JAMES T. RANDERSON results 19
· Newest (Page 1/1, per page 25)
Author: JAMES T. RANDERSON ×Clear All Filters
Search Results
Wildfire‐induced increases in photosynthesis in boreal forest ecosystems of North AmericaNARA Subscribed
Observations of the annual cycle of atmospheric CO 2 in high northern latitudes provide evidence for an increase in terrestrial metabolism in Arctic tundra and boreal forest ecosystems. However, the mechanisms driving these changes are not yet fully understood. One proposed hypothesis is that ecological change from disturbance, such as wildfire, could increase the magnitude and change the phase of net ecosystem exchange throug...
Using remote sensing to quantify the additional climate benefits of California forest carbon offset projectsNARA Subscribed
Nature‐based climate solutions are a vital component of many climate mitigation strategies, including California's, which aims to achieve carbon neutrality by 2045. Most carbon offsets in California's cap‐and‐trade program come from improved forest management (IFM) projects. Since 2012, various landowners have set up IFM projects following the California Air Resources Board's IFM protocol. As many of these projects approach th...
The role of fire in global forest loss dynamicsNARA Subscribed
Fires, among other forms of natural and anthropogenic disturbance, play a central role in regulating the location, composition and biomass of forests. Understanding the role of fire in global forest loss is crucial in constraining land‐use change emissions and the global carbon cycle. We analysed the relationship between forest loss and fire at 500 m resolution based on satellite‐derived data for the 2003–2018 period. Satellit...
Climate change decreases the cooling effect from postfire albedo in boreal North AmericaNARA Subscribed
Fire is a primary disturbance in boreal forests and generates both positive and negative climate forcings. The influence of fire on surface albedo is a predominantly negative forcing in boreal forests, and one of the strongest overall, due to increased snow exposure in the winter and spring months. Albedo forcings are spatially and temporally heterogeneous and depend on a variety of factors related to soils, topography, climat...
Vegetation controls on northern high latitude snow‐albedo feedback: observations and CMIP 5 model simulationsNARA Subscribed
The snow‐masking effect of vegetation exerts strong control on albedo in northern high latitude ecosystems. Large‐scale changes in the distribution and stature of vegetation in this region will thus have important feedbacks to climate. The snow‐albedo feedback is controlled largely by the contrast between snow‐covered and snow‐free albedo (Δα), which influences predictions of future warming in coupled climate models, despite b...
The impacts and implications of an intensifying fire regime on Alaskan boreal forest composition and albedoNARA Subscribed
Climate warming and drying are modifying the fire dynamics of many boreal forests, moving them towards a regime with a higher frequency of extreme fire years characterized by large burns of high severity. Plot‐scale studies indicate that increased burn severity favors the recruitment of deciduous trees in the initial years following fire. Consequently, a set of biophysical effects of burn severity on postfire boreal succession...
We used satellite‐derived estimates of global fire emissions and a chemical transport model to estimate atmospheric nitrogen (N) fluxes from savanna and deforestation fires in tropical ecosystems. N emissions and reactive N deposition led to a net transport of N equatorward, from savannas and areas undergoing deforestation to tropical forests. Deposition of fire‐emitted N in savannas was only 26% of emissions – indicating a ne...
Systematic assessment of terrestrial biogeochemistry in coupled climate–carbon modelsNARA Subscribed
With representation of the global carbon cycle becoming increasingly complex in climate models, it is important to develop ways to quantitatively evaluate model performance against in situ and remote sensing observations. Here we present a systematic framework, the Carbon‐LAnd Model Intercomparison Project (C‐LAMP), for assessing terrestrial biogeochemistry models coupled to climate models using observations that span a wide r...
Large‐scale plant light‐use efficiency inferred from the seasonal cycle of atmospheric CO 2NARA Subscribed
We combined atmospheric CO 2 measurements, satellite observations, and an atmospheric transport model in an inverse modeling framework to infer a key property of vegetation physiology, the light‐use efficiency (LUE) of net primary production, for large geographic regions. We find the highest LUE in boreal regions and in the northern hemisphere tropics. Within boreal zones, Eurasian LUE is higher than North American LUE and has...
Postfire response of North American boreal forest net primary productivity analyzed with satellite observationsNARA Subscribed
Fire is a major disturbance in the boreal forest, and has been shown to release significant amounts of carbon (C) to the atmosphere through combustion. However, less is known about the effects on ecosystems following fire, which include reduced productivity and changes in decomposition in the decade immediately following the disturbance. In this study, we assessed the impact of fire on net primary productivity (NPP) in the Nor...
Global carbon emissions from fires are difficult to quantify and have the potential to influence interannual variability and long‐term trends in atmospheric CO 2 concentrations. We used 4 years of Tropical Rainfall Measuring Mission (TRMM) Visible and Infrared Scanner (VIRS) satellite data and a biogeochemical model to assess spatial and temporal variability of carbon emissions from tropical fires. The TRMM satellite data exte...
Impulse response functions of terrestrial carbon cycle models: method and applicationNARA Subscribed
To provide a common currency for model comparison, validation and manipulation, we suggest and describe the use of impulse response functions , a concept well‐developed in other fields, but only partially developed for use in terrestrial carbon cycle modelling. In this paper, we describe the derivation of impulse response functions, and then examine (i) the dynamics of a simple five‐box biosphere carbon model; (ii) the dynamic...
Previous1Next