Collembolan communities in a peat bog versus surrounding forest analyzed by using self-organizing map

The structure of Collembolan assemblages in a peat bog surrounded by forest in the French Pyrenees was analyzed using self-organizing map (SOM). The dataset included 68 samples (48 in the peat bog, 20 in the forest) for 63 species. Peat bog communities were shown to be always well separated from forest communities, with very few overlap in terms of species composition. From the dataset, five community groups (two in the forest, three in the peat bog) were defined by SOM, indicating an unexpected heterogeneity. No special assemblage was clearly differentiated at the interface zone of forest-peat bog. These variations were strongly correlated with a series of environmental parameters, substrate water content, Sphagnum and grass cover. An apparently homogeneous peat bog may therefore host rather different communities, the ecotone being not necessarily the most species-rich zone. Manipulating wetland habitats for biodiversity conservation should therefore not be done before having carefully established the real pattern of biodiversity in the area.