In the first part of our response, we will critically revisit the points in support of fire being an evolutionary driver in the Zambezian region. Our field data on vegetation, soil temperature and microclimate show that night frosts occur frequently during the dry season, shaping the landscape boundaries between forests on topslopes and hills and geoxylic grasslands on midslopes and footslopes. The natural vegetation of the Bié Plateau is composed of closed Miombo forests, geoxyle-rich ‘grasslands’, and wetlands. This region is situated in the core of the Zambezian phytoregion as delineated by White ( 1983) and is rich in geoxyle diversity (White, 1976). We base our argument on our own observations and measurements from the Angolan Plateau in the provinces of Bié and Moxico. ( 2014) does not explain the coexistence of the geoxylic life form with closed forests in the immediate proximity. In our response we would like to challenge this interpretation and point out that the fire and precipitation hypothesis of Maurin et al. In their final analysis, however, the authors formulate the hypothesis that geoxyles have evolved in response to the interactive effects of high precipitation and frequent fires, and rather nonchalantly negate the possibilities of other environmental factors such as frost driving the evolution of suffrutices. From there, the authors delineate very convincingly the phylogenetic relationship and evolutionary origin of the geoxylic life form, dating it back in most cases to the Pliocene. Based on a large sample of geoxyles and their tree counterparts the paper places these species in a comprehensive dated phylogeny of the southern African flora. ( 2014) has a lot of merit, bringing the fascinating and widely understudied subject of the ‘underground forests of Africa’ (White, 1976) back onto the scientific agenda.
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