RESPOSTAS ECO-FISIOLÓGICAS DAS ÁRVORES AO C02 ELEVADO E AO STRESS AMBIENTAL NAS CONDIOES DE CLIMA MEDITERRÁNICO

Research on the effects of climatic global changes on trees is particularly relevant because forests are the main biotic reservoir for carbon at the global scale. Research in this area and its interaction with the environmental stresses on Mediterranean trees is stilllimited. In terms of growth response to elevated C02 Mediterranean trees may not be different from the Temperate zone trees, i.e., growth enhancement seems to be short-lived with a decline after the first hrowing seasons. In Mediterranean landscapes important soil fertility gradients, namely nitrogen can be found, which can interfere with response to elevated C02, as shown by our results on Fraxinus angustifolia and Quercus suber. On the other hand, in the Mediterranean aninteraction between elevated C02 and other "summer stresses", like water deficits and elevated temperature and light, is likely to occur. We discuss the possibility that elevated C02 may alleviate sorne of the negative effects of these stresses.