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Microtus richardsoni, the water vole, was listed as a sensitive species in Region 2 of the USDA Forest Service in 1994. Historical records indicate water voles were found in the Big Horn Mountains, but little was known about their current status. The purpose of this study was to locate water voles in the Big Horn Mountains of Wyoming, develop a habitat profile, and evaluate the extent to which livestock grazing affects them. Accessible creeks with habitat requirements for water voles were surveyed. Water voles were not captured below 2440 m. Grazed and ungrazed sites occupied by water voles were matched and analyzed for percent plant cover, dry weight biomass, riparian classification, mean stream depth, channel...
Historical and geologic records may be used to enhance magnitude estimates for extreme floods along mountain channels, as demonstrated in this study from the San Juan Mountains of Colorado. Historical photographs and local newspaper accounts from the October 1911 flood indicate the likely extent of flooding and damage. A checklist designed to organize and numerically score evidence of flooding was used in 15 field reconnaissance surveys in the upper Animas River valley of southwestern Colorado. Step-backwater flow modeling estimated the discharges necessary to create longitudinal flood bars observed at 6 additional field sites. According to these analyses, maximum unit discharge peaks at approximately 1.3 m3 s-1...
The vegetation and climatic history of subalpine forests on the Colorado Plateau is documented from Lowder Creek Bog and Alpine Pond on the Markagunt Plateau. Pollen and macrofossil data demonstrate substantial changes at sites above 3150 m elevation during the last ca. 13,000 yr. During and after Late Wisconsin deglaciation, subalpine tree species (Picea engelmannii and Abies lasiocarpa) were rare or absent near the Lowder Creek Bog site, but nonarboreal species predominated. P. engelmannii-A. lasiocarpa forest became well-established there between 11,000 and 9800 yr BP and subalpine trees dominated this elevation throughout the Holocene. By ca. 8500 yr BP, however, Picea declined somewhat, with minimal pollen...
We examine trends in surface air temperature for the San Juan Mountain region in southwestern Colorado from 1895 to 2005. Observations from both National Weather Service (NWS) and Snow Telemetry (SNOTEL) sites are analyzed. Results show a net warming of 1 �C between 1895 and 2005. Most of this warming occurred between 1990 and 2005, when the region experienced rapid and secular increases in temperature. Between 1950 and 1985, there was a cooling trend in the region during which there were significant decreases in the maximum temperature (Tmax) and almost no trend in the minimum temperature (Tmin). This cooling trend appears to be, in part, associated with increases in atmospheric aerosols. Between 1990 and 2005,...
The dominant mechanisms of soil formation on a sequence of Smiths Fork, Blacks Fork, and Pre–Blacks Fork moraines in West Fork of Beaver Creek, Uinta Mountains, Utah, (equivalent to Pinedale, Bull Lake, and Pre–Bull Lake moraines of the Wind River Range, respectively) are clay translocation (argilluviation), increasing soil redness (rubification), and the accumulation of organic matter (melanization) and silt-sized particles. The quantity of clay-sized particles and degree of soil redness increase with soil age, but clay accumulation may plateau in the oldest soils. In contrast, the quantity of accumulated organic matter and abundance of silt-sized particles do not appear to correlate to soil age. The Smiths...
We measured thalli diameters of the lichen Rhizocarpon subgenus Rhizocarpon on 48 individual lobes of 18 rock glaciers and rock glacier complexes in the Elk Mountains and Sawatch Range of central Colorado. Cumulative probability distribution and K-means clustering analyses were used to separate lichen thalli measurements into statistically distinct groups, each interpreted as representing a discrete episode of rock glacier activity driven by an interval of cooler climate. Lichen ages for these episodes were assigned using a growth curve developed for Rhizocarpon geographicum in the nearby Front Range. An early Neoglacial episode, ca. 3080 yr BP, is correlative to other glacial and periglacial activity in the southern...
I replicated and analyzed six photographs taken in A.D. 1870 near the subalpine forest-alpine tundra ecotone in the northern Uinta Mountains to quantify changes in the distribution of vegetation. Three dramatic differences were noted. First, the historical photographs document a treeline 60 to 180 m (mean of 100 m) lower than at present, with greater depression on west-facing slopes. Given the modern lapse rate for mean July temperature (6.9�C km?1), this difference corresponds to a temperature depression in A.D. 1870 of 0.4 to 1.2�C (mean of 0.7�C). Second, timberline forests in A.D. 1870 were significantly (P < 0.01) less dense, with tree densities approximately half those measured in the modern photographs. Third,...
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We examine instrumental meteorological records to compare recent precipitation regimes in the eastern and western Uinta Mountains region of Utah. The comparison demonstrates that, although the summer monsoon contributes a higher proportion of annual precipitation in the east, the two regions are significantly correlated in terms of precipitation variations including summer precipitation. Major droughts, such as the 1930s Dustbowl event, the 1976–1977 event, and the 1987–1989 event, are largely typified by strong decreases in winter precipitation, although deficits can extend into summer. Droughts generally impact the entire region when they occur. Unlike the Southwest and the Pacific Northwest, year-to-year...
In mid-February 2006, windstorms in Arizona, Utah, and western Colorado generated a dust cloud that distributed a layer of dust across the surface of the snowpack throughout much of the Colorado Rockies; it remained visible throughout the winter. We compared the chemical composition of snowfall and snowpack collected during and after the dust deposition event with pre-event snow at 17 sites extending from central Colorado into southern Wyoming. The chemistry of dust-event snowfall and the post-event snowpack were compared to long-term wetfall precipitation and snowpack chemistry at the Fraser Experimental Forest (FEF). The pH of the snowpack formed during the dust event was 1.5 units higher, calcium was 10-fold...
In July 1969 a large female boreal toad was found at timberline( 3,557 m, 11,560 ft) in the Rocky Mountain National Park, Larimer County, Colorado. A total of 46 boreal toads have been found at different localities in the Colorado Front Range, all above 3,385 m (11,000 ft) elevation, and all within 200 m of timberline. These new records extend the known evaluational range of the species upward more than 250 m. A brief description of the habitat of the two highest known localities is given. Published in Arctic, Antarctic, and Alpine Research, volume 2, issue 2, on pages 157 - 159, in 1970.
Eolian sediment collected at three locations in the Wind River Range at seven seasonal intervals from December 1988 to October 1990 were used as a baseline from which to estimate the effects of eolian sedimentation in this region. Dust was collected from snow- and rain-catch instruments installed by the U.S. Forest Service at Hobbs Lake, Lester Pass, and Black Joe Lake. These data show that dust influx rates varied from 0.23 to 31.0 x 10-7g cm-2 d-' during the sampling period. The highest sedimentation rates occur during the late summer from July through September and the lowest rates occur during the winter. High influx rates during the summer months apparentlyreflect the dry, snow-free conditions in the adjacent...


    map background search result map search result map Recent and Multicentennial Precipitation Variability and Drought Occurrence in the Uinta Mountains Region, Utah Recent and Multicentennial Precipitation Variability and Drought Occurrence in the Uinta Mountains Region, Utah