Impacts of livestock grazing activities on stream insect communities and the riverine environment
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Authors: M. Strand, and R. W. Merritt
Date: 1999
Journal: American Entomologist
Volume: 45
Number: 1
Pages: 13-29
Summary of Methods: Strand and Merritt reviewed the evidence of livestock production impacts on riverine ecosystems throughout the United States. Emphasis is placed on examinations of direct responses of aquatic insects to the activities of cattle, and on studies that illustrate the potential of grazing in riparian areas that indirectly affect aquatic insects through habitat alteration. Some of the effects of overgrazing on aquatic insects include clearing of woody vegetation, which ultimately leads to sensitive organisms being eliminated. Denudation of bank vegetation can increase erosion, which can lead to domination by burrowing taxa. Excrement deposition can cause eutrophication and bacterial pollution, which can eliminate sensitive aquatic organisms. The authors also cite studies where overgrazing has destroyed microhabitats frequented by California golden trout. The authors end their review with a description of a case study on Carlson Creek, Michigan. Carlson Creek was an overgrazed stream. In a prerecovery analysis of the stream, depth, current velocity, and water temperature were similar in forest and pasture sites. Therefore, differences in riparian characteristics were believed to be the most important source of variation for invertebrate abundance, diversity, and community composition between reaches. This evidence from the Carlson Creek survey is strong in that recent human activities have produced dramatic change in the pasture-reach invertebrate community. Cattle exclusion apparently has started to reverse this trend of alteration and promises ultimately to satisfy the management objectives of limiting erosion and restoring brook trout habitat. Unfortunately, Carlson Creek is an all-too rare example of restoration of overgrazed riparian habitat, particularly where laws do not require farmers or ranchers to limit impacts on riverine habitat.
Article Summary / Main Points: None
Vegetation Types:
MLRA Ecoregions:
Agrovoc Control Words: Riparian zones Rangelands Wildlife
Article Review Type: Refereed
Article Type: Scientific Synthesis
Keywords: livestock grazing, insects, riparian habitat, water quality, riverine ecosystems, habitat alteration
Annotation: Season of use is not specified.
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