The present study was undertaken with the aim of to characterize, according to physiognomic point of view, the vegetation communities in the UMA forest and to evaluate the influence of physico-chemical and pedo-morphological parameters in the spatial organization of floristic diversity in the UMA forest. Five vegetation communities were identified in the UMA forest which sharing many common species. The restriction of certain species of plots belonging to the diameter class ≥ 50 cm show a variation even on the level of arborescent layers in this forest. The floristic variability is mainly explained by the soil humidity in the Limbali mono-dominant vegetation communities in the western part. In the easten part, it is explained by the pH, the conductivity and the soil depth in the heterogeneous vegetation communities. However, in the transition forest, it is explained by the retention of the soil phosphorus. The UMA forest is classified among the semideciduous dense heterogeneous forests. The identified vegetation communities are inserted in the alliances Gilbertiodendrion Devred 1958 and Oxystigmo-Scorodophleion Lebrun & Gilbert 1954 in the class of Strombosio-Parinarietea Lebrun & Gilbert 1954. The Guinean-Congolese element represents more than 82% of listed species, of which the endemic species of the center of Guinean-Congolese endemism accounts for at least 90% of species. The presence of Afro-American elements (2%) shows stochastic transgression. The sedentary species are abundant in the plant communities of the Western
part, while the pioneers and cicatricial species are abundant in the plant communities of the Eastern part