More and more science is finding the importance of protecting headwater streams for aquatic ecosystem health, biodiversity, and downstream water quality and drinking water protection. In this research note, USDA Forest Service ecologists examined the effect of variable-width buffers greater than 50 ft (15.24 m) on non-fish-bearing streams. This has implications for improving stream protection in our active forestry areas, where there is very little protection for small streams and wetlands.
Since the Northwest Forest Plan implemented riparian buffers along non-fish bearing streams in 1994, there have been questions about how wide those buffers need to be to protect aquatic and riparian resources from upland forest management activities. The Density Management and Riparian Buffer Study of western Oregon, also initiated in 1994, examines the effects of thinning and different buffer widths on aquatic and riparian vertebrates and habitats, tree growth, and vegetation along headwater streams.
Dede Olson, a research ecologist with the Pacific Northwest Research Station, leads the riparian component of the study. Olson and her colleagues found that aquatic and riparian species and habitat were retained with no-entry, 50-foot minimum variable-width buffers.
Their research has characterized both aquatic and terrestrial amphibian assemblages that rely on headwater streams and near-stream riparian forest habitats. For example, they documented that terrestrial salamanders have heightened movements within 50 feet of headwater streams. By extending such buffers along headwater streams over ridgelines, landscape connectivity could be provided, enabling gene flow among populations of terrestrial salamanders.
Scientists found that thinning upslope accelerated growth of trees within the buffer within 50 feet from the thinned edge. Larger trees ultimately lead to larger pieces of down wood, which form critical habitat both on land and in streams