Floristic diversity and structural parameters on the forest tree population in the Luki biosphere reserve, Democratic Republic of Congo

Tropical rainforests play an important role in the global Eco-climatic balance and its sustainable management is a major concern that has attracted the attention of researchers. The Luki biosphere reserve, while under a status of protected area, experiences anthropic pressures without spare. In order to control the activities of local populations and particularly to implement the principles of natural resources management enacted by the Man and Biosphere program of the United Education, Scientific, and Cultural Organization, a zoning plan has been implemented in the Luki biosphere reserve since 1979. The aim of this study was to evaluate the floristic composition, the diversity and structural parameters on floristic groupings of forest tree species in the Luki Biosphere Reserve (LBR) to evaluate whether the implemented zoning has an effect on plant diversity and population structure of forest trees species in the Luki Biosphere Reserve. Floristic data were collected on a set of 15 plots of 1 hectare (ha) each following the management zoning, in which tree species with diameter at breast height (dbh) ≥ 10 cm were measured and identified. Floristic diversity analysis was carried out and the relationship between within plots species richness and physical and chemical properties of soil was established. In total, 6497 individual trees were inventoried belonging to a total of 218 species grouped in 41 families making an average tree density of 433 ± 13 individual per hectare. Two floristic groups emerged from the ordination of species and cluster analysis. Prioria balsamifera and Dialium pachyphyllum were among the most represented and characteristic tree species in the floristics groups. The families Sterculiaceae, Fabaceae, Ebenaceae, Olacaceae, Rubiaceae, Annonaceae, Myristicaceae, Meliaceae and Sapotaceae displayed high values of specific important index. Tree populations from the three zoning displayed an "inverted J" shape in an axil distribution of classes of diameters while the horizontal distribution of tree height displayed a bell structure. A significant difference exists in species richness among zones and floristic groupings. The floristics groupings were distributed following the soil texture. This work provides the basic elements for a sustainable management plan adapted with the current zoning plan in the Luki Biosphere Reserve.