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Ecological Responses at Mount St. Helens: Revisited 35 years after the 1980 Eruption

Updated: Jul 8, 2018

The spectacular 18 May, 1980, eruption of Mount St. Helens was the largest and most deadly volcanic eruption in historical times in the conterminous United States. The catastrophic eruption and its aftermath captured the attention of people worldwide who witnessed the event as it was broadcast by numerous media. Social, economic, and ecological systems over a wide swath of the Pacific Northwest were disrupted, and the hazards of living in a volcanically active region were quickly realized. At the same time, the eruption created unprecedented scientific opportunities for investigating initial and long-term responses of ecosystems to a range of volcanic disturbance processes. Given its close proximity to population centers, transportation networks, and academic institutions, scores of scientists arrived on the scene within months of the eruption, where they established hundreds of studies that focused on numerous biological groups (microbes to mammals) and ecological processes across a range of terrestrial and aquatic system types. A number of these studies are still active today, and, with nearly 40 years of accumulated data, they provide a wealth of information on the resilience of the Mount St. Helens landscape and waters. Many lessons have been distilled from this body of research, which has strongly influenced and even reshaped our understanding of biological community assembly and successional processes. This book tells the story of ecological responses around Mount St. Helens spanning almost four decades since the eruption and synthesizes much of what has been learned. Mount St. Helens offers an exemplary arena to investigate both the forces that cause dramatic change in ecosystems as well as the resilience of nature. A diversity of disturbance mechanisms operated at the volcano, and they induced high gradients of disturbance intensity. The variability in response trajectories was quite large, with rapid ecological responses in some places and slow transformation in others. Where they occurred, biological legacies, both living and dead, strongly influenced development of ecological communities. Chance events and contingencies played a large role in reestablishment processes, particularly where no biological legacies persisted and where populations experienced boom and bust cycles. Spatial heterogeneity in both disturbance and pace and pattern of ecological response is a hallmark of the post-eruption area and has led to high biodiversity, rich with complex early-seral communities that are of both local and regional significance. In addition, secondary disturbances, ongoing geological processes, and human activities were important in some locations. As a result of all of these influences, successional processes were highly diverse. Thus, responses of ecological systems subsequent to the eruption of Mount St. Helens have been an integral part of the emergence of the field of disturbance ecology.


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