Treesearch

Pyrenophora semeniperda can infect nondormant Bromus tectorum seeds under optimal germination conditions, but most escape mortality. This reduces pathogen fitness relative to infection of dormant seeds, which are almost always killed. However, field experiments showed that a large proportion of seeds killed following inoculum addition were not accounted for as dormant seeds, but instead were likely nondormant seeds that would have germinated without inoculum addition. We hypothesized that widely fluctuating water availability to seeds would favor pathogenesis by delaying germination and...

The complex and interdisciplinary nature of socio-environmental (SE) problems has led to numerous efforts to develop organizing frameworks to capture the structural and functional elements of SE systems. We evaluate six leading SE frameworks, i.e., human ecosystem framework, resilience, integrated assessment of ecosystem services, vulnerability framework, coupled human-natural systems, and social-ecological systems framework, with the dual goals of (1) investigating the theoretical core of SE systems research emerging across diverse frameworks and (2) highlighting the gaps and research...

Skipjack Herring (Alosa chrysochloris) has long been proposed as the sole host for Reginaia ebenus (Ebonyshell) and Elliptio crassidens (Elephantear), but these relationships were unconfirmed because of difficulties with maintaining this fish species in captivity. We confirmed the suitability of Skipjack Herring as host for both mussel species, and we also showed that Alabama Shad (Alosa alabamae) is an additional suitable host for E. crassidens; both fish species produced large numbers of juvenile mussels. No other fish species tested (n =12) were suitable hosts for either mussel species....

This is the executive summary of a three-volume science synthesis that addresses various ecological and social concerns regarding management of federal forests encompassed by the Northwest Forest Plan (NWFP). Land managers with the U.S. Forest Service provided questions that helped guide preparation of the synthesis. It builds on the 10-, 15-, and 20-year NWFP monitoring reports and synthesizes the vast body of relevant scientific literature that has accumulated in the 24 years since the NWFP was initiated. Here we summarize scientific findings and considerations for management that were...

During the last two centuries, thousands of insect species have been transported (largely inadvertently) and established outside of their native ranges worldwide, some with catastrophic ecological and economic impacts. Global variation in numbers of invading species depends on geographic variation in propagule pressure and heterogeneity of environmental resistance to invasions. Elton's diversityinvasibility hypothesis, proposed over sixty years ago, has been widely explored for plants but little is known on how biodiversity affects insect invasions. Here we use species inventories from 44...

The amount of biomass stored in forest ecosystems is a result of past natural disturbances, forest management activities, and current structure and composition such as age class distributions. Although natural disturbances are projected to increase in their frequency and severity on a global scale in the future, forest management and timber harvesting decisions continue to be made at local scales, e.g., the ownership or stand level. This study simulated potential changes in natural disturbance regimes and their interaction with timber harvest goals across the Superior National Forest (SNF)...

Determining the extent of soil property changes following forest management activities (e.g., timber harvest, fuels abatement, site preparation) is an ongoing concern for land managers. Monitoring the long-term effects of various harvest operations and fuels treatment methods on soil physical properties and hydrologic function is critical to maintaining forest productivity. We document changes in detrimental soil disturbance (DSD) in harvest units located on the Kootenai National Forest that occurred over two decades. From 1992 through 2006, 251 harvest units on the Kootenai National...

This study explored the consequences for long-term projections and impact analysis of the uncertainty in model parameters and initial conditions. Using the Global Forest Products Model, multiple replications of projections were carried out with parameters or initial condition data sampled randomly from their assumed distribution. The results showed that parameter uncertainty led to uncertainty of the projections increasing steadily with the time horizon, and more rapidly than the uncertainty stemming from initial conditions. Among the parameter uncertainties, those in the supply and demand...

The objectives of this study were to investigate the wear behavior of drill bits in wood drilling resistance measurements and to understand how the blunting of the cutting edges may affect the cutting forces and ultimately the measurement results. Laboratory resistance drilling experiments were conducted using an IML-RESI PD 400 tool (IML Instrumenta Mechanik Labor GmbH, Wiesloch, Germany) and a standard spade-type drill bit. Results were based on 375 drillings made on a 2.58 m long, freshly cut, defect-free yellow birch (Betula alleghaniensis) log with an average MC of 55.5%, an average...

The objective of this study was to determine the technical feasibility of combining acoustic wave data with high-resolution laser scanning data to improve the accuracy of defect detection and quality assessment in hardwood logs. Using acoustic impact testing and high-resolution laser scanning techniques, 21 yellow poplar logs (Liriodendron tulipifera) obtained from the central Appalachian region were evaluated for internal and external defects. These logs were then sawn into boards and the boards were visually graded based on the National Hardwood Lumber Association grading rules. The...