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Abstract
Retention of particulate and dissolved nutrients in streams is a major determinant of food avail-ability to stream biota. Retention of particulate matter (leaves) and dissolved nutrients (nitrogen) was studied experimentally during summer 1987 in four 300-500 m reaches of Lookout Creek, a fifth-order stream in the Cascade Mountains of Oregon. Constrained (narrow valley floor) and unconstrained (broad valley floor) reaches were selected within old-growth and second-growth riparian zones. Gingko leaves and ammonium were re-leased into the channel and retention rates were measured. Retention of leaves and nutrients was 2-4 times higher in unconstrained reaches than in constrained reaches, in both old-growth and second-growth riparian zones. Retention was enhanced by increased geomorphic complexity of channels, diversity of riparian vegetation, presence of woody debris, and heterogeneity in stream hydraulics, sediments, and lateral habitats. Unconstrained reaches express these qualities and thus are critical areas for retention of particulate and dissolved nutrients in stream ecosystems.
Parent Publication
Citation
Lamberti, Gary A.; Gregory, Stan V.; Ashkenas, Linda R.; Wildman, Randall C.; Steinman, Alan G. 1989. Influence of Channel Geomorphology on Retention of Dissolved and Particulate Matter in a Cascade Mountain Stream. In: Abell, Dana L., Technical Coordinator. 1989. Proceedings of the California Riparian Systems Conference: protection, management, and restoration for the 1990s; 1988 September 22-24; Davis, CA. Gen. Tech. Rep. PSW-GTR-110. Berkeley, CA: Pacific Southwest Forest and Range Experiment Station, Forest Service, U.S. Department of Agriculture; p. 33-39
