A biogeographical regionalization of Angolan mammals

We developed a biogeographical regionalization of Angolan mammals based on data collected before major declines occurred during the civil war (1975-2002). In terms of its biodiversity, Angola is one of the least known of all African countries. We used 9880 grid records of 140 species (rodents, ungulates and carnivores) collected mainly in 1930-80, at a quarter degree cell resolution. Biogeographical regions were identified by using cluster analysis, based on (sim) dissimilarity matrices and a hierarchical classification using Ward's method. An indicator value analysis was used to identify species characterizing each region. Distance-based redundancy analysis was used to investigate the environmental correlates of mammalian assemblages. Four biogeographical subdivisions emerged from ungulate distributions, while rodent and carnivore data were largely uninformative. In the north, the Zaire-Lunda-Cuanza region was mainly characterized by ungulate species associated with Congolian forests. In the south, the Namibe and Cunene-Cuando Cubango regions were mainly characterized by ungulates widespread in south-western and southern Africa. In between these regions, the Central Plateau region was mainly characterized by a few widespread ungulate species that are relatively common in dense miombo woodlands. Biogeographical patterns were significantly associated with a dominant north-south gradient of decreasing humidity and increasing temperature, and with a concurrent gradient from dense forests and woodlands to open savannas, grasslands and deserts. The biogeographical regions we identified in Angola were largely consistent with other bioregionalizations developed using various taxonomic groups at larger spatial scales. Biogeographical patterns reflected the southward penetration of Congolian forest species in the north, and the northward penetration of southern African desert/grassland species in the south-west and of open savanna species in the south. These processes seem to be controlled by the distribution of vegetation types, which in turn are associated with climatic gradients and soil types. The stronger patterns observed for ungulates than for other mammals may reflect the close association of ungulates to specific vegetation types.