Ecological fire influences on Quercus suber forest ecosystems

Abstract

The effects of fire on the vegetation is one of the main factors in the present structure of Portugal’s landscape. Although caused exclusively through anthropogenic activities, the effects of fire have influenced the territory for so long that it can be considered as part of the natural evolutionary process. In the north, the highly fire-resistent deciduous oak forests were almost totally destroyed by man, they were consequently substituted by pine forests which in the last decades, due to increment of the understorey, have become a high-risk fire system. The effects of fire in the south of Portugal have produced a tree-steppe system, locally known as "montado”, a complex, multiple land-use system offering such activities as cereal production, game species habitats, and even recreation and tourism. Apart from substituting cork oak forest, the cork oak "montado" has also extended its distribution areas to formerly semi-evergreen forests. This may be attributed to the cork oak's strong fire resistence. The cork oak "montado" occupies approximately one quarter of Portugal's forest area where it presently constitutes one of the most productive multiple land use systems.