Conservation Evidence strives to be as useful to conservationists as possible. Please take our survey to help the team improve our resource.

Providing evidence to improve practice

Individual study: Temporal changes in the relative abundance of amphibians relative to riparian buffer width in western Washington, USA

Published source details

Hawkes V.C. & Gregory P.T. (2012) Temporal changes in the relative abundance of amphibians relative to riparian buffer width in western Washington, USA. Forest Ecology and Management, 274, 67-80


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Retain riparian buffer strips during timber harvest Amphibian Conservation

A replicated, controlled, before-and-after study in 1992–2004 of conifer plantations in Washington, USA (Hawkes & Gregory 2012) found that retaining riparian buffers during harvest had mixed effects on amphibians. Western red-backed salamanders Plethodon vehiculum and ensatinas Ensatina eschscholtzii appeared to benefit from riparian buffers. However, coastal tailed frogs Ascaphus truei declined significantly immediately after harvest at sites with wide buffers and 10 years after treatment the species was almost locally extinct at narrow and wide buffered sites. For other species there was suggestion of treatment effects, but analyses were confounded by patterns of natural population changes. In 1992, 18 sites (33–50 ha) were selected and assigned to three treatments: forest harvested with a riparian buffer of approximately 8 m or a wider buffer (plus wildlife reserve trees/logs) and control sites of previously logged second-growth forests. Streams were 2–6 m wide and had clear-cutting of 15 ha either side. Amphibians were monitored in October–November before harvest (1992–1993), 2-years after (1995–1996) and 10-years after harvest (2003–2004). Eighteen pairs of pitfall traps were placed in buffers and adjacent habitat.