Effects of leaf-litter accumulation on riparian plant diversity across Europe

Floods in rivers can deposit large quantities of organic debris in the ripa rian corridor and cause considerable change to its vegetation. We studied t he importance of leaf-litter accumulation on riparian vegetation in differe nt climates by constructing gradients ranging from complete litter removal to addition of up to 6000 g/m(2) (35-40 cm deep) of leaf litter and recorde d the consequent changes in vegetation. Experiments were located along rive rs in northern and southern Sweden, Italy, and Romania. Plant biomass decre ased with increasing litter mass but did not vary with site-dependent varia bles such as climate and soil. Species density for various plant life trait s varied with litter mass, summer temperature, and summer precipitation. Li tter mass was the most important variable for all life traits except rhizom atous and stoloniferous species, which were most dependent upon summer prec ipitation. These findings are useful for the prediction of responses in rip arian vegetation following future climatic changes.