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Scientists Study Long-term Response of Ground Beetle Communities to an Operational Herbicide Application

Photo of One of the common ground beetles Pterostichus melanarius that responded to lepidopteran outbreaks. Todd Ristau, USDA Forest ServiceOne of the common ground beetles Pterostichus melanarius that responded to lepidopteran outbreaks. Todd Ristau, USDA Forest ServiceSnapshot : Ground beetles comprise a large and diverse group of mostly predatory beetles that have long been recognized as a useful barometer of ecosystem health. As part of a long-term, large-scale study of the impacts of an operational herbicide-shelterwood treatment, Forest Service scientists found no treatment response by ground beetles as measured by abundance or diversity. However, their numbers and diversity were strongly correlated with natural outbreaks of forest lepidopterans, an order of insects that include moths and butterflies.

Principal Investigators(s) :
Ristau, ToddStoleson, Scott H.
Research Location : Pennsylvania
Research Station : Northern Research Station (NRS)
Year : 2013
Highlight ID : 495

Summary

Forest management that promotes biodiversity requires an understanding of the effects of silvicultural practices on a range of forest species and communities. As part of a larger Forest Service study, scientists evaluated ground beetle (Coleoptera; Carabidae) responses to operational herbicide and shelterwood seed cut treatments in northern hardwood stands on the Allegheny National Forest, Pennsylvania, from 1992 to 2000. Ground beetle community composition differed among years and increased in dissimilarity over the course of the study but did not differ between herbicide-treated and no herbicide plots. Shelterwood seed cutting had no effects on beetle species richness, abundance or community composition. Although we found no effect of herbicide or shelterwood cutting on ground beetle communities, their abundance and species richness increased greatly during coincidental outbreaks of native forest caterpillars during the course of this study. These results support previous findings that forestry practices that have relatively minor and short-term effects on forest vegetation are unlikely to have any substantial effects on ground beetles; however, natural resource variation resulting from forest lepidopteran outbreaks may have important cascading effects for ground beetle communities.

Forest Service Partners

External Partners

  • Allegheny National Forest, PA
  • State & Private Forestry, Northeastern Area
  • Carnegie Mellon University, Pittsburgh, PA
  • Matthew Trager, National Forests of Florida

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