GRASS VERSUS TREES: MANAGING RIPARIAN AREAS TO BENEFIT STREAMS OF CENTRAL NORTH AMERICA1

Authors

  • John Lyons,

    1. Respectively, Research Scientist, Wisconsin Department of Natural Resources, 1350 Femrite Dr., Monona, Wisconsin 53716–3736; Professor, Department of Geography, 405 Hilgard Ave., University of California-Los Angeles, Los Angeles, California 90024–1524; and University of Wisconsin County Extension Agriculture Agent, Columbia County Agriculture Center, 120 West Conant St., P.O. Box 567, Portage, Wisconsin 53901–0567 (formerly Research Specialist, Department of Agronomy, University of Wisconsin-Madison) (E-Mail/Lyons: lyonsj@dnr.state.wi.us).
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  • Stanley W. Thimble,

    1. Respectively, Research Scientist, Wisconsin Department of Natural Resources, 1350 Femrite Dr., Monona, Wisconsin 53716–3736; Professor, Department of Geography, 405 Hilgard Ave., University of California-Los Angeles, Los Angeles, California 90024–1524; and University of Wisconsin County Extension Agriculture Agent, Columbia County Agriculture Center, 120 West Conant St., P.O. Box 567, Portage, Wisconsin 53901–0567 (formerly Research Specialist, Department of Agronomy, University of Wisconsin-Madison) (E-Mail/Lyons: lyonsj@dnr.state.wi.us).
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  • Laura K Paine

    1. Respectively, Research Scientist, Wisconsin Department of Natural Resources, 1350 Femrite Dr., Monona, Wisconsin 53716–3736; Professor, Department of Geography, 405 Hilgard Ave., University of California-Los Angeles, Los Angeles, California 90024–1524; and University of Wisconsin County Extension Agriculture Agent, Columbia County Agriculture Center, 120 West Conant St., P.O. Box 567, Portage, Wisconsin 53901–0567 (formerly Research Specialist, Department of Agronomy, University of Wisconsin-Madison) (E-Mail/Lyons: lyonsj@dnr.state.wi.us).
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  • 1

    Paper No. 99013 of the Journal of the American Water Resources Association. Discussions are open until April 1, 2001.

Abstract

ABSTRACT: Forestation of riparian areas has long been promoted to restore stream ecosystems degraded by agriculture in central North America. Although trees and shrubs in the riparian zone can provide many benefits to streams, grassy or herbaceous riparian vegetation can also provide benefits and may be more appropriate in some situations. Here we review some of the positive and negative implications of grassy versus wooded riparian zones and discuss potential management outcomes. Compared to wooded areas, grassy riparian areas result in stream reaches with different patterns of bank stability, erosion, channel morphology, cover for fish, terrestrial runoff, hydrology, water temperature, organic matter inputs, primary production, aquatic macroinvertebrates, and fish. Of particular relevance in agricultural regions, grassy riparian areas may be more effective in reducing bank erosion and trapping suspended sediments than wooded areas. Maintenance of grassy riparian vegetation usually requires active management (e.g., mowing, burning, herbicide treatments, and grazing), as successional processes will tend ultimately to favor woody vegetation. Riparian agricultural practices that promote a dense, healthy, grassy turf, such as certain types of intensively managed livestock grazing, have potential to restore degraded stream ecosystems.

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