A multiscale study to analyse the response of vegetation to climatic conditions

The climatic changes predicted for the next century need to better understand the effects of water stress on the ecophysiological response of the plants in the Mediterranean areas. Gas exchanges, water potential and Leaf Area Index measurements were carried out during three years summer campaigns. Moreover remotely sensed analysis were performed to analyse vegetation indices. Measurements performed at lear level on the four species have shown in Fraxinus ornus L. a reduction of more than 50% in net CO2 assimilation in the hottest hours of the day. The two species belonging to Quercus genus showed a more costant assimilation rate, where the evergreen Mediterranean Stone Pine shows a reduction in not photosynthesis during midday hours. Leaf area index average data from field measurements have enabled to discriminate broadleaf deciduous communities (LAI=4.21 +/-0.53) from coniferous evergreen communities (LAI=3.2 +/-0.28). Remote sensing vegetation index results conducted on a multitemporal basis are in agreement with the response obtained from the field functional and structural data. The multiscale integrated experimental approach applied in this study seems a useful tool to define more clearly the ecological response of the main woody species of the Circeo National Forest and their sensitivity to global changes.