Disentangling the land-use effects on different dimensions of multitrophic ecosystem structure and functioning

• Applicant: Oksana Buzhdygan, Ph.D.
• Subject Area: Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 512415551

Land management alters biodiversity and reduces ecosystem functioning and services. Yet, most evidence is limited to single trophic levels, but to forecast the multitrophic whole-ecosystem-level responses to land use we require a mechanistic understanding of how the multiple dimensions of community structure and ecosystem functioning across all trophic levels constrain one another. In this project, we will consider the size, structure, and shape of food webs and the dynamics of energy and of carbon-to-nitrogen ratio (C:N) across trophic network as the central processes to multitrophic ecosystem functioning. We will assemble trophic models of energy and C:N budgets by analytically calculating stocks (i.e., energy stored), fluxes (i.e., energy exchanged between stocks and with environment), and rates (the energy-exchange efficiency) using large-scale data on multiple freshwater macroinvertebrate taxa, detritus, and ecosystem processes, all sampled for multiple tree holes in temperate forests along the wide gradients of forest management intensity and environmental factors within the Biodiversity Exploratories, Germany. Such explicit empirically driven ecosystem models have rarely been made so far in multiple replicates. Well-defined boundaries and the relatively small size of tree holes makes them explicitly promising models of natural ecosystems for studying mechanisms of land-use effects on multitrophic ecosystem functioning. With these trophic-network models we will assess the research questions critical for ecosystem management and decision making. Specifically, we will test the effects of land use on ecosystem functioning for each trophic level and for the entire trophic network. We will examine the mechanisms (i.e., direct and indirect effects) underlying the land-use effects on ecosystem functioning. Also we will test whether the land-use effects on ecosystem functioning differ with environmental factors; between trophic levels; ecosystem function types; quantity (energy) vs. quality (C:N); biotic vs. abiotic ecosystem parts; and between the different facets of ecosystem functioning (stocks vs. fluxes vs. rates). Finally, we will test the mechanisms underlying the relations between land use, multitrophic community composition and diversity, and multitrophic ecosystem functioning. In this study we will integrate methods from different disciplines, i.e. network modelling, ecosystem energetics, community ecology, stoichiometry, and metabolic scaling theory, the fusion of which will allow us to go beyond the traditional boundaries in the ecosystem functioning research and to address the multitrophic complexity and holistic understanding of real-world ecosystems undergoing the land-use intensification.

• DFG Programme: Infrastructure Priority Programmes
• Subproject of: SPP 1374: Biodiversity Exploratories