Treesearch

Sorption of water vapor in cellulosic materials has been studied for more than 100 years. However, the last 2 decades have seen a surge in studies of sorption kinetics due to the adoption of automated sorption balances in laboratories world-wide. Sorption kinetic data is commonly fitted with the parallel exponential kinetics (PEK) model, which is the sum of two exponential functions. The PEK model parameters are often interpreted as representing phys-ical quantities or material properties, but their exact definition remains undetermined. Nonetheless, PEK fitting of sorption data has been...

The Pacific marten once ranged throughout coastal forests of the Pacific Northwest, but by the late 1940s, it was thought to be extinct. In 1996, however, a population was found in northern California. This member of the mustelid family, which includes weasels and fishers, depends on diverse, mixed-conifer forests with a dense understory of salal and other shrubs. Habitat loss, forest fragmentation, disease, trapping, and fatality from collisions with motor vehicles have contributed to the decline of the Humboldt marten, a subspecies found in limited areas of coastal Oregon.Conservation...

This publication provides forest resource statistics contributing to the 2020 Resources Planning Act (RPA) Assessment to provide current information on the Nation's forests. Resource tables present estimates of forest area, volume, mortality, growth, removals, and timber-product output in various ways within the context of changes since 1953. Additional analyses look at the resource from an ecological, health, and productivity perspective. Downloadable tables should be available via the Research Data Archive in the future, but for now users may query Forest Inventory and Analysis data...

Plant-fungal symbioses play critical roles in vegetation dynamics and nutrient cycling, modulating the impacts of global changes on ecosystem functioning. Here, we used forest inventory data consisting ofmore than 3million trees to develop a spatially resolved “mycorrhizal tree map” of the contiguousUnited States.Weshowthat abundances of the two dominant mycorrhizal tree groups—arbuscular mycorrhizal (AM) and ectomycorrhizal trees—are associated primarily with climate. Further, we show that anthropogenic influences, primarily nitrogen (N) deposition and fire suppression, in concert with...

Wild apple Malus sieversii (Ledeb.) M. Roem. (Rosales: Rosaceae), the ancestor of cultivated apples, is widely distributed in Central Asia and is recognized as an important germplasm bank. Recently, the invasive pest Agrilusmali Matsumura (Coleoptera: Buprestidae), originally distributed in eastern Asia, has damaged endemic apple forests in the Yili River valley, Xinjiang, China, and has spread rapidly, infesting more than 80% of wild apple trees in this region. We investigated the life-history traits and native natural enemies in the recently invaded range during 2016 and 2017. Agrilus...

The wildfires that burned in the Northern Rockies region of the USA during the 2017 fire season provided an opportunity to evaluate the suitability of using broadscale and temporally limited infrared data on hot spot locations to determine the influence of several environmental variables on spotting distance. Specifically, correlations between the maximum observed spot fire distance for each unique combination of fire and day and geo-referenced environmental data on wind speed, vegetation, and terrain, along with specific fire characteristics (size, fire perimeter shape, and growth), were...

Total nitrogen (N) deposition has declined in many parts of the U.S. and Europe since the 1990s. Even so, it appears that decreased N deposition alone may be insufficient to induce recovery from the impacts of decades of elevated deposition, suggesting that management interventions may be necessary to promote recovery. Here we review the effectiveness of four remediation approaches (prescribed burning, thinning, liming, carbon addition) on three indicators of recovery from N deposition (decreased soil N availability, increased soil alkalinity, increased plant diversity), focusing on...

Turbulent fluxes of heat and momentum in the vicinity of wildland fires contribute to the redistribution of heat and momentum in the fire environment, which in turn can affect the heating of fuels, fire behavior, and smoke dispersion. As an extension of previous observational studies of turbulence regimes in the vicinity of wildland fires in forested environments, this study examines the effects of spreading surface fires and forest overstory vegetation on turbulent heat and momentum fluxes from near the surface to near the top of the overstory vegetation. Profiles of high-frequency (10...

Remotely sensed radiation, attractive for its spatial and temporal coverage, offers a means of inferring energy deposition in fires (e.g. on soils, fuels and tree stems) but coordinated remote and in situ (in-flame) measurements are lacking. We relate remotely sensed measurements of fire radiative energy density (FRED) from nadir (overhead) radiometers on towers and the Wildfire Airborne Sensor Program (WASP) infrared camera on a piloted, fixed-wing aircraft to energy incident on in situ, horizontally oriented, wide-angle total flux sensors positioned,0.5 m above ground level. Measurements...

The fates of native bee communities in the Great Basin sagebrush steppe are linked with the susceptibilities of their floral hosts to increasingly frequent wildfires. Postfire survival and subsequent flowering of six prevalent perennial wildflowers representing five families were quantified across a range of realistic fire severities created using a calibrated propane burn barrel. Five burn prescriptions of varying intensity and duration were applied to cultivated rows of basalt milkvetch (Astragalus filipes Torr. ex A. Gray), Blue Mountain prairie clover (Dalea ornata Eaton & J. Wright),...