Exploring Patterns of Exotic Earthworm Distribution in a Temperate Hardwood Forest in South-Central New York, USA |
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Authors: | Esteban R Suárez Geraldine L Tierney Timothy J Fahey Robert Fahey |
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Institution: | (1) Department of Natural Resources, Cornell University, Ithaca, New York 14853, USA;(2) Present address: Wildlife Conservation Society-Ecuador, San Francisco 441 y Mariano Echeverría, Apartado Postal 17-21-168, Quito, Ecuador |
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Abstract: | Exotic earthworms invading forests in Canada and northeastern United States that were naturally devoid of large detritivores
cause major changes in ecosystem function. To assess their long-term impacts, studies are needed to elucidate the factors
that control the patterns of earthworm invasion at the landscape level. We analyzed the distribution patterns of exotic earthworms
in a northern hardwood forest in south-central New York (USA), as explained by landscape variables thought to be important
in determining earthworm distribution. Forest type, slope angle, elevation, and the distance to agricultural clearings and
wet refugia were significant predictors of earthworm presence, whereas local wetness index and the distance to streams and
roads were not. Forest type and distance to agricultural clearings were the two most significant predictors. Our data suggest
that areas close to agricultural clearings, dominated by mixed hardwoods, and located towards valley bottoms or on gentle
slopes are very likely to support communities of exotic earthworms. Steeper slopes, areas dominated by American beech or eastern
hemlock, and locations in the core of extensive forest landscapes have lower probabilities of invasion by exotic earthworms.
When applied to a nearby area, our statistical model correctly predicted earthworm presence for 67% of 377 sampling points.
Most of the mistakes were incorrect predictions of earthworm absence, suggesting that our statistical model slightly underestimated
earthworm presence, possibly because of the pervasive influence of active agricultural fields adjacent to the test site. |
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Keywords: | Earthworm invasion Exotic earthworm distribution Habitat quality Northern hardwood forests |
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