Spatial variability of an invasive earthworm (<Emphasis Type="Italic">Amynthas agrestis</Emphasis>) population and potential impacts on soil characteristics and millipedes in the Great Smoky Mountains National Park,USA |
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Authors: | Bruce A Snyder Jr" target="_blank">Mac A CallahamJr Paul F Hendrix |
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Institution: | (1) Odum School of Ecology, University of Georgia, Athens, GA 30602, USA;(2) Division of Biology, Kansas State University, Manhattan, KS 66506, USA;(3) Center for Forest Disturbance Science, Southern Research Station, USDA Forest Service, Athens, GA 30602, USA;(4) Department of Crop & Soil Science, University of Georgia, Athens, GA 30602, USA |
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Abstract: | European and Asian earthworm invasions are widespread in North America. European earthworms especially are well-known to cause
dramatic changes in ecosystems in northern, formerly glaciated portions of the continent, but less is known about the impacts
of earthworm invasions in unglaciated areas inhabited by indigenous earthworms. We monitored fluctuations in the spatial extent
of an Amynthas agrestis (Megascolecidae) population in the Great Smoky Mountains National Park in eastern Tennessee, USA. Two years of monthly growing-season
observations revealed that the distribution of the earthworm population was dynamic, but overall distribution was closely
linked to temperature and moisture with dramatic reductions of earthworm numbers associated with very dry conditions. In plots
where A. agrestis were more often detected, we measured increased A-horizon soil aggregation and decreased thickness of the Oe/Oa-horizon.
However, A. agrestis was not related to A-horizon microbial biomass, A-horizon C:N, Oi-horizon (litter) thickness, or mass of forest floor (O-horizon).
Reductions in millipede species richness and density were associated with frequency of A. agrestis presence, possibly due to direct competition for food resources (Oe/Oa material). This evidence for potentially negative
interactions between millipedes and A. agrestis suggests that expansion of the non-native earthworm into new habitats in the Park may alter soil physical properties and
could pose a threat to native millipede diversity. |
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