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

Floods in rivers can deposit large quantities of organic debris in the riparian corridor and cause considerable change to its vegetation. We studied the importance of leaf-litter accumulation on riparian vegetation in different 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 recorded the consequent changes in vegetation. Experiments were located along rivers in northern and southern Sweden, Italy, and Romania. Plant biomass decreased with increasing litter mass but did not vary with site-dependent variables such as climate and soil. Species density for various plant life traits varied with litter mass, summer temperature, and summer precipitation. Litter mass was the most important variable for all life traits except rhizomatous and stoloniferous species, which were most dependent upon summer precipitation. These findings are useful for the prediction of responses in riparian vegetation following future climatic changes