Demographic structure and natural regeneration of natural stands of pterocarpus erinaceus poir. (fabaceae) in the savannah regions of côte d’ivoire

Abstract

Pterocarpus erinaceus Poir. (Fabaceae) grows in Africa’s sparse woodlands and tree savannahs and is a valued species for its wood, fodder and causes of its ove-rexploitation in Côte d’Ivoire. This study analyses the demographic structure of natural stands of this species and potential for its natural regeneration according to logging intensity in the three types of savannah (Guinean, sub-Sudanian and Sudanian) in Côte d’Ivoire, with a view to their conservation. Dendrometric measurements (diameter at 1.30 m in height, total height and bole height) were made in 30 transects 200 m in width of individual P. erinaceus trees with a diameter of 5 cm or more in six sites. Regeneration was assessed in 186 30 m x 30 m plots 50 m apart within the transects. The results show that the highest average tree and regeneration densities were in Guinean (9.9 trees/ha and 33.8 stems/ ha) and sub-Sudanian savannah (12.6 trees/ha and 25.2 stems/ha) whereas the average diameter (33.9 cm), average total height (10.6 m) and average bole height (3.83 m) were significantly greater (p < 0.001) in Sudanian savannah. The study shows that the species regenerates by natural seeding, stump shoots and suckering. The distribution of diameter classes matches the reverse J-shaped Weibull curve in Guinean and sub-Sudanian savannah, and forms a bell curve in Sudanian savannah with average-sized trees. Except for the Kouassi-Ndawa protected area, the five other stands are affected by various human pressures (fel-ling, debarking and branch cutting).