Land-use effects on plant regeneration strategies in grasslands and their relation to community assembly

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The capacity to successfully reproduce is vitally for the persistence and stability of plant populations and processes of community assembly. Plant reproduction strategies differ in their reliance on seed production or clonal reproduction. In temperate grasslands, which are dominated by perennial herbaceous plant species, almost all plant species reproduce by sexually produced seeds often complemented by clonal (asexual) reproduction. However, it is not well studied how changes in land use of temperate grasslands affect plant regeneration strategies. Therefore, this project has the major goal to characterize land-use effects on plant regeneration strategies at the community level in the Joint multi-site grassland experiments (Reduced Land-use Intensity Experiment (REX), Land-use Experiment (LUX)) of the Biodiversity Exploratories. The following specific objectives will be addressed: First, we will sample the belowground bud bank to assess the total density and composition (different bud bank types), which consists of all buds that can potentially be used for vegetative regeneration. Second, we will estimate the reproductive output (i.e. seed production and seed rain) of the plant communities, which is potentially available for plant regeneration from seeds. Third, we will determine the density, species richness and composition of the viable soil seed bank in the top soil, which is an important component of demographic storage for regeneration from seeds. By combining these measurements, we will collect data on different plant regeneration strategies and demographic storage, which are rarely studied in parallel, and thereby quantify effects of changes in land use on different plant regeneration strategies. Using these data we will evaluate to what extent changes in the viable soil seed bank and the belowground bud bank in response to changes in land-use intensity resemble shifts in the diversity and composition of the aboveground vegetation and how these changes depend on differences in previous land-use intensity, changes in the individual components of land use (mowing, grazing, fertilization) and environmental differences between sites. Moreover, we will test how changes in land-use intensity affect correlations and/or trade-offs of different plant regeneration strategies with each other and with growth-related plant traits. The proposed project will extend trait-based approaches by incorporating plant regeneration traits, which can jointly or independently act as key determinants of population growth or abundance, and thereby contribute to a more comprehensive understanding of plant community assembly processes after changes in land use.