Abundance of Western Red-Backed Salamanders (Plethodon vehiculum) in the Washington Coast Range After Headwater Stream-Buffer Manipulation

Abstract

We evaluated the effect of forest riparian alternative tree buffer designs on Western Red-backed Salamanders (Plethodon vehiculum) along headwater stream banks in managed forests of the Washington Coast Range. We used pit trap live removals in early autumn to estimate relative abundances of surface-active salamanders before and after 3 levels of riparian buffer retention (strip, patch, and no-buffer clear-cut) with upland regeneration harvest. The study spanned a pre-treatment year, the harvest year after logging, and 2 post-treatment years (post1, post2). We observed reduced average tree canopies and increased average down-wood cover along streams that received the buffer treatments, especially in the cut portion of patch buffer and no-buffer clear-cut treatments. Compared to pre-treatment, mean salamander relative abundance was lower in no-buffer treatments in the harvest year and in the post2 year, but not the post1 year. Weather differences between years likely partially influenced these results. Plethodon vehiculum abundance in the no-buffer clear-cut treatment was lower than in both the control units in post2 and patch buffer treatments during the harvest year and post2 year. Retention of existing down-wood and recruitment of post-treatment down-wood may have ameliorated treatment effects on P. vehiculum abundances in patch buffers by maintaining microclimates and microhabitats. In the no-buffer clear-cut treatments, however, there was no similarly-moderating influence (no effect) from down-wood except when mediated by higher rainfall and cooler conditions. It appears that maintaining amounts of dead down-wood in no-buffer clear-cut treatments and the cut areas of patch buffers that averaged amounts 3 to 6 times greater than occurred before buffer creation along these headwater streams may help lessen initial treatment effects on these woodland salamanders.