From land management through habitat heterogeneity to biodiversity in grassland ecosystems: A combined theoretical, experimental, and observational study

This project is part of the DFG Priority Programme ‘Biodiversity Exploratories’ since 2014 (HEDGE) and since 2017 in the second funding phase (HEDGE 2).

Spatial heterogeneity in habitat conditions is widely considered as a major factor affecting biodiversity but has rarely been studied in the framework of the Biodiversity Exploratories.

This project attempts to fill this gap and adds to the relatively limited number of basic theoretical work in the exploratories. Specifically, we apply a tightly integrated theoretical-experimental-observational research plan directed at promoting our understanding of the mechanisms by which heterogeneity in land management and heterogeneity caused by land management affects the diversity of grassland communities. The theoretical (modeling) part of the study relies on recent advances in ecological theory indicating that the mechanisms by which environmental heterogeneity affects species diversity are much more complex than has been assumed in the past, and may generate positive, negative, or unimodal heterogeneity-diversity relationships (Allouche et al. 2012) The experimental part of phase 1 attempts to test the theoretical predictions using an extensive microcosm experiment focusing on plant species and environmental factors characterizing the grassland sites of the exploratories. In phase 2 the microcosm experiment will be continued and completed by a pot experiment to measure the growth characteristics of the used species. Additionally fieldwork is conducted in all three exploratories allowing the transfer to a real system.

By using a microcosm experimental approach we will avoid limitations and confounding effects caused by strong associations between natural habitat conditions and land use. The observational part of the study will then test the degree to which the theoretical and experimental results are relevant for the natural communities of the exploratories and how they are affected by different types of management (grazing, mowing and fertilization). Another objective of the observational part is to provide basic knowledge about the patterns and scales of heterogeneity in both habitat conditions and species composition (beta-diversity) and the manner by which these two aspects of heterogeneity (as well as their correlation) are affected by land management.

This will enable us to propose appropriate protocols for future monitoring of the Biodiversity Exploratories which take into account the scale-dependency of abiotic and biotic heterogeneity. We believe that this integrative approach will contribute significantly to our understanding of the causal links between land management, habitat heterogeneity, and biodiversity.

Main Investigators: Lara Braun, Ronja Ratzbor & Katja Tielbörger

Collaborators: Prof. Dr. Ronen Kadmon (Hebrew University of Jerusalem).