Fig. 1. Examples of six types of savanna grassland based on bedrock (basalt and granite) and habitat combinations (crests, seasonal rivers, perennial rivers). A) plot with a high grass cover at basaltic crest dominated by Bothriochloa radicans with Cenchrus ciliaris ; B) grass species-rich plot at granitic crest with Urochloa mosambicensis , Eragrostis superba , Melinis repens andTrichoneura grandiglumis; C) plot at seasonal river on basalt with abundant Digitaria eriantha , Panicum coloratum andPanicum maximum; D) plot at seasonal river on granite withUrochloa mosambicensis , Panicum maximum andEragrostis cilianensis; E) plot at perennial river on basalt with a sparse vegetation with Eragrostis rigidior , Urochloa mosambicensis and Tragus berteronianus ; F) grass species-poor plot at perennial river on basalts with Sporobolus nitens andTragus berteronianus .