Treesearch

Wildfires are altering forested landscapes across western North America. These wildfires are increasingly burning with high severity across large areas and driving the conversion of forest to non-forest. Understanding how longterm vegetation structure differs between low- and high-severity portions of burned landscapes, and how fire severity and post-fire vegetation structure relate to avian species and communities, is crucial for avian conservation efforts. We quantified vegetation structure and avian species composition in low- and high-severity portions of two wildfires - the 2002 Ponil...

Context: Changes in climate and associated disturbance regimes are altering patterns of biodiversity by shifting macroenvironmental conditions and modifying the structure and composition of critical habitat. These threats require understanding the climate vulnerability of species habitat to inform conservation planning.Objectives: We developed a framework to address this need for the Mexican spotted owl (Strix occidentalis lucida), a species whose range is experiencing widespread climate-driven increases in wildfire and drought that can have adverse impacts upon large, old trees, a vital...

Many widespread plant taxa of western North America have diversified into phenotypically and genetically divergent lineages due to complex biogeographic histories across heterogeneous landscapes. Mosaic hybrid zones can form when geographically co-occurring, yet environmentally distinct, lineages cross-pollinate and form hybrids that occupy unique environmental niches absent of a geographic cline. This expands the total environmental space across which parental and hybrid individuals grow, resulting in larger, less fragmented geographic distributions. Here, we highlight hybridization...

Sagebrush, the iconic gray-green shrub of the American West, occupies an area so vast it is often described as an ocean or sea. The Sagebrush Sea once stretched across nearly 175,000 square miles in western North America, but it has dwindled to nearly half that size since the arrival of European settlers in the 1800s. Today, the sagebrush biome, which encompasses parts of 11 western States in the Great Basin, is experiencing rapid transformations.

When smoke from a prescribed fire pops up on an otherwise clear day, people may question the rationale behind the haze. After all, smoke from wildland fires can be a major health hazard due to fine particulates (PM2.5) and gaseous pollutants. At the same time, prescribed fires are one of our best tools to reduce hazardous fuels and restore fire-prone forests and grasslands. In recent years, land managers have been asked to expand the use of prescribed fire, but smoke is consistently cited as a barrier. New research by USDA Forest Service scientists sheds light on one key smoke challenge -...

Like Goldilocks, ground-nesting birds in the southeastern U.S. need habitat conditions that are “just right.” They need just the right food and just enough protective cover, all in close proximity - talk about high maintenance! Recently published research syntheses in the Fire Effects Information System (FEIS) about ground-nesting bird species of management concern describe how prescribed fire can help meet these needs for chuck-will’s-widows, eastern whip-poor-wills, and northern bobwhites.

When the Black Fire ignited in southwestern New Mexico in 2022, it had all the ingredients for disaster: record-high winds, extremely low humidity, and over 131,000 hectares (323,708 acres) of forest fuels to feed on. But something unexpected happened. Instead of becoming another catastrophic megafire, it burned mostly at low to moderate severity. The secret? The landscape had already experienced dozens of previous fires, both planned and natural, that helped tame the beast.

It’s no secret that wildland fires kill trees, but are more trees killed by fire when they are already stressed from drought? New research from the U.S. Department of Agriculture, Forest Service indicates that prefire drought can increase tree mortality after fire, even with the same level of tree damage.

Land managers rely on best available information and relevant research for decision making, but matching the right information to the right questions can sometimes be challenging. To close this gap, when researchers and managers co-produce research from the beginning it is more likely research findings will have practical applications. Recently published work by USDA Forest Service researchers Chris Armatas, Teresa Hollingsworth, and colleagues working at the Aldo Leopold Wilderness Research Institute (ALWRI) in Missoula, Montana, reflects on both the benefits and tradeoffs of using a...

Positron annihilation lifetime spectroscopy (PALS) was employed to study the waterdependent free volume characteristics of wood cell walls in earlywood and latewood of loblolly pine (Pinus taeda). Measurements were conducted across relative humidity levels (1–80% RH) at room temperature, demonstrating good reproducibility and consistency with polymer science principles. The Tao-Eldrup model was applied to the measured ortho-positronium lifetimes to estimate the mean sizes of free volume elements in wood cell walls. At low relative humidity (below ~ 11%), water absorption resulted in...