Effects of climate warming and declining species richness in grassland model ecosystems: acclimation of CO2 fluxes
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AuthorVicca, Sara; Serrano-Ortiz, Penélope; Boeck, H. J. de; Lemmens, C. M. H. M.; Nijs, I.; Ceulemans, R.; Kowalski, Andrew S.; Janssens, I. A.
Copernicus Publications; European Geosciences Union (EGU)
Leaf dark respirationRoot respirationThermal acclimationPlant respirationGrowth temperatureSoil respirationCarbon cycleLong termPhotosynthesisProductivity
Vicca, S.; et al. Effects of climate warming and declining species richness in grassland model ecosystems: acclimation of CO2 fluxes. Biogeosciences, 4: 27-36 (2007). [http://hdl.handle.net/10481/32276]
SponsorshipThis research was funded by the Fund for Scientific Research – Flanders (Belgium) as project “effects of biodiversity loss and climate warming on carbon sequestration mechanisms in terrestrial ecosystems”, contract #G.0434.03N. H. J. De Boeck holds a grant from the Institute for the Promotion of Innovation by science and Technology in Flanders. P. Serrano-Ortiz benefits from a pre-doctoral grant from the Junta de Andalucía.
To study the effects of warming and declining species richness on the carbon balance of grassland communities, model ecosystems containing one, three or nine species were exposed to ambient and elevated (ambient +3°C) air temperature. In this paper, we analyze measured ecosystem CO2 fluxes to test whether ecosystem photosynthesis and respiration had acclimated to warming after 28 months of continuous heating, and whether the degree of acclimation depended on species richness. In order to test whether acclimation occurred, short term temperature response curves were established for all communities in both treatments. At similar temperatures, lower flux rates in the heated communities as compared to the unheated communities would indicate thermal acclimation. Because plant cover was significantly higher in the heated treatment, we normalized the data for plant cover. Subsequently, down-regulation of both photosynthesis and respiration was observed. Although CO2 fluxes were larger in communities with higher species richness, species richness did not affect the degree of acclimation to warming. These results imply that models need to take thermal acclimation into account to simulate photosynthesis and respiration in a warmer world.