Olifants River Rugged Veld | Gertenbach Landscapes 7
Location and Geomorphology
This landscape includes the direct drainage area adjoining the Olifants River, from the western boundary of the KNP to approximately the sandstone koppies at Shiswayini. To the north it extends to about the Letaba / Phalaborwa powerline and southwards to the northern boundary of the neighbouring area of Peru. It is a strongly undulating terrain with steep slopes and a great number of small spruits which drain into the Olifants River. Among the most important are the Tshutsi, Mulalane, Misumane, Manyukelani from the north and the Klaseri, Tseri, Nhlaralume and Mvubuspruits from the south. According to Schutte (1982) the parent material of the area comprises metamorphic rock such as amphibolite, serpentine, quartzite, quartz-schist and other rocks of Swazium age.
The altitude varies a lot but the greater portion of the landscape is situated between 250 and 300 metres. In the north-western part of this area the uplands can reach 400 metres above sea level. The landscape occupies 360 km/2 or 1.8 percent of the KNP.
This landscape is relatively dry with a rainfall of between 450 and 500 mm per year. The dryness of the area is accentuated by the steep slopes and shallow soils. High temperatures are experienced during the summer months and a temperature of 40o/c at Letaba is not uncommon. Frost sometimes occurs during the winter but is limited to the low lying areas. Table 5 provides the temperature data for Letaba which is largely applicable to this landscape.
The soils of this landscape are shallow and stony and can only be described by the term lithosols. Shallow Mispah and Glenrosa soils also occur. The shallow soil is a result of steep slopes and a relatively stable parent material. Loose rocks of all sizes are present on the surface.
As a result of the steep slopes and shallow stony soil, the landscape is relatively dry and the vegetation shows xerophytic characteristics (Fig.18). The field layer, especially, is very sparse and never developes a stable grass cover even under circumstances of no grazing. The woody component is usually not higher than 5 metres and can sometimes be quite dense. The reason for the relative high density of the woody component lies in the absence of regular fires. Woody plants that dominate the landscape are as follows: Combretum apiculatum, Colophospermum mopane, Commiphora mollis, C. africana, Terminalia prunioides, Grewia villosa, Boscia albitrunca, Acacia nigrescens, Combretum hereroense, Albizia harveyi, Cissus cornifolia, Dichostachys cinerea subsp. Africana, Grewia bicolor, Selerocarya caffra, Dalbergia melanoxylon, Lannea stuhlmannii, Maerua parvifolia, Rhigozum zambesiacum, Zanthoxylum humilis, Ziziphus mucronata, Combretum imberbe, Acacia nilotica, Securinega virosa, Acacia exuvialis, Maytenus heterophylla, Ozoroa engleri, Tricalysia allenii, Grewia flavescens and Pappea capensis. As a result of the Variation in habitat a variety of trees occur here which are relatively scarce in the KNP. Species that can be mentioned are Holmskioldia tettensis, Kirkia wilmsii, Ficus smutsii, Olax dissitiflora, Hexalobus monopetalus, Albizia anthelmintica,
Fig. 18. Landscape 7. Olifants River Rugged Veld. –page 36
Albizia brevifolia, Garcinia livingstonei and Bridelia micrantha. Species differentiating the field layer are Melhania forbesii, Justicia kraussii, Sporobulus panicoides, Bidens pilosa, Calostephane divaricata, Hemizygia elliotii, Hibiscus sidiformis and Ocimum americanum. A rare species of grass. Schizachyrium exile also occurs in this landscape. Sansevieria hyacinthoides is common in this as in all other rugged veld in KNP.
Table 5 … Temperature data for Letaba. (Data collected since September 1981). Temperature in Degrees C
|Absolute Maximum||Average Daily
The field layer seldom develops further than the pioneer stage and the grasses which normally dominate are Rhynchelytrum repens, Sporobulus panicoides, Bothriochloa radicans, Digitaria eriantha var. pentzii, Panicum maximum, Aristida congesta subsp. Barbicollis, Brachiaria xantholeuca, Enneapogon cenchroides, Tragus berteronianus, Fingerhutia africana, Aristida congesta subsp. Congesta, Enteropogon monostachus, Aristida curvata, Oropetium capense and Cymbopogon plurinodis, Forbs, on the other hand, are relatively common and the following species dominate: Hibiscus sidiformis, Melhania forbesii, Hemizygia elliotti, Xerophyta retinervis, Archyranthus aspera, Justicia kraussii, Asparagus plumosus, Bidens pilosa, Carbbea velutina, Melhania rehmannii, Hibiscus micranthus, Phyllanthus asperulatus, Heliotroplum steudneri, Mariscus rehmannianus, Tephrosia polystachya, Commelina bengalensis, Cyphocarpa angustifolia, Corchorus asplenifolius, Solanum panduraeforme, Calostephane divaricata, Waltheria indica and Abutilon austro-africanum.
A large variety of game occurs in this landscape despite the sparse veld. Elephant are regularly found along the Tshutshi and Manyukelani, while zebra are common but in small groups. Impala are plentiful along the rivers, but buffalo herds only move sporadically into the area. Giraffe, kudu and waterbuck (Kobus ellipsiprymnus) are relatively abundant. A herd of sable antelope are also found in this landscape every year during the aerial census. Lion, leopard and spotted hyaena are the most important carnivores.