Millipede diversity, distribution and conservation assessment in the Douala-Edea Wildlife Reserve, Cameroon

Biodiversity inventories are essential for planning, managing and monitoring of ecosystem, especially those located in tropical protected areas. Wildlife surveys and inventories are considered by conservationists as strong investments, since they are essential for determining the level of diversity within an area including communities’ assemblages and species distributions. In the Afrotropical region, the effort of biodiversity conservation is mostly focused on vertebrates, compared to terrestrial invertebrates such as millipedes which are largely endemic and indicators of habitat welfare. To have a real idea on the conservation status of millipedes in protected areas of Cameroon, this study was initiated with the objective to determining the diversity, distribution and conservation assessment of the millipede in the Douala-Edea Wildlife Reserve in Cameroon. After characterization of the habitats that potential sheltered millipedes, an ethnozoological study was carried out in order to have a clear idea on the knowledge and the perception of millipede by the populations who live around the Douala-Edea Fauna Reserve. To determine the diversity, distribution and level of conservation of diplopods in this protected area, three sampling methods were applied, namely active searching, pitfall trapping and litter sifting. For each collection site, the microhabitats sheltering the diplopods were characterized. The surveyed sites in Douala-Edea Wildlife Reserve revealed the presence of ca. 156 species of plants with a wide dominance of Euphorbiaceae, Rubiaceae, Cesalpiniaceae and Fabaceae. Five types of vegetation were recorded including primary forest, secondary forest, mangrove, agroforest and open meadows. Concerning millipede species richness and distribution, we identified 36 millipede species belonging to 22 genera and 9 families from 799 individuals collected. The Chelodesmidae was the most representative family in terms of species richness (8 species). The most species rich habitat in this study was primary forest (24 species), followed by mangrove (17 species), secondary forest (13 species), open meadows (11 species), while agroforest was the less species rich habitat. Millipede species diversity among habitat types showed that the primary forest, mangrove and secondary forest has the highest values of diversity indices (H’= 2.86, E= 0.73 for primary forest; H’= 2.55, E= 0.76 for mangrove and H’= 2.31, E= 0.77 for secondary forest), while the agroforest and open meadows showed the lowest (H’= 0.97, E= 0.66 for agroforest and H’= 1.45, E= 0.39 for open meadows). The cluster analysis based on Bray-Curtis distance, revealed that there was a very weak dissimilarity among habitat types. Overall, 799 specimens collected during the study period, the highest millipede abundance being observed in open meadows (334 specimens, representing 41.80% of all millipedes collected). Next to this habitat were primary forest (215 specimens, representing 26.91% of all the specimens collected) and mangrove forest (179 specimens, representing 22.40% of all the specimens collected). Despite of high species richness and abundance, anthropogenic disturbances such as agricultural activities are ongoing which extend towards the forest in the Douala-Edea Wildlife Reserve area. Anthropogenic pressures that can affect millipede ranging from the clear-cuts to the anarchic exploitation of forest species as Lophira alata, Pycnanthus angolensis, and Baillonella toxisperma. In addition, intensive agricultural activity with destructive practices were noted, viz. slash-and-burn which is negative to millipedes. People living near and in the Douala-Edea wildlife Reserve known millipede and used them for several purposes. Conservation initiatives must be implemented to protect the endemic and rare millipede species in this study area.