Dominance of an invasive earthworm in native and non-native grassland ecosystems
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- Sánchez-de León, Y. & Johnson-Maynard, J. Biol Invasions (2009) 11: 1393. doi:10.1007/s10530-008-9347-6
More attention is currently being focused on earthworm invasions; however, in many ecosystems the relative abundance of native and invasive earthworm species is unknown. We characterized earthworm populations of two grassland types within the Palouse region: native prairie remnants and Conservation Reserve Program (CRP) set asides planted with exotic grasses. The earthworm community in both grassland types was completely dominated by the exotic-invasive Aporrectodea trapezoides. Only one individual of a native species, Driloleirus americanus (the giant Palouse earthworm), was found in a prairie remnant. No differences were found between prairie remnants and CRP sites for mean earthworm density (24–106 individuals m−2) or fresh weight (12–45 g m−2). Our results suggest that the combined effects of land-use change, habitat fragmentation and competitive interactions have resulted in the decimation of native earthworm populations and dominance of invasive earthworms in native and non-native grasslands of the Palouse region.