Partenaires et organisations internationales
(Anglais)
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Justus-Liebig-Universität Giessen (D); Res. Institute for Agrobiology and Soil Fertility Wageningen (NL); University of Sheffield (UK); Bundesforschungsanstalt, Braunschweig (D); University of Newcastle upon Tyne (UK); Centro de Investigaciones Energeticas, CIEMAT (E); Università degli Studi die Pisa (I)
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Résumé des résultats (Abstract)
(Anglais)
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BIOSTRESS aims to understand and detect changes in, and drivers of, biodiversity in and between species. The project uses a global change component - ozone - as a tool to perturb plant growth in several types of semi-natural, herbaceous ecosystems across Europe in virtual and real world experi-ments. Through modelling work using plant traits and a system of plant functional types (CSR system, sensu Grime), the project should provide users with a general expert system tool for vegetation sci-ence. This will serve for the translation into action of the Convention on Biological Diversity, the EU Habitats Directive and other biodiversity strategies. The main FAL contribution to BIOSTRESS consists of a long-term open-air ozone exposure experi-ment with a permanent grassland field, which already started in 1998. The experiment is based on 6 exposure units, 3 of which are exposed to elevated ozone and 3 are used as control. The circular units are 7 m in diameter. In each of these circles, 6 permanent plots are installed for vegetation assess-ments. The field site 'Le Mouret' is located about 15 km from the city of Fribourg. In 2001, the prepara-tion for the field season, including re-installing the fumigation equipment for each experimental plot, installation and testing of the ozone generation and monitoring system, started at the beginning of March. Ozone fumigation and exposure in ambient air, together with plant (LAI) and soil monitoring started in April and was maintained until the end of October. One non-destructive botanical analysis (Daget-Poissonet) and three destructive harvests were carried out in the course of the season. Dry plant material from all harvests was sent to the Laboratory at the Department of Animal Sciences at Auburn University (AL) for quality analyses. Additional measurements of leaf diffusive conductance and - in collaboration with the partner from Pisa University- chlorophyll fluorescence were carried out for selected species to detect physiological responses to ozone stress, and to estimate leaf uptake rates of ozone. The biomass data for the control and ozone plots in term of Shannon-Weaver and Eveness diversity indices for the biomass data collected from 1999 to 2001 indicated that the system has now reached a more stable state, but that a significant change due to ozone exposure cannot (yet) be detected. How-ever, total dry matter yield is declining in the exposed plots, relative to the controls, and some species show a continues decline or increase in biomass over time. But at this stage, no systematic trends in specific responses corresponding to the CSR strategies could be detected.In collaboration with the partner from Sheffield University, the data from this experiment were used to test new versions of the long-term cellular-automaton model of plant functional types to simulate ozone effects in specimen virtual communities, and to develop the general expert system.
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