I investigated ecological relationships between Pacific salmon (Oncorhynchus spp.) and riparian forests along the streams in which they spawn. Initially, I conducted a pilot study that provided evidence of a positive, subdecadal-scale relationship between salmon abundance and tree-ring growth – although this was ostensibly a nutrient fertilizer effect, the mechanisms regulating a nutrient response were unknown. My goals, then, were to derive a mechanistic understanding of the pathways and fate of salmon nutrients in riparian forests, and to evaluate dendroecological methods of salmon abundance reconstruction. First, I measured nutrient contributions of decaying salmon carcasses to the riparian soils; I used ion exchange resins to estimate cumulative bioavailability of major ions in soils, and soil extracts to examine timing and lateral movement of ammonium (NH4+), and nitrate (NO3-) from carcasses. Skeletonization of carcasses took ~76 days. During that time, bioavailability of NH4+ was ~250x, soluble P (primarily PO4-2) was ~2x, and sulfur (SOx) was ~5.5x higher than baseline within 20 cm of carcasses, while availability of other ions was not affected. When protected from large scavengers, an average minimum of 49.3% of total carcass N was contributed to soils, and NH4+ and NO3- moved through soils laterally at least 50 cm. Approximately 97% of salmon N is in quickly decaying soft tissues, while 88% of Ca and 50% of P is in the slowly decaying skeleton. Different lag-times in bioavailability of nutrients result; NH4+ becomes available within weeks, NO3- within months, and P and Ca+2 over months to years. These findings provided a potential timing mechanism for feedbacks between salmon and riparian vegetation. In a companion study, I introduced a 15N tracer to soils of the same riparian system to mimic salmon nutrient input and determine the fate of salmon-derived N. I added isotopically labeled NH4+ (the initial product of salmon carcass decay) and other important nutrients provided by carcasses (P, S, K, Mg, Ca) to soils in late October 2003, coincident with local salmon spawning, and followed the 15N tracer through soil and tree pools for one year. Biological uptake of the 15N tracer occurred quickly; 63% was bound in soil microbiota within 14 days, and roots of riparian trees began to take up 15N tracer within 7 days. Root uptake continued through the winter. The 15N tracer content of soil organic matter reached a maximum of ~61%, 5 weeks after the application. At least 37% of the 15N tracer was taken-up by trees, and total loss from the plots was only ~20% over one year. The large portion of tracer N taken up in the fall and reallocated to leaves and stems the following spring provides evidence for a 1-year lagged tree-growth response to salmon nutrients. Last, I conducted dendroecological analyses at 9 riparian forest sites from southeast Alaska to Southern Oregon, and found evidence of annual- to decadal- scale relationships between salmon abundance and tree-ring growth that were not related to (confounded by) climate. These relationships conform to expectations in time lags based on the mechanistic studies, and were evident in about half of the sites examined. I am currently constructing models to reconstruct stream-specific salmon abundance. Although still under development, initial reconstructions provide a novel source of stream-specific information about salmon abundance over the last several hundred years.