in the model. A four-parameter model with inflection points at 11 and 75% of total tree height was slightly superior to the six- and eight-parameter models in estimating tree diameters. The fit statistics and predictive ability of the model were not sensitive to the lower and upper inflection points in the range of 9–12% and 70–80%, respectively. For. Sci. 49(2):324–330.

A Reformulation of the Cost Plus Net Value Change (C+NVC) Model of Wildfire Economics - Geoffrey H. Donovan; Douglas B. Rideout (Forest Science, 2003)
The Cost plus Net Value Change (C+NVC) model provides the theoretical foundation for wildland fire economics and provides the basis for the National Fire Management Analysis System (NFMAS). The C+NVC model is based on the earlier least Cost plus Loss model (LC+L) expressed by Sparhawk (1925). Mathematical and graphical analysis of the LC+L model illustrates two errors in model formulation. First, suppression is incorrectly modeled as a model output. Second, suppression and primary protection are incorrectly modeled as negatively correlated. These errors are shown to be perpetuated by the contemporary C+NVC model and to have serious implications for the model's capacity to correctly identify the most efficient level of fire management expenditure. A corrected graphical representation of the C+NVC model is presented, which allows the most efficient level of fire management expenditure to be correctly identified. FOR. SCI. 49(2):318–323.

Inherent Correlations Between Stand Biomass Variables Calculated from Tree Measurements - Thomas J. Dean; Quang V. Cao (Forest Science, 2003)
Correlating stand-level variables is an important component of forest production ecology; however, correlations among variables calculated with equations having common independent variables are potentially spurious. Monte Carlo simulation techniques were used to determine the inherent or null correlation coefficients among stand-level biomass variables calculated with published, individual-tree equations using loblolly pine (Pinus taeda L.) data. Null correlations of foliage mass/ha with branch mass/ha, stem mass/ha, and periodic annual increments of biomass were high with similar equation forms and exponents in the equations. Most, but not all, correlation coefficients of foliage mass/ha with other biomass components and periodic annual increments of biomass were significantly different from the corresponding, null correlation coefficients. Stating the probability of a greater difference between the observed and the null correlation coefficients proved crucial in distinguishing between potentially meaningful and spurious correlations because in many cases, the observed correlation coefficients were close to the null values. Interpretation of the correlations among stand variables varied with the equations used to predict the variables. Consequently, in addition to comparing correlation coefficients to appropriate null values, conclusions drawn from the correlation among stand-level variables depend on the accuracy and precision of the equations used to calculate them. FOR. SCI. 49(2):279–284.

Genetic Gain and Selection Efficiency of Loblolly Pine in Three Geographic Regions - Bin Xiang; Bailian Li; Steve McKeand (Forest Science, 2003)
Genetic parameters of annual height to 8 yr and 4 to 8 yr volume were examined for Northern, Coastal, and Piedmont populations of loblolly pine (Pinus taeda L.) from analyses of 23 disconnected half-diallel progeny tests in the southern United States. Genetic gains in year 8 volume predicted by various selection methods at age 6 revealed that selection on volume yielded more gain than selection on height. Among test regions, the Coastal population had the greatest correlated response, followed by the Piedmont population and Northern populations. Family plus within family selection was the most effective to achieve genetic gain for early selection on both height and volume. Additional gain (10–40%) can be achieved by capturing the nonadditive genetic component through mass production of fullsib crosses or vegetative propagation. Early selection efficiency was examined by using the ratio of either gain per year or present value between indirect selection and selection of year 8 volume. Optimal selection ages were determined for various selection methods. The analysis of selection efficiency showed earlier selection could be more efficient than selection on volume at age 8 or later. Family selection can be performed as early as age 3 for height and at age 4 for volume, which was the earliest measurement year for volume in this study. Family plus within family had its optimal selection age at age 3 or age 4. Based on the relatinship of age 8 with rotation gain, the selection criteria and timing were also appropriate. FOR. SCI. 49(2):196–208.

Estimating and Validating Ground-Based Timber Harvesting Production Through Computer Simulation - Jingxin Wang; Chris B. LeDoux (Forest Science, 2003)
Estimating ground-based timber harvesting systems production with an object-oriented methodology was investigated. The estimation model developed generates stands of trees, simulates chain saw, drive-to-tree feller-buncher, swing-to-tree single-grip harvester felling, and grapple skidder and forwarder extraction activities, and analyzes costs and productivity. It also measures the traffic intensity level of extraction machines across sites. The model components were validated using data from several independent field studies. The model was used to evaluate the interaction of stand variables, harvest treatments, machines, and extraction patterns. Using two main skid trails to harvest a block minimized traffic intensity. The model can be best used to evaluate alternative skidding configurations and their impact on cost, production, and traffic intensity. FOR. SCI. 49(1):64–76.

Estimates of Additive, Dominance and Epistatic Genetic Variances from a Clonally Replicated Test of Loblolly Pine - Fikret Isik; Bailian Li; John Frampton (Forest Science, 2003)
Nine full-sib families were generated using a factorial mating design consisting of three female and three male loblolly pine (Pinus taeda L.) parents. Full-sib seedlings and clones of the same families were planted in two test sites in Alabama and Florida. Additive, dominance, and epistatic genetic variances were estimated for growth traits and for fusiform rust incidence for ages 1 through 6. Epistatic variances did not have a significant role in growth traits, but additive gene actions were the major source of genetic variance in loblolly pine. Dominance variance for height, diameter, and volume was negligible at early ages, but it was considerable at age 6, particularly for volume. Fusiform rust incidence appeared to be partially under additive and epistatic gene actions and genetic differences among the clones within families accounted for 48.6% of the total variance. Within-plot variance for clones was always smaller than that within-plot variance for seedlings of the same full-sib families. Clonally replicated progeny tests may provide special advantages for loblolly pine tree improvement programs, as they would substantially increase the efficiency of testing by reducing the microenvironmental variance and better estimation of genetic parameters. This may provide greater genetic gains, particularly for fusiform rust incidence. Potential effects of the small parental size and violations of the assumptions of the genetic model are discussed. Negative additive and nonadditive genetic correlations between the growth traits and fusiform rust incidence are encouraging for rapid and simultaneous improvement of the traits during the same cycle selection. FOR. SCI. 49(1):77–88.

Book Reviews: Forest Dynamics and Disturbance Regimes: Studies from Temperate Evergreen-Deciduous Forests - George R. Parker (Forest Science, 2003)
The structure of forests in any place is largely the result of the timing and character of past disturbance events. Disturbance opens forest ecosystems for colonization of species and is essential for the long-term survival of both plant and animal species within a forested region. This book focuses on the long-term dynamics of the Lake States Region located within the states of Michigan, Wisconsin, and Minnesota in the United States. While the book is regional in its coverage, the approach used in examining disturbance factors that drive forest change could be used for any other region. The author concentrates on three main disturbance factors: fire, wind, and herbivores.

Book Reviews: Burning Questions: A Social Science Research Plan for Federal Wildland Fire Management - Hayley Hesseln (Forest Science, 2003)
Social science will play an important role in addressing wildfire issues in the 21st century as fire risk continues to escalate and society moves farther into forests and wildlands at the periphery of urbanization. A better understanding of the social relationships encompassing fire management will be useful for policymakers, fire personnel, and the public. Furthermore, the use of social science will be beneficial in elucidating the complex relationships among these groups.

Landscape Ecosystems of Northern Lower Michigan and the Occurrence and Management of the Kirtland's Warbler - Daniel M. Kashian; Burton V. Barnes; Wayne S. Walker (Forest Science, 2003)
The Kirtland's warbler (Dendroica kirtlandii Baird) is an endangered songbird that nests in northern Lower Michigan in ecosystems dominated by young jack pine (Pinus banksiana Lamb.). An ecological, multifactor approach was used to determine the range and characteristics of landform-level ecosystems supporting the warbler and to compare the spatial and temporal patterns of warbler occupation among these ecosystems. Using an ecosystem rather than a strictly biological approach, the landforms occupied by the warbler are very diverse. Twelve landforms were identified based on 61 sites currently or formerly occupied by the warbler. Average annual jack pine height growth, an indicator of stand structural features that influences initial warbler colonization and duration of occupancy, differed significantly among landforms, resulting in marked differences in warbler occurrence in time and space across the breeding range. Landforms with favorable growing conditions for jack pine were colonized earliest and were occupied for the shortest duration, whereas landforms with unfavorable growing conditions were colonized relatively late but were occupied longest. Different ecological factors, such as the spatial position of landforms, microclimate, soil texture, or a combination of these factors, may account for favorable or unfavorable growing conditions for jack pine, which in turn affects the timing and duration of warbler occupancy. The classification and description of ecosystems occupied by the warbler provides an ecological framework for warbler management, especially when plantations rather than wildfire are the primary source of warbler habitat. FOR. SCI. 49(1):140–159.

Landscape Ecosystems of the Mack Lake Burn, Northern Lower Michigan, and the Occurrence of the Kirtland's Warbler - Wayne S. Walker; Burton V. Barnes; Daniel M. Kashian (Forest Science, 2003)
The Kirtland's warbler (Dendroica kirtlandii Baird) is a federally endangered songbird that nests only in ecosystems dominated by young jack pine (Pinus banksiana Lamb.) in northern Michigan. Although considerable research has focused on the bird, comparatively little information is available on the specific landscape ecosystems occupied by the warbler. The 9,700 ha Mack Lake burn provided an opportunity to track the pattern of Kirtland's warbler occurrence in relation to the ecosystems of a highly diverse and productive area of its breeding range. Using a multifactor landscape ecosystem approach, two high-elevation and four low-elevation landform-level ecosystems were identified, described, and mapped. The spatial pattern of warbler occurrence over time was strongly mediated by the physical and biotic components of the ecosystems. During the first 3 yr of warbler occupation (1986–1988), the high-elevation landforms, characterized by relatively warm temperatures, moister, more fertile soils, and faster growing jack pines, supported 62% of the population. Thereafter, a major shift occurred to the low-elevation landforms. During the last 3 yr of record (1995–1997), the low-elevation landforms, characterized by colder temperatures, drier, less fertile soils, and slow-growing jack pines, supported 86% of the population. The juxtaposition of high- and low-elevation landforms, and the fine-scale ecosystem diversity within them, prolonged the duration of warbler occupancy beyond what would be expected in less heterogeneous conditions. As demonstrated here, the landscape ecosystem approach provides a sound, ecological framework for understanding patterns of Kirtland's warbler occurrence and for assisting managers in identifying appropriate management areas for the continued recovery of the species. FOR. SCI. 49(1):119–139.

Production Efficiency and Productivity Growth in Norwegian Sawmilling - Anders Q. Nyrud; Sjur Baardsen (Forest Science, 2003)
Production efficiency of Norwegian sawmilling was examined using Data Envelopment Analysis. The analysis was carried out on an extensive panel data set, including about 200 sawmills during the period 1974 to 1991. Productivity growth throughout the period was investigated using the Malmquist productivity index. The results indicate that approximately 30% of the sawmills were producing efficiently when assuming constant returns to scale. Estimated production growth approximated 1% per year. FOR. SCI. 49(1):89–97.

Comparison of Estimators for Rolling Samples Using Forest Inventory and Analysis Data - Devin S. Johnson; Michael S. Williams; Raymond L. Czaplewski (Forest Science, 2003)
The performance of three classes of weighted average estimators is studied for an annual inventory design similar to the Forest Inventory and Analysis program of the United States. The first class is based on an ARIMA(0,1,1) time series model. The equal weight, simple moving average is a member of this class. The second class is based on an ARIMA(0,2,2) time series model. The final class is based on a locally weighted least-squares regression prediction. The estimator properties were tested using a simulation population created from Forest Inventory and Analysis (FIA) data from northeastern Minnesota. Estimates of total volume per acre, on-growth volume per acre, mortality volume per acre, proportion of sawtimber acreage, proportion of poletimber acreage, and proportion of sapling acreage were calculated using several weighted average estimators in each year. These were compared to the simulation population, for which the true values are known, and an unbiased yearly estimator. When computing estimates, the ARIMA(0,1,1) based estimators produced the lowest root mean squared error of each of the three classes. However, in a few years the bias for some variables was high. The maximum percent increase between the estimator with the lowest root mean squared error and the simple moving average was 7.31%. Of all the estimators, the simple moving average performed well in terms of mean square error in virtually every situation. It tended to be best among the estimators tested if spatial variation was large and change was relatively small. It was not consistently best in terms of mean square error in the presence of moderate change and large spatial variation. For. Sci. 49(1):50–63.

Spatial Methods for Quantifying Forest Stand Structure Development: A Comparison Between Nearest-Neighbor Indices and Variogram Analysis - Vincent Kint; Marc van Meirvenne; Lieven Nachtergale; Guy Geudens; Noël Lust (Forest Science, 2003)
Insight into forest stand structure is of capital importance for understanding forest ecosystem structure and function. The ability of two spatial methods—based on (1) nearest-neighbor indices and (2) geostatistical variogram analysis—to quantify forest stand structure and its development over short time periods was investigated in two mixed Scots pine stands. Results show that the two methods are complementary in quantifying the three components of forest stand structure: positioning, mixture, and differentiation. The principal advantage of nearest-neighbor indices was their capacity for detecting subtle structure changes; moreover, they are easy to calculate and interpret. Variograms of height and indicator variograms of presence/absence data were more complicated in their use and required more input data, but provided additional information on the number, impact, and range of structure-determining factors such as competition and management. In this context, the concept of the mark variograms is discussed. FOR. SCI. 49(1):36–49.

An Indirect Search Algorithm for Harvest-Scheduling Under Adjacency Constraints - Kevin Crowe; John Nelson (Forest Science, 2003)
An indirect search heuristic is described for solving harvest-scheduling problems under adjacency constraints. This method works in combination with a greedy algorithm by diversifying the search through random changes in prioritized harvest queues. The indirect search is tested on a series of tactical problems and compared with published results for tabu search, simulated annealing, integer programming and linear programming. Results for large strategic problems are compared to a simulated annealing search algorithm. Objective function values are comparable to tabu search and simulated annealing, and solution times range from 38 seconds to 40 minutes, depending on the problem size and the number of iterations. Benefits of the indirect search method are: (1) objective function values can be higher than those computed through other heuristic algorithms, and (2) the algorithm produces good results without time-consuming experimentation with parameters of the search algorithm. The method also has potential for solving more complicated, multiple objective problems. FOR. SCI. 49(1):1–11.

2002 Contents (Forest Science, 2003)

Book Reviews: Integrated Public Lands Management: Principles and Applications to National Forests, Parks, Wildlife Refuges, and BLM Lands - Peter E. Linehan (Forest Science, 2003)
The intense wildfire season of 2002 devastated hundreds of thousands of acres of forest lands in the western United States. A bigger impact in the public awareness came from the intense media attention on the large number of homes and buildings threatened as well as cities such as Denver, Colorado, and many small towns in New Mexico and Oregon. It would appear to be relatively easy to arrive at a consensus to deal with such a serious threat to the public welfare. Yet, as the intensely critical reaction to the Bush administration's relatively modest set of proposals to streamline administrative procedures and promote fuel load reductions with thinning and harvesting shows: there is no consensus on natural resource management policy on public lands. This book shows how federal natural resource management policies developed over time to meet the conflicting and changing desires of the public. While learning resource analysis and management techniques, readers can also see their history and justification.

Effects of Registration Errors Between Remotely Sensed and Ground Data on Estimators of Forest Area - Paul L. Patterson; Michael S. Williams (Forest Science, 2003)
The estimation of area by land cover type is a key component of most large-scale forest inventories. Historically, these estimates were derived from a large sample of points, taken from aerial photos, followed by a smaller sample of ground points, which were used to correct errors in the classification of the aerial photo points. There has been interest in replacing aerial photography with satellite imagery. One problem with using satellite imagery is the registration errors between a pixel and a plot or a point on the ground. The estimators and modes of inference can differ substantially depending on whether the sample unit is a plot or point on the ground. Two terms, tessellated and point paradigm, are used to differentiate between the two approaches when the ground data consists of plots or points, respectively. The effects of registration errors are compared using the two paradigms for estimating the area of land by cover type. The effects of registration errors on the expected value and variance of the forest area estimator under both the tessellated and point paradigm were studied using a simulation study, where a percentage of the samples had a random one- or two-pixel registration error. The simulation study shows that registration errors increased the variance of the estimator of forest area from 4% to 434%. The estimator of forest area under both the tessellated and point paradigm exhibited no detectable bias. In the presence of registration errors, the estimated variance under the tessellated paradigm tended to overestimate the true variance with the achieved coverage rate for a nominal 80% confidence interval ranging from about 81% to 86%. For sample sizes of fewer than 100 ground points, the estimated variance under the point paradigm tended to underestimate both the 80% confidence interval and the true variance, regardless of whether there were registration errors. Further testing showed that sample sizes of between 100 and 250 ground points were needed before the estimator of the variance under the point paradigm converged to within 5% of the true variance of the estimator of forest area. Thus, we conclude that registration errors can drastically increase the variance of area estimators and the resulting confidence intervals will not achieve their nominal coverage rates. In this study, the forest area estimator under the tessellated paradigm was clearly more robust to registration errors than the area estimator under the point paradigm. FOR. SCI. 49(1):110–118.

Estimating Stand Characteristics by Combining Single Tree Pattern Recognition of Digital Video Imagery and a Theoretical Diameter Distribution Model - M. Maltamo; T. Tokola; M. Lehikoinen (Forest Science, 2003)
This article presents a new method combining pattern recognition of single trees and a theoretical diameter distribution to determine stand characteristics. The applied remote sensing material was digital video imagery. A super-resolution technique was used in order to improve the quality of the video imagery. Tree crowns were identified and crown areas segmented from the super-resolution image. After that, tree diameters were predicted using detected crown areas. However, only large trees (dbh >17 cm) could be recognized from digital video image. Therefore, the theoretical Weibull distribution was predicted to be able to also calculate the number of small trees (dbh <17 cm). The mean characteristics information needed for predicting the parameters of Weibull distribution was obtained from the resulting truncated distribution of large trees. The final estimate of the diameter distribution is a combination of these two parts. The reliability of prediction of stand characteristics considered, i.e., number of stems, stand basal area, and volume was improved with the use of the theoretical diameter distribution model. However, these results should be considered preliminary, because they are based on a small validation data set. According to these results, especially the accuracy of the estimate of the number of stems was increased considerably. This improvement is important when simulating future stand development in forest management planning software packages. FOR. SCI. 49(1):98–109.

National-Scale Biomass Estimators for United States Tree Species - Jennifer C. Jenkins; David C. Chojnacky; Linda S. Heath; Richard A. Birdsey (Forest Science, 2003)
Estimates of national-scale forest carbon (C) stocks and fluxes are typically based on allometric regression equations developed using dimensional analysis techniques. However, the literature is inconsistent and incomplete with respect to large-scale forest C estimation. We compiled all available diameter-based allometric regression equations for estimating total aboveground and component biomass, defined in dry weight terms, for trees in the United States. We then implemented a modified meta-analysis based on the published equations to develop a set of consistent, national-scale aboveground biomass regression equations for U.S. species. Equations for predicting biomass of tree components were developed as proportions of total aboveground biomass for hardwood and softwood groups. A comparison with recent equations used to develop large-scale biomass estimates from U.S. forest inventory data for eastern U.S. species suggests general agreement (±30%) between biomass estimates. The comparison also shows that differences in equation forms and species groupings may cause differences at small scales depending on tree size and forest species composition. This analysis represents the first major effort to compile and analyze all available biomass literature in a consistent national-scale framework. The equations developed here are used to compute the biomass estimates used by the model FORCARB to develop the U.S. C budget. FOR. SCI. 49(1):12–35.

Pheasants, Partridges, and Grouse: A Guide to the Pheasants, Partridges, Quails, Grouse, Guineafowl, Buttonquails, and Sandgrouse of the World - John P. Carroll (Forest Science, 2002)
The pheasants and relatives have been the subject of a large number of extensive treatises, including works by Beebe (1918– 1922) and Delacour (1977), which are considered classic treatments of some of the species included in Pheasants, Partridges, and Grouse. Although these “gamebirds” contain a number of the best-known and studied birds in the world, most notably the domestic chicken, the ring-necked or common pheasant (Phasianus colchicus), and the wild turkey (Meleagris gallopavo), many species are not familiar even to ornithologists.

Bayesian Melding of a Forest Ecosystem Model with Correlated Inputs - Philip J. Radtke; Thomas E. Burk; Paul V. Bolstad (Forest Science, 2002)
Bayesian melding, a method for assessing uncertainties in deterministic simulation models, was augmented to make use of prior knowledge about correlations between model inputs. The augmentation involved the use of a nonparametric correlation induction algorithm. The modified Bayesian melding technique was applied to the process-based forest ecosystem computer model PnET-II. The Bayesian posterior distribution for this analysis did not reflect prior knowledge of input correlations for five input pairs tested unless the correlations were explicitly accounted for in the Bayesian prior distribution. For other input pairs not known to be correlated prior to the analysis, numerous significant posterior correlations were identified. For one such pair of model inputs, a moderate posterior correlation was substantiated by empirical evidence that had not previously been taken into consideration. We conclude that, when possible, efforts should be made to account for prior knowledge of correlated inputs; however, Bayesian melding may elucidate input correlations in its posterior sample, even when no prior knowledge of such correlations exists. FOR. SCI. 48(4):701–711.

Nutrient Use Efficiency in Three Fast-Growing Tropical Trees - Ankila J. Hiremath; John J. Ewel; Thomas G. Cole (Forest Science, 2002)
We measured nutrient use efficiency (NPP/nutrient uptake) in three species of tropical trees, Hyeronima alchorneoides, Cedrela odorata, and Cordia alliodora. We tested the prediction that on fertile soils species with very different biomass and nutrient allocation and turnover would converge on a common value of nutrient use efficiency. Due to high soil fertility, nutrient use efficiencies of the species studied were low (95–150 and 433–962 for N and P use efficiency, respectively). Nutrient use efficiency was examined in terms of its components, nutrient productivity and the mean residence time of nutrients. Although the species converged on the same nitrogen (but not phosphorus) use efficiency, differences in nutrient productivity and nutrient residence time may confer varying abilities to deal with nitrogen limitation. A combination of high nutrient productivity and longer nutrient retention (e.g., Hyeronima) signals an ability to prosper on infertile sites, whereas high nutrient productivity in the absence of long nutrient retention (e.g., Cedrela) indicates a capacity for high productivity, but only on fertile soil. Nutrient use efficiency and its components help explain species' distributions in natural communities and can be important criteria in selecting perennial plants for human use. For. Sci. 48(4):662–672.

A Finite Mixture Model for Characterizing the Diameter Distributions of Mixed-Species Forest Stands - Chuangmin Liu; Lianjun Zhang; Craig J. Davis; Dale S. Solomon; Jeffrey H. Gove (Forest Science, 2002)
A finite mixture model is used to describe the diameter distributions of mixed-species forest stands. A three-parameter Weibull function is assumed as the component probability density function in the finite mixture model. Four example plots, each with two species, are selected to demonstrate model fitting and comparison. It appears that the finite mixture model is flexible enough to fit irregular, multimodal, or highly skewed diameter distributions. Compared with traditional methods in which a single Weibull function is fit to either the whole plot or each species component separately, the finite mixture model produces much smaller root mean square error and bias, and fits the entire distribution of the plots with extreme peaks, bimodality, or heavy-tails well. In some cases, a single Weibull function fitted to individual species separately may produce more accurate estimations for the component distributions of the two species than the finite mixture model. The summation of the two independent species results, however, may not produce a better prediction for the entire plot. This study shows that the finite mixture model is a promising alternative method for modeling the diameter distribution of multispecies mixed forest stands. For. Sci. 48(4):653–661.

Erratum (Forest Science, 2002)

Oak Forest Ecosystems: Ecology and Management for Wildlife - Constance Harrington (Forest Science, 2002)
Oaks (Quercus spp.) are important components in many temperate forest ecosystems, and a new book that synthesizes information on their management is always of interest. The intent of this book was to bring together knowledge from a diverse group of people who study oak forests and make that information available to those interested in managing those forests in a sustainable manner for wildlife. I think the authors have done a good job in achieving their objectives.

Leptographium Species: Tree Pathogens, Insect Associates, and Agents of Blue-Stain - Lori G. Eckhardt (Forest Science, 2002)
This is an outstanding monograph of the genus Leptographium, a group of fungi that occurs predominantly in pine. Leptographium species have been associated with pine decline and mortality, primarily as associates of root feeding bark beetles and weevils that attack living trees. Several studies have shown that Leptographium plays a major role in decline syndromes both in plantations and aging forests. There are several Leptographium species which are important internationally and are becoming more important in the United States due to their obvious impact on western coniferous forests (L. wageneri) and their involvement in red pine decline (L. terebrantis and L. procerum), making this monograph a timely contribution.

Potential Demand for Certified Wood Products in the United Kingdom and Norway - Knut Veisten (Forest Science, 2002)
Representative samples of the British and Norwegian population were surveyed by telephone and asked to make a hypothetical choice between unlabeled wooden furniture and more expensive eco-labeled wooden furniture. Choice behavior was modeled as a random utility model with utility-theoretic restrictions on choice and estimated willingness to pay (WTP). To counteract upward biased hypothetical values, a followup question assessed the certainty of respondents' choices. For those not choosing the eco-labeled alternative, another followup question assessed if these individuals could be regarded as indifferent.Compared to the unlabeled wooden furniture with a price of US$332 in the UK and US$275 in Norway, the extra median WTP for the eco-labeled alternative was estimated to be US$5.16 (1.6%) in the UK and US$2.79 (1%) in Norway, with a censored log-logistic binary choice model. In these estimates only the “absolutely sure ” were counted as valid choices of the eco-labeled alternative. The censoring implied that those who indicated indifference between unlabeled and eco-labeled furniture had their estimated WTP adjusted to 0. About 39% of the UK population and 32% of the Norwegian population are predicted to choose the eco-labeled alternative when the price difference is less than 5%. FOR. SCI. 48(4):767–778.

Scale and Unit Specification Influences in Harvest Scheduling with Maximum Area Restrictions - Alan T. Murray; Andrés Weintraub (Forest Science, 2002)
This article examines alternative approaches for representing a forest region to be scheduled for harvesting, where the primary concerns are maximizing return and imposing a maximum contiguous area of disturbance restriction. One approach assumes that any two adjacent management units exceed a regulated maximum area of disturbance. An alternative approach recognizes that management units may be substantially smaller than the maximum area restriction, so simultaneously disturbing two neighboring units does not necessarily represent a maximum area violation. The distinguishing feature of these two approaches is the way in which a forest is spatially represented. A single time period, 351 management unit harvest scheduling problem is utilized to investigate whether analysis results are subject to manipulation when forest representation, and associated modeling, is interpreted in different ways. Empirical results highlight significant economic and spatial variation in harvest schedules when maximum area restrictions are imposed using alternative approaches. For. Sci. 48(4):779–789.

Comparative Analysis of Stochastic Models for Financial Uncertainty in Forest Management - Atsushi Yoshimoto; Isao Shoji (Forest Science, 2002)
We propose 13 continuous time stochastic models based on the state-dependent volatility process for stochastic log price dynamics, and then conduct a comparative analysis for their performance. Comparison is carried out on the basis of AIC (Akaike's Information Criterion), the mean squared error of the model, and the likelihood ratio test. Parameter estimation is performed by using the local linearization method. Our experiments with 13 tree species sold on the Japanese timber market show that the general form of the state-dependent stochastic model yields the highest performance in terms of AIC for most logs. In addition, we find that price dynamics with a tendency to increase over time can be captured by such a stochastic model, with the drift term as a linear function of the state. It is also shown that a functional form of the diffusion part or volatility of the model plays an important role in model performance with regard to the AIC, while a functional form of the drift part of the model does so in the mean squared error for forecasting one period ahead. FOR. SCI. 48(4):755–766.

Density and the Growth of Even-Aged Stands - Boris Zeide (Forest Science, 2002)
This study develops a density-driven module and combines it with conventional growth equations, making the resulting model applicable to managed stands. The relationship between the diameter increment of an average tree and density evolves from the analysis of amount of light coming to the unshaded (upper) part of the crown, distribution of foliage along the stem, proportion of light transmitted through the crown, probability of shading the lower part of the crown, and other processes. The density module contains seven parameters, all of which can be assessed from existing knowledge. One of the parameters quantifies phenotypic adaptation, which mitigates competition stress. The entire model starts and ends with basic measurable variables: number of trees per unit area and their average diameter. The growth processes are evoked only to connect the current and future values of stand variables. FOR. SCI. 48(4):743–754.

Periodicity of Two-Year Cycle Spruce Budworm Outbreaks in Central British Columbia: A Dendro-Ecological Analysis - Qi-Bin Zhang; René I. Alfaro (Forest Science, 2002)
An outbreak of the two-year cycle budworm (Choristoneura biennis Freeman) has caused defoliation damage to interior spruce (Picea engelmannii Parry × P. glauca (Moench)) and subalpine fir (Abies lasiocarpa [Hook.] Nutt.) forests of north central British Columbia for more than 10 yr and was ongoing in 1999. A sample of 429 increment cores from spruce, subalpine fir, and lodgepole pine (Pinus contorta var. latifolia Engelm.) was collected in areas of chronic defoliation, and used in a dendro-ecological study. The objective was to develop accurately dated ring-width chronologies of each species and, by comparing growth rates of the budworm host tree species (spruce and fir) with those of the nonhost pine, to determine the past history of budworm outbreaks in the region. This history would help in estimation of the potential duration and severity of the current outbreak in the region.Four periods of decade-long reduced growth attributable to budworm defoliation were identified in the increment cores from both spruce and subalpine fir. These occurred in the mid-1890s to the early 1900s, the mid-1920s to the mid-1930s, the 1950s to the early 1960s, and the late 1980s to present (1999). Outbreaks recurred approximately every 32 yr. The reduced growth period, indicative of past outbreaks, consisted of a growth reduction phase lasting 7 to 11 yr in which rings generally exhibited a pattern of alternating wide and narrow rings (a “saw-tooth” pattern). This pattern was attributed to the biennial nature of the life cycle of this budworm, in which severe damage is caused every other year. The growth reduction phase was followed by a growth recovery phase lasting 3 to 5 yr in which ring-width gradually returned to pre-outbreak levels. Thus, the entire growth loss period could last from 10 to 16 yr and cause an average annual loss in radial increment from 16 to 21%. The 32 yr cycle of outbreak recurrence was attributed to changes in forest structure in which the forest evolves from a nonsusceptible to a susceptible state as the proportion of subalpine fir present in the upper canopy increases relative to the spruce component. A 2 yr cycle budworm outbreak will selectively remove the subalpine fir component returning the forest to a less susceptible state. It was concluded that the 2 yr cycle budworm is an important disturbance agent of northern British Columbia forests causing significant growth loss. FOR. SCI. 48(4):722–731.

Performance Differences and Genetic Parameters for Four Coastal Provenances of Loblolly Pine in the Southeastern United States - V. Sierra-Lucero; S.E. McKeand; D.A. Huber; D.L. Rockwood; T.L. White (Forest Science, 2002)
Provenance-progeny test plantations of loblolly pine (Pinus taeda L.) were assessed for survival, height, mean annual increment for volume (MAIV), and fusiform rust infection (caused by Cronartium quercuum [Berk] Miyabe ex Shirai f. sp. fusiforme) at 5, 10 and 15 yr. Each of the 7 sites contained from 6 to 15 open-pollinated families from each of 4 provenances: Atlantic Coastal Plain (ACP), Central Florida (CF), Marion County Florida (MCF), and Gulf Coastal Plain (GCP). The main objectives for establishing these trials were to: (1) characterize the genetic architecture among and within these provenances; and (2) determine the relative genetic worth of these provenances for possible inclusion in advanced-generation breeding programs in the Coastal Plain in the southeastern United States. Provenance and family within provenance effects were strong and highly significant for height and MAIV, but only family effects were significant for rust infection. The Florida provenances were the best growers at all ages and at all sites. The poor growth of the Gulf Coastal Plain provenance compared to the Atlantic Coastal Plain provenance could not be explained by climatic or edaphic differences between the regions of origin. We speculate that gene flow from slower growing sources on the western side of the Mississippi River may be at least partly responsible for the poor growth of the GCP loblolly. Because of the relatively stable performance of the provenances and the families within provenances at each site and across ages, selection of superior families for growth and rust resistance between ages 5 and 10 yr should result in substantial genetic gain in the Coastal Plain. For. Sci. 48(4):732–742.

Economic Analysis of the Canada–United States Softwood Lumber Dispute: Playing the Quota Game - G. Cornelis van Kooten (Forest Science, 2002)
The Canada–U.S. Softwood Lumber Agreement (SLA) was the latest measure to restrict Canadian exports of softwood lumber to the United States. Rather than a countervail duty or export tax, SLA employed a quota that provides a large windfall (quota) rent to Canadian lumber producers in addition to extra quasi-rents to U.S. producers, all at the expense of U.S. consumers. However, Canadian producers have not taken full advantage of the quota regime to maximize their overall gains, which exceed what they could earn under free trade or an export/import tax. This is demonstrated using a theoretical framework and numerical illustration. It is shown that the net gain to Canadian producers does not occur when the quota rent is maximized, but rather when the sum of producer surplus and quota rent is maximized. It is also argued that the existence of resource rents from logging does not constitute a subsidy to lumber producers. It is concluded that, from Canada's perspective, export quotas are preferred to both free trade or an export/import tax, at least in the short run, but only if all provinces and all softwood lumber products are included in the Agreement and a means for sharing the windfall rents can be found. For. Sci. 48(4):712–721.

The Epidemiology of Pitch Canker of Monterey Pine in California - Andrew J. Storer; David L. Wood; Thomas R. Gordon (Forest Science, 2002)
The progression of pitch canker disease, caused by Fusarium circinatum, was followed over 4 yr (1992–1996) in urban stands of Monterey pine, Pinus radiata, with initially zero, light, moderate, and severe disease intensity. The disease progressed from a few to many branch tip symptoms, followed by the appearance of cankers on the main stem. Symptomatic branch tips at the start of the study were predictive of tree mortality or removal after 4 yr. Trees with canopy dieback and stem cankers were often attacked by the red turpentine beetle, Dendroctonus valens. Among initially disease-free trees, disease progression and final severity were greater in plots with initially severe and moderate disease intensity. Apparent infection rates did not differ between plots with different initial disease intensities. Over the 4 yr of the study, 2% of trees in the five plots with most severe disease never exhibited disease symptoms and thus may be resistant to pitch canker. In addition, 7% of symptomatic trees in these plots never had more than two symptomatic branch tips, which may reflect a moderate level of resistance. FOR. SCI. 48(4):694–700.

Understanding Broadscale Wildfire Risks in a Human-Dominated Landscape - Jeffrey P. Prestemon; John M. Pye; David T. Butry; Thomas P. Holmes; D. Evan Mercer (Forest Science, 2002)
Broadscale statistical evaluations of wildfire incidence can answer policy-relevant questions about the effectiveness of microlevel vegetation management and can identify subjects needing further study. A dynamic time series cross-sectional model was used to evaluate the statistical links between forest wildfire and vegetation management, human land use, and climatic factors in Florida counties. Four forest wildfire risk functions were estimated: one for fires regardless of ignition source, and three others for fires of specific ignition sources: arson, lightning, and accident (unintentional anthropogenic). Results suggest that current wildfire risk is negatively related to several years of past wildfire and very recent site prep burning, and risk is positively related to pulpwood removals. The effect of traditional prescribed burning on wildfire risk varies by ignition source. El Niño–Southern Oscillation (ENSO) sea surface temperature (SST) anomalies were also significantly linked to forest wildfire risk, but a measure of the wildland-urban interface was not significant. Although these county-level results hold promise for aggregate risk assessment, modeling at finer spatial and temporal scales might further enhance our understanding of how land managers can best reduce the longer term risk of catastrophic wildfire damages. For. Sci. 48(4):685–693.

Applying Fuzzy Logic to Tree Bucking Control - Veli-Pekka Kivinen; Jori Uusitalo (Forest Science, 2002)
In this article, we introduce a fuzzy logic based control system that calibrates the price list controlling the tree bucking of a modern harvester according to the unique conditions of an individual stand prior to harvesting. The system employs a bucking simulator that predicts an output distribution for any price list generated. A fuzzy controller is used to recalculate the price list according to the difference between the demand distribution and the actual output distribution. The tests with perfect knowledge of the stems showed that the control system clearly works efficiently. However, calibrating the price list prior to harvesting seemed to be very sensitive to the precision of the prior information on the trees. The simulations showed that while no gain can be achieved by preharvest inventorying of the stands and fine-tuning the price lists with this imperfect knowledge, the same or even better bucking results can be obtained by the bucking-to-demand process in which the price list is continuously adjusted after each cutting. For. Sci. 48(4):673–684.

Modeling Forest Dynamics with a Combined Matrix/Individual-Based Model - Nicolas Picard; Avner Bar-Hen; Alain Franc (Forest Science, 2002)
A combined model, with a matrix component to describe the trees whose diameters are below a threshold, and an individual-based component for the trees above the threshold, is proposed. The combined model is derived from a matrix model and simulates the dynamics of a tropical rainforest in French Guiana, with a management orientation. The methodology to build a combined model starting from a matrix model is specified. The crucial point lies in three continuity conditions at the transition diameter. To establish them, both the matrix and the individual-based components are reformulated into a continuous distribution-based model, which is analytically more tractable. The combined model provides a more detailed description of the tail of the diameter distribution, which can be useful for management purposes. It also permits the separation of the dynamics of small trees, which are numerous and for which matrix coefficients can be quite precisely assessed, from the dynamics of large trees. For. Sci. 48(4):643–652.

Harvest Scheduling with Area-Based Adjacency Constraints - Marc E. McDill; Stephanie A. Rebain; Janis Braze (Forest Science, 2002)
Adjacency constraints in harvest scheduling models prevent the harvest of adjacent management units within a given time period. Two mixed integer linear programming (MILP) harvest scheduling formulations are presented that include adjacency constraints, yet allow the simultaneous harvest of groups of contiguous management units whose combined areas are less than some predefined limit. These models are termed Area Restriction Models, or ARMs, following Murray (1999). The first approach, the Path Algorithm, generates a set of constraints that prevent concurrent harvesting of groups of contiguous stands only when the combined area of a group exceeds the harvest area restriction. The second approach defines the set of Generalized Management Units (GMUs) that consist of groups of contiguous management units whose combined areas do not exceed the maximum harvest area limit. This formulation of the model can recognize direct cost savings—such as sale administration costs or harvest costs—or higher stumpage prices that may be realized by jointly managing stands. Example problems are formulated and solved using both ARM approaches and compared with models that restrict concurrent harvests on all adjacent units, regardless of area [termed Unit Restriction Models, or URMs, again following Murray (1999)]. The ARM formulations usually result in larger models and take longer to solve, but allow for higher objective function values than otherwise similar URM formulations. While the proposed ARM approaches should be applicable to more general problems, the examples are constructed so that the largest number of contiguous stands that can be harvested jointly is three. Strategies for reducing the size of the ARM formulations are discussed and tested. FOR. SCI. 48(4):631–642.

Erratum (Forest Science, 2002)

Causes for Continuation of State Cost-Share Programs for Nonindustrial Private Forest Landowners - Sayeed R. Mehmood; Daowei Zhang (Forest Science, 2002)
State cost-share programs for nonindustrial private forest landowners are public assistance programs in the form of direct subsidy payments. A total of 18 states have such programs. This article presents a political economy model and empirical evidences of the factors that determine their presence and continuation. A logit regression is used in the empirical analysis, and the results suggest that the importance of forestry in a state's economy and healthy state finances are significant determinants. Furthermore, there is also evidence of significant regional differences within the United States and some effects of bureaucratic intent. Irrespective of the rationales or justifications for these programs, political pressure on the forest industry made them possible, and a healthy state economy made them a reality. FOR. SCI. 48(3):471–478.

Resource Assessment of Non-Wood Forest Products: Experience and Biometric Principles - David Pilz (Forest Science, 2002)
Forest managers increasingly recognize that management of non-wood forest product (NWFP) harvesting is important for conserving biological diversity and sustaining human use of forests. Importantly, many of these products, and the forests they grow in, are integral to the persistence of indigenous cultures. Similarly, rural communities are more likely to support forest conservation or longer timber rotations if they can annually harvest and market products derived from local forests. Managing NWFP resources poses a daunting task, however, because such products are numerous and diverse; the organisms that produce them differ widely in form, abundance, distribution, and autecology; and harvesting typically occurs in a complex social, economic, political, land tenure, and forest management context. Nevertheless, forest managers, researchers, development workers, harvesters, and affected local communities agree that assessing the status of, and changes in, resource abundance is central to sustainable NWFP management.

The Silver Lining: The Benefits of Natural Disasters - Chris J. Peterson (Forest Science, 2002)
In this welcome and accessible volume, Seth Reice, a stream ecologist who specializes in the study of disturbance effects on community structure, explains to the informed nonspecialist how important are disturbances to the health and diversity of ecosystems. It is important to note that this book is intended to enlighten a lay audience; it is not intended strictly or even primarily for forest scientists or ecologists. And therein lies its potential value: by making the benefits of natural disasters clear to the nonspecialist, Reice communicates how, by embracing the inevitability of natural disturbances and recognizing their benefits for natural systems, we can adopt more sustainable policies, behaviors, and attitudes. I wholeheartedly applaud this goal, and believe as a whole that Reice's book is an excellent step in that direction.

Polya Posterior Frequency Distributions for Stratified Double Sampling of Categorical Data - Steen Magnussen; Michael Köhl (Forest Science, 2002)
Estimates of category frequencies in stratified double sampling are generally obtained by methods of maximum likelihood assuming a multinomial distribution of data. Although the distribution of estimation errors is asymptotically normal, a reliance on the normal assumption for inference can be problematic for low frequency categories (<10%) and small sample sizes (<1,000). In these situations, a Bayesian approach appears more robust. A vague Dirichlet prior is adopted to compute a Polya posterior distribution. In a simulation study of sampling from eight small-to medium-sized populations, we found that the resampling distributions of maximum likelihood estimates were generally closer to the Polya posteriors than to the assumed normal distributions. Resampling distributions and Polya posteriors deviated frequently and significantly from a normal distribution. A Polya posterior was often orders of magnitude faster to compute than a resampling distribution. FOR. SCI. 48(3):569–581.

Continuing Growth Response to Phosphate Fertilizers by a Pinus radiata Plantation over Fifty Years - J. Turner; Marcia J. Lambert; F.R. Humphreys (Forest Science, 2002)
The period of growth response of forest plantations to phosphate fertilizer applications has been variable and difficult to predict. Significant growth responses by Pinus radiata (D. Don) to two different phosphate fertilizers, superphosphate and rock phosphate applied at 96 kg P ha-1 (previously reported by the authors) have continued for the 50 yr period since the fertilizers were initially applied in 1947. There have been no further fertilizer applications. At the end of the second rotation of 33 yr (50 yr after the fertilizer was applied), the growth and biomass of the trees were determined, together with soil and foliage chemical analyses, and comparisons made with those obtained earlier. The standing volume of the phosphate treatments was 430 m3 ha-1, an increase of 50% over the 287 m3 ha-1 in the untreated control. Soil total phosphorus concentrations were increased from 64 mg kg-1 in the control to 105 mg kg-1 and 134 mg kg-1 in the superphosphate and rock phosphate treatments, respectively, and have remained constant. The aboveground biomass of the treated plots was about 380 tonne ha-1 compared with 278 tonne ha-1 in the control. The single application of phosphorus has led to a significant change in site characteristics. The implications for forest management are that a relatively low application of fertilizer on some nutritionally poor sites changes the productive capacity of the site. FOR. SCI. 48(3):556–568.

Optimization of Land Use in Afforestation Areas Using Evolutionary Self-Organization - Niels Strange; Henrik Meilby; Bo Jellesmark Thorsen (Forest Science, 2002)
This article presents a cellular automaton approach to the optimization of land use planning in afforestation areas. The case study deals with 110 ha of recently afforested land in Denmark. A modified two-dimensional automaton containing 2,345 active cells is used for optimizing the land use setup in this area. Four land use alternatives are considered: pasture, beech (Fagus sylvatica L.), Norway spruce (Picea abies [L.] Karst.), and oak (Quercus robur L.). The objective is to maximize a weighted sum of soil expectation value, scale-dependent costs, recreational value, and the value of structural variation. It is demonstrated that for this sort of problem, appropriately modified cellular automata may yield acceptable solutions within a comparatively low number of iterations. Furthermore, for a simplified hypothetical problem, it is shown that the cellular automaton approach was able to identify optimal solutions within reasonable time. FOR. SCI. 48(3):543–555.

A Site Dependent Simultaneous Growth Projection Model for Pinus kesiya Plantations in Zambia and Zimbabwe - Kalle Eerikäinen (Forest Science, 2002)
The aim of this study was to create a stand level yield model for Pinus kesiya (Royle × Gordon) plantations in Zambia and Zimbabwe based on the simultaneous projection model approach. The purpose was to prepare prediction models for the measurable and allometrically related stand variables which characterize the development of planted P. kesiya stands. The modeled stand characteristics are assessable in the inventories of forest plantations and are frequently employed in traditional stand yield tables and modern growth simulators. Special attention was paid to the selection of flexible nonlinear model forms that are simple and stable. Two model forms were developed: (1) a polymorphic and base age invariant site index equation, used as a growth projection model for stand dominant height, and (2) a stand volume prediction model based on Honer's single tree volume model. The projection form of the site index equation was obtained using the algebraic difference approach to solve analytically the rate parameter of the autocatalytic growth model. The simultaneous growth projection model included a model for basal area median diameter. The basal area median diameter was also used as a predictor of stand basal area. This improved the accuracy of stand basal area predictions. A model for the basal area median diameter also makes it possible to apply theoretical diameter distributions for the prediction of future stand stages. FOR. SCI. 48(3):518–529.

Competitive Capacity of Quercus rubra L. Planted in Arkansas' Boston Mountains - Martin A. Spetich; Daniel C. Dey; Paul S. Johnson; David L. Graney (Forest Science, 2002)
Results of an 11 yr study of the growth and survival of planted northern red oak (Quercus rubra L.) seedlings (2-0 bare-root) are presented. More than 4,000 seedlings were planted under shelterwood overstories that were harvested 3 yr after planting. Results are expressed as planted-tree dominance probabilities. Dominance probability is the probability that a planted tree will live to attain a favorable competitive position (i.e., at least 80% of the mean height of dominant competitors) at a specified year. We interpret the resulting probability as a measure of the competitive capacity of an individual seedling, i.e., its potential of attaining dominance in a specified environment. Based on logistic regression analysis, dominance probabilities increase with time after shelterwood overstory removal for any given environment and initial seedling characteristics. At any specified time, dominance probabilities depend on initial seedling basal diameter before planting (stem caliper 2 cm above the root collar), site quality, intensity of weed control, and shelterwood percent stocking. Dominance probabilities increase with decreasing shelterwood stocking, increasing initial stem caliper, and increasing intensity of weed control. Other factors being equal, top clipped seedlings have higher dominance probabilities than unclipped seedlings. The reciprocals of the dominance probabilities provide silviculturally useful estimates of the numbers of trees that would need to be planted to obtain, on the average, one competitively successful tree. For example, if clipped seedlings averaging 6 mm in caliper were planted where oak site index was 24 m, shelterwood stocking was 80%, and the site was given no weed control before or after planting, obtaining one competitively successful tree 11 yr after planting (8 yr after shelterwood removal) would require planting 144 seedlings. Other factors remaining the same, increasing initial caliper to 22 mm would require planting only 5 trees to obtain 1 competitively successful tree. For the same size (22 mm) and type of seedling planted on site index 18 m under a shelterwood at 40 to 60% stocking and given two weed control treatments, only 1.4 trees would need to be planted. Results emphasize the sensitivity of competitive capacity, and thus the silvicultural potential, of planted northern red oaks in the Boston Mountains of Arkansas to the joint effects of field environment and initial seedling characteristics. FOR. SCI. 48(3):504–517.

How Joint is Joint Forest Production? An Econometric Analysis of Timber Supply Conditional on Endogenous Amenity Values - Subhrendu K. Pattanayak; Brian C. Murray; Robert C. Abt (Forest Science, 2002)
In search of ways to enhance and sustain the flow of services from forests, policy makers in the public and private sectors look to forest sector models to project future forest uses. A major shortcoming of these models is a timber supply specification that inadequately accounts for suppliers choosing the structure of their forest capital to self-produce nontimber amenities. This inadequate characterization of resource use, if significant, can impede the development of sound forest policy, particularly in settings where forest owners possess diverse preferences for forest amenities. In this article, we develop and estimate a timber supply model that is consistent with the idea of joint self-production of timber and nontimber amenities, such that timber supply is a function of an endogenous distribution of forest inventory that correlates to ownership and management characteristics. Using data for the U.S. South and three-stage least squares procedures, we confirm that timber and nontimber amenities are jointly produced by private forest owners. We also note that owner and management characteristics influence joint production decisions. We believe that the parameters estimated through such an integrated empirical exercise could critically improve forest sector forecasting models and the related forest policy analyses. FOR. SCI. 48(3):479–491.

Nonconstant Risk Attitudes and Timber Harvesting - Jussi Uusivuori (Forest Science, 2002)
This article explores the effects of risk attitudes on the harvesting behavior of forest landowners. In particular, the effects of changing risk behavior on the forest owners' optimal harvesting decisions are studied under timber price uncertainty. With a theoretical model introducing an endogenous risk premium and addressing nonconstant risk attitudes, it is shown how the commonly predicted increase of wealth among nonindustrial private forest owners can have profound effects on harvesting behavior and timber supply from the private forest sector. For example, the model predicts that if landowners' aversion toward risk declines with increasing wealth, the standing timber stock in nonindustrial private forests will increase in the future, and the intensity of timber harvests declines. Contrary to now-popular timber harvest models, these results are obtained without dividing the benefits of forest into timber and nontimber ones. FOR. SCI. 48(3):459–470.

Terrestrial Global Productivity - Shibu Jose (Forest Science, 2002)
Terrestrial primary productivity has been a central focus of ecologists worldwide for the last three decades. The International Biological Program (IBP) of the early 1970s laid the foundation and provided a wealth of knowledge on the biological basis of productivity in different environments. However, there was little progress, until recently, in estimating productivity of large regions and biomes. The growing realization that productivity of terrestrial ecosystems is strongly affected by changes in climate and land-use patterns has prompted ecologists to translate ecological hypotheses derived from the local or stand level into continental or global scales. In recent years, policymakers also have focused their attention on terrestrial primary productivity because of the importance of land ecosystems as carbon sinks and their role in mitigating the impacts of rising atmospheric CO2. Hence, an effort in updating and synthesizing the current state of knowledge and research on global primary productivity should be appreciated. Through the publication of this book the editors have done a commendable job in bringing together the collective wisdom of 50 prominent ecologists in analyzing primary productivity from the canopy to global level and identifying gaps in our knowledge base.

Combining Random and Systematic Search Heuristic Procedures for Solving Spatially Constrained Forest Management Scheduling Models - André O. Falcão; José Borges (Forest Science, 2002)
This article analyzes three heuristics for solving forest management scheduling models encompassing both timber production and landscape structure objectives. Emphasis is on developing an efficient solution approach that may address complex temporal and spatial interactions of forest management scheduling decisions. Two random search approaches, simulated annealing and evolution programs, are compared with a new heuristic, sequential quenching and tempering, that combines random and systematic search techniques. The three heuristics were applied to four large eucalyptus forest management problems. The test forests encompassed 300 to 900 stands. The number of management alternatives ranged from 33,000 to 220,000. Model building encompassed the generation of binary decision variables for all the problems considered. In order to address economic and ecological management objectives, all the models included timber volume flow constraints, minimum and maximum clearcut opening constraints and constraints on the minimum number of old forest patches with minimum area requirements. All constraints were defined over a temporal horizon extending to thirty 1 yr periods. Results from over 1,300 test computer runs are discussed for application to these large problems. Results show that the new strategy can be compared favorably to the random search approaches. They suggest that in order to find feasible solutions to such a complex problem, random search may be combined with a systematic search component within a heuristic procedure. FOR. SCI. 48(3):608–621.

Derivation, Fitting, and Implication of a Compatible Stem Taper-Volume-Weight System for Intensively Managed, Fast Growing Loblolly Pine - Yujia Zhang; Bruce E. Borders; Robert L. Bailey (Forest Science, 2002)
Geometry-oriented methodology yielded a compatible taper-volume-weight system of models whose parameters were estimated using data from intensively managed loblolly pine (Pinus taeda L.) plantations in the lower coastal plain of Georgia. Two segments (separated at a stem ratio of 0.60 of total height) depicted taper, volume, and weight variations of the stems as well. The taper function defines stem taper as a proportion of the diameter at breast height. The segmented volume equation was derived from integration of the taper function along the stem, and it can be readily transformed into a ratio volume equation. Likewise, the segmented weight equation was obtained from integration of the volume function and a wood density function. Data analysis showed that fertilization has significantly reduced taper (inside and outside bark) on the upper segment and augmented stem merchantable volume in this segment. However, unit-weight (green wood and bark, green wood only, and dry wood only) was not significantly different between fertilized and unfertilized trees, implying that annual fertilization did not reduce the specific gravity very much. Finally, our analysis showed no significant impacts of complete vegetation control on taper, volume or weight characteristics. FOR. SCI. 48(3):595–607.

A Method for Characterizing and Mimicking Forest Canopy Gaps Caused by Different Disturbances - John E. Lundquist; Jerome S. Beatty (Forest Science, 2002)
Forest canopy gaps are measurable indicators of past small-scale disturbances. These disturbances can impact forest stand dynamics in ways that help maintain and enhance many ecosystem values. Impacts are commonly assessed using timber production metrics based on average stand values, but metrics based on smaller scales are needed to assess impacts on nontimber resources. In this study, we developed a multivariate method of quantitatively characterizing individual canopy gaps in Douglas-fir/grand fir stands in the Blue Mountains of eastern Oregon. We then established a reference or target range of variability by profiling gaps according to numbers of snags, downed logs, gap size and shape, and recolonizing vegetation. Cluster analysis, multidimensional scaling, and classification “trees” were used with these profiles to quantify similarity among individual gaps. Gaps fell into four groups, which could be interpreted as three ecologically functional groups on the basis of their role in stand development. Gaps caused by the same agents commonly fell within the same functional group: (1) flooding, logging, spruce budworm, and windfall cause stand level impacts that reset the stand development sequence; (2) bark beetles, tree fall, and root diseases cause within stand impacts that altered the rate of stand development; and (3) stem decay and dwarf mistletoe, and, under some circumstances, all disturbance agents, could kill trees yet have no impact on stand development except create space into which neighboring trees expand. We present a simple test to monitor how gaps change with silvicultural manipulations. Results indicate that this method offers (1) a way to systematically guide silvicultural manipulations aimed at mimicking natural disturbances at the canopy gap scale, and (2) a way to monitor the effectiveness of such silvicultural treatments and management actions using gap-based silviculture prescriptions. FOR. SCI. 48(3):582–594.

On the Optimality of a Normal Forest with Multiple Land Classes - Seppo Salo; Olli Tahvonen (Forest Science, 2002)
We analyze a discrete time forestry model with nonlinear utility and any number of forest age and land classes. It is shown that under discounting, this model possesses a cyclical stationary state instead of an even flow of timber. The cycle length in timber flow equals the least common multiple of the rotation lengths of the various land classes. The cycle structure is dependent on the initial age-class allocation. As the discount factor approaches unity, the cyclicality in total timber harvest vanishes, but the forest age-class structure may not approach a normal forest in any land class. An aggregate even timber flow is associated with a normal forest in each land class only if there does not exist any pair of land classes with rotation periods having a common divisor greater than one. FOR. SCI. 48(3):530–542.

A Forest-Level Bucking Optimization System that Considers Customer's Demand and Transportation Costs - Julio Eduardo Arce; Celso Carnieri; Carlos Roberto Sanquetta; Afonso Figueiredo Filho (Forest Science, 2002)
This article describes a system that deals with a forest-level bucking optimization problem considering customer's demand and transportation costs. The system was used to evaluate three scenarios: an observed medium-term forest harvesting scenario, with 32 stands harvested during one month, a simulated demand-oriented scenario and a simulated supply-oriented one. Data was obtained from Pinus taeda L. plantations located in southern Brazil. Various forest multiproducts with their respective local market prices were considered for modeling. The system has two main modules: the Cutting Pattern Generation (CPG) and the Global Bucking Optimization (GBO). In both modules, different algorithms are activated depending on the analyzed scenario (demand-oriented or supply-oriented). Additional biometric modules are also integrated into the system for height, taper, and volume calculations. In the demand-oriented scenario, the CPG exhaustively generates all possible cutting patterns for each diametric class in each stand, and the GBO, formulated as a Mixed Integer Linear Programming problem, optimizes the net revenue at forest level subject to constraints that consider bounds for timber volumes and maximum number of different multiproducts obtained in each stand. In the supply-oriented scenario, the CPG generates the Optimum Cutting Pattern through a heuristic algorithm that identifies the potential cuts to evaluate along the stem and a Dynamic Programming-based algorithm to determine the optimum combination of products that maximizes the stem profit, and the GBO calculates the net profit, summing up the profits per stem for each stand and sum of the stands. Illustrative examples and numerical results are given. FOR. SCI. 48(3):492–503.

Competitive Effects on Plantation White Spruce Saplings from Shrubs That Are Important Browse for Moose - Scott D. Posner; Peter A. Jordan (Forest Science, 2002)
Conifer planting is often accompanied by herbicide control of surrounding broadleaf, woody plants that may interfere with conifer growth, a process that releases conifers from competitive suppression. Because potential competitors often provide browse for wildlife, their removal may conflict with objectives in multiple-resource management. While some agencies, such as the USDA Forest Service (USFS), have greatly reduced herbicide use, many other timber producers still rely on chemicals to release conifers from competing vegetation. In northeastern Minnesota, where moose (Alces alces) are a highly valued resource, we studied impacts of broadleaf shrubs on 4- to 16-yr-old white spruce (Picea glauca) along with the extent of browsing by moose on these shrubs. Height, diameter, and current vertical growth increment of spruce were compared among four levels of presence (density strata) of shrubs immediately surrounding each sapling. Spruce grew as well or better in the low and medium density strata as in the no-shrub stratum. In the high density stratum, height and growth increment, particularly in 10- to 16-yr-old spruce, appeared reduced. Presence of shrubs seemed to reduce frost damage in young spruce. Moose browsing reduced height of most shrub species, suggesting that these animals provide a release effect on adjacent spruce. We recommend a release strategy that avoids reduction of shrubs beyond the level that assures normal growth in young spruce, so as both to minimize loss of browse for wildlife and avoid unnecessary silvicultural costs. FOR. SCI. 48(2):283–289.