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Presented at the NABS Annual meeting, Vancouver, British Columbia, 2004
in Small Streams and Forestry 4
Riparian deforestation, stream narrowing, and loss of stream ecosystem services
B.W. Sweeney1, T.L. Bott1, J.K. Jackson1, L.A. Kaplan1, J.D. Newbold1, L.J. Standley1, W.C. Hession2, and R.J. Horwitz3. 1Stroud Water Research Center, Avondale, PA, USA 19311, 2University of Vermont, Burlington, VT, USA 05405, 3Academy of Natural Sciences, Philadelphia, PA, USA 19103
A study of 16 streams in the Piedmont region of eastern North America shows that riparian deforestation causes channel narrowing which reduces the total amount of stream habitat and ecosystem per unit channel length and compromises in-stream processing of pollutants. Wide forest reaches had significantly more macroinvertebrates, total ecosystem processing of organic matter, and nitrogen uptake per unit channel length than contiguous narrow deforested reaches. Stream narrowing nullified any advantage of deforestation regarding abundance of fish, quality of dissolved organic matter, and pesticide degradation. These findings show that forested stream channels have a wider and more natural configuration, which significantly affects the total in-stream amount and activity of the ecosystem, including the processing of pollutants. The results reinforce: (i) current US policy that endorses riparian forest buffers as best management practice on landscapes that were forested historically; and (ii) federal and state programs that subsidize riparian reforestation for stream restoration and water quality. Not only do forest buffers prevent non-point source pollutants from entering small streams, they also enhance the in-stream processing of both non-point and point source pollutants, thereby reducing their impact on downstream rivers and estuaries.
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