Treesearch

We examined the effect of logging-debris retention and competing-vegetation control (CCC, initial or annual applications) on dissolved organic carbon (DOC), dissolved organic nitrogen, and nitrate-N leaching to determine the relative potential of these practices to contribute to soil C and N loss at two contrasting sites. Annual CVC resulted in higher soil water nitrate-N concentration and flux, with the magnitude and duration of the effect greatest at the high-N site. Most of the increase in nitrate-N at the low-N site occurred in treatments where logging debris was retained. Dissolved...

We radiocollared 45 red tree voles (Arborimus longicaudus) in western Oregon and monitored their movements during July 2002-September 2003. We predicted that home range areas would be larger in young forests than in old forests and that males would have larger home ranges and use more nests than females. We tracked individual voles for 82 ± 9 days (mean ± SE; range = 24-307 days). Voles were active primarily at night, although we did see voles outside their nests during the day on two occasions. Of the 45 voles, 18 (4 males, 14 females) occupied a single nest tree and adjacent foraging...

Water dynamics in decaying conifer logs of four species (Abies amabilis [Pacific silver fir], Pseudotsuga menziesii [Douglas-fir], Thuja plicata [western red cedar], and Tsuga heterophylla [western hemlock]) were studied in the Coast Range of Oregon. Measurements were made of throughfall, leachate, runoff, and absorption for logs during their 6th through 8th year of decay. During this period 47 to 70 percent of the throughfall landing on the logs evaporated, 18 to 35 percent flowed through the log and leached out; 3 to 29 percent ran off the surface, and absorption accounted for 3 to 11...

We present a six-gene, 420-species maximum-likelihood phylogeny of Ascomycota, the largest phylum of fungi. This analysis is the most taxonomically complete to date with species sampled from all 15 currently circumscribed classes. A number of superclass-level nodes that have previously evaded resolution and were unnamed in classifications of the fungi are resolved for the first time. Based on the six-gene phylogeny we conducted a phylogenetic informativeness analysis of all six genes and a series of ancestral character state reconstructions that focused on morphology of sporocarps, ascus...

Hydrological controls on DOC and N transport at the catchment scale were studied for five storm events from the fall of 2004 through the spring of 2005 in WS10, H,J, Andrews Experimental Forest in the western Cascade Mountains of Oregon, This catchment is devoid of any riparian zone and characterized by hillslopes that issue directly into the stream. This enabled us to compare a trenched hillslope response to the stream response without the influence of riparian zone mixing. DOC and N concentrations and dissolved organic matter (DOM) quality (specific UV-absorbance (SUVA) and C:N of DOM)...

1. Digital hydrographic data are commonly employed in research, planning, and monitoring for freshwater conservation, but hydrographic data sets differ in spatial resolution and accuracy of spatial representation, possibly leading to inaccurate conclusions or unsuitable policies for streams and streamside areas. 2. To examine and illustrate the potential for different hydrographic data sets to influence in-channel and streamside characterizations, a study area in the U.S. Pacific Northwest was chosen because 1:100 000, 1:24 000, and densified 1:24 000 hydrography are available and widely...

This study examines how stand age affects ecosystem mass and energy exchange response to seasonal drought in three adjacent Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests. The sites include two early seral (ES) stands (0 to 15 years old) and an old-growth (OG) (~450 to 500 years old) forest in the Wind River Experimental Forest, Washington, USA. We use eddy covariance flux measurements of carbon dioxide, latent energy, and sensible heat to derive evapotranspiration rate, Bowen ratio, water use efficiency, canopy conductance, the Priestley-Taylor coefficient, and a canopy...

Carbon dioxide (CO2), water vapor, and energy fluxes were measured using eddy covariance (EC) methodology over three adjacent evergreen forests in southern Washington State to identify stand-level age-effects on ecosystem exchange. The sites represent Douglas-fir forest ecosystems at two contrasting successional stages: old-growth (OG) and early seral (ES). We show an alternative approach to the usual friction velocity method for determining periods of adequate atmospheric boundary layer mixing based on the ratio of mean horizontal or vertical windflow to a modified turbulent kinetic...

The developed land area of the United States increased by 14,2 million hectares between 1982 and 2003. Along with a projected U.S. population increase to more than 360 million individuals by 2030, is an expected continuation of expanding rural land development. Related to population growth, rural land development and the associated loss of rural open space are expected to have a number of social, economic, and ecological implications. To gain greater insight into land development patterns, we used U.S. Census Bureau and National Resources Inventory data to quantify per-housing-unit rates...

Because of the characteristically low temperatures and ambient CO2 concentrations associated with greater altitudes, mountain forests may be particularly sensitive to global warming and increased atmospheric CO2. Moreover, the upper treeline is probably the most stressful location within these forests, possibly providing an early bellwether of forest response. Most treeline studies of the past century, as well as recently, have correlated temperatures with the altitudinal limits observed for treelines. In contrast, investigations on pre-establishment seedlings, the most vulnerable life...