Helfield, J.M., and R.J. Naiman. 2001. Nutrients from salmon carcasses enhance streamside forest growth and long-term salmon production. Ecology. in press.

Abstract. Anadromous Pacific salmon (Oncorhynchus spp.) transport marine-derived nitrogen (MDN) to the rivers in which they reproduce. Isotopic analyses indicate that trees and shrubs near spawning streams derive approximately 22 - 24% of their foliar nitrogen (N) from spawning salmon. As a consequence of this nutrient subsidy, growth rates are significantly increased in Sitka spruce (Picea sitchensis) near spawning streams. As riparian forests affect the quality of instream habitat through shading, sediment and nutrient filtration and production of large woody debris (LWD), this fertilization process serves not only to enhance riparian production, but may also act as a positive feedback mechanism by which salmon-borne nutrients improve spawning and rearing habitat for subsequent salmon generations and maintain the long-term productivity of river corridors along the Pacific coast of North America.

Key words: Alaska; feedback; fertilization; forest growth; marine-derived nutrients; nitrogen; nutrient cycling; river; riparian forest; salmon; Sitka spruce (Picea sitchensis); stable isotopes.