Geomorphic and Riparian Influences on the Distribution and Abundance of Salmonids in a Cascade Mountain Stream

Abundance of resident cutthroat (Salmo clarki) and rainbow (Salmo gairdneri) trout was generally 1.5 to 3.5 times greater in unconstrained reaches than in con-strained reaches of Lookout Creek， a fourth-order tributary to the McKenzie River， Oregon. The presence of adult rainbow trout depressed juvenile abundance in pools with little habitat complexity but had no effect in pools with more heterogeneous structure. The greater abundance of trout in unconstrained reaches was related to habitat structure， the influence of the riparian canopy on stream productivity， and the effect of channel morphology on stream hydraulics. Valley floor landforms are major determinants of channel complexity and habitat structure， providing a hierarchical geomorphic context for interpreting riparian influences on patterns of abundance and distribution of salmonids within a basin. Citation: Moore， Kelly M.S.; Gregory， Stan V. 1989. Geomorphic and Riparian Influences on the Distribution and Abundance of Salmonids 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. 256-261