Treesearch

The gravitational component of water potential contributes a standing 0.01 MPa m1 to the xylem tension gradient in plants. In tall trees, this contribution can significantly reduce the water potential near the tree tops. The turgor of cells in buds and leaves is expected to decrease in direct proportion with leaf water potential along a height gradient unless osmotic adjustment occurs. The pressure-volume technique was used to characterize height-dependent variation in leaf tissue water relations and shoot growth characteristics in young and old Douglas-fir trees to determine the extent to...

Mule deer (Odocoileus hemionus), elk (Cervus elaphus) and cattle share rangeland throughout much of interior western North America. Considerable debate exists about the degree to which facilitation or competition occurs for forage between these three species (Nelson 1982, Wisdom and Thomas 1996, Miller 2002).

In the old-growth temperate rainforests of southeast Alaska, concerns over clearcutting effects on habitat, visual quality, slope stability, and biodiversity have created a demand for the use of other silvicultural systems. The forest vegetation and animal taxa of southeast Alaska appear to be well adapted to frequent, widespread, small-scale disturbance, suggesting that variable-retention harvesting and maintenance of important structural features could sustain desired old-growth conditions in wood producing forests. This hypothesis is tested in the alternatives to clearcutting (ATC)...

We used concurrent measurements of soil water content and soil water potential (Ψsoil) to assess the effects of Ψsoil on uptake and hydraulic redistribution (HR) of soil water by roots during seasonal drought cycles at six sites characterized by differences in the types and amounts of woody vegetations and in climate. The six sites included a semi-arid old-growth ponderosa pine (Pinus ponderosa Dougl. ex P. Laws & C. Laws) forest, a moist old-growth Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forest, a 24-year-old Douglas-fir forest and three Brazilian savanna sites differing in...

During the 1970s, there was growing concern by scientists, policy officials and the general public in the USA over the possible effects of acid rain on human health and the environment (crops, forests, water, etc.). The lack of science-based information needed for policy and regulatory decisions led Congress to create an interagency task force in 1980 called the National Acid Precipitation Assessment Program (NAPAP 1991). By 1985, forest decline in Europe (Mayer & Ulrich 1978) had been widely reported, and concerns over similar symptoms of this decline were mounting in the northeastern...

Chromated copper arsenate (CCA) is the most widely used chemical wood preservative in the United States. Concerns about the safety of CCA led to an agreement between the Environmental Protection Agency and the wood treatment industry to withdraw CCA for nonindustrial uses by the end of 2003. In light of the publicity surrounding the withdrawal of CCA, this article evaluates consumers' willingness to pay a premium for products manufactured from naturally decay-resistant wood as opposed to chemically treated wood. We use a national contingent valuation survey to quantify consumer willingness...

This is a classification of aquatic, wetland, and riparian series and plant associations found within the Colville, Okanogan, and Wenatchee National Forests. It is based on the potential vegetation occurring on lake and pond margins, wetland fens and bogs, and fluvial surfaces along streams and rivers within Forest Service lands. Data used in the classification were collected from 1,650 field plots sampled across the three forests. This classification identifies 32 series separated into four physiognomic classes: coniferous forests, deciduous forests, shrubs, and herbaceous vegetation. In...

Alaska yellow-cedar has declined in Southeast Alaska over the past 100 years, resulting in half a million acres of dead or dying trees. The natural decay resistance of Alaska yellow-cedar means that many of these trees are still merchantable. However, the topography of Southeast Alaska is such that selectively harvesting Alaska yellow-cedar may often require helicopter-yarding. This paper tests two hypotheses. First, do consumers perceive salvage logging of standing-dead Alaska yellow-cedar as more environmentally friendly than harvesting living trees, and therefore, are they willing to...

In Alaska, red alder (Alnus rubra Bong.) is an abundant but commercially underutilized species despite having properties suitable for higher value products, including furniture and cabinetry. However, it laces the name recognition of mote traditional hardwoods. Our research measured the effect of this lack of familiarity on consumer preferences for red alder products, allowing the development of more effective marketing strategies for the species. Our study wad conducted in two West Coast markets--Seattle, WA, and Anchorage, AK, where attendees at home shows were surveyed about their...

Wet meadows are important biological components in the Blue Mountains of eastern Oregon. Many meadows in the Blue Mountains and elsewhere in the Western United States are in a state of change owing to grazing, mining, logging, road development, and other factors. This project evaluated the utility of remotely sensed data to characterize and monitor meadow vegetation for 32 meadows in the Wallowa Whitman and Umatilla National Forests. The meadows had been previously classified into different plant community types based on the occurrence of specific indicator species of sedge (Carex spp). We...