Saving Streams at Their Source: Managing for Amphibian Diversity in Headwater Forests

摘要

Although stream protection has become a central tenet of forest management in the Pacific Northwest, it is often only the larger, fish-bearing streams that are afforded the strongest safeguards. Yet, even without fish, headwater streams and riparian areas are hotspots of biodiversity, and they are the source of much of the water, gravel, and nutrients that subsidize downstream environments. Amphibians, in particular, thrive in the relatively cool and moist microclimate created by headwater streams. In fact, more than a quarter of amphibian species in the region have life histories reliant on headwaters. Scientists working on the Density Management and Riparian Buffer study recently completed the first phase of research into the effectiveness of riparian buffers as habitat reserves in headwater forests. They found that even when using the narrowest riparian buffer (20 feet), thinning upslope did not adversely affect headwater amphibian populations; slightly wider buffers (approximately 50 to 75 feet) defined by transitions from riparian to upslope vegetation or by streamside topography were sufficient to maintain headwater stream microclimates. In some cases, abundances of upslope, terrestrial salamanders were reduced within the region of active thinning, but these impacts were small and short-lived. This suggests that combined stream buffers and upslope thinning may effectively retain amphibian headwater habitat and communities, and could aid in establishing connectivity for terrestrially dispersing amphibians across ridgelines and adjacent headwater drainages.