Treesearch

In 2003, lightning-caused fires burned through relict ponderosa pine (Pinus ponderosa) stands in the Bob Marshall Wilderness, Montana, after decades of fire exclusion. Since many trees in these stands had Native American bark-peeling scars, concern arose about the adverse fire effects on this cultural and ecological resource. In 2004, Keane and others (2006) began a post-fire monitoring study of the relict pine stands. In 2009, we completed a six year re-measurement of those stands. We found that many of the pines with major fire injury had recovered, and tree mortality was not as high as...

How people make choices about activity engagement during discretionary time is a topic of increasing interest to those studying quality of life issues. Assuming choices are made to maximize individual welfare, several factors are believed to influence these choices. Constraints theory from the leisure research literature suggests these choices are heavily influenced by intrapersonal, interpersonal and structural constraints. Within these constraints, the individual is motivated to make choices that maximize perceived personal welfare. Leisure affordance theory focuses on these motivations...

Describing the spatial variability of heterogeneous snowpacks at a watershed or mountain-front scale is important for improvements in large-scale snowmelt modelling. Snowmelt depletion curves, which relate fractional decreases in snowcovered area (SCA) against normalized decreases in snow water equivalent (SWE), are a common approach to scale-up snowmelt models. Unfortunately, the kinds of ground-based observations that are used to develop depletion curves are expensive to gather and impractical for large areas. We describe an approach incorporating remotely sensed fractional SCA (FSCA)...

Disturbances and propagule pressure are key mechanisms in plant community resistance to invasion, as well as persistence of invasions. Few studies, however, have experimentally tested the interaction of these two mechanisms. We initiated a study in a southwestern ponderosa pine (Pinus ponderosa Laws.)/bunch grass system to determine the susceptibility of remnant native plant communities to cheatgrass (Bromus tectorum L.) invasion, and persistence of cheatgrass in invaded areas. We used a 2 x 2 factorial design consisting of two levels of aboveground biomass removal and two levels of...

Recent estimates indicate that nearly 40.5 million ha (100 million ac) of forest lands that were historically burned by frequent surface fires in the western United States may benefit from the restoration of surface fire. An additional 4.5 million ha (11 million ac) of forests need to be treated to protect communities from wildfire (Aplet and Wilmer 2003). Rummer and others (2003) estimate that over 26.7 million ha (66 million ac) of forestlands could benefit from fuel reduction. Even with uncertainties in these estimates and arguments as to their precision and accuracy, they clearly...

Controversy over fuel treatments on public forestlands often focuses on the potential for such treatments to contribute to cumulative watershed impacts. If a fuel treatment project modifies the production or transport of water, sediment, or woody debris through a channel network, downstream habitats and aquatic resources may respond adversely to the changes. If these changes augment impacts from previous or on-going activities, the fuel treatment project will have increased the overall level of impact-the cumulative impact-to downstream resources.

Assessing forest carbon storage and cycling over large areas is a growing challenge that is complicated by the inherent heterogeneity of forest systems. Field measurements must be conducted and analyzed appropriately to generate precise estimates at scales large enough for mapping or comparison with remote sensing data. In this study we examined spatial variability in three small temperate forest landscapes. Our objectives were (1) to quantify the magnitude and scale of variability in stand structure, carbon pools and carbon fluxes and (2) to assess how this variability influences both...

Forests play an important role in the U.S. and global carbon cycle, and carbon sequestered by U.S. forest growth and harvested wood products currently offsets 12-19% of U.S. fossil fuel emissions. The cycle of forest growth, death, and regeneration and the use of wood removed from the forest complicate efforts to understand and measure forest carbon pools and flows. Our report explains these processes and examines the science behind mechanisms proposed for increasing the amount of carbon stored in forests and using wood to offset fossil fuel use. We also examine the tradeoffs, costs, and...

Heating soil during intense wildland fires or slash-pile burns can alter the soil irreversibly, resulting in many significant long-term biological, chemical, physical, and hydrological effects. To better understand these long-term effects, it is necessary to improve modeling capability and prediction of the more immediate, or first-order, effects that fire can have on soils. This study uses novel and unique observational data from an experimental slash-pile burn to examine the physical processes that govern the transport of energy and mass associated with fire-related soil heating....

Understanding the relationships between climate and carbon exchange by terrestrial ecosystems is critical to predict future levels of atmospheric carbon dioxide because of the potential accelerating effects of positive climate-carbon cycle feedbacks. However, directly observed relationships between climate and terrestrial CO2 exchange with the atmosphere across biomes and continents are lacking. Here we present data describing the relationships between net ecosystem exchange of carbon (NEE) and climate factors as measured using the eddy covariance method at 125 unique sites in various...