Entwicklung von Bodendiasporenbanken im Laufe der Grünlandsukzession: Effekte der Korngrößenverteilung im Boden und der räumlichen Heterogenität der Samen

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Soil seed banks play an important role in determining the composition and dynamics of plant communities. They are particularly significant for the regeneration of disturbed communities e.g. during early grassland succession. To study the development of seed banks during succession numerous studies of successional series were carried out. However, these studies often suffer from methodological problems; they lack detailed data and investigate a temporal trend by comparing different aged sites (“space for time substitution”). In contrast to these studies, we will use an experimental approach that will examine the seed bank after introduction of a seed mixture in microcosms filled with sterilised soil. Here we will focus on the effects of different soil types and seed characteristics on seed bank composition and vertical distribution of seeds in the soil. To examine seed bank development on a larger scale, we will also study the seed bank beneath meadows which were restored five years ago by the introduction of grassland species through plant litter transfer. For these meadows a substantial data base about the initial seed bank composition and vegetation development is available. To understand seed bank formation during succession it is also important to study the horizontal distribution of buried seeds in the soil. With more information about small-scale heterogeneity of seeds in the soil, we may understand spatial distribution of species in the above-ground vegetation during succession. With a focus on an introduced short-lived model species we will examine in detail the spatial pattern of the soil seed bank. The main goal of this study is to analyse the vertical and horizontal development of soil seed banks and their effects on community dynamics during early grassland succession in floodmeadow communities. In contrast to many other grassland species which built up a transient soil seed bank, flood-meadows are characterised by a relatively high percentage of species with a persistent seed bank. Beside new information about temporal changes in composition of seed banks in flood-meadows and their correlation with above-ground vegetation, the study is also important for assessing the potential reliance of the vegetation on soil seed banks during grassland succession.