Temperature stress and survival ability of Mediterranean sclerophyllous plants

The Mediterranean climate with hot and dry summer periods, and low winter t emperatures and episodic frosts in northern, altitudinal and continental di stricts; demands from evergreen. broadleaved woody plants an adequate anti flexible acclimation to thr climatic constraints. In this brief survey on s ome responses of Mediterranean sclerophylls to temperature stress, the foll owing is presented and discussed: criteria for cold and heat limits ol phot osynthetic function; winter depression and summer photoinactivation or phot osynthesis; peculiar patterns of tissue freezing of scleromorphous leaves a nd limits of frost resistance of various plant parts and ontogenetic stages ; heat impairment of chloroplasts and thermotolerance of sclerolphyllous sp ecies; survival capacity and recovery after damage. Risks of damage to plan ts in relation to stressful temperatures in Mediterranean regions are estim ated. Cold stress and drought stress indices, according to MITRAKOS; (1980) , have been applied to characterise different localities in Italy. Addition ally, a heat stress index for the Mediterranean region is proposed. Future research topics are suggested.