Biotic homogenization and differentiation in weed vegetation over the last 70 years

Abstract

Biotic homogenization is the increasing similarity of the species composition of communities over time and represents a loss of biodiversity. We analysed changes in weed vegetation over a period of 70 years by comparing three datasets (from 1939, 2002 and 2012) sampled with the same methodology. We present the results of changes in species richness, homogenization and differentiation as expanding neophytes and generalist species. The species richness of weed communities decreased and the number of neophytes in cereal fields and root crops increased over time. The decreased ratio of specialists to generalists in vernal communities and cereal crops indicates homogenization, while the ratio of generalists to specialists increased in root crops.