Treesearch

Nitrogen enters terrestrial ecosystems through multiple pathways during primary succession. We measured accumulation of total soil nitrogen and changes in inorganic nitrogen (N) pools across a 300-y sequence of river terraces in northwest Alaska and assessed the contribution of the nitrogen-fixing shrub Shepherdia canadensis. Our work compared 5 stages of floodplain succession, progressing from a sparsely vegetated silt cap to dense shrubby vegetation, balsam poplar-dominated (Populus balsamifera) and white spruce-dominated (Picea glauca) mixed forests, and old-growth white spruce forest....

Quantifying critical conditions of rill formation can be useful for a better understanding of soil erosion processes. Current studies lack a consensus and related rationale on how to describe these conditions. This study was based on the concepts that (1) the shear stress available for erosion at any given point is a function of the runoff rate, the slope steepness, and hydraulic characteristics of the surface; (2) rill incision begins when overland flow shear stress exceeds soil critical shear stress; and (3) the distance from the top of the slope to the point where rills form can be...

The potential for forest harvest to increase snowmelt rates in maritime snow climates is well recognized. However, questions still exist about the magnitude of peak flow increases in basins larger than 10 km2 and the geomorphic and biological consequences of these changes. In this study, we used observations from two nearly adjacent small basins (13 and 30 km2) in the Coeur d'Alene River basin, one with recent, relatively extensive, timber harvest, and the other with little disturbance in the last 50 years to explore changes in peak flows due to timber harvest and their potential effects...

Many fishes migrate extensively through stream networks, yet patterns are commonly described only in terms of the origin and destination of migration (e.g., between natal and feeding habitats). To better understand patterns of migration in bull trout, Salvelinus confluentus we studied the influences of body size (total length [TL]) and environmental factors (stream temperature and discharge) on migrations in the Boise River basin, Idaho. During the autumns of 2001-2003, we tracked the downstream migrations of 174 radio-tagged bull trout ranging in size from 21 to 73 cm TL. The results...

Recent large-scale wildfires have increased populations of wood-boring insects in the Black Hills of South Dakota. Because little is known about possible impacts of wood-boring insects in the Black Hills, land managers are interested in developing monitoring techniques such as flight trapping with semiochemical baits. Two trap designs and four semiochemical attractants were tested in a recently burned ponderosa pine, Pinus ponderosa Dougl. ex Laws., forest in the Black Hills. Modified panel and funnel traps were tested in combination with the attractants, which included a woodborer...

Gravel bedload transport rates were measured at eight study sites in coarse-bedded Rocky Mountain streams using 4-6 bedload traps deployed across the stream width and a 76 by 76 mm opening Helley Smith sampler. Transport rates obtained from bedload traps increased steeply with flow which resulted in steep and well-defined transport rating curves with exponents of 8 to 16. Gravel transport rates measured by the Helley-Smith sampler started with much higher transport rates during low flows and increased less steeply, thus fitted bedload rating curves were less steep with exponents of 2 to 4....

This is the third compilation of imperiled (i.e., endangered, threatened, vulnerable) plus extinct freshwater and diadromous fishes of North America prepared by the American Fisheries Society's Endangered Species Committee. Since the last revision in 1989, imperilment of inland fishes has increased substantially. This list includes 700 extant taxa representing 133 genera and 36 families, a 92% increase over the 364 listed in 1989. The increase reflects the addition of distinct populations, previously non-imperiled fishes, and recently described or discovered taxa. Approximately 39% of...

We conducted a soil monitoring project in 1992 after a shelterwood harvest. One year after harvesting, we determined that 21.32 percent of the area in Unit 5 of the Pool Timber Sale was considered to have detrimental soil compaction. In 2007, we conducted another monitoring project on the same stand by the same person to determine the degree of soil compaction recovery on skid trails. Results from the 2007 monitoring showed that detrimental soil compaction still existed in the stand and that there was no significant difference between the 1992 and the 2007 skid trail bulk densities....

A statistical model is presented that predicts periodic height growth for released Pseudotsuga menziesii var. glauca [Beissn.] Franco advance regeneration in central Idaho. Individual tree and site variables were used to construct a model that predicts 5-year height growth for years 6 through 10 after release. Habitat type and height growth prior to release were the most important predictors of post-release height growth. Douglas-fir and subalpine fir habitat types had longer adjustment periods compared to grand fir habitat types, and damaged trees did not recover to growth rates as...

This delightful essay records Frank Wadsworth’s early forestry career at FVEF in the late 1930s. Frank married Margaret Pearson, G.A. and May Pearson’s daughter, in 1941. Pearson believed Frank could not continue to work for him because of nepotism rules, so Frank and Margaret moved to San Juan, Puerto Rico in 1942 where Frank continued his forestry career. His retirement now includes writing up research that he didn’t get to while employed and tending his multi-acre orchards in Puerto Rico.