Projects

DISCOVER (Biological Diversity and Ecosystem Functioning - Understand and Evaluate Key Experiments in Grasslands by Mechanistic Modelling)

Scientist(s): Hans Dähring (Scientific programmer), Christian Wirth (PI)
Funding: Agence Nationale de la Recherche, France
Duration: 2006-2007

Overall Project summary: The debate on the role of biodiversity for ecosystem functioning has recently been fuelled by manipulative experiments in grasslands allowing to test the effects of species and functional group diversity for ecosystem processes such as productivity. Quite separately, the study of the biological diversity dynamics in grasslands has allowed to define plant functional traits and plant functional types that affect productivity and decomposition and play a role for soil biota and for herbivory, as well as for biogeochemical cycles. No attempt was made, however, to link those two kinds of studies using mechanistic modelling. This project will use two major grassland experiments that have recently been started in Europe and that both study the role of biological diversity for ecosystem functioning: the long-term ecological experiment (ORE) 'Grasslands, Biodiversity and Biogeochemical Cycles' in France and the Jena Experiment in Germany. Those experiments are complementary: The first manipulates management factors for the same initial biodiversity; the second manipulates the plant species and functional diversity for the same extensive management. We planned to complete the measurements in the two experiments by measuring above and below-ground plant traits and by assessing microbial communities and soil biota for key groups (nitrifiers, denitrifiers, earthworms) that affect ecosystem functioning. These measurements will allow to parameterise a mechanistic model which allows to simulate the dynamics of local populations (or of functional types) of plants and soil microbes, their plasticity and their main effects for productivity, decomposition and herbivory. The model will be further developed, and evaluated against the experimental data. Sensitivity analysis will allow to determine the key factors for complementarity and selection effects in diversity experiments, as well as the major determinants of changes in productivity, decomposition and herbivory in long-term management experiments.

Partners: Jean-Francois Soussana (INRA, Clermont-Ferrand, France), Jens Schumacher (MPI BGC)