Study of diameter structure of Pterocarpus soyauxii Taub species has been undertaken in Yoko Forest Reserve and Biaro Forest into two permanent dispositive of 400 ha each one. This work has objectives based on density distribution by diameter class and pedological parameters in the two selected sites. All stems of dbh ≥ 10 cm of the studied species have been inventoried, measured through 40 bands of 10 ha each one and soil samples were also collected in the two sites. 1051 trees were indexed with 663 inventoried in Biaro forest. This one present a good reconstitution of stems species for having many individuals into inferior diameters classes. The results of the pedological analyses showed that the two sites have an acid soil.

The present study is based on the structural analysis of the diameters of the three species: Musanga cecropioides R.BR, (Parasolier), Prioria balsamifera (Vermoesen) Breteler (Tola) and Prioria oxyphylla (Harms) Breteler (Tchitola) Illegal settlements by people living on the Yoko Forest Reserve. P. balsamifera and P. oxyphylla do not have a good regeneration, M. secropioides to a trend towards a good generation but does not have individuals from class 9. The results show that M. cecropioides is declared non-vulnerable (94.5%) in Yoko while P. balsamifera and P. oxyphylla are said to be vulnerable. This is explained by the low vulnerability index obtained for these two species, ie 30.9% and 26.7%.

A floristic inventory of grass and undergrowth was carried out in the southern block of the Yoko Forest Reserve in the Eastern Province. This study aimed to identify grasses and undergrowth, and evaluate the wealth of this areal florula. Transect methods and phytosociological survey was the approach used. A total of 116 plant species have been inventoried and are belonging to 92 genera and 44 families. Note that the dominant families and features are: Commelinaceae (7.76%) and Rubiaceae (6.90%). The relative densities of species and the highest are those of family Marantochloa congensis (174.0 feet/ha) and Marantaceae (360.0 feet/ha). The relative frequencies of the most observed species are those of Palisota barteri (3.21%) and Cola congolana (3.39%), while those of family are Arecaceae, Commelinaceae, Connaraceae, Euphorbiaceae, Lomariopsidaceae, Malvaceae, Marantaceae and Menispermaceae (6.25%). Simpson's diversity index (0.957), Shannon’s diversity index (3.619) and equitability (0.798) revealed that this florula is diversified and its species are well distributed. It is thus desirable that this study is extended to other forest reserves and forest groupings of Kisangani city and its surroundings in order to establish a better database necessary for the sustainable management of the classified forests and other sites of high value for the conservation.

This work aims to characterize the structure and diversity of the heterogeneous population of Yoko Forest Reserve. First, we considered (i) the floristic variability (specific richness and diversity), and (ii) the structural variability (in terms of density, ground surface and diametric structure) evaluated at the scale of a hectare. The second step consisted on the analysis of the spatial structure (i) generally and its comparison to the whole plot, and (ii) specific structure of the whole plot (only the spatial structure of the important species was analyzed). So, a systematic inventory of all trees of 10 cm dbh was conducted over five hectares. It should be also noted that the position of each foot has been taken according to the coordinate system (x, y). In total, 1,919 trees of 10 cm dbh were inventoried in five hectares. These individuals were distributed into 98 genera, 141 species and 31 families; with average density of 19.6 genera per hectare, 28.2 species per hectare, and 6.2 families per hectare. The resemblance or similarity degree among the plots (Hectares) showed clearly two coherent plant communities, with a low coefficient of similarity, and each consisting of more or less close plots. Although the density is dominated by Microdesmis yafungana species J. Léonard J. but Pericopsis elata Harms species and Fabaceae family dominated other quantitative parameters. As for the structural analysis, the individuals presented a shape with a significant decrease as we moved to the next class and the most significant densities were observed in classes of diameter 1, 2, 3 and 4. Therefore, a study on the structure and diversity of heterogeneous forest populations is very important because it gives information about the natural processes of trees (growth, regeneration, demographics) as well the anthropogenic action on the forest ecosystem.