Caractérisation structurale des formations naturelles enrichies en essences forestières locales : cas des vertisols de la Lama au Benin

Tree species, namely Afzelia africana Sm., Khaya grandifoliola Welw C.D.C. and Khaya senegalensis Desr. introduiced through enrichment planting in degraded zones of the Lama forest reserve were used to assess the impact of  introduction of young plants on the structure and the ecology of degraded habitats. A total of 24 plots each aparted at least 100 m from one to another were establieshed within enrichment plantings aging 17, 18, 19 and 20 years. Within these plots all trees fitting dbh superior to 10 cm were measured for diameter and height. Data were first used to assess the relationship between diameter and heigth of trees and build diameter size structures. Then a covariance analysis was performed on dendrometric characteristics to compare introduced species and the hoste stands. To this end, variable such as age and planting space were sucessively used. Besides, tree densities were coputed and compared using the Kruskall Wallis test. The mean density of target tree species (291 trees/ha) represented about 40 % of the inventoried individuals, and contributed up to 20 % of (5.9 m²/ha) to the over all basal area. Diameter size structures were found to be skewed to the left however the planting space, with a predominance of young stems, suggesting a low growth rate. This may partly be due to the competition effect of preexisting naturally establiehd stems. On the basis of our findings, we recommand sylvicultural activities such as thinning  to favour growth of plus trees among introduced plants.

Source de publication: International Journal of Biological and Chemical Sciences, 5(4): 1628-1638.

Contacts du ou des auteurs: Djodjouwin L. (djodjou@yahoo.fr), Glèlè Kakaï R (glele.romain@gmail.com). & Sinsin B.