African Wildlife & Environment Issue 84 2023

FAUNA, FLORA & WILDLIFE

Where the substrate is on calcrete a rather different structural and floristic Cape Fynbos Heathland occurs - that generally has more shrubs and fewer restios (as seen here in the De Hoop Nature Reserve). Note the totally different plant community on the coastal dunes in the background

To set the scene one has to go back a good few million years into the geological past, when the Cape Mountain formations occurred in a continuous belt all the way up the east coast to just north and inland of Durban (and possibly as far north as the Limpopo River). Back then plants were able to freely migrate, on the same sandy substrates , in a north-south (from about the Limpopo to Gqeberha in the east, and Clanwilliam to Cape Town in the west) and in an east-west direction (Gqeberha to Cape Town) – this long before Mediterranean climates were present. Then a chunk of these mountains sheared off Africa and drifted away (today this piece of ‘Africa’ is the Falklands!); leaving a huge gap without sandstone substrates that impacted the migration of ‘sand-loving plants’ north-south and vice versa . The resultant ‘island of Cape Mountains’ was thereby cut off and gene-flow restricted to what we now know as the CFR. Much of this unique CFR vegetation is simply determined by soils extremely low in plant-available nutrients (phosphorus in particular), and are also fire maintained shrublands - that has nothing to do with a Mediterranean climate. In fact, they are typical southern hemisphere heathlands.

heathlands in South Africa are few and far between (e.g. DJ Killick’s PhD work in the Natal Drakensberg, Cathedral Peak 1962). The reasons why this is so I certainly do not comprehend? To me this demonstrates that one should never stop learning, and recently I found an explanation for this phenomenon, where researchers studiously avoided consideration of two disparate lines of scholarship, and it is called ‘confirmation bias’. However, in this article I simply want to focus on some of a handful of non-heathland tree species that are also endemic to the CFR. I also speculate why this could be? And in doing so I challenge some of the existing concepts on why the CFR and the Fynbos Biome ( sensu Mucina & Rutherford’s 2006 Vegetation tome [page 53 of Strelitzia 19] and map) only occurs in the Western Cape AND why there are so many plant endemics; not just in the many Cape Fynbos Heathland vegetation types recognised, but also in Renosterveld, Western Strandveld and Fynbos Thicket (and/or in the islands of Afrotemperate Forest – but I prefer to use White’s Africa-wide terminology and call them ‘Afromontane Forest’ White 1983]).

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