Treesearch

Phellinus weirii (Mum.) Gilb is a native pathogen in the forests of the Northwestern United States causing laminated root rot and mortality in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and other susceptible conifer species. This facultative saprophyte is a natural part of the ecosystem, present in most Douglas-fir forests of the Pacific Northwest. In a natural stand, the tree mortality caused by P. weirii creates openings that will be occupied by resistant or early-successional plant species, and creates habitat changes that increase overall species diversity in the forest. In a...

Changes in forest management have detrimentally affected the economic health of small communities in the Blue Mountain region of Oregon over the past few decades. A build-up of small trees threatens the ecological health of these forests and increases wildland fire hazard. Hoping to boost their economies and also restore these forests, local leaders are interested in the economic value of timber that might be available from thinning treatments on these lands. This study identified densely stocked stands where thinning could provide a reliable source of wood, and examined the quantity,...

This paper describes a growth model for young plantations of Douglas-fir(Pseudotsuga menziesii (Mirb.) Franco) growing in the Pacific Northwest. The overall model has three major components. The first is a yield model for diameter and height distributions describing stands prior to pruning or precommercial thinning. The second component is an annual per-acre net increment model adapted from a recent model for Douglas-fir plantations in New Zealand; thinning and pruning are features of the model. The third component is growth equations for cohorts of individual trees; the results from this...

Four types of tree shelters were evaluated in southwestern Washington for their effects on seedling microenvironment and performance of two tree species. Shelter types were fine-mesh fabric shelters, solid-walled white shelters with and without vent holes, and solid-walled blue unvented shelters. Summer mean and daily maximum air temperatures were increased by 0.8 °C and 3.6 °C, respectively, in solid-walled tree shelters. Shelter color and shelter venting did not influence air temperatures. Tree shelters only affected vapor pressure deficit late in the growing season. Midday photosynthetic...

Carbon is a naturally occurring compound, essential to life on this planet. We exhale it, while plants absorb it as part of the photosynthetic process. Human activities have altered the carbon balance, however, and as a result have triggered changes in climates around the world. By extracting and burning oil, coal, and natural gas, carbon that was locked in long-term storage underground has been released into the atmosphere. The associated greenhouse gases such as carbon dioxide, methane, and nitrous oxide trap heat that would otherwise radiate back into space. Changes to the global...

Estimates of national forest recreation visitor spending serve us inputs to regional economic analyses and help to identify the economic linkages between national forest recreation use and local forest communities. When completing recreation-related analyses, managers, planners, and researchers frequently think of visitors in terms of recreation activity. When completing recreation visitor spending analyses, we argue that visitors should be segmented based primarily on the type of recreation trip taken. Using survey data collected as part of the U.S. Forest Service National Visitor Use...

For this study, hierarchical data sets--in that several sample plots are located within a stand--were analyzed for study sites in the USA and Germany. The German data had an additional hierarchy as the stands are located within four distinct public forests. Fixed-effects models and mixed-effects models with a random intercept on the stand level were fit to each data set. The coefficients varied significantly also between adjacent study sites. The mixed-effects models significantly improved the estimates and especially reduced the bias that was present for numerous stands in the predictions...

This report examines socioeconomic changes that occurred between 1990 and 2003 associated with implementation of the Northwest Forest Plan (the Plan) in and around lands managed by the Okanogan-Wenatchee National Forest in Washington state. Our findings are based on quantitative data from the U.S. census, the USDA Forest Service and other federal databases, historical documents, and interviews with Forest Service employees and members of five case study communities: Naches Valley, Cashmere, Entiat, Twisp, and the Upper Okanogan Valley. We explore how the Plan affected the flow of socioecono...

Fire regimes are complex systems that represent an aggregate of spatial and temporal events whose statistical properties are scale dependent.\r\nDespite the breadth of research regarding the spatial controls on fire regime variability, few data sets are available with sufficient resolution to test spatially explicit hypotheses. We used a spatially distributed network of georeferenced fire-scarred trees to investigate the spatial structure of fire occurrence at multiple scales. Mantel's tests and geostatistical analysis of fire-occurrence time series led to inferences about the mechanisms...

Coniferous stands that regenerate following clearcutting in southeast Alaska can be characterized by the amount of soil disturbance during logging. There are indications that red alder in mixed stands mitigates some of the negative effects of clearcutting. We compared invertebrate biomass in four stands each of (1) young conifers, (2) young mixed alder and conifer, and (3) old conifers to determine if alder was beneficial to invertebrates. Collembola, then Aranac taxa were most abundant but Colcoptera had the greatest invertebrate biomass on boles of red alder, Sitka spruce, or western...