Water as a determinant of the distribution of trees at the boundary of the Mediterranean zone.

At the boundary of the Mediterranean zone in southern France different woodland communities occur on north-facing and south-facing slopes. The regional climate is transitional between that of the Mediterranean zone with a well-marked summer drought and that of the cooler and moister mountains. Summer-green deciduous woodland with many species characteristic of central Europe (e. g. Fraxinus excelsior and Tilia cordata) occurs on steep north-facing slopes and in ravines. Woodland dominated by the evergreen Quercus ilex with many Mediterranean species (e. g. Cistus salvifolius and Lavandula stoechas) occurs on south-facing slopes (...)