Rainy tropical forests are characterized by a very hetergenous complex structure in green space. The study of factors that are responsible of that heterogeneity is important in case of setting up a lasting fitting out in areas. Then, we studied the influence of ecologic parameters (light and chablis) about structural heterogenty (density, earth surface and diametric structure of mixed forests ofYoko). Finally, for trees of dbh ::::10cm, we used placing up method that consist subdividing hectare into four equal compounds of 50 m X 50 m each of them. We defined one hectare in disrupted area and another in a disrupted area, we received 408 individuals shared into 74 species and 60 kinds belonging to 27 families but in a non disrupted area, we received 363 individuals shared into 74 species and 53 kinds belonging to 22 families. About specific diversity point of view and diversity, the disrupted area is more diversified than the non disrupted area. Concerning the diameter, our analysis proved the presence of individuals of big diameter in the two first classes in the two areas (sites). In the end, statistic tests applied on the density, the earth surface and diametric structure allowed us to make a conclusion that ecologic parameters that we studied (light and chablis) have not influenced the floristic composition of the forests.