Salmon runs link together freshwater and saltwater ecosystems. When they die in the river after spawning, they leave behind marine nutrients that are incorporated into the food webs of at least 137 different species. Some of the animals that feed on salmon in the river then disperse the nutrients into surrounding forests, contributing to up to 25 percent of the nitrogen in the foliage of trees. The results are trees that grow faster and taller than trees in areas without spawning salmon.  

The enhanced trees provide numerous benefits back to the salmon. They supply shade to keep the waters cool and protect the stream banks from erosion. Macroinvertebrates feed on leaves that fall into the river, and young salmon fry feed on those macroinvertebrates.  

An additional service is provided to the salmon as the trees grow, age, and eventually fall into the stream, forming log jams that give shelter to juvenile salmon, and slow down waters to provide refuge for spawning adults.  

In more recent years, logging clear-cuts and development projects along rivers have severely reduced log jams in rivers and streams. The reintroduction of large woody debris is now a prominent restoration technique to improve and maximize habitat for the declining Pacific salmon.  

The next presenter in our virtual learning series, Caroline Walls, has been looking into the productivity of this new technology;  

“Pacific salmon face numerous threats, including the widespread decline of freshwater habitat. In recent decades, large woody debris placement has become one of the most common forms of salmon habitat restoration, but little is known about its long-term effectiveness. Through an analysis of 14 restoration projects with 10+ years of monitoring, I evaluate the long-term physical habitat changes and salmon community responses to large woody debris placement.” CW Click here to register!