Used by humans since ancient times, evergreen oak forests still cover extensive mountain areas of the Mediterranean Basin. These broadleaved evergreen forests occupy a transitional zone between the cool-temperate deciduous forest biome and the drier Mediterranean pine forests and shrublands. Slow growing and casting a deep shade, the sclerophyllous holm oak ("Quercus ilex") absolutely dominates the closed canopy of many Mediterranean evergreen oak forests. This is a synthesis of 20 years of research on the structure, function, and dynamics of holm oak forests in two intensively studied experimental areas in Spain. By combining observational measurements at the leaf, tree, plot, and catchment scales with field experiments and modelling, the authors explore how these forests cope with strong water limitation and repeated disturbances.

Broadleaved evergreen forests where holm oak (Quercus ilex 1.) is almost the only canopy tree are a distinctive ecosystem of the Mediterranean Basin. Biogeographically, these forests lie between cool-temperate deciduous forests to the north and drier shrublands to the south. In a more general view, they are ecologically intermediate between these deciduous forests and humid warm-temperate evergreen forests, such as the laurisilva of the Macarone- sian islands or the broadleaved evergreen forests of eastern Asia. Holm oak forests are characterized by small-stature trees (usually 5 to 12 m tall), which are slow growing, cast a deep shade, and have small, evergreen, sclerophyl- lous leaves. Summer drought is the major environmental constraint. Mediterranean broadleaved evergreen forests have been underrepre- sented in the open literature. For example, The Woodlands Data Set of the International Biological Program (IBP) contained data from just one holm oak forest plot, Le Rouquet in southern France (Reichle 1981). Also, some models of European forests consider just two major forest types, broad- leaved deciduous and evergreen conifers, forgeting the extensive forests and woodlands of holm oak and cork oak (Quercus suber 1.), which are the ma- jor evergreen oak tree species in the Mediterranean Basin. The extensive lit- erature on Mediterranean-type ecosystems has also largely neglected these forests, being centred mostly on Mediterranean-type shrublands.