Das Projekt "The organisation of ecological networks in time and space" wird vom Umweltbundesamt gefördert und von Universität Freiburg, Institut für Biologie II durchgeführt. Current global changes put pressure on natural communities. Understanding how these communities are organized in time and space is crucial to predict how they will react to more variable meteorological conditions, increased temperature, or fragmentation of habitats. We will tackle the question of the organization, functioning, and evolution of communities by considering the trophic (who eats whom) and non-trophic (e.g., pollination, nest provisioning...) relations between species, thus considering communities as interaction networks. A 'large-scale' and a 'small-scale' system will be studied. The former consists of sown wildflower strips in agroecosystems, the latter of urn-like leaves (pitchers) of Sarracenia purpurea, a North American plant species introduced in Europe and inhabiting bogs. The ecological networks in the wildflower strips will be used to test several models of community organization and notably how the spatial arrangement of communities influences their composition and structure (metacommunity models). The small size of pitchers allows recording the evolution of the abundances of the species inhabiting the leaves, notably with molecular techniques for bacteria. The network in pitchers will be used in two lines of research: firstly, we will manipulate the presence/absence of key species (e.g., top predators) and of environmental conditions (e.g., temperature) and follow the dynamical response of the communities. Secondly, we will perform reciprocal transplant experiments to explore the question of 'local adaptation' at a network level.
Das Projekt "Biodiversity in agroecosystems: a multi-trophic approach to metacommunities" wird vom Umweltbundesamt gefördert und von Universität Freiburg, Institut für Biologie II durchgeführt. The goal of the proposal is to explore the structure and functioning of metacommunities in ecological compensation areas at a multi-trophic level. First, we will assess the effect of plant diversity and herbivore and/or predator exclusion on metacommunity functioning in sown wildflower strips. We will document the communities inhabiting these experimental plots, paying attention at interactions between species, and with consideration of larger consumers linking these habitats with the surrounding matrix. Second, we will explore the relationship between various measures of the environment (isolation, habitat size) and descriptors of the metacommunities (diversity, composition, abundances, and productivity of various taxonomic groups, food-web structure, temporal variability, local invasions and extinctions). Third, using a high-quality dataset on quantitative food webs and the present data, we will conduct meta-analyses to test various models of community organisation (neutral models of biodiversity, species-area relationship in trophic levels, regional similarity hypothesis, food-web structure). Fourth, we will develop various models describing food-web structure and metacommunities dynamics. We will synthesize our results to develop a theory of 'meta food-webs'. Fifth, we will apply the gained knowledge to improve current agri-environment schemes. The study of species interactions in spatially structured metacommunities is comprehensive and global. As such, this project has a strong potential to provide fundamental insight into conservation biology. This project is multidisciplinary, putting together practitioners, ecologists and mathematicians, and is expected to yield important results both of fundamental and conservation relevance. We will use various methodologies to reach our goals. For the first part, we will set up an experiment with replicated sown wildflower strips where plant species richness and the abundance of major predators (foxes and birds of prey) and/or of major herbivores (voles and slugs) will be controlled (balanced incomplete block design). The other parts will rely on classical meta-analyses, multivariate statistics, and mathematical modelling. For the latter part, we will develop stochastic models to explore the dynamics of communities.
Das Projekt "Untersuchungen zur Dynamik und raeumlichen Verteilungen terrestrischer Lebensgemeinschaften in Offenlandbereichen (Struktur, Dynamik und Leitung der Bodenmakro-, meso- und -mikrofauna, Mechanismen der Sukzession von terrestrischen Phytozoenosen, Ve" wird vom Umweltbundesamt gefördert und von Technische Universität Cottbus, Institut für Umweltmanagement, Lehrstuhl für Allgemeine Ökologie durchgeführt.
Das Projekt "A novel experimental approach with complex pollination network analysis to quantify the impact of habitat restoration on ecosystem integrity" wird vom Umweltbundesamt gefördert und von Aarhus University, National Environmental Research Institute durchgeführt. Plant-animal interactions, such as pollination, play a vital role in biodiversity maintenance. Interaction networks are essential for understanding ecological processes, consequences of species extinction and invasion, and effects of humans on ecosystem organisation and functioning. This research will use complex pollination networks in an experimental model system to investigate the impact of human-mediated disturbance on ecosystem functioning and native plant population viability. Species invasion and habitat degradation have devastated natural ecosystems worldwide, but especially so on islands. We will use restored, previously degraded, and non-invaded control sites of endemic plant communities in the Seychelles, a biodiversity hotspot, as a model system. Fully-quantitative pollination networks will be used to detect dynamic effects of habitat restoration on plant reproduction and pollinator diversity. Further, these will be compared to pre-restoration networks and null-model predictions based on the same communities to investigate the impact of disturbance on network structure, dynamics and secondary extinctions. The proposed research will contribute greatly to our understanding of human-induced changes in ecosystem functions and it will assist in alleviating anthropogenic impact on endangered species, and more importantly on their interactions, which ensure long-term viability and robustness of ecosystems.