Amphibian Responses to the 1980 Eruption of Mount St. Helens

Volcanism is a major agent of natural disturbance in the Pacific Northwest and other regions of the world. Volcanic eruptions alter surrounding landscapes and ecosystems and strongly influence the distribution and abundance of species. Although ecologists documented responses of vegetation (del Moral and Grishin 1999; see Chapters 4 to 8, this volume), mammals (MacMahon et al. 1989; Crisafulli et al., Chapter 14, this volume), and arthropods (Edwards and Sugg, Chapter 9, this volume; Parmenter et al., Chapter 10, this volume) to volcanic disturbance, no equivalent work exists for amphibians. The 1980 eruption of Mount St. Helens created an opportunity to examine the initial responses of an amphibian assemblage to a diverse array of volcanic disturbances and to describe patterns of species colonization in areas that were influenced by the eruption. In addition, amphibian responses to the 1980 eruption may provide insights into how amphibians respond to major environmental changes over large spatial scales. This information is important because of the apparent declines of amphibian species during the past two to three decades (Blaustein and Wake 1990, 1995; Pechmann et al. 1991; Pechmann and Wilbur 1994; Sarkar 1996; Green 1997; Corn 2000).