Plant Interaction Networks

Interacting organisms and species are ideal models to explore the potentials of systems biology. In contrast to systems at the cellular level they can be easily assembled and simplified without losing their functional properties altogether. Biodiversity researchers have assembled such systems and obtained large amounts of data regarding the relationship between system structure and functioning, but so far did not look at them from the perspective of systems biology.

In an Interdisciplinary Pilot Project (IPP) of the SystemsX.ch initiative we focused on plant interaction networks. Using mathematical modelling and analysis of empirical data, we study multi-species systems of plants and of plants and mycorrhizal fu ngi.

We model the dynamics and interactions of species in plant–plant and plant–mycorrhizal interaction networks using Lotka-Volterra type equations. Our goal is to test whether sets of species with particular trait combinations form more stable interaction networks than randomly assembled sets and whether the structure of the networks influences system behavior such as species rank–abundance distribution, biomass production and its stability and invasion resistance. To make model outcomes comparable with empirical data, interaction strength is defined as covariance between species population sizes (in the case of empirical data mostly assessed via aboveground plant biomass). Because we have participated in a number of biodiversity experiments, we have access to well-replicated empirical data where the biomass of different species within multi-species systems has been separated. We have assembled the data in a combined data base containing also information about species traits.

Prof. Dr. Bernhard Schmid (Project Leader)
Prof. Dr. Andy Hector
Dr. Stefanie von Felten, WSL Birmensdorf
Prof. Jasmin Joshi, Potsdam University, Germany
Dr. Prasenjit Saha, Institute for Theoretical Physics
Dr. Lindsay Turnbull

Dr. Eric Allen, Jena University, Germany
Prof. John Connolly, University College Dublin, UK
Dr. Carsten Dormann, UFZ Leipzig, Germany
Prof. Markus Fischer, Institute of Plant Sciences, University of Bern
Dr. Marcel van der Heijden, agroscope ART Reckenholz-Zurich
Forest Isbell, Iowa State University, USA
Prof. Michel Loreau, McGill University, Montreal, Canada
Prof. Claire de Mazancourt, McGill University, Montreal, Canada
Dr. Raphael Proulx, Leipzig University, Germany
Prof. Michael Scherer-Lorenzen, Freiburg University, Germany
Dr. Alexandra Weigelt, Leipzig University, Germany
Prof. Christian Wirth, Leipzig University, Germany

• Hector A., Bell T., Hautier Y., Isbell F., Kéry M., Reich P. B., van Ruijven J., Schmid B. (2011). BUGS in the analysis of biodiversity experiments: species richness and composition are of similar importance for grassland productivity. PLoS ONE, 6(3):e17434. DOI: 10.1371/journal.pone.0017434
• Isbell F., Calcagno V., Hector A., Connolly J., Harpole WS., Reich PB., Scherer-Lorenzen M., Schmid B., Tilman D., van Ruijven J., Weigelt A., Wilsey BJ., Zavaleta ES., Loreau M. (2011). High plant diversity is needed to maintain ecosystem services. Nature, 477(7363):199-202. DOI: 10.1038/nature10282
• de Mazancourt C., Isbell F., Larocque A., Berendse F., De Luca E., Grace JB., Haegeman B., Polley HW., Roscher C., Schmid B., Tilman D., van Ruijven J., Weigelt A., Wilsey BJ., Loreau M. (2013). Predicting ecosystem stability from community composition and biodiversity. Ecology Letters, 16(5):617-625. DOI: 10.1111/ele.12088