Carbon and Water Fluxes in Mediterranean-Type Ecosystems — Constraints and Adaptations

Abstract

The regions with a climate of the Mediterranean-type have a rainy winter and a dry and hot summer. They are located on the western side of continents between latitudes 30 to 43° north or south (Walter 1973). The dry summer climate of Mediterranean regions arises from the seasonal change in position of the semi-permanent high-pressure zones that are centred over the tropical deserts at about 20° latitude north and south of the equator. The persistent flow of stable air out of these high-pressure centres during summer brings several months of hot, dry weather (Archibold 1995). This type of climate occurs in the Mediterranean Basin, California, on the western foot of the High Andes (Chile), the southwestern tip of Africa and southwestern Australia. In all these regions evergreen sclerophyllous woody plants are the dominant type of vegetation (Walter 1973), but high diversity of species and life forms is the rule. All the areas with Mediterranean endemics belong to the so-called hot-spots for biodiversity. Although the Mediterranean biome represents less than 2% of the world’s surface, it houses 20% of the world’s total floristic richness (Medail and Quezel 1997).