Treesearch

Hyporheic exchange is principally driven by spatial variations of near-bed pressure, which can be sensitive to seasonal changes in discharge, flow depth, and watersurface profile (Tonina and Buffington, 2003, 2007). Simulations of hyporheic exchange across two-dimensional pool-riffle topography show that the strength and spatial extent of the hyporheic exchange vary with discharge.

Our focus is on the Pacific Northwest and Intermountain Region including the Great Basin, Columbia Plateau, Colorado Plateau, and surrounding areas. The climate of this large, arid to semiarid region is defined by generally low and highly variable precipitation. Much of the yearly precipitation arrives as winter snow because most of the moisture comes as frontal storms in winter instead of convective storms in summer. Strong gradients in both temperature and precipitation exist with mountainous areas receiving as much as 127 cm (50 inches) of precipitation a year, and lower elevation cold...

Previous studies assessing the accuracy of bed-load transport equations have considered equation performance statistically based on paired observations of measured and predicted bed-load transport rates. However, transport measurements were typically taken during low flows, biasing the assessment of equation performance toward low discharges, and because equation performance can vary with discharge, it is unclear whether previous assessments of performance apply to higher, geomorphically significant flows e.g., the bankfull or effective discharges . Nor is it clear whether these equations...

In the late summer of 2007 the Institute for Pacific Islands Forestry (IPIF), which is part of the US Forest Service Pacific Southwestern Research Station, asked the USFS Rocky Mountain Research Station's (RMRS) Air, Water and Aquatic Program's (AWA) Southwest Watershed Science Team for assistance in the establishing baseline data in the initial phase of a long term research project in the newly established Hawaiian Experimental Forest. RMRS and its predecessors have a history of the long standing watershed related research in the southwestern United States which was established experimenta...

Dense, small-diameter stands generally require thinning from below to improve fire-tolerance. The resulting forest biomass can be used for energy production. The cost of harvesting, processing, and transporting small-diameter trees often exceeds revenues due to high costs associated with harvesting and transportation and low market values for forest biomass. Productivity and cost were evaluated in a whole-tree harvesting system on four fuel-reduction thinning treatment units in Arizona. Thinning required removal of trees less than 5.0 inches in diameter at breast height (DBH). Time studies...

Bark beetles cause extensive tree mortality in coniferous forests of western North America and play an important role in the disturbance ecology of these ecosystems. Recently, elevated populations of bark beetles have been observed in all conifer forest types across the western United States. This has heightened public awareness of the issue and triggered legislation for increased funding for state and federal agencies to address issues associated with bark beetle outbreaks. Recently, US Forest Service, Research and Development entomologists from the western research stations met with US...

What amount of extra energy can be generated after subtracting the total energy consumed to produce the biomass energy? Knowing the ratio between energy output and input is a valid question when highly mechanized systems that consume fossil fuels are used to harvest and transport forest biomass for energy. We estimated the net energy generated from mechanical fuel reduction thinning treatments on pure ponderosa pine stands in Arizona. The mechanized system (felling, skidding, loading, grinding, and hauling) was monitored for energy consumption. Potential energy output from harvested forest...

Designing a fuel-sampling program that accurately and efficiently assesses fuel load at relevant spatial scales requires knowledge of each sample method's strengths and weaknesses.We obtained loading values for six fuel components using five fuel load sampling techniques at five locations in western Montana, USA. The techniques included fixed-area plots, planar intersect, photoloads, a photoload macroplot, and a photo series. For each of the six fuels, we compared (1) the relative differences in load values among techniques and (2) the differences in load between each method and a reference...

Bull trout (Salvelinus confluentus) is an imperiled species of char native to the Pacific Northwest. Combinations of habitat degradation (e.g., Fraley and Shepard 1989), barriers to migration (e.g., Rieman and McIntyre 1995), and the introduction of non-natives (e.g., Leary et al. 1993) have led to the decline of bull trout populations across their native range (Rieman et al. 1997). Consequently, bull trout in the coterminous United States were listed as threatened, under the Endangered Species Act (ESA), on November 1, 1999 (64 FR 58910) (USFWS 2002). The U.S. Fish and Wildlife Service...

Consistency in determining Rosgen stream types was evaluated in 12 streams within the John Day Basin, northeastern Oregon. The Rosgen classification system is commonly used in the western United States and is based on the measurement of five stream attributes: entrenchment ratio, width-to-depth ratio, sinuosity, slope, and substrate size. Streams were classified from measurements made by three monitoring groups, with each group fielding multiple crews that conducted two to three independent surveys of each stream. In only four streams (33%) did measurements from all crews in all monitoring...