ABSTRACT PROPOSAL # : DEB-9806575 INVESTIGATOR(S) : NAIMAN INSTITUTION: UNIVERSITY OF WASHINGTON TITLE: Keystone Interactions: Salmon, Bear and Riparian Vegetation in Riverine Corridors of the Pacific Northwest Interactions between Pacific salmon (Oncorhynchus spp.) and bear (Ursus spp.) appear to play an important role in influencing the stature and dynamics of riparian vegetation in the Pacific Northwest. Preliminary data suggest that marine-derived nutrients accumulate in riparian vegetation, and that bears may act as an important vector for moving nutrients from the stream to the riparian zone through the killing and consumption of salmon and subsequent deposition of carcasses and feces within the riparian forest. Inputs of marine-derived nutrients may enhance growth rates of riparian trees and influence the production of large woody debris, which may in turn affect structural habitat and productivity within the stream corridor. The objectives of this project are to discover the extent to which riparian vegetation acquires marine-derived nitrogen from spawning salmon; to assess the impacts of marine-derived nutrients on riparian growth and community composition; to assess the relative importance of bear activity (e.g., carcass and feces distribution) and hyporheic flow as pathways for transfer of N from stream to riparian systems; and to assess the community importance of salmon-bear interactions with regard to the growth of riparian vegetation. The principal methods used in the evaluation of these objectives are the measurement of stable isotopes (15N) and experimental manipulation of salmon carcasses and bear feces. The significance of this research lies in the discovery of how synergistic interactions between the ocean, salmon and bear can act to influence riparian forests, and how materials from those forests act to influence salmon population strength.
