Community dynamics of soil Collembola in floodplains of the Upper Rhine Valley

In floodplain habitats inundation is a seasonally reoccurring phenomena. It represents a natural disturbance for the biocoenoses, causing their successional development to be reset. Collembola generally have developmental cycles that coincide with the yearly inundation incidences. They show perpetual regeneration, which is dependent on flooding intensity. Collembolan communities have been studied in floodplains of the Upper Rhine Valley since the mid-1990s. The development of collembolan communities was followed spatially in different floodplain levels in close vicinity to one another (with different inundation durations within the same year) as well as temporally within the same floodplain levels in different sites. Community development and structure depended mostly on inundation duration and differed from year to year in the same site. Through the differences in the population densities of the various species between sites as well as in different years, species groups, differing in their inundation tolerance, were distinguished. The species occurred either sympatrically or belonged to a common regional species pool (metacommunity). Which species dominated at individual sites depended on the inundation intensity of the individual site and year. The mixture of different inundation tolerances as well as regeneration strategies in the metacommunity, coupled with probable species exchange between patches, determines the composition and structure of local collembolan communities in floodplain forests. These communities are very heterogeneous at small spatial scales. They can thus differentially respond to different flooding intensities and maintain stabile metacommunities despite frequent, but irregular natural disturbances.