Tree diversity and its relation to habitat was examined using the tree dataset of 57 linear transects totaling 70.2 ha in the Mengame Gorilla Reserve (MGR), south Cameroon. In nine different habitats defined based on physiognomy and ecological criteria, all trees with average dbh ≥ 10 cm were enumerated. Caesalpiniaceae is the leading dominant family in MGR. Tree diversity totaled 304 species in 192 genera of 51 families. Included are 31 species cited in the IUCN red list of threatened species. Tree density varied from 80 to 366 stems⁄ha, basal area from 0.06 to 19.82 m2⁄ha, species richness from 11 to 269 species in each of the nine habitats. When compared with other tropical rainforests in Congo Basin, the results showed great similarities in tree density, family occurrence and Shannon diversity index values. Excluding the marshy grasslands where only 24 trees were recorded, 27 families and 30 species appeared common in the other eight habitats. We examined floristic similarities among the nine habitats using the NNESS similarity index, followed by a Chi-square test. The results revealed that habitat type affected tree composition, the main triggering factors being soil hygrometry, stage of stand development and disturbance. The study emphasizes the importance of the MGR as a refuge of threatened species and reinforces the idea of its inclusion in the African biodiversity hotspot.
Read full abstract