02932naa a2200133 a 450000100080000000500110000800800410001910000210006024501320008126000090021352022390022270000160246177303210247713149452008-09-25       2008    bl uuuu     u00u1 u    #d1 aJIMÉNEZ, J. -J.  aSpecies co-occurrence and spatial pattern of earthworm community related to soil heterogeneity in a Neotropical gallery forest.  c2008  aCompetitive interactions and environmental factors act as filters and both determine community assembly at different scales. The description of species co-occurrence patterns through relevant null-model analysis has been seldom addressed for soil animals in the scientific literature. In this study, we assessed the spatial distributional features of an earthworm community and selected soil properties in a gallery forest of the Colombian ?Llanos?. Non-parametric statistical tools, namely Spatial Analysis Distance IndicEs (SADIE), Null-model (Co-occurrence) analysis, and Partial Mantel test combined with multivariate analyses (correspondence and Co-Inertia analyses) were used. Our hypotheses were: i) species of the gallery forest co-occur at shortscale by occupying different areas of varying physico-chemical properties, and ii) the species co-occurrence pattern is not structured by competition. At the local scale of our study (tens of meters) earthworm species co-occurred more frequently than expected by chance (EBC), and the C-score was significantly different to the observed value only for one algorithm (fixed-proportional). The SADIE analyses confirmed the presence of small patches and gaps of varying size. The number of clusters (i.e. patches or gaps) ranged from a minimum of 2 to a maximum of 7. SADIE analysis also confirmed the randomness pattern of the spatial distribution of species. A significant species association and dissociation was observed for different pair of species. The Co-Inertia analysis showed the correlation between earthworms and soil variables, and the Partial Mantel test revealed which soil variable was significantly linked to the spatial distribution of species, which seemed to be species-specific. Compared to other studies conducted in the area, and where a clear opposite spatial pattern was detected for two species, there was no significant spatial exclusion in the gallery forest. This might be an indication of no resource use limitation in this ecosystem, although this hypothesis needs to be tested further. In conclusion the earthworm community of the gallery forest was not structured by interspecific competition, although species showed a patchy distribution in space.1 aDECAENS, T.  tIn: INTERNATIONAL COLLOQUIUM ON SOIL ZOOLOGY, 15; INTERNATIONAL COLLOQUIUM ON APTERYGOTA, 12., 2008, Curitiba. Biodiversity, conservation and sustainabele management of soil animal: abstracts. Colombo: Embrapa Florestas. Editors: George Gardner Brown; Klaus Dieter Sautter; Renato Marques; Amarildo Pasini. 1 CD-ROM.