Botanically, the Mayoko district is known only through anecdotal descriptions made in the colonial era. The present study was undertaken as part of the prerequisite for a mining feasibility study where a benchmark of the floristic composition, diversity and structure of the vegetation was needed to evaluate potential biodiversity offset areas and to guide species selection for post-mining re-vegetation. The study area comprised approximately 160,000 ha and 235 sample sites were surveyed using the Braun-Blanquet method of phytosociology. Diversity of each plant association was expressed in terms of various diversity parameters. Twelve associations were described and mapped. The associations ranged from highly disturbed and degraded to fairly intact forest associations. A wet to dry gradient and permanently inundated to temporary inundated gradient could also be distinguished. The approach followed here proved remarkably robust in illustrating the complexity in a topographically complex region of the Chaillu Massif. The data provided a high level of insight into the possible dynamics of the rainforest and indications as to possible successional pathways. This information provides a better level of understanding of forest structure and evolution potential than studies limited to trees, remote sensing carbon assessments, or time change series.

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A floristic and structural analysis of the Djoumouna forest in the suburban belt, southeast of Brazzaville, was carried out in a forest area of about 10 hectares. This paper focuses on deepening the knowledge of plant diversity by characterizing the structure of the forest stand. 25 vegetation surveys were carried out, taking into account dendrometric measurements of all DBH woody individuals ≥ 10 cm at 1.30 m height from the ground. After processing the structural data, the forest stand has a basal area of 28 m²/ha. This is with an average density of 653 individuals from 123 plant species, of which the Leguminosae family is the most important. It realizes 6.94 bits and 1.4 respectively as indices of diversity of Shannon-Weaver and evenness of Piélou. Two species dominate the structural framework, Pentaclethra eetveldeana (De Wild. and T.Durand) and Pentaclethra macrophylla (Benth). This achieves the highest basal area and Value Index of Importance values. The two species realize 11 m²/ha and 05 m²/ha respectively with corresponding values of 54 and 30.5. This feature justifies the structural denomination of the forest block. As a result of the rich and diversified forest population, a good structure is projected, thus testifying to its maturity. The feature militates in favour of the elaboration of a development plan as a precautionary measure.

An inventory of commercial timber species was undertaken in two peri-urban forests of Brazzaville, the continental site of Djoumouna and the Loufézou island site. This inventory was strengthened by the analysis of phytosociological and structural vegetation data. These two habitats have a basal area of 35.7 and 53 m 2 /ha, respectively. The floristic matrix, dominated by Fabaceae, projects a richness of 51 species emanating respectively from 462 and 414 individuals of Ddh ≥ 10 cm. Pentaclethra eetveldeana De Wild. & T. Durand and Pentaclethra macrophylla Benth., dominated the structural framework in the continental forest, both in the basal area and the significance of value index. On the island site, Antiaris toxicaria Lesch var. welwitschii (Engl.) Berg and Ceiba pentandra (L.) Gaertn., on the one hand, and Pterocarpus soyauxii Taub. and Pentaclethra eetveldeana De Wild., on the other hand, take turns for both parameters. The continental site is richer and more diversified compared to its island neighbor. All the same, these two particular habitats project a good structure in commercial timber in relation to the ecological maturity of these forest sites. This feature militates in favour of the elaboration of management plans as a precautionary measure.

The objectives were to quantify aboveground, belowground and dead wood carbon pools near Mayoko in the Chaillu massif of Republic of Congo and explore relationships between carbon storage and plant diversity of all growth forms. A total of 190 plots (25 m by 25 m) were sampled (5072 stems, 211 species) and data analysed using recommended central‐African forest allometric equations. Mean stem diameter at breast height was 33.6 cm, mean basal area 47.7 m2 ha−1 and mean density of individuals 407 ha−1. Mean aboveground carbon (AGC) ranged from 13.93–412.66 Mg C ha−1, belowground carbon from 2.86–96.97 Mg C ha−1 and dead wood from 0.00–7.59 Mg C ha−1. The maximum AGC value recorded in a plot was 916 Mg C ha−1. The analysis performed using phytosociological association as basis rather than broad vegetation type is unique. AGC values for undisturbed terra firme forest sites featured among the highest recorded for African tropical forests. Considering only tree diversity, a weak, yet significant, relationship existed between AGC and species richness, Shannon‐Wiener index of diversity and Fisher's alpha. However, if diversity of all plant growth forms is considered, no relationship between carbon and plant diversity existed.