Treesearch

We examined patterns of size-associated morphological variation within the Red Tree Vole (Arborimus longicaudus) for the purposes of 1) identifying differences between the Red Tree Vole and the Dusky Tree Vole (A. l. silvicola), a putative subspecies of the Red Tree Vole; and 2) examining spatial patterns of morphological variation across the species' range. Our results illustrate subtle, but significant, morphological differences across the boundary that has been proposed to delimit the ranges of the Dusky Tree Vole and Red Tree Vole. However, the morphological characters examined have...

Geographically extensive forest inventories, such as the USDA Forest Service's Forest Inventory and Analysis (FIA) program, contain millions of individual tree growth and mortality records that could be used to develop broad-scale models of forest dynamics. A limitation of inventory data, however, is that individual-level measurements of light (L) and other environmental factors are typically absent. Thus, inventory data alone cannot be used to parameterize mechanistic models of forest dynamics in which individual performance depends on light, water, nutrients, etc. To overcome this...

Forest policymakers, public lands managers, and scientists in the Pacific Northwest (USA) seek ways to evaluate the landscape-level effects of policies and management through the multidisciplinary development and application of spatially explicit methods and models. The Interagency Mapping and Analysis Project (IMAP) is an ongoing effort to generate landscape-wide vegetation data and models to evaluate the integrated effects of disturbances and management activities on natural resource conditions in Oregon and Washington (USA). In this initial analysis, we characterized the spatial...

In severely burned plantations, dynamics of (1) shrub, herbaceous, and cryptogam richness; (2) cover; (3) topographic, overstory, and site influences were characterized on two contrasting aspects 2 to 4 years following fire. Analysis of variance was used to examine change in structural layer richness and cover over time. Non-metric multidimensional scaling, multi-response permutation procedure, and indicator species analysis were used to evaluate changes in community composition over time. Vegetation established rapidly following wildfire in burned plantations, following an initial...

Goal three of the current U.S. Department of Agriculture, Forest Service strategy for improving the use of woody biomass is to help develop and expand markets for woody biomass products. This report is concerned with the existing volumes of renewable wood energy products (RWEP) that are currently used in Alaska and the potential demand for RWEP for residential and community heating projects in the state. In this report, data published by the U.S. Department of Commerce, Bureau of Census and the U.S. Department of Energy, Energy Information Agency have been used to build a profile of...

This study’s objective was to document and describe the current seedling bank of Sitka spruce (Picea sitchensis (Bong.) Carr.) and western hemlock (Tsuga heterophylla (Raf.) Sarg.) stands in southeast Alaska that were partially cut between 1900 and 1984. We investigated the following: (1) What are seedling bank densities? (2) What are seedling size- and age-class distributions? (3) Do seedbed type, treatment, and understory vegetation affect seedling density and species composition? and (4) What are seedling growth rates? Density was high for both Sitka spruce (22,000 seedlings/ha) and...

In popular imagination, the oak tree stands for strength, endurance, and longevity. But in the coastal lowlands and central valleys of British Columbia, Washington, Oregon, and California, oaks face a battery of natural and human-induced threats. Sudden oak death, caused by a virulent pathogen identified in 2000, has killed millions of tanoaks, California black oaks, and coast live oaks in California and southern Oregon. In 2008, scientists linked oak deaths in San Diego County to the newly named goldspotted oak borer, an insect first detected in the state in 2004. Over the years, much of...

Most temperate woody plants have a winter chilling requirement to prevent budburst during midwinter periods of warm weather. The date of spring budburst is dependent on both chilling and forcing; modeling this date is an important part of predicting potential effects of global warming on trees. There is no clear evidence from the literature that the curves of chilling or forcing effectiveness differ by species so we combined our data and published information to develop new curves on the effectiveness of temperature for chilling and forcing. The new curves predict effectiveness over a wide...

Mechanical thinning and prescribed burning practices are commonly used to address tree stocking, spacing, composition, and canopy and surface fuel conditions in western US mixed conifer forests. We examined the effects of these fuel treatments alone and combined on snag abundance and spatial pattern across 12 10-ha treatment units in central Washington State. A snag census was conducted before and immediately after treatments on each unit where all snags were measured and classified as either "new" (< 1 year as a snag) or "old" (> 1 year as a snag) mortality, and bark beetle species were...

Off-highway vehicle (OHV) use is a rapidly growing outdoor activity that results in a host of environmental and management problems. Federal agencies have been directed to develop travel management plans to improve recreation experiences, reduce social conflicts, and diminish environmental impacts of OHVs. We examine the effect of land access restrictions on the welfare of OHV enthusiasts in Utah using Murdock's unobserved heterogeneity random utility model (Murdock 2006). Our models indicate that changing access to public lands from fully "open" to "limited" results in relatively small...