Vegetation Map of the Federation of Rhodesia and Nyasaland

Summary

This paper presents the rationale, methods, and classification system used in producing the Vegetation Map of the Federation of Rhodesia and Nyasaland (Federal Atlas Map No. 10). Compiled by J. M. Rattray and H. W. Wild, the map aimed to follow as closely as possible the recommendations of the 1956 Yangambi meeting of the Scientific Council for Africa South of the Sahara (C.S.A.), while also consulting Keay's (1959) Vegetation Map of Africa and Rattray's (1960) Map of the Grass Cover of Africa. The map was largely compiled from existing sources: Henkel (1931) for Southern Rhodesia, Trapnell, Martin and Allen (1950) for Northern Rhodesia, and unpublished maps by Willan and Jackson for Nyasaland, with revisions contributed by several specialists. A colour and hatching system was used to reflect a moisture gradient from the wettest (montane and submontane grasslands with forest patches, shown in violet) to the driest areas (mopane woodlands or savannas, shown in red), while different line patterns indicated physiognomic categories such as forest, thicket, woodland, and savanna. The paper then describes in detail the vegetation types mapped, including evergreen forests, montane grasslands dominated by Themeda, Loudetia or Exotheca, Hyparrhenia grasslands, Loudetia grasslands, Andropogon grasslands, swamp and papyrus sudd, and numerous savanna types (Diplorhynchus, Parinari, Combretum-Afromosia-Pterocarpus-Acacia, Burkea-Dialium-Baikiaea-Colophospermum, Terminalia, Acacia, Adansonia-Hyphaene-Acacia-Sterculia-Cordyla, and Colophospermum mopane savannas), discussing their distribution, dominant species, and ecological relationships. The authors note difficulties in applying the Yangambi definitions of 'savanna' versus 'steppe', particularly in Southern Rhodesia and the Bechuanaland Protectorate, where grass height and leaf form vary with season and grazing pressure. They conclude that the mapped formations form a single broad physiognomic unit and acknowledge the need for larger-scale mapping and more detailed surveys in the future.