Treesearch

In frequent fire forests of the western United States, a legacy of fire suppression coupled with increases in fire weather severity have altered fire regimes and vegetation dynamics. When coupled with projected climate change, these conditions have the potential to lead to vegetation type change and altered carbon (C) dynamics. In the Sierra Nevada, fuels reduction approaches that include mechanical thinning followed by regular prescribed fire are one approach to restore the ability of the ecosystem to tolerate episodic fire and still sequester C. Yet, the spatial extent of the area...

We modeled the normal fire environment for occurrence of large forest wildfires (>40ha) for the Pacific Northwest Region of the United States. Large forest wildfire occurrence data from the recent climate normal period (1971–2000) was used as the response variable and fire season precipitation, maximum temperature, slope, and elevation were used as predictor variables. A projection of our model onto the 2001–2030 climate normal period showed strong agreement between model predictions and the area of forest burned by large wildfires from 2001 to 2015 (independent fire data). We then used...

Several spatial forest disturbance datasets exist for the conterminous USA. The major problem with forest disturbance mapping is that variability between map products leads to uncertainty regarding the actual rate of disturbance. In this article, harmonized maps were produced from multiple data sources (i.e., Global Forest Change, LANDFIRE Vegetation Disturbance, National Land Cover Database, Vegetation Change Tracker, and Web-Enabled Landsat Data). The harmonization process involved fitting common class ontologies and determining spatial congruency to produce forest disturbance maps for...

Due to the hotter droughts occurring with climate change, grasslands of southwestern deserts and southern plains in the United States are predicted to increasingly lose cover of native plant species, be invaded by nonnative species, and have accelerated soil erosion. We evaluated these predictions for desert grasslands in the Paint Gap Hills of Big Bend National Park, Texas. We used data from 10 monitoring transects established in 1981 and surveyed vegetation composition, canopy cover, and soil surface elevations in 1981, 1983, 1995, and 2014. Four longer and hotter droughts occurred...

Background and aims In northern regions, moss and lichen mats are the major carbon-cycling interface between soils and the atmosphere. We aimed to quantify sensitivity of ground layer nutrient stores to environmental predictors, to better understand interactions with vegetation, topography and climatic conditions. Methods With non-destructive forest inventory techniques, we estimated distributions of biomass, carbon and nitrogen among moss/lichen ground layers in a 1.1 million-ha watershed within Alaska’s boreal forest region. Using nonparametric multiplicative regression, we fit response...

Los inventarios forestales nacionales proporcionan datos básicos sobre la biodiversidad, la integridad de los ecosistemas, y la productividad de los recursos naturales en países de todo el mundo. Con mediciones repetidas, estos datos son una base de información muy poderosa para avanzar en nuestro conocimiento de los procesos ecológicos y su respuesta a la gestión forestal y las perturbaciones naturales. Aunque el análisis de datos dispares (“big data”) con nuevas técnicas (por ejemplo, aprendizaje automático) puede ser de utilidad, no hay sustituto para un diseño estadístico riguroso y...

Boreal forests play critical roles in global carbon, water and energy cycles. Recent studies suggest drought is causing a decline in boreal spruce growth, leading to predictions of widespread mortality and a shift in dominant vegetation type in interior Alaska. We took advantage of a large set of tree cores collected from random locations across a vast area of interior Alaska to examine long-term trends in carbon isotope discrimination and growth of black and white spruce. Our results confirm that growth of both species is sensitive to moisture availability, yet show limited evidence of...

Forest inventories require estimates and measures of uncertainty for subpopulations such as management units. These units often times hold a small sample size, so they should be regarded as small areas. When auxiliary information is available, different small area estimation methods have been proposed to obtain reliable estimates for small areas. Unit level empirical best linear unbiased predictors (EBLUP) based on plot or grid unit level models have been studied more thoroughly than area level EBLUPs, where the modelling occurs at the management unit scale. Area level EBLUPs do not...

Climate change over the past several decades has resulted in shifting rainfall pattern and modifying rainfall intensity, which has, in turn, exacerbated stream flow and sediment load and imposed uncertainties to these processes. This study projected impacts of potential future rainfall variations on stream flow and sediment load from the Lower Yazoo River Watershed (LYRW) in Mississippi using the BASINS (Better Assessment Science Integrating Point and Nonpoint Sources)-HSPF (Hydrological Simulation Program-FORTRAN)-CAT (Climate Assessment Tool) modeling system. Several simulation scenarios...

Biomass holds tremendous potential as a renewable feedstock for the production of fuels and chemicals. However, significant technological advancement is required before production of biofuels and bio-based chemicals will become widespread and economically self-sustaining at the industrial scale. Many of the greatest challenges surrounding biomass conversion stem from the complex nature of the feedstock. Biomass consists of the remains of once-living plant tissue, and therefore retains many of the characteristics of the original organism. These characteristics, such as microstructure,...