Résumé.-Le faciès forestier à Aucoumea klaineana du littoral congolais pré-sente une diversité floristique très hétérogène dans sa composition spécifique autant que spatio-temporelle. Quoique A. klaineana soit l'élément caractéristique et dominant de ce faciès, sa dynamique connaît une évolution régressive en rapport avec le stade de développement. On passe progressivement d'un sousfaciès presque monospécifique à okoumé à des faciès de complexité et hétérogénéité variables. La forêt étudiée met en relief les Fabaceae avec un indice de diversité relative de 18,31%. A. klaineana est l'espèce dominante, avec 46,4% des effectifs, suivi de Trichilia heudelotii, Carapa procera et Sacoglottis gabonensis (22% des 1 186 individus de d.b.h. ≥ 10 cm recensés dans le dispositif d'étude). Une analyse concomitante des indices écologiques calculés et la dynamique forestière observée sous-tendent que le faciès observé n'est qu'une brève phase. Ce stade est reconnu comme étant la phase pionnière de l'installation de la forêt ombrophile typique du littoral congolais.Mots clés : forêt littorale -Aucoumea klaineana -indices écologiques -dynamique floristique -Congo.Abstract.-The forest facies with Aucoumea klaineana of the Congolese littoral has a very heterogeneous floristic diversity in its specific composition, space and life period. Though A. klaineana is the characteristic element and dominating of this facies, its dynamics knows a regressive evolution in correlated to the development stage. To the present stage of his dynamics, one passes gradually from an almost monospecific facies with A. klaineana to a facies with variable heterogeneous complexity. A. klaineana is the dominant species with 46.4% of stand, followed by Trichilia heudelotii, Carapa procera and Sacoglottis gabonensis (22% of 1,186 individus having d.b.h. ≥ 10 cm in the experimental plot). Like the local forests, the studied facies highlights Fabaceae with an index of relative diversity of 18.31%. Lastly, a concomitant analysis of the calculated ecological indices and forest dynamics observed underlie that the facies monospecific is only one short transitional stage. This stage is recognized as being the first step of the installation of the typical ombrophilous forest of the Congolese littoral.

The floristic dynamics of the woody facies of the Aucoumea klaineana forest of the Congolese littoral has been done according to a gradient evolving of the pioneer front towards the interior of the ecosystem. This settlement integrates a dynamics going from the youthful stages towards the most stable of this formation. The objective of this study was focused on the dynamics of the woody formation, the monodominant installation of the Aucoumea klaineana facies with d 1.30 ≥ 10 cm and highlights the evolution and the correlation between the density, the basal area and the floristic diversity. The phytoecological parameters count 1186 trees of d 1.30 ≥ 10 cm (an average 395 arbres.ha -1 ) for 71 species. The trees number by subplot oscillated between 70 and 159 trees (6 to 13% of listed trees). The species number by subplot varies from 8 to 28 (11 to 39% of inventoried species). Basal area by plot oscillates of 22 and 35 m 2 .ha -1 (27 m 2 .ha -1 an average). It varies from 4 to 10 m 2 per subplot (7 m 2 by ¼ ha an average). The trees number by subplot and diameter classes vary from 3 to 636 trees (1 to 212 trees.ha -1 an average). The trees of 10 < d 1.30 ≤ 20 cm are dominating with 54% and this prevalence is regular in all the subplots. As for the indices of diversity, the Green index (GI) decrease from 0.9 to 0.1 as the ecosystem increases in age. This observation is also true for the skewness coefficient which regresses from pioneer front towards the interior of the forest. The values are respectively 2.10 -2 in the first plot, 7.10 -4 in the second and 4.10 -3 for the third. In this inventory where Aucoumea klaineana is dominating, its density by subplot varies from 42 to 384 trees.ha -1 (183 trees.ha -1 an average). Just like the density, basal area is decreasing to pioneer front towards the interior of the forest. The values oscillate from 87 to 32% of basal area of the subplot (19 m 2 .ha -1 an average). The report basal area by the density of Aucoumea klaineana is lower than 1 for an average of 0.1. The ecological parameters analysis which allowed seizing the floral dynamics of this forest is stressed by a numerical multivariate analysis (grouping and ordination). It highlights the weak resemblance degree between the twelve plots of the inventory and clearly marks the existence of variation characterizing the Congolese coastal forest, notably during the first stages of installation.