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Quantifying the tropical forests' carbon stocks is presently an important component in the implementation of the emerging carbon credit market mechanisms. This calls for appropriate allometric equations predicting biomass which currently are scarce. In this study, we aimed to estimate above-and below-ground biomass and carbon stocks of trees, and to identify the variation in diameter-height allometry of Ipendja mixed terra firme lowland tropical forest's trees. The study area is located at Ipendja forest management unit (UFA), close to Dongou district (Likouala Department), in Northern Republic of Congo. This study combined forest inventory data of 1340 trees recorded from eight studied plots distributed in two sites, respectively Mokelimwaekili (i.e., Old-growth forest) and Sombo (i.e., Selective logging forest). Trees measurements were done with rectangular plots, each 25 × 200 m (i.e., 0.5 ha, 5000 m 2 ). In eight studied plots (4 plots per site), only trees with DBH ≥ 10 cm were measured and identified. 1340 trees founded were belonged 145 species and 36 botanical families (n = 733 and n = 607, for Sombo and Mokelimwaekili respectively). The analyses were conducted using allometric method for aboveground biomass (AGB) and belowground biomass (BGB) estimations. The results showed that in Ipendja forest ecosystem the mean biomass is built up for AGB (346 Mg·ha ). By this study, Ipendja forest ecosystem has clearly variations on the diameter-height relationship and biomass across the plots and the sites.

Floristic inventory and diversity assessments are necessary to understand the present diversity status and conservation of forest biodiversity. Studying the variation height-diameter woody provides insight into the general characteristics of the trees diversity pattern. This study mainly focuses on aimed to assess the effectiveness of trees diversity and structure in two study sites. The study was conducted at Ipendja evergreen lowland moist forest in northern Republic of Congo. The sampling design was systematic consisted of parallel transect 1 or 2 km part, and divided into consecutive rectangular plots, each 5000m 2 (25 x 200 m, i.e. 0.5 ha). Within eight plots censuses, all trees with a DBH ≥ 10 cm were identified and measured. A total of 1340 trees has been recorded belonged 145 species and 36 families (n = 607 and n = 733, respectively in Mokelimwaekili and Sombo sites). The results show that the leading botanical families were Sapotaceae follows by Euphorbiaceae, Meliaceae, Caesalpiniaceae, Sterculiaceae, Annonaceae and Rubiaceae. The most representative species were C. mildbraedii, S. kamerunensis and P. oliveri, i.e. 62.06%, 30.34% and 28.27% respectively, demonstrated that they were the leading dominant species of this forest ecosystem. Shannon index were 4.29 bits for Mokelimwaekili and 4.22 bits for Sombo. While Pielou's evenness index was between 0.88 and 0.90, respectively for the Mokelimwaekili and Sombo sites. The similarity coefficient for Jaccard was 62% and 58% for Sorensen. There are highlight variations in tree diversity indices across sites and plots in Ipendja forest.

Coarse Woody Debris (CWD; defined here as fallen and standing dead trees and tree branches) is