Floristic and structural vegetation typology of bonobo habitats in a forest-savanna mosaic (Bolobo Territory, D.R.Congo)

Abstract

Background and aims – Forest-savanna mosaics are some of the very diverse habitat types of the Congo Basin; multiple factors influence their dynamics such as climatic and edaphic conditions, animal dispersion, and anthropogenic activities. Presently, few studies have described this type of habitat, despite their important role in biodiversity conservation and their fragmentation. This study identified and described the floristic and structural composition of eight vegetation types of a long-term study site for bonobos in a forest-savanna mosaic of Bolobo Territory in the southwestern Congo Basin, Democratic Republic of the Congo (DRC). Methods – We surveyed trees, lianas and terrestrial herbaceous vegetation in 51 sampling units using a nested plot sampling, totaling 12.75 ha for trees with diameter at breast height (1.30 m above ground level, dbh) ≥ 30 cm, 5.1 ha for tree species with 10 cm ≤ dbh < 30 cm, and 0.02 ha for herbaceous vegetation, seedlings and saplings. First, detrended correspondence analysis of floristic data allowed the discrimination of seasonally inundated forests from terra firma forests. Then, structural data were analyzed to discriminate five terra firma forest types using hierarchical cluster analysis. Key results – In this survey, 146 trees, 50 lianas and 42 herbaceous species were identified. Eight vegetation types were characterized. Each vegetation type was described in terms of structure (trees and lianas densities, basal areas, herbaceous vegetation densities) and floristic characteristics (species diversity, importance value index of tree species). Conclusions – Some characteristics of vegetation types were particularly relevant to discuss (1) the forest-savanna dynamics and the important role of Pentaclethra eetveldeana in the plant succession, and (2) the effects of anthropogenic activities on different vegetation types