C-13 IN MODERN PLANTS - AN INDICATOR OF R AINFALL FOR SAHEL

Relationships between the delta(13)C values in modern wood of Acacia a lbida and the climatic parameters were investigated under semi-arid an d arid sites in Senegal, between the southern tropical forest and the desert edge in the north (12 degrees 30-16 degrees 30 n). The C-13 val ues in the cellulose nitrate of Acacia albida show a strong south-nort h isotopic enrichment and reflect the gradient of aridity which charac terizes the Sahelan fringe. Significant correlations were established between the delta(13)C and the basic climatic parameters, precipitatio n and air humidity. Elsewhere, an exceptional delta(13)C enrichment fo und in the innermost rings of Azadiracta indica seems to be a faithful record of the drought of the seventies. (C) Academie des sciences/Els evier, Paris.