Effects of Riparian Timber Management on Amphibians in Maine

Riparian areas are one of the most complex, diverse, and dynamic environments in forested ecosystems. In areas managed for timber, riparian areas are often protected with unharvested forested buffers, but it is unclear whether these buffers are adequate to maintain the floral and faunal diversity of riparian areas. Amphibians are sensitive to forest management, have high diversity in riparian areas, and are among the most abundant vertebrates in temperate forests; therefore, they are excellent candidates to use in a study of the effects of riparian timber management. We conducted a field experiment with 15 headwater streams in western Maine, USA, randomly assigned to 5 silvicultural treatments. We examined amphibian abundance for 1 year prior to and 2 years following treatment. We also undertook a retrospective study on 12 headwater streams representing 3 treatments where harvests had occurred 4–10 years earlier. We used pitfall traps with drift fences and cover-controlled, active-searches to sample terrestrial and stream amphibians. Wood frogs (Rana sylvatica), eastern red-backed salamanders (Plethodon cinereus), and spotted salamanders (Ambystoma maculatum) were sensitive to timber harvesting along headwater streams. American toads (Bufo americanus) were either unaffected or increased in abundance postharvest. Buffers ranging in width from 11 to 35 m appeared to partially mitigate the effects of timber harvest because abundances were generally higher within the buffer than in the adjacent clearcut for wood frogs, American toads, and to a lesser extent red-backed salamanders. Partial harvests adjacent to headwater streams had the least effect on the riparian amphibian community and should be considered for harvests along headwater streams when managing at the stream scale. Our results show that managers can conduct riparian timber harvesting in a manner that allows a diverse suite of amphibian species to persist in the first years after harvest. It is plausible that these same practices may also mitigate the effects of timber harvesting on other forest species. Long-term effects of riparian timber harvesting on amphibians and other forest species population persistence and viability is a logical next step.