The significance of the seed bank as a potential for the reestablishment of arable-land vegetation in a marginal cultivated landscape

Abstract

As part of the German Research Foundation (DFG) project "Land Use Concepts for Marginal Regions", since 1997 we have made analyses of the seed bank of 22 cultivated allotments, as well as of 15 meadow/pasture and 16 fallow allotments on former arable land of the Lahn-Dill Highlands, a marginal cultivated landscape in Hesse, Germany. One aim of this study is to determine according to which dynamic laws the seed bank of arable-land weeds is depleted after cultivation is abandoned. Depending on the intensity of the arable use, the seed banks of rankers and cambisols that are presently still cultivated contain up to 1 004800 seeds if arable-land species capable of germination m-3. Soils that were last cultivated less than ten years ago have much lower seed densities, while the seed bank of arable-land species is largely exhausted after only ca 20 yr. This points to an exponential depletion of the seed bank of arable-land species and their abundance over time. On the basis of the present results, < 20 yr remain in the Lahn-Dill Highlands for the reestablishment of characteristic arable-land vegetation from the seed bank.