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 "Trophische Interaktionen in tropischen Waldfragmenten" wird vom Umweltbundesamt gefördert und von Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, Fachbereich Biologie durchgeführt. In diesem Forschungsvorhaben sollen die Effekte von Habitatfragmentierung auf Nahrungsnetze untersucht werden. Als Modellsystem dient die trophische Kaskade 'Pflanze - Pilz/Blattschneiderameise - Prädator/Parasit' im Atlantischen Regenwald Brasiliens, eines der weltweit am stärksten gefährdeten Waldökosysteme. Seit langem wird eine Zunahme der Dichte und Diversität von Blattschneiderameisen (BSA) in gestörten Habitaten beobachtet. Die Gründe hierfür sind jedoch weitgehend ungeklärt. Die diesem Projekt zugrunde liegenden Arbeitshypothesen basieren auf der Annahme, dass sowohl die Kontrolle durch Resourcenqualität als auch durch Prädation und Parasitismus in fragmentierten Wäldern weniger effizient sind als in geschlossenen Waldsystemen. Zur Beurteilung der bottom-up-Kontrolle wird daher untersucht, ob (1) pflanzliche Abwehr, (2) BSA Nahrungsbreite, (3) -Aktionsradius und (4) -Herbivorierate in Waldfragmenten zunehmen. Die Effizienz der top-down Kontrolle wird darüber bestimmt ob (1) Prädationsrate sowie (2) Ameisen- und Pilzparasitierung in kontinuierlichen Wäldern zunehmen und (3) der Koloniegründungserfolg abnimmt. Die Evaluierung der einzelnen Parameter und ihrer relativen Bedeutung soll das Verständnis der funktionellen Rolle trophischer Interaktionen am Beispiel dieser Schlüsselarten neotropischer Ökosysteme verbessern
Das Projekt "Food-web and ecosystem responses to global change: testing ecological theory in aquatic mesocosms" wird vom Umweltbundesamt gefördert und von Eawag - Das Wasserforschungsinstitut des ETH-Bereichs durchgeführt. How will the current rate and spatial extent of environmental change affect the functioning of future ecosystems? Food webs are structurally diverse and are remarkably persistent despite multifaceted and spatially variable environmental change. Ecological theory posits that the structural complexity of food webs will help ecosystems weather environmental change, but few experiments have tested this idea. To truly understand how ecosystems and their constituent food webs will respond, we must explore, experimentally, how environmental change affects the structure of food webs, for example the number of species and the interactions among them, and, consequently, the the functioning of ecosystems, for example, the rates of biomass production, decomposition, and sequestration. Our proposed research focuses on the environmental changes associated with rising levels of dissolved organic carbon (DOC) in freshwater ecosystems, but also considers climate warming, eutrophication, and changes in biodiversity. As microbial communities closely regulate the decomposition of DOC, we propose to examine the effect of changes in the environment and in the architecture of food webs on the composition of microbial communities, including viruses and prokaryotes. In doing so, we can link the ecological structure and evolutionary dynamics of food webs to the biogeochemistry of ecosystems. We propose a series of experiments to test how environmental change affects the complex interactions between food web assemblages and ecosystem functioning. The experiments test predictions from three bodies of ecological theory, namely the theory of biodiversity and ecosystem functioning, the theory of evolving metacommunities, and the landscape theory of food-web structure. These theories provide a strong foundation for understanding interactions between environmental change, food-web architecture, and ecosystem functioning, but they fail to fully address the feedbacks between structural changes of food-webs at upper trophic levels (e.g. plankton and fish) and the biogeochemistry of ecosystems that is regulated by microbial communities. Our experiments bridge this gap, and will improve our ability to predict how entire ecosystems respond to environmental change.
Das Projekt "Arctic health risks: Impacts on health in the Arctic and Europe owing to climate-induced changes in contaminant cycling (ARCRISK)" wird vom Umweltbundesamt gefördert und von Arctic Monitoring and Assessment Programme Secretariat durchgeführt. Objective: Long-range transport of contaminants to the Arctic, the resulting exposures observed in Arctic human populations, and impacts of such exposures on human health have been the subject of considerable work in recent years, providing a baseline against which to compare future developments. Global climate change has the potential to remobilize environmental contaminants and alter contaminant transport pathways, fate, and routes of exposure in human populations. The Arctic is particularly sensitive to climate change and already exhibits clear impacts. Research into contaminant exposure and its effects on human health in the Arctic, in comparison with other exposed populations in Europe, presents an opportunity to gain insight into changes that may later impact other areas. The influence of climate change on contaminant spreading and transfer and the resultant risk to human populations in the Arctic and other areas of Europe will be studied by: - Research on the ways in which climate change will affect the long-range transport and fate of selected groups of contaminants, and possible implications for the re-distribution of contaminants (geographically and between relevant environmental media). This will involve modelling, utilizing the information base that exists on the distribution of such contaminants in the Arctic and other areas of Europe - Research on the impacts that changing pathways and climatic conditions will have on contaminant uptake and transfer within food webs, leading to foods consumed by humans. This will involve experimental work, process studies and targeted analytical studies, the latter focussed on supporting the modelling work and process studies related to human exposure to contaminants - Research focussing on human health, aimed at determining how climate-mediated changes in the environmental fate of selected groups of contaminants will result in changes in exposure of human populations, in the Arctic and in selected areas of Europe.
Das Projekt "Strukturen und Mechanismen in Nahrungsnetzen und Nahrungsketten in Seen" wird vom Umweltbundesamt gefördert und von Universite Paris-Sud (XI), Ecologie des populations et communautes durchgeführt. One of the motivations for the study of trophic relations is the necessity to predict how ecological mommunities will respond to major perturbations like global warming or nutrient enrichment. Ecological communities can be modelled as webs in which each species is represented by a variable and each trophic link by a dynamic equation. Properties of model food webs depend on the form of the trophic interactions. The project aims to explore the alternative forms of the trophic interactions using three approaches. (a) Food web theory. The consequences of the alternative forms of the trophic interactions on food web structure and on responses to large perturbations will be explored. (b) Plankton time series. Models with alternative forms of the trophic interactions will be fitted to non-equilibrium plankton time series. This should help determine which form of the trophic interactions better applies to lakes. (c) Behavioural mechanisms. The echanistic background of trophic interactions will be explored.^L'etude des realtions trophiques est motivee par la necessite de predire comment des communautes ecologiques reagiront a de grandes perturbations comme le rechauffement du climat ou l'apport de nutriments. Les communautes ecologiques peuvent etre modelisees comme des reseaux trophiques ou chaque espece est representee par une variable et chaque interaction trophique par une equation dynamique. Les proprietes du modele dependent de la forme des interactions trophiques. Le but du projet est d'explorer les formes alternatives des interactions trophiques en utilisant trois approches. (a) Theorie des reseaux trophiques. On etudiera leurs effets sur la structure trophique et sur les reponses a de grandes perturbations. (b) Series temporelles. Des modeles alternatives seront ajustes a des series temporelles de plancton. Cela aidera a determiner quelle forme des interactions trophiques s'applique mieux aux lacs. (c) Mecanismes comportementaux. On etudiera les fondations'mecanistiques' des interactions trophiques. (FRA)