Treesearch

Pine wilt disease (PWD) invaded southern Japan in the early 1900s and has gradually expanded its range to northern Honshu (Japanese mainland). The disease is caused by a pathogenic North American nematode, which is transmitted by native pine sawyer beetles. Recently, the disease has invaded other portions of East Asia and Europe where extensive mortality of host pines is anticipated to resemble historical patterns seen in Japan. There is a critical need to identify the main drivers of PWD invasion spread so as to predict the future spread and evaluate containment strategies in newly...

This resource update provides an overview of timber product output (TPO) and use in Nebraska based on questionnaires designed to determine the size and composition of the State's primary wood-using industry, its use of roundwood, and its generation and disposition of wood residues. This study was a cooperative effort between the Nebraska Forest Service (NFS) and the Forest Inventory and Analysis (FIA) program at the Northern Research Station (NRS) of the USDA Forest Service. The NFS surveyed all known primary wood-using mills and FIA processed and analyzed the survey responses. Mill...

Climate change is already resulting in changes in cold desert ecosystems, lending urgency to the need to understand climate change effects and develop effective adaptation strategies. In this review, we synthesize information on changes in climate and hydrologic processes during the past century for the Great Basin and Columbia Plateau and discuss future projections for the 21st century. We develop midcentury projections of temperature and climate for the Great Basin and Columbia Plateau at timescales relevant to managers (2020-2050) and discuss concepts and strategies for adapting to the...

The boundary between woodlands and shrublands delineates the distribution of the tree biome in many regions across the globe. Woodlands and shrublands interface at multiple spatial scales, and many ecological processes operate at different spatial scales to determine the position of the woodland-shrubland boundary. The overall objective of this dissertation was to examine processes affecting vegetation dynamics at the woodland-shrubland interface in the western United States, at spatial scales ranging from biomes to individual plants. In Chapter 1, I examined broad-scale drivers of the...

Diameter growth is seasonal in Douglasfir, the evergreen tree found in much of western Washington, Oregon, and northern California. Initiation and cessation of diameter growth are both triggered by environmental cues. The tree responds to these cues to improve its chances of growing under favorable conditions. As environmental conditions change, however, land managers want to know how warmer summers and falls may affect diameter growth in Douglas-fir. Forest Service scientists Connie Harrington, Brad St. Clair, and Kevin Ford conducted a study to examine the environmental cues that drive...

We investigated relationships between the spatial patterns of burn severity in Chinese boreal forests and weather parameters. Patch size, shape and arrangement differed between high-severity and low/moderate-severity patches.Wind speed and relative humidity were dominant weather parameters of spatial variation in burn severity. Patch size negatively correlated with relative humidity; patch complexity and aggregation positively correlated with wind speed.

Invasions of introduced species have homogenized ecological communities worldwide, leading to losses of native species and the services they provide. Some of these invaders substantially alter nutrient cycling, which changes conditions for all other organisms, but less is known about the potential influence of these species on nitrogen (N) trace gas emissions that affect atmospheric processes. We used a natural experiment to explore whether the establishment of an introduced nitrogen (N) fixing tree (Falcataria moluccana) and recent invasion of an amphibian predator, the Caribbean tree...

Ecological restoration is needed to counter global-scale ecosystem degradation, but can conflict with endangered species conservation when restoration impacts habitat quality. In such cases, prioritizing long-vacant patches for restoration is an intuitively appealing strategy for minimizing the effects on endangered species. Metapopulation models grounded in empirical data potentially provide a rigorous framework for developing theoretical “patch vacancy thresholds” (i.e., duration of vacancy required before implementing restoration) and assessing the implications of such criteria for...

Rising temperatures and extended periods of drought compromise tree hydraulic and carbohydrate systems, threatening forest health globally. Despite winter's biological significance to many forests, the effects of warmer and dryer winters on tree hydraulic and carbohydrate status have largely been overlooked. Here we report a sharp and previously unknown decline in stem water content of three conifer species during California's anomalous 2015 mid‐winter drought that was followed by dampened spring starch accumulation. Recent precipitation and seasonal vapor pressure deficit (VPD) anomaly,...

Species that breed in stream environments with unpredictable interannual variability in hydrological regimes may exhibit plasticity in the timing of their breeding activities. Breeding phenology should coincide with conditions and habitats that maximize a species' reproductive success. For the lotic-breeding frog Rana boylii, the timing of breeding activities of a population can vary by more than a month among years. To examine the influence of abiotic factors on the variation in the timing of onset and patterns (i.e., peaks and pauses) in breeding activity of R. boylii, we sampled seven...