The Influence of Timber Harvest on the Structure and Composition of Riparian Vegetation in the Coastal Redwood Region

Photo by pellaea, Flickr Creative Commons
Photo by pellaea, Flickr Creative Commons

Dr. William Russell found that the negative effects of timber harvesting in riparian coast redwood forests lessen with respect to two conditions; (1) longevity of the forest and (2) wider no-cut buffer zones. Longer-lived forests and forests with wider buffer zones surrounding rivers show less harm from logging. Riparian buffers are strips of forest left on either side of rivers after logging that control the amount of sediment and nutrients filtering into the water. In recently harvested forests and ones with thin or no buffers, young tree crowns crowd the canopies, letting through less sunlight, deciduous hardwoods thrive, extra dead wood litters the forest floors, and exotic and disturbance-prone understory species invade. These alterations, in addition to affecting the physical structure of rivers, down the line cause higher levels of organic material to filter into them.

Among Russell’s study sites in Russian Gulch State Park and the Jackson State Demonstration Forest, dead wood on the forest floor was abnormally high in the most recently harvested forests, a result of human management rather than the natural death of trees. Although these logs—termed large woody debris by ecologists —contribute substantially to biodiversity in undisturbed forest ecosystems, too many of them can reek havoc on riparian habitats. They can change the course and structure of rivers and, once decomposed, overload them with too many nutrients, which have a drastic affect on aquatic life.

The question arises, then, “Are logged riparian forests doomed?” Russell believes the altered streams in his study are resilient and that given enough time and freedom from additional human disturbance, they can return to historic conditions. With respect to harvesting practices, the results of this study show that leaving wider buffer strips along rivers facilitates this process.

Dr. William Russell’s report was published in the journal Landscape Ecology under the title “The influence of timber harvest on the structure and composition of riparian vegetation in the coastal redwood region”

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