Effects of spatial subsidies and meta-community dynamics on the relationship between island size and food chain length

• Applicant: Professor Dr. Michael Bonkowski
• Subject Area: Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
• Term: from 2010 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 165112753

The spatial dynamics and determinants of food web properties are central to the understanding of biodiversity and ecosystem function. Traditionally ecosystem size, a continuous spatial variable was used to explain variations in food chain length. Knowledge on the spatial dependencies of food chain length in terrestrial systems is scarce, but aquatic studies show that ecosystem size may be of strong, but not always pivotal influence. The openness of natural habitats leads to an almost implicit flux of materials and organisms across ecosystem boundaries and between habitat patches. These spatial subsidies and meta-community dynamics represent discontinuous spatial variables, which often have the most perpetual influences on local food webs. However, their influence on many food web properties, such as food chain length is unexplored. By combining classical numerical community responses and stable isotope techniques, our proposal integrates continuous space (island area) with spatial subsidy and meta-community dynamics, both being the most prominent discontinuous spatial processes, to explore their influence on food chain length, dynamics and structure of arthropod food webs. In using lake islands as study site, we base our research program on classical island biogeography, the most basic and approved theory on spatial processes in modern ecology. The synergy of modern techniques, ideal natural experimental conditions and sound theoretical approaches will significantly advance our understanding of the factors governing community and food web patterns in terrestrial systems.

• DFG Programme: Research Grants