Treesearch

The Density Management Study and Young Stand Th inning and Diversity Study were initiated to investigate whether alternative thinning treatments can accelerate the development of forests toward late-successional structures. An overview of overstory and understory vegetation responses indicates that the magnitude and direction of thinning eff ects initially varied among structural stand components. Average crown length, diameter growth, and seedling and sapling density increased rapidly after thinning. However, diameter growth of the largest trees was less responsive to thinning, at least...

Tree mortality shapes forest structural development and the resulting dead wood provides habitat for many species. However, the eff ects of thinning on mortality and large snag recruitment have been variable and remain poorly understood. We examined thinning eff ects on tree mortality at eleven Density Management Study (DMS) sites in western Oregon. Th inning reduced mortality rates for small trees, especially Douglas-fi r (Pseudotsuga menziesii), but had little infl uence on mortality of large trees (¡Ý50 cm dbh). Gaps created by harvest did not result in increased mortality during the...

Accurate estimates of foliar biomass (FB) are important for quantifying carbon storage in forest ecosystems, but FB is not always reported in regional or national inventories. Foliar biomass also drives key ecological processes in ecosystem models. Published algorithms for estimating FB in conifer species of the Pacific Northwest can yield signifi cantly different results, but have not been rigorously compared for species other than Douglas-fi r (Pseudotsuga menziesii (Mirb.) Franco). We compared fi ve algorithms for estimating FB for seven common coniferous species in the Pacifi c...

The amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), causes the infectious disease chytridiomycosis, which has triggered massive die-offs and extinctions of amphibians around the world. The disease, identified in 1998, is a significant contributor to the global amphibian biodiversity crisis, and no clear means of arresting its spread has been found. Conservationists, scientists, and wildlife managers are grappling with understanding the extent and severity of chytrid disease and its ramifications on species and ecosystems. Enlisting collaborators around the world, Dede Olson,...

Long-term ecological data are crucial in helping ecologists understand ecosystem function and environmental change. Nevertheless, these kinds of data sets are difficult to analyze because they are usually large, multivariate, and spatiotemporal. Although existing analysis tools such as statistical methods and spreadsheet software permit rigorous tests of pre-conceived hypotheses and static charts for simple data exploration, they have limited capacity to provide an overview of the data and to enable ecologists to explore data iteratively, and interactively, before committing to statistical...

This guidebook describes Upper Elk Meadows Research Natural Area (RNA), a 90-ha (223-ac) area that supports a mixture of coniferous forest and open, shruband herb-dominated wetlands. The major forest plant association present within Upper Elk Meadows RNA is Pacific silver fir/vine maple/coolwort foamflower (Abies amabilis/Acer circinatum-Tiarella trifoliata).

This guidebook describes major biological and physical attributes of the 119-ha (293-ac) Mohawk Research Natural Area. The area supports old-growth Douglas-fir (Pseudotsuga menziesii) forest characterized by plant associations representative of the western Cascade foothills. These include the western hemlock/Oregon grape-salal (Tsuga heterophylla/Berberis nervosa-Gaultheria shallon); western hemlock/Oregon grape/swordfern (Tsuga heterophylla/Berberis nervosa/Polystichum munitum); and western hemlock/Oregon oxalis (Tsuga heterophylla/Oxalis oregana) forest plant associations.

This paper deals with 3D numerical simulations of two fires fronts (head and backfire) propagating simultaneously through a grassland fuel. The simulations were carried out using a “fully” physical and three-dimensional fire model (namely WFDS). One of the objectives of this work, was to evaluate the potential for fully physical fire model to simulate the interactions between two fire fronts (a head fire and a backfire), in conditions similar to those encountered during suppression fire operations. A set of numerical simulations was first carried out for standalone head fires propagating...

Research Benefits Society. Forest Service research helps society make choices about water, wildlife, and natural resources. Scientific understanding gained from research transforms the way land managers rise to challenges. For example, the tools and information used daily by managers and policymakers to make cost-effective and environmentally sound fire management decisions are based on research about fire behavior, fire ecology, fuels, and smoke in ecosystems. As a result, citizens are provided ways to secure their homes from fire, are warned when smoke requires them to take precautions,...