PARENT SESSION
Symposium 2: Soil Biodiversity: Scaling from microbe to ecosystem
Organized by: A Fitter, C Kennan, and H Jones
Monday, August 8, 8:00 AM - 11:30 AM, Meeting Room 517 B, Level 5, Palais des congrès de Montréal
Vital soil: Modelling biodiversity and soil ecosystem functioning.
de Ruiter, Peter1, Neutel, Anje-Margriet1, Moore, John2, 1 Department of Environmental Sciences, Utrecht University, Utrecht, The Netherlands2 School of Biological Sciences, University of Northern Colorado, Greeley, Colorado, USA
ABSTRACT- Soil harbours the majority of the worlds biodiversity and governs processes that are regarded as globally important components in the cycling of materials, energy and nutrients. While in the aboveground ecosystem compartment biodiversity and ecosystem processes are importantly influenced by intraspecific and interspecific competition and habitat exploitation, in soils the relationship between biodiversity and soil processes is primarily controlled by dynamics and interactions in the soil community food web. As the trophic interactions in food webs represent transfer rates of energy and matter, food webs provide a way to connect the dynamics of populations to the dynamics in soil processes. Our presentation focuses on models that link soil food web structure to soil ecosystem processes. Central hypothesis in our approach is that there should be a balance between food web structure and process rates to ensure community and ecosystem stability. The food web models are strongly derived from observations on real soil ecosystems. The model results show that in real complex soil food webs, a balance between food web structure and ecosystem functioning is indicated by the distribution of biomass over trophic levels. Trophic pyramids, in population sizes as well as in feeding rates, translate into stabilising patterns in interaction strengths. Key-component in these patterns is the weights of trophic interaction loops, which provide an ecological as well as mathematical explanation of the stabilising effects of the patterns. The shape of the biomass pyramid, common in soil ecosystems, emerges from energy conversion efficiencies, which in turn depend to trophic levels dependent characteristics like body size. The results show therefore that the biodiversity-ecosystem functioning relationship in soils is governed by the interplay between ecosystem processes, community structure and the properties of populations and individuals.
Key words: food web structure, ecosystem functioning, stability, balance