The role of forest harvesting and subsequent vegetative regrowth in determining patterns of amphibian habitat use

Conservation of forest-dependent amphibians is dependent on finding a balance between timber management and species’ habitat requirements. To examine the effect of short-term vegetative regrowth post-harvesting on amphibian habitat use, we studied the response of eight species (four forest specialists and four habitat generalists) to four forestry treatments (partial harvest, clearcut with coarse woody debris [CWD] removed, clearcut with CWD retained, and uncut control) over a 6-year period, using replicated experimental treatments in Maine, USA. Forest amphibians showed a strong negative response to clearcutting through the duration of the study, regardless of the presence of CWD, but only during the post-breeding season (i.e., summer). The spring breeding migrations of wood frogs and spotted salamanders to experimental pools were not affected by the forestry treatments. The use of partial cut treatments by forest amphibians differed between animals emerging from experimental pools (i.e., juvenile wood frogs and spotted salamanders), and animals originating from outside the experimental arrays (i.e., adults of all forest species, juvenile wood frogs and spotted salamanders). Animals emerging from our experimental pools showed no difference in the use of control and partial cut treatments, while all the other animals preferred control plots. In addition, we found a modest increase in the use of clearcuts over the 6years following harvesting by juvenile wood frogs from experimental pools (from an 8-fold difference between forest and clearcut treatments in the first year post-clearcutting to a 3-fold difference during years 3–5). However, this increase was not significantly associated with vegetation regrowth. Forest specialists declined in abundance in all treatments beginning 2–3years post-disturbance. Despite high yearly fluctuations in abundance, there was a shift in relative abundance towards habitat generalist species, most notably green frog juveniles. Most habitat generalist species were not affected by clearcutting or vegetative regrowth; however, we observed a lower use of clearcut treatments by green frogs starting 3years post-harvesting, perhaps due to an increase in habitat resistance to movements associated with vegetative regrowth. These general patterns of habitat use were overridden at the local scale by site-specific variation in the use of forestry treatments, most evident in emigrating juvenile wood frogs. From a management standpoint, implementing broad silvicultural prescriptions could be a viable strategy in extensively forested landscapes, but local variation in habitat use has to be acknowledged when managers focus on a limited area.