Cocoa-based agroforestry systems and its potential for tree resource conservation around the Dja Biosphere Reserve Southeastern Cameroon

Abstract

The objective of this study was to evaluate tree species diversity, structure and conservation status of these tree species in cocoa-based agroforestry systems around the Dja Biosphere Reserve, South East of Cameroon. This reserve is divided into four clusters due to its large nature and location between two regions. A random sampling approach was adopted, whereby, 100 plots of 100 m × 20 m and 10 m × 20 m were laid down in cocoa agroforestry systems on a total surface area of 18.02 ha. In each plot, all tree species were identified, counted and their diameter at breast height and height were measured. These data were used to assess parameters such as, tree density, basal area, importance value index and Shannon diversity index of cocoa-based agroforestry systems in the four clusters around the Dja Biosphere Reserve. A tree abundance of 1582 was recorded in the study area, belonging to 67 species, 63 genera and 29 families. Species richness was lowest in the east cluster (30) and highest in the west cluster (50). Shannon diversity index varied from (2.95) for the east cluster to (3.39) for the west cluster. Mean basal area varied from 11.72 m2 for the North cluster to 12.21 m2 for the South cluster. Mean density varied from 108 stems/ha for the North cluster to 113 stems/ha for the South cluster. Terminalia superba had the highest important value index for the East cluster (47.6%) and South cluster (22.9%) and Ricinodendron heudelotii for the West cluster (31.78%) and the North cluster (41.7%). The ANOVA test indicates a significant difference for tree density between clusters, while Turkey test shows that this significant difference was between the East and North clusters. However, no significant difference was observed for basal area between the four clusters. Thirty percent of tree species found in cocoa-based agroforestry systems were listed on the IUCN red list of plants species, indicating the contribution of these systems in conserving threatened tree species. The study concluded that cocoa agroforestry systems around protected areas can serve as reservoirs for biodiversity conservation if managed effectively. \n \n \xa0 \n \n Key words: Tree, species, conservation, diversity, cocoa, agroforestry, system.