The relationship between climate and vegetation in the Moroccan Western High Atlas Mountains.
Principal component analysis was applied to raw monthly data to analyse rainfall variability in the Western High Atlas Mountains. The internal climatic domain and the southern parts of the Atlas Range have very variable precipitation. The effect of this variability on plant communities is very marked, particularly in the development of endemism. Four categories of vegetation are distinguished: broadleaved sclerophyllous or lauraceous plant communities (including Olea europaea, Ceratonia siliqua, Argania spinosa and Quercus rotundifolia); Cupressus communities (including Juniperus oxycedrus, J. phoenicea, J. thurifera, Tetraclinis articulata, and Cupressus atlantica); communities dominated by locally endemic species (including Genista florida, Adenocarpus anagyrifolias and Retama dasycarpa); and communities without trees at higher altitude (including Alyssum spinosum, Bupleurum spinosum, Cytisus purgans, Erinacea anthyllis and Ononis atlantica).