The Matrix the Evolutionary

The Matrix The evolutionary ............ Present day development of coastal coastline renosterveld ...... Coastline 25 000 years age "...a 1-2 m high matrix of cupressoid and leptophyllous ... shrubs" . McDowell, defining renosterveld by Ian P Newton and Richard Knight, Department of Biodiversity and Conservation Biology, University of the Western Cape There have been a number of articles about coastal renos Cape were being grazed by blue antelope, bontebok, giant terveld appearing in Veld & Flora lately: rare geophytes, buffalo, white rhinoceros, giant hartebeest and the Cape farmers' attitudes, seed dispersal, but all have avoided the 'horse'. Twenty thousand years ago the world was in the grip question 'What is renosterveld?' Why should this be? A look of the Last Glacial Maximum (LGM). Sea levels were 140 ill at the literature describing the vegetation occurring within lower than at present, while average temperatures were five the regions that are currently classified as coastal renoster degrees lower. Grasslands were common on the south and veld shows that there has been a big change in the landscape west coast lowlands, and forest species grew north of Elands over the past 400 years. Bay. We attempt to define renosterveld in two ways. Firstly, But slowly, world temperatures began to rise. Over the next from an histo'rical viewpoint: what the vegetation of the areas 10 000 years the polar ice caps began melting faster than presently defined as west coast and south-west/south coast they were accumulating fresh snow. Sea levels rose and the renosterveld would have been like before the Khoekhoen climatic belts moved towards their present-day positions. herders or the European farmers arrived. Secondly, we look The frontal storms that allowed forest to grow at Elands Bay at the problem from an etymological (the origin and meaning became weaker, and the coastal grassland and mesic shrub of the name) point of view. The map indicates the extent of species started retreating southwards in the face of reduced coastal renosterveld - both west coast and south coast precipitation. renosterveld. Coastal renosterveld occurs on relatively nutri The current interglacial ent-rich soils compared with the soils upon which fynbos By 10000 years before the present (ybp) the current inter grows, which are generally derived from shales and granites. glacial had begun. The west-coast lowlands were still covered The last Glacial with grass, but they were isolated from the grasslands of the Grab your winter woolies and your raincoat, and lets central interior of South Africa by mountains to the east, and return to a time when the coastal lowlands of the Western by dry shrubland to the north. The south coast lowlands 162 December 2004 Veld&Flora became similarly isolated from the And then a certain Mijnheer van structurally a grassland for most of the other grasslands of southern Africa by Riebeeck decided that Cape Town time, but tended towards an open mountains to the north and by the would be a nice place to build a holiday shrubland during the brief (10 000 Knysna forests to the east. The climate cottage. Within a hundred years, all the year) interglacials. We know it is a dis continued becoming drier, the grass prime coastal renosterveld sites had turbed system, yet persist in basing lands continued to contract and the been taken over by European farmers, our studies and conclusions upon the killer ape made another technological and the big renosterbos invasion was condition it is in now. Margaret Levyns breakthrough. There is evidence that on as a '...punishment for their sins'. noted in 1922 that on Signal Hill (clas around 10 000 years ago there was a Two hundred years later Acocks pub sified as renosterveld) the vegetation on big advance in the development of lished Veld types of South Africa and granite soils tended to have typical fyn hunting implements. The first major renosterveld became official. bos species, while the shale soils had extinctions, believed to be partly The name that defined the typical renosterveld species. ascribable to human activities, attitude So, what is renosterveld? occurred: giant buffalo, giant harte We now turn to two etymological The first extant written reference to beest, southern springbok, Cape horse. problems. The purpose for the publica the renosterbos (Elytropappus* The blue antelope, bontebok and other tion of Acock's Veld types of South rhinocerotis) was by the person keeping grazers became locally extinct on the Africa was to indicate areas in which the journal of Simon van der Stel's west coast lowlands, but on the south the farming potential was the same. expedition to what is now Springbok in th coast lowlands they survived. There was no claim that the veld types 1685. On September 12 they camped The middle of the current interglacial had any ecological significance! somewhere in the Lange River valley, (5 000 ybp) saw the warmest driest Unfortunately, it proved a useful surro near where the present-day Sandberg period of the last 125 000 years. In gate for vegetation mapping, and the siding is situated. The valley was west coast renosterveld, grasses were areas and terms used were absorbed described as being overgrown with under pressure from invading astera into the local botanical lingo and onto 'Rhenosters bosch', so called because ceous shrubs. The summer drought the botanists' own maps. Renosterveld, rhinoceros was usually found in it. Let conditions resulted in very poor sum being difficult to explain ecologically, us ignore the fact that they were in an mer grazing, which aided the extinction largely followed Acocks' boundaries, area that is currently on the border of of large grazing species. It is notable and this is where the problems have sand plain fynbos and mountain fyn that the common large herbivores risen. Ecologically, coastal renosterveld bos. Let us further ignore the fact that recorded in the western Cape by the is not homogeneous (all the same). Soil Burchell mentioned that even in 1811 early European settlers (eland, red har type, rainfall amount and seasonality, 'Rhinoster bosch' was still a term given tebeest, elephant, black rhinoceros) disturbance, and evolution have all without distinction to several species of were capable of surviving with a sub shaped the different regions of 'coastal Stoebe. stantial shrub component in their diet. renosterveld'. South coast renosterveld Descriptions of the vegetation of the Along the south coast, the return of has probably evolved (over the past half Cape by the numerous visitors it the warm Agulhas current (believed to million years, at least) as a grassland. received between 1488 and 1662 con have been weak or absent during much Species composition may have changed tinually refer to the grass, and to the of the previous glacial) had resulted in from one glacial/interglacial cycle to cattle and sheep of the Khoekhoen. Van year-round precipitation being received another, but for most of the time it has Riebeeck's Journal makes reference to in this area. The higher temperatures structurally been a grassland. West it in 1652: 'Table Valley (now central and summer rainfall allowed C4 (tropi coast renosterveld was also, probably, Cape Town) covered with grazing sheep cal) grasses to spread across the south coast plains, and a fierce battle between grassland and shrubland South coast renosterveld has probably evolved (over the past half million years, at least) as a grassland. ensued. The grassland won: indicated by the survival of a greater range of grazing species such as bontebok, blue antelope, reedbuck and buffalo. An increase in rainfall from about 4 000 ybp, gave the grasses a further advan tage, but the final victory of grassland over shrubland came with the intro duction of herding by the Khoekhoen about 2 000 years ago. Regular burns led to the destruction of the astera ceous shrublands within south coast renosterveld. On the west coast, where the sum mer drought conditions meant that the tropical grasses were unable to prolifer ate, the temperate C3 grasses were able to rally with the help of those regular burns; and the shrublands began retreating. December 2004 Veld&Flora 163 and cattle', and in 1657 he describes THE RENOSTERVELD RELOADED the 'Exceptionally rich pasturage' of the • The first and last person to correctly use the term 'renosterveld' was present-day Somerset West region. In Acocks. 1661, he writes of 'Valleys with waist • From an ecological point of view, the only definition that currently satis high grass' between Piketberg and Olifantsrivierberg. Theal (writing his fies the term 'renosterveld' is that it is those parts of the country where history in 1922) observes that by 1670, renosterbos will grow, and which have not been allocated to some other thirty to forty wagon loads of grass veld type. were being collected annually from the • The current interglacial is due to end within the next two thousand years Tygerberg. In 1726, Valentyn writes of the Bottleray hills:' in all of Africa no (assuming the current global warming process does not over-ride the lovelier grass fields than here'. cosmic level of influence). 'Renosterveld' will migrate northwards. Wheat Where were the renoster bosches? farming will become viable around Vanrhynsdorp, and scientists in Probably on the Cape Flats - an area 25003* will be trying to conserve 'the most endangered veld type in South that is currently described as sand plain fynbos. If the areas currently Africa', except that this time it will be situated 300 km north of its present classified as coastal renosterveld were position. described as grasslands, the sandy plains of the Cape Flats were typically *Allowi ng for an extra 20-odd thousand years for the general inertia of described as being 'pale and bleak tracts of heath' (Sparmann in the early systems, the climatic changes will take a few thousand years to occur and 1770s).

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