Treesearch

Despite widespread acknowledgment that disturbance favors invasion, a hypothesis that has received little attention is whether non-native invaders have greater competitive effects on native plants in undisturbed habitats than in disturbed habitats. This hypothesis derives from the assumption that competitive interactions are more persistent in habitats that have not been recently disturbed. Another hypothesis that has received little attention is whether the effects of non-native plants on native plants vary among habitats that differ in soil fertility. We documented habitat occurrences of...

Mosaics of tree clumps and openings are characteristic of forests dominated by frequent, low-and moderate-severity fires. When restoring these fire-suppressed forests, managers often try to reproduce these structures to increase ecosystem resilience. We examined unburned and burned forest structures for 1937 0.81 ha sample areas in Yosemite National Park, USA. We estimated severity for fires from 1984 to 2010 using the Landsat-derived Relativized differenced Normalized Burn Ratio (RdNBR) and measured openings and canopy clumps in five height strata using airborne LiDAR data. Because our...

Large trees (>76 cm breast-height diameter) are vital components of Sierra Nevada/Cascades mixed-conifer ecosystems because of their fire resistance, ability to sequester large amounts of carbon, and role as preferred habitat for sensitive species such as the California spotted owl. To investigate the likely performance of large trees in a rapidly changing climate, we analyzed growth rings of five conifer species against 20th century climate trends from local weather stations. Over the local station period of record, there were no temporal trends in precipitation, but maximum temperatures...

We compared canopy arthropod responses to common fuels reduction treatments at Teakettle Experimental Forest in the south-central Sierra Nevada of California. We sampled arthropod communities among four dominant overstory conifer species and three dominant understory angiosperm species before and after overstory or understory thinning or no thinning treatments followed by burning or no burning treatments. Arthropods were sampled in overstory trees by climbing and bagging foliage-bearing branches and counting all arthropods by taxon in each sample. Understory plants were sampled similarly...

Quantifying the impacts of changing climatic conditions on forest growth is integral to estimating future forest carbon balance. We used a growth-and-yield model, modified for climate sensitivity, to quantify the effects of altered climate on mixed-conifer forest growth in the Lake Tahoe Basin, California. Estimates of forest growth and live tree carbon stocks were made for low and high emission scenarios using four downscaled general circulation model (GCM) projections. The climate scenarios were coupled with a range of commonly-used fuels reduction treatments to quantify the combined...

Many high-elevation regions in the western USA are protected public lands that remain relatively undisturbed by human impact. Over the last century, however, nonnative trout and cattle have been introduced to subalpine wetland habitats used by sensitive amphibian species. Our study compares the relative importance of cattle and trout impact on amphibian assemblages, abundance, and occupancy within a broader context of high-elevation environmental variables. We evaluated amphibian species richness and abundance across 89 subalpine wet meadow sites in the Klamath Mountains of Northern...

There is currently a considerable interest in developing bio-based and green nanocomposites in industrial and technological areas owing to their biodegradability, biocompatibility, and environmental friendliness. In this study, a bio-based nanosized material, cellulose nanocrystals (CNC), extracted from southern pine pulp was employed as a reinforcing agent in a natural rubber (NR) matrix. NR/CNC nanocomposites were prepared by a solution mixing and casting method. The morphology, thermal, and mechanical properties of the nanocomposites were investigated using scanning electron microscopy,...

Global forests capture and store significant amounts of carbon through photosynthesis. When carbon is removed from forests through harvest, a portion of the harvested carbon is stored in wood products, often for many decades. The United States Forest Service (USFS) and other agencies are interested in accurately accounting for carbon flux associated with harvested wood products (HWP) to meet greenhouse gas monitoring commitments and climate change adaptation and mitigation objectives. National-level forest carbon accounting has been in place for over a decade, but there is an increasing...

Global forests capture and store significant amounts of carbon through photosynthesis. When carbon is removed from forests through harvest, a portion of the harvested carbon is stored in wood products, often for many decades. The United States Forest Service (USFS) and other agencies are interested in accurately accounting for carbon flux associated with harvested wood products (HWP) to meet greenhouse gas monitoring commitments and climate change adaptation and mitigation objectives. National-level forest carbon accounting has been in place for over a decade, but there is an increasing...