TIMBER HARVEST IMPACTS ON SMALL HEADWATER STREAM CHANNELS IN THE COAST RANGES OF WASHINGTON1

Authors

  • C. Rhett. Jackson,

    1. Respectively, Assistant Professor, Daniel B. Warnell School of Forest Resources, University of Georgia, Athens, Georgia 30602–2152; Water Resources Analyst, City of Thornton, Water Resources Division, 9351 Grant Street, Suite 280, Thornton, Colorado 80229; and Graduate Student, Daniel B. Warnell School of Forest Resources, University of Georgia, Athens, Georgia 30602–2152 (E-Mail/Jackson: rjackson@smokey.forestry.uga.edu).
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  • Christopher A. Sturm,

    1. Respectively, Assistant Professor, Daniel B. Warnell School of Forest Resources, University of Georgia, Athens, Georgia 30602–2152; Water Resources Analyst, City of Thornton, Water Resources Division, 9351 Grant Street, Suite 280, Thornton, Colorado 80229; and Graduate Student, Daniel B. Warnell School of Forest Resources, University of Georgia, Athens, Georgia 30602–2152 (E-Mail/Jackson: rjackson@smokey.forestry.uga.edu).
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  • Jason M. Ward

    1. Respectively, Assistant Professor, Daniel B. Warnell School of Forest Resources, University of Georgia, Athens, Georgia 30602–2152; Water Resources Analyst, City of Thornton, Water Resources Division, 9351 Grant Street, Suite 280, Thornton, Colorado 80229; and Graduate Student, Daniel B. Warnell School of Forest Resources, University of Georgia, Athens, Georgia 30602–2152 (E-Mail/Jackson: rjackson@smokey.forestry.uga.edu).
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  • 1

    Paper No. 00154 of the Journal of the American Water Resources Association.Discussions are open until August 1, 2002.

Abstract

ABSTRACT: We evaluated changes in channel habitat distributions, particle-size distributions of bed material, and stream temperatures in a total of 15 first-or second-order streams within and nearby four planned commercial timber harvest units prior to and following timber harvest. Four of the 15 stream basins were not harvested, and these streams served as references. Three streams were cut with unthinned riparian buffers; one was cut with a partial buffer; one was cut with a buffer of non-merchantable trees; and the remaining six basins were clearcut to the channel edge. In the clearcut streams, logging debris covered or buried 98 percent of the channel length to an average depth of 0.94 meters. The slash trapped fine sediment in the channel by inhibiting fluvial transport, and the average percentage of fines increased from 12 percent to 44 percent. The trees along buffered streams served as a fence to keep out logging debris during the first summer following timber harvest. Particle size distributions and habitat distributions in the buffered and reference streams were largely unchanged from the pre-harvest to post-harvest surveys. The debris that buried the clearcut streams effectively shaded most of these streams and protected them from temperature increases. These surveys have documented immediate channel changes due to timber harvest, but channel conditions will evolve over time as the slash decays and becomes redistributed and as new vegetation develops on the channel margins.

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