Why does Quercus suber species decline in Mediterranean areas?

The cork oak (Quercus suber L.) is a prevalent tree species in the Mediterranean climate zones of western Europe and north Africa with a quite narrow geographical range of distribution, as compared with the other Mediterranean evergreen oak species such as Quercus calliprinos (holly oak) and Quercus ilex (holm oak). This species offers the ecological, economic and social importance, including their biodiversity and sustainable forest production in these areas. The increase of mean annual temperature and rainfall extremes during recent decades follows the trends predicted by present climate change models projecting a higher frequency of droughts and intense rain events in the Mediterranean climate areas. Nevertheless, various biotic and abiotic factors, including climate change (increased frequency and rigor of high temperature and drought) and related physiological decline of trees, increases in the outbreaks of disease, and an excessive development of forest resources has been recognized as main factors to induce a cork oak forest decline. In general, sustainable cork oak forest management and proper agroforestry activity that can generate income for local people through local community participation would be the ways to prevent cork oak forest decline in northern Tunisia.