Spatial distribution of earthworm species assemblages in a chalky slope of the Seine Valley (Normandy, France) |
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Authors: | Pierre Margerie, Thibaud Decaë ns, Fabrice Bureau,Didier Alard |
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Affiliation: | 1. Soil Science Department, Faculty of Agriculture, University of Tabriz, Iran;2. Sydney Institute of Agriculture & School of Life and Environmental Sciences, The University of Sydney, Eveleigh, NSW 2015, Australia;3. CSIRO Agriculture and Food, Bruce E. Butler Laboratory, PO Box 1700, Canberra, ACT 2601, Australia;1. Åbo Akademi University, Geology and Mineralogy, Domkyrkotorget 1, 20500 Åbo, Finland;2. Geological Survey of Finland, PO Box 97, 67101 Kokkola, Finland |
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Abstract: | The aim of this study was to characterize the spatial distribution of earthworm species assemblages on a chalky slope of the Seine Valley (Upper Normandy, France), with contrasting vegetation cover representing the different stages of a typical post-pastoral secondary succession. Samples were hand sorted in a spatially explicit design consisting of a regular grid. A Principal Component Analysis was performed to identify species associations. Maps of the factorial coordinates of sample points together with geostatistical analysis were used to describe the spatial structure of the assemblages. The first axis of the PCA opposed points with high density to others with low. The resulting spatial structure was significant. The second axis opposed points where species assemblages were dominated either by an endogeic (Allolobophora chlorotica), an anecic (Aporrectodea longa) and an epigeic species (Lumbricus castaneus) to others dominated by two endogeics (Aporrectodea rosea and Octolasium cyaneum). A significant spatial structure was detected, with alternating patches characterised by one species assemblage or the other. The location of these structures did not seem to be clearly associated with a specific vegetation type. These results revealed a complex determinism of species co-occurrence at small spatial scale. |
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Keywords: | chalk grassland earthworms semivariograms spatial distribution species assemblages |
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