HR: 17:05h
AN: B44B-05    [Abstracts]
TI: Does Plant Diversity Affect Carbon and Water-Use Efficiency in Grasslands? Evidence from a Biodiversity and Ecosystem Functioning Experiment
AU: * Temperton, V M
EM: vtemp@bgc-jena.mpg.de
AF: Max Planck Institute for Biogeochemistry, Hans-Kn”ll-Strasse 10, Jena, 07743 Germany
AU: Buchmann, N
EM: nina.buchmann@ipw.agrl.ethz.ch
AF: Instiute of Plant Sciences ETH Zrich, Universit„tsstr. 2, Zrich, 8092 Switzerland
AU: Steinbeiá, S
EM: sstein@bgc-jena.mpg.de
AF: Max Planck Institute for Biogeochemistry, Hans-Kn”ll-Strasse 10, Jena, 07743 Germany
AU: Gleixner, G
EM: gerd.gleixner@bgc-jena.mpg.de
AF: Max Planck Institute for Biogeochemistry, Hans-Kn”ll-Strasse 10, Jena, 07743 Germany
AU: Schulze, D
EM: dschulze@bgc-jena.mpg.de
AF: Max Planck Institute for Biogeochemistry, Hans-Kn”ll-Strasse 10, Jena, 07743 Germany
AB: In view of rapid species loss on a global scale it is imperative that we shed more light on how this loss of diversity will affect the functioning and functions of ecosystems. Previous research on biodiversity and ecosystem functioning has shown that plant biodiversity often has a positive relationship to net primary productivity (NPP), and/or net ecosystem productivity (NEP), particularly in temperate grassland systems (Hector et al 2002). One of the big ensuing questions is whether plant diversity also affects nutrient cycling and biogeochemical cycles in ecosystems. A more detailed look at the dynamics of carbon and water-use changes caused by plant diversity has only recently occurred (Caldeira et al 2001) but there is still much work to be done in this area. A large-scale grassland experiment entitled "The Jena Experiment" was started in spring 2002 in Germany in order to investigate the effect of plant diversity on ecosystem functioning, focussing mainly on element cycling and trophic interactions. Out of a total species pool of 60 species mixtures of 1 to 16 species and one to four functional groups were randomly selected and seeded as newly established communities on 82 plots of 20 x 20 m. The four functional groups consist of grasses, small and tall herbs, and legume species. With the use of natural abundance stable isotope ratios (δ13C and δ 15N) in aboveground plant material, the relationship between plant diversity (both functional and species-driven) and productivity, water-use efficiency and nitrogen cycling was investigated. Results so far, show increased above-ground productivity with increasing species diversity as well as with increasing functional diversity of plants in a system. At community level, both carbon and nitrogen concentrations as well as δ13C in plants remained similar across the diversity gradient. In contrast we found a decrease in δ 15N values with increasing plant diversity. This suggests that bigger total carbon pools in more diverse systems can be attributed only to higher biomass, whereas some form of fractionation of δ 15N seems to be occurring during N uptake or in the soil in the most species-rich systems. Soil carbon also did not tend to respond to plant diversity levels. At the whole system scale there was no evidence for changes in water-use efficiency over the diversity gradient. Implications for the functioning of future grassland systems with reduced diversity will be discussed. References Caldeira, M. C., R. J. Ryel, et al. (2001) Mechanisms of positive biodiversity-production relationships: insights provided by delta C-13 analysis in experimental Mediterranean grassland plots. Ecology Letters 4(5): 439-443. Hector, A., E. Bazeley-White, et al. (2002). Overyielding in grassland communities: testing the sampling effect hypothesis with replicated biodiversity experiments. Ecology Letters 5(4): 502-511.
DE: 4805 Biogeochemical cycles (1615)
DE: 1851 Plant ecology
DE: 1040 Isotopic composition/chemistry
DE: 1615 Biogeochemical processes (4805)
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting