Treesearch

The frequency, extent, and severity of wildfire strongly influence the structure and function of ecosystems. Mixed-severity fire regimes are the most complex and least understood fire regimes, and variability of fire severity can occur at fine spatial and temporal scales, depending on previous disturbance history, topography, fuel continuity, vegetation type, and weather. During high fire weather in 2013, a complex of mixed-severity wildfires burned across multiple ownerships within the Klamath-Siskiyou ecoregion of southwestern Oregon where northern spotted owl (Strix occidentalis...

Scientific knowledge and tools have central roles in contemporary federal forest programs that promote restoration in large landscapes and across ownerships. Although we know much about the role of science in decisionmaking and ways that science can be better linked to practice, we know less about manager perspectives about science and science tools, and the perceived role of both in planning. We surveyed Forest Service resource managers in the western United States to address this knowledge gap. Respondents engaged most frequently with science via reading research publications; direct...

Wildland firefighters are exposed to wood smoke, which contains hazardous air pollutants, by suppressing thousands of wildfires across the U. S. each year. We estimated the relative risk of lung cancer and cardiovascular disease mortality from existing PM2.5 exposure-response relationships using measured PM4 concentrations from smoke and breathing rates from wildland firefighter field studies across different exposure scenarios. To estimate the relative risk of lung cancer (LC) and cardiovascular disease (CVD) mortality from exposure to PM2.5 from smoke, we used an existing exposure-respons...

Statistically downscaled climate change scenarios from four General Circulation Models for two Representative Concentration Pathways (RCP)were applied as inputs to a biogeochemical model, PnET-BGC, to examine potential future dynamics of water, carbon, and nitrogen in an old-growth Douglas-fir forest in the western Cascade Range. Projections show 56% to 77% increases in stomatal conductance throughout the year from 1986–2010 to 2076–2100, and 65% to 104% increases in leaf carbon assimilation between October and June over the same period. However, future dynamics of water and carbon under...

In Elko County, Nevada, grazing practices on federal and private lands began to change in the early 1990s to restore proper functioning condition to degraded riparian areas that provide habitat for Lahontan cutthroat trout (Oncorhynchus clarkii henshawi), which is listed as threatened under the Endangered Species Act. Changes in grazing management focused on changing the frequency and duration of hot-season grazing in riparian areas. These changes led to the recovery of riparian vegetation accompanied by the natural colonization of streams by beavers. Beavers and their dams, in turn, have...

PREMISE OF THE STUDY: Aboveground biomass (AGB) of herbaceous vegetation is a primary source of fuel in frequent surface fires that maintain grasslands, savannas, and woodlands. Methods for nondestructively estimating AGB are required to understand the mechanisms by which fuels affect fire behavior and the effects of time since the last burn. We developed allometric equations to estimate AGB in wiregrass (Aristida beyrichiana/A. stricta), a dominant bunchgrass in Pinus palustris ecosystems and a key species for ecological restoration. METHODS: We collected wiregrass from North Carolina to...

Scotch broom, Cytisus scoparius (L.) is a globally important nitrogen (N)-fixing invasive plant species that has potential to alter soil water dynamics, soil chemistry, and plant communities. We evaluated the effects of Scotch broom on soil moisture, soil chemistry, soil temperature, photosynthetically active radiation (PAR), and vegetation communities over 4 years at a site recently harvested for timber. Treatments of Scotch broom (either present via planting or absent) and background vegetation (either present or absent via herbicide treatments) were applied to 4 m2 plots. Background...

Fuel treatments are designed with multiple management goals, including improving suppression capacity and restoring the historical structure of dry forests. Fuelbreaks are a class of fuel treatment that remove fuels within a wide strip of land, with an overarching objective to reduce fire behavior and provide safe access for suppression. In an empirical analysis of shaded fuelbreaks that burned during the 2014 Bald Fire (15,950 ha on the Lassen National Forest, California, USA), we found that overall fire severity was reduced in the treated areas relative to untreated. A non-linear mixed...

Piling and burning is widely used to dispose of unmerchantable debris resulting from thinning in forests throughout the western United States. Quite often more piles are created than are burned in a given year, however, causing piles to persist, accumulate, and age on the landscape. The effects of burning piles of increasing age has not been studied. We examined the effects of time since construction (i.e., pile age, in roughly six month increments for two years) and burn season (fall and spring) on fuelbed properties, combustion dynamics, fuel consumption, and charcoal formation for...

Long-term conservation planning for diadromous fishes would benefit from a better understanding of both the role of connectivity among environments and habitat variability in the expression of life-history diversity. Most of the scientific knowledge on habitat fragmentation and connectivity has been developed in terrestrial systems in the discipline of landscape ecology. Research on habitat connectivity in aquatic systems (e.g., salmonid research that spans the spectrum of habitats from freshwater to the sea) is uncommon and largely focused on barriers to fish passage. Here, we present a...