The mountain top flora and vegetation of the remote Ovahimba Highlands in the Kaokoveld Centre of Endemism : a reconnaissance

Abstract

The Kaokoveld Centre of Endemism is a hotspot of biodiversity and endemism, largely underexplored while new species are continually described. A reconnaissance survey of flora and vegetation was undertaken on three remote mountain tops of the western Great Escarpment: Cafema and Tchamalindi in Angola’s Iona National Park, and Middelberg in the Otjihipa Range of Namibia, providing the first floristic account for Serra Cafema. Vegetation cover and woody vegetation structure were assessed, and botanic surveys were performed. Previously collected occurrence data allowed to determine Kaokoveld endemics. Commiphora woodlands were found on the mountains despite the semi-desert on the surrounding plains. Woodlands were interspersed with montane savanna and on Cafema with sclerophyll dwarf shrubs. Our study provides the first assessments of species richness in the Ovahimba Highlands with the highest for Serra Cafema: 56 species per 1000 m2 compared to 47 species per 1000 m2 for the other mountains. Species composition, especially Cafema, is very different from the surrounding lowlands, making a case for a satellite population of Afromontane vegetation. The distribution of sixteen species was expanded from Namibia to Angola. Of the 285 taxa, 12% were Kaokoveld endemics, of which 65% woody species, both relatively high compared to Afromontane vegetation in Eastern Africa. Only a fraction of the flora could be recorded and more surveys after good rainfall are required, especially considering the threats of climate change and overgrazing. The mountain flora deserves priority conservation efforts to protect endemic plants and old taxa that survived in these refuge sites.