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173 records · Page 10Linked to original sources
USGS2003

Endangered toads in the Rockies

The western toad species complex, endemic to western North America, includes two montane species that have undergone extensive declines. These are the Yosemite toad, Bufo canorus, in the Sierra Nevada, and the southern Rocky Mountain populations of the boreal toad, B. borea. Most declines in the Rockies appear to have occurred before 1980, but a recent episode in Rocky Mountain National Park illustrates the rapidity and severity with which populations of toads can succumb, and that the phenomenon is still occurring. Causes of these declines, with experimental or observational support, include increasing ultraviolet radiation; disease; and interactions among several factors. However, significant questions about the generality of each of these hypotheses remain to be answered. Regardless of the cause of past and current declines, climate change in the coming decades may create conditions that will challenge the persistence of these species, and others not currently threatened.

Rocky Mountains↗
USGS1997

The spring runoff pulse from the Sierra Nevada

A spring runoff pulse is identified in the Merced River record from the Sierra Nevada, that makes the transition from low streamflow conditions in winter to the high streamflow conditions in the later spring-early summer period. The timing of the pulse is delayed with greater seasonal accumulation of snow pack in the Yosemite region. Also, the runoff pulse is triggered by a regional weather fluctuation that establishes a warm high pressure ridge over the California region during the spring (mid-March to Mid-May) period. Since this ridge often blankets the entire western United States, it is found that a simultaneous pulse occurs over a broad collection of high-elevation streams in the region.

California↗
USGS2010

Responding to climate change: A toolbox of management strategies: Chapter 11

Climate change and its effects are writ large across the landscape and in the natural and cultural heritage of parks and wilderness. They always have been and always will be. The sculpted walls of Yosemite National Park and the jagged scenery of the Sierra Nevada wilderness would not be as spectacular if periods of glaciation had not been followed by periods of deglaciation. High biodiversity in forests of the Great Smoky Mountains reflects a legacy of climate change, migrating species, and isolated climatic refugia. Fossils unearthed at Dinosaur National Monument reflect a time when the climate was very different than it is today, as do ruins left by peoples who practiced agriculture in places in the American Southwest where food production is not possible today. Over eons, climate change has molded the diversity of life and landscape in areas now protected as parks and wilderness.

Book chapter↗
USGS2021

Economic effects assessment approaches: US National Parks approach

This chapter discusses the data and methods used by the US National Park Service to estimate the economic effects of National Park visitor spending to local and regional economies. Topics covered include a summary of economic effects analyses, required data for analysis (visitor count data, trip characteristics and spending patterns, and regional economic multipliers) and how these data are combined to estimate visitor spending and economic effects. The chapter includes an applied example for Yosemite National Park and shows how park-level data can be combined to estimate and showcase state- and national-level visitor spending effects.

Book chapter↗
USGS1978

Fusion of granodiorite by basalt, central Sierra Nevada

A trachybasalt plug, 100 m in diameter, has partially fused inclusions and wallrock of porphyritic granodiorite near Tuolumne Meadows, Yosemite National Park, Calif. Granodiorite surrounding the plug was altered within distances of about 3.5 m. Within this distance, (1) trace amounts of glass occur along fractures and grain boundaries, (2) biotite has been altered from dark olive to dark reddish brown and contains bands of fine reddish iron oxide grains, and (3) optic axial angles of potassium feldspar decrease toward the contact. As much as 20 volume percent of glass occurs in the granodiorite in a reentrant and in inclusions within the plug. Detailed study of two partially fused samples shows that, relative to unfused granodiorite, SiO 2 is clearly depleted in both samples, whereas K 2 O is depleted in one but not the other. Total iron, Al 2 O 3 , MgO, Na 2 O, and H 2 O show apparent increases in both samples; other constituents show no significant changes. Chemical analyses suggest that much original material was lost from the partially fused rocks, probably by mass migration of melt rather than by chemical diffusion. The composition of glasses now present in the partially fused rocks was dominated by melting of quartz and feldspars, whereas the composition of the early-formed "lost" melt was strongly influenced by subsolidus reaction and subsequent melting of biotite.

California↗
USGS1977

Application of a hydrometeorological model to the south-central Sierra Nevada of California

A hydrometeorological streamflow-prediction model (HM model) developed for the North Cascades of Washington has been tested in the south-central Sierra Nevada of California. Twenty-four drainages ranging in mean altitude from 770 to 3,160 metres, including several of the major ones such as those of the Kern, Kings, and Merced Rivers, were examined. Eight U.S. National Oceanic and Atmospheric Administration precipitation stations were evaluated. Of these, three proved to be of significant value for nearly all the drainages used. Results are given for predictions on February 1, March 1, and April 1 of monthly runoff of five major drainages for the April-September season. Also demonstrated is the April 1 prediction of a daily hydrograph for the April-September season for 2 diverse years. The altitude distribution of storage and runoff, both observed and predicted, is determined by using several drainages with different area-altitude profiles. Results of this calculation for two drainages show that, on the average, approximately 50 percent of the April-July runoff originates above 2,800 m. The influence of subsequent precipitation on prediction accuracy is determined by relating prediction error and actual precipitation occurring after the prediction day. Results for three basins show that about 75 percent of the error of a January-September prediction on January 1 is due to precipitation occurring during the prediction season. Comparisons of prediction accuracy are made for five major drainages: the Kern River near Kernville; the Kings River below North Fork, near Trimmer (inflow to Pine Flat Dam); the Kings River at Piedra; the Merced River at Pohono Bridge, near Yosemite; and the Merced River below Merced Falls Dam, near Snelling. The accuracy of the HM model appears to be about 24 percent higher than existing operational methods in predicting the April-July runoff on April 1.

California↗