Mid and Submontane Altitude Forests Communities on the West Hillside of Mount Bambouto (Cameroon): Floristic Originality and Comparisons

Abstract

Background and Aims: Situated on the oceanic part of the Cameroon mountainous chain, the Western flank of Bambouto Mountains include the Atlantic biafran forests rich in endemic species but not well known. The objective of this work is to compare specific diversity, floristic composition and structure of two forests on this hillside. Methods: The inventories have been carried out in 18 plots of 20 m x 250 m plot established to cover all corners and centers of each forest in order to collect as many species as possible; also depending on the size of the forest block, vegetation physiognomy and altitude. Therefore, on a total area of nine hectares, all individuals with diameter at breast height ≥10 cm (dbh =1.30 m above ground) were counted. Phytodiversity has been assessed based on the usual diversity indices; these are the Shannon, Equitability and Simpson indices. The chi-square and Anova test were used to compare the data obtained. Keys Results: With 168 species recorded in four hectares, the submontane forest noticeably appears richer than that of low and mid altitude (161 species in 5 hectares). Among these species, 46 are common to the two forests. The mean stands density with diameter at breast height (dbh) ≥ 10 cm recorded per hectare is 855 ± 32,7 at low and mid altitude forest and 1182 ± 38,4 at submontane forest. The diversity index, specific richness and the endemism rate values are comparable to those registered in other Central African sites. Shannon's diversity means are 3 ± 0.25 in Fossimondi forest and 3.17 ± 0.22 in Bangang forest. While species evenness means are 0.80 ± 0.03 and 0.83 ± 0.03 respectively in Fossimondi and Bangang. The Simpson means index are 0.91 ± 0.02 and 0.92 ± 0.02 in Fossimondi and Bangang respectively. This result shows a great species diversity in the area as well as a good stability of these forests. Mean basal areas (respectively 60 m2/ha and 52 m2/ha in Fossimondi and in Bangang) are similar to those regularly observed in tropical rainforests. A total of 14 endemic species in Cameroon and 7 vulnerable were recorded in this study area. Conclusions: The most meaningful differences in these two forests reside in their floristic composition and in the importance of some species in term of individual’s number and basal area. Since the area is not yet profoundly explored, this work highlights its floristic importance for basis of a good management strategy.