Vegetation Studies of Selected Islands and Adjacent Mainland on Lake Kariba, Zimbabwe.

Abstract

The objective of this study was to classify and describe the vegetation of selected islands on Lake Kariba. A total of forty-six islands were surveyed. Two hundred and eleven samples were classified into twenty-six vegetation types. The types were described in terms of their location, floristic composition andfactors that determine or influence them. Woodlands consisted of ten types: Colophospermum mopane woodland, Colophospermum mopane-Combretum apiculatum woodland, Colophospermum mopane mixed woodland, Combretum apiculatum mixed woodland, Mixed Combretum woodland, Combretum elaeagnoides mixed woodland, Julbernardia globiflora woodland, Ficus sycomorus woodland, Acacia nilotica woodland and Acacia nigrescens-Afzelia quamensis mixed woodland. Thickets and woodland thickets consisted of four types: Karomia tettensis thicket, Diospyros quiloensis thicket, Combretum celastroides woodland thicket and Guibourtia conjugata woodland thicket. Shrublands consisted of five types: Colophospermum mopane shrubland, Mundulea sericea shrubland, Croton menyhartii shrubland, Pteliopsis myrtifolia shrubland and Indigofera tinctoria shrubland. Grasslands consisted of seven types: Melinis repens wooded grassland, Panicum repens grassland, Aristida rhiniochloa grassland, Aristida adscensionis grassland, Heteropogon contortus grassland, Urochloa trichopus wooded grassland and Eragrostis viscosa wooded grassland. Populations of large herbivores, especially elephants are having a negative impact on vegetation structure and species composition on some of the islands. The influence of soil texture in determining species composition is also significant with most thickets and woodlands occurring on sands. Twenty-nine years of isolation from the mainland has not had a significant influence on species richness and composition of the vegetation of the islands.