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Biomass production in experimental grasslands of different species richness during three years of climate warming
1Research Group of Plant and Vegetation Ecology, Department of Biology, Universiteit Antwerpen (Campus Drie Eiken), Universiteitsplein 1, 2610 Wilrijk, Belgium
2Division Soil and Water Management, Faculty of Bioscience Engineering, Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, 3001 Leuven/Heverlee, Belgium
3Laboratory of Plant and Microbial Ecology, Institute of Plant Biology B22, University of Liège, Sart Tilman, 4000 Liège, Belgium
Abstract. Here we report on the single and combined impacts of climate warming and species richness on the biomass production in experimental grassland communities. Projections of a future warmer climate have stimulated studies on the response of terrestrial ecosystems to this global change. Experiments have likewise addressed the importance of species numbers for ecosystem functioning. There is, however, little knowledge on the interplay between warming and species richness. During three years, we grew experimental plant communities containing one, three or nine grassland species in 12 sunlit, climate-controlled chambers in Wilrijk, Belgium. Half of these chambers were exposed to ambient air temperatures (unheated), while the other half were warmed by 3°C (heated). Equal amounts of water were added to heated and unheated communities, so that warming would imply drier soils if evapotranspiration was higher. Biomass production was decreased due to warming, both aboveground (−29%) and belowground (−25%), as negative impacts of increased heat and drought stress in summer prevailed. Increased resource partitioning, likely mostly through spatial complementarity, led to higher shoot and root biomass in multi-species communities, regardless of the induced warming. Surprisingly, warming suppressed productivity the most in 9-species communities, which may be attributed to negative impacts of intense interspecific competition for resources under conditions of high abiotic stress. Our results suggest that warming and the associated soil drying could reduce primary production in many temperate grasslands, and that this will not necessarily be mitigated by efforts to maintain or increase species richness.
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Citation: De Boeck, H. J., Lemmens, C. M. H. M., Gielen, B., Malchair, S., Carnol, M., Merckx, R., Van den Berge, J., Ceulemans, R., and Nijs, I.: Biomass production in experimental grasslands of different species richness during three years of climate warming, Biogeosciences Discuss., 4, 4605-4629, 2007. Bibtex EndNote Reference Manager
