In her poem “When Great Trees Fall” Maya Angelou wrote:
When great trees fall
small things recoil into silence,
eroded beyond fear.
The famous poet evokes images of animals at odds with these great falling trees, but it turns out that the same trees that send creatures scurrying into the underbrush can be essential for their survival. Whether on the forest floor or on the stream bottom, fallen trees continue to function as an important part of the ecosystem by providing food, nutrients, and habitat to many creatures large and small — including some of California’s most vulnerable species.
Coho salmon are in serious peril in California where their numbers have fallen by 99% in 60 years. Three hours north of San Francisco in Mendocino County in a region known for its grand forests, conservation organizations and forest products companies are racing against time to save endangered coho salmon before they are lost to extinction in the state. With time running out for this iconic species and budgets at all levels of government facing cuts, conservation scientists seeking solutions for coho need to be innovative, and they are turning to efforts that are both less expensive and more efficient.
The reasons for their decline are diverse and include impacts to both the ocean and the freshwater rivers and streams. On the freshwater side, one of the main concerns is a lack of habitat and shelter. When trees fall into streams they help form essential salmon habitat by creating deep, cool pools and clean nesting areas, and provide ample food and cover from predators. Yet more than 80% of rivers where coho live in California don’t have enough fallen trees and logs to create the habitat elements that salmon need for survival. This is a legacy of historic logging practices that cut right down to the rivers’ edges.
Saving coho requires restoring more than 1,000 miles of streams across California, and many thousands more across the entire Northwest. Traditionally, restoration practitioners have constructed complex structures with wood and steel cable to recreate “artificial salmon habitats.” These structures are designed to stay rigidly in the places they were built, and they involve large investments of both time and materials to construct.
But with extinction looming and budgets decreasing, scientists and restoration practitioners put their heads together to think of a method of restoring habitat for salmon that would be more natural, cheaper, and more effective.
The technique they developed is simple: instead of carefully constructing cable and wood structures to simulate natural habitat, they are placing loose logs and directly falling streamside trees into the river at strategic locations and letting the power of winter rains and high stream flows move the wood to create log jams and salmon habitat naturally.
The change seems simple, but the results are dramatic. This new technique reduces costs by more than a third and effectively improves habitat in 12 months or less.
Both non-profit conservation organizations like The Nature Conservancy and The Conservation Fund and for-profit forest product companies have demonstrated the effectiveness and the pragmatism of this new restoration practice. We are putting money and people on the ground to fall trees into streams, restoring coho habitat with impressive results.
Although this new restoration practice isn’t the only thing we need to do if we want to save coho salmon, it addresses one of the top threats to their recovery – a lack of stream habitat for both adult and young fish. If we can’t restore streams quickly and cheaply, we will certainly lose this iconic California species and potentially other salmon species across the Pacific Northwest. Using these inexpensive techniques, it will be economically feasible to do this type of restoration across an entire watershed in a relatively short period of time.
Our state, nation, and world are facing big problems—from species disappearing to the impact of our changing climate to the ongoing financial crisis. In the face of these challenges, it would be easy to throw up our hands and say we can’t make a difference in short time we have with limited resources. But with a little creativity and ingenuity, we can work smarter and more efficiently to save our natural heritage.