Cork oak (Quercus suber L.) forest decline in Tunisia: A linkage between physiological adaptation and stress

In the past, several decades, the decline of Quercus suber forests has been observed over wide areas of the Mediterranean basin. Mediterranean-climate sclerophyllous trees are known to typically possess anatomical and morphological structures in their leaves, or other vegetative organs, which provide high resistance to desiccation induced damage during substantial water stress. Long-term exposure of cork oaks to water-deficit and a shaded environment might also alter the morphology, anatomy and physiology of the plant. Even though cork oaks are able to acclimate in response to changes in their abiotic environment, such as drought regime and shading, many studies have suggested that the cork oak forest decline phenomenon in Tunisia seems to be strongly associated to changes in tree physiology.