GROWTH AND YIELD OF CASUARINA-EQUISETIFOLIA PLANTATIONS ON THE COASTAL SAND DUNES OF SENEGAL AS A FUNCTION OF MICROTOPOGRAPHY

Casuarina equisetifolia Forst. & Forst. plantations, established to stabilize sand dunes on the north coast of Senegal and thus protect inland agricultural areas, were sampled to determine if growth and yield were affected by microtopography. Microtopographical position, classified as interdune depressions, flanks, or summits, was found to have a highly significant effect on height, diameter, and volume growth. Maximum mean annual height increment was attained at Age 6 years ( 1.6 m year-1) in interdune depressions, at Age 7.5 (1.3 m year-1) on flanks, and at Age 8.5 (1.1 m year-1) on summits. Diameter distributions showed that the interdune depressions had a greater percentage of large diameter trees than flanks or summits. Maximum mean annual volume increment was 4.2 m3 ha-1 year-1 at Age 18 years for the interdune depressions, 2.0 m3 ha-1 year-1 at Age 29 for flanks, and 1.7 m3 ha-1 year-1 at Age 30 for summits. Thus, different rotation lengths can be recommended for specific microsites depending on microtopographical position and on whether fiber production or soil amelioration is the dominant management objective.