African Wildlife & Environment Issue 77 FINAL ISSUE

FAUNA, FLORA & WILDLIFE

An excellent specimen of Faurea saligna some 7 m in height

understorey trees that can be classified as heathland trees are Monotes and Faurea , that are patchily distributed understorey trees to the Brachystegia spiciformis overstorey. Thus, in essence, where we have Proteas as the overstorey we are in fact seeing some African heathlands at their purist. Additionally, heathlands are the only major global vegetation type that are not climatically determined - but driven primarily by low P values in the soil. Expanding on this realisation, we see patches of heathland vegetation occurring in the Vazi Swamp in Maputaland, on quartzite ridges in Gauteng, in mountains such as the Drakensberg and Chimanimani, and in scattered isolated places from Pondoland to Kilimanjaro.

To better understand what tree species dominate our heathlands, let me take you to the extreme, i.e. where the soils have the lowest P value. These are the Cave Sandstones of the KZN Drakensberg and the quartzite areas of upland Mpumalanga where various species of Protea are common. Thus, I am arguing that where you find these two species you are in a heathland; the sourest of our veld types. Clearly as the P value in the soil increases, trees less well-adapted to thrive in the extremely low P level soils start to occur. Examples are Terminalia sericea and Ochna pulchra , and as the P levels increase a little more, then Combretum spp. and other bushveld trees start to dominate – outcompeting those that are tolerant of lower P values. One feature pure heathland trees have is that they are evergreen, and their leaves are tough and leathery (in botanical-speak they are 'sclerophyllous'). As P levels increase so does deciduousness. If one goes further north into the Miombo woodlands of the African central plateau,

Prof Eugene Moll Department of Biodiversity and Conservation Biology University of the Western Cape emoll@telkomsa.net

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