Mount St. Helens: Still erupting lessons 31 years later

Abstract

The massive volcanic eruption of Mount St. Helens 31 years ago provided the perfect backdrop for studying the earliest stages of forest development. Immediately after the eruption, some areas of the blast area were devoid of life. On other parts of the volcanic landscape, many species survived, although their numbers were greatly reduced. Reassembly began at many different starting points along the spectrum of disturbance. Within the national volcanic monument, natural regeneration generally has been allowed to proceed at its own pace.

Charlie Crisafulli and Fred Swanson, scientists with the Pacific Northwest Research Station, along with numerous collaborators, have found that the sunlit environment, dominated by shrubs, herbs, and grasses that characterize early-seral ecosystems, supports complex food webs involving numerous herbivores. These biologically rich areas provide habitat for plant and animal species that are either found only in these early-seral ecosystems or reach their highest densities there.

Although much of the focus of forest ecosystem management over the past 20 years in the Pacific Northwest has been on protecting old forests and hastening development of conditions associated with older forests, the research on Mount St. Helens points to the ecological value of allowing a portion of a managed landscape to develop characteristics of a complex early-seral ecosystem.

Based on science by Charlie Crisafulli, and Fred Swanson

Citation

Mazza, Rhonda. 2011. Mount St. Helens: Still erupting lessons 31 years later. Science Findings 135. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 6 p.