The role of biodiversity in controlling biogeochemical processes under experimental climate change in grassland and forest systems
Final Report Abstract
Biodiversity, in particular the richness of species in a given site, is believed to be the main insurance of ecosystems against changing conditions. The Biodiversity Exploratories offer a unique range of grassland sites differing in geology, land use and hence species richness. In 45 of these sites we experimentally prolonged summer drought and advanced spring by four and two weeks, respectively, and assessed the response of the vegetation (biomass and relative species coverage), above- and below-ground C- and N- pools as well as decomposition processes. Our initial hypothesis was that diverse grasslands should be able to buffer our experimental manipulations and hence show little difference between treatment and control after two seasons. Instead, we found strong effects of summer drought, and sometimes of spring warming, in particular on plant growth and the related C- and N-budgets, which were independent of plant species richness. Below-ground parameters were less affected, and while decomposition was strongly reduced under drought, litter decay caught up with control plots after the end of the simulated drought. While our field study ran for far too short to speculate about long-term climate change effects, its results are clear enough to reject a role of species richness in buffering short-term droughts in these management-dominated agroecosystems. It is, however, difficult to anticipate the results of such an experiment in a natural ecosystem, where the vegetation has assembled under multiple constraints and may hence comprise a richer set of response traits.
Publications
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(2011) The responses of grassland plants to experimentally simulated climate change depend on land use and region. Global Change Biology, 18,127-137
Bütof A, von Riedmatten LR, Dormann CF, Scherer-Lorenzen M, Welk E & Bruelheide H
