The effects of timber harvest on headwater stream amphibians have been studied extensively, but with conflicting or ambiguous results.
USGS scientists Nathan Chelgren and Michael Adams analyzed demographic rates – such as survival, movement, and growth – of aquatic life stages of coastal tailed frogs and coastal giant salamanders in a before-after timber harvest study in the Coast Range of western Oregon. By focusing on strictly aquatic life stages, authors were able to disentangle the effects of timber harvest from terrestrial life stages, like dispersal and breeding, which may be differentially impacted by logging treatments. Using captures of marked individuals and a model combining survival, movement, and capture probability, the authors found that increased timber harvest intensity reduced survival and movement for coastal giant salamanders but not coastal tailed frogs.
Chelgren, N.D., Adams, M.J., 2017, Inference of timber harvest effects on survival of stream amphibians is complicated by movement: Copeia, v. 105, no. 4, p. 714-727, https://doi.org/10.1643/CE-16-573.