The riparian ecosystem management study: response of small mammals to streamside buffers in western Washington

Abstract

One of the fundamental concepts behind the conservation strategy in the U.S. federal Northwest Forest Plan is the importance of habitat buff ers in providing functional stream and streamside ecosystems. To better understand the importance of riparian buff ers in providing habitat for associated organisms, we investigated responses of small mammals to various streamside management options in western Washington forests. First, we conducted a retrospective study at 49 first- to thirdorder streams on state, federal, and private lands on the Olympic Peninsula, Washington. Streams represented six forest and stream-buffer conditions ranging from unlogged control to young second growth with no buff ers. Because of high variability among sites within each condition, we found few diff erences in responses of mammals to site conditions; however there were species-specific associations with stream size, gradient, and site elevation. In hopes of reducing site variability, we subsequently undertook an experimental study on state lands in western Washington along 23 fi rst- and second-order headwater streams to evaluate small mammal populations both before and after riparian and upland forest treatment. Th e four treatments, grouped within blocks of adjacent catchments, included an unlogged control, and continuously buff ered streams, patch buffered streams, and unbuffered streams within upland clearcuts. We sampled small mammals in 2003 before logging and then for two years following logging. We found signifi cant changes in abundance of most common species following logging, including a decline in abundance of Keen’s Mouse (Peromyscus keeni) in all treatments relative to controls, and increases in abundance of the Creeping Vole (Microtus oregoni), Southern Red-backed Vole (Myodes gapperi), and Townsend’s Chipmunk (Tamias townsendii). We found capture rates of some of the more specialized species were too low to allow conclusions about treatment eff ects. For these rarer species, more focused autoecological studies will be needed to better evaluate their habitat relationships along headwater streams and their potential responses to streamside buffer treatments.

Parent Publication

• Density management in the 21st century: west side story

Citation

Raphael, Martin G.; Wilk, Randall J. 2013. The riparian ecosystem management study: response of small mammals to streamside buffers in western Washington. In: Anderson, P.D.; Ronnenberg, K.L., eds. Density management in the 21st century: west side story. Gen. Tech. Rep. PNW-GTR-880. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station: 163–168.