Variation in vernal species composition in alluvial forests of the Rhine valley,eastern France

Patterns of vernal synusiae in alluvial forests of the upper Rhine valley were analysed phytosociologically. Five synusial types were described. Environmental factors included in the analysis were spring water level, texture, trophic status and soil reaction. A separate environmental study was undertaken in pure stands of six competitive geophytes in the most fertile habitats. In a laboratory experiment effects of water stress and interspecific competition were studied for three competitive geophytes. The vernal species can be grouped into eight groups with respect to species position along the environmental gradients occurring in the floodplain. These groups can be used for bioindication.