Aquatic habitat condition index, stream type, and livestock bank damage in northern Nevada
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Authors: T. J. Myers, and S. Swanson
Date: 1991
Journal: Water Resources Bulletin
Volume: 27
Number: 4
Pages: 667-677
Summary of Methods: The parameters of habitat condition index (HCI) and the effects of livestock grazing were related to stream classification across a collection of streams from two central locations in western Nevada and northern Nevada. Data was collected over 5 non-continuous years. The level of ungulate bank damage was classified as excessive, high, moderate or light to no damage. Parameters such as pool/riffle ratio, percent pool structure, percent stream bottom, vegetation stability related to stream type and level of bank damage were estimated.
Article Summary / Main Points: Pool/riffle ratios increased as the gradient decreased from steep streams to those of a low gradient with high sinuosity and no ungulate bank damage. Bank damage caused by frequent grazing does not allow the stable stream bottom features responsible for pool/riffle sequences to form. The percentage of pools varied with stream type, but not with level of ungulate bank damage. Structure improves with decreasing stream gradient. Percent of gravels and cobbles in stream bottom varied with stream type; low-gradient streams had the smallest amount of gravel and cobbles in the steam bottom. Percent of gravel and cobbles in stream bottom did not decrease with ungulate bank damage for steeper stream types. Moderate and low gradient streams did not have a consistent pattern, illustrating dependence on upstream conditions. As percent soil instability increased bank damage also increased. Riparian area width was not correlated to stream type, level of bank damage, or interactions.
Vegetation Types: Riparian and Wetlands
MLRA Ecoregions: 24 Humboldt Area 26 Carson Basin and Mountains
Agrovoc Control Words: Riparian zones Grazing River fisheries
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: stream morphology, stream stability, riparian vegetation, livestock grazing impact, fish habitat, aquatic ecosystems, watershed management, wildland hydrology
Annotation: The results from this replicated study are applicable to most riparian ecosystems and rangelands. Most importantly this paper relates stream type and potential impact from grazing management. Results suggest that that management must be specific to each stream type and reach, and not to forget that what is happening upstream can affect a specific site. Myers and Swanson (1992, Water Resour Bull 28:743-754) related stream stability to stream type and bank damage; they found that stream type was very important in determining how a stable a stream is in relation to livestock grazing impacts. This article is available in the RSIS database.
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