Mopane Trees and Shrubs Savanna on Basic Soils | Gertenbach Landscape 9: Colophospermum mopane

Location and Geomorphology

The parent material underlying this landscape is mainly amphibolite from the Swaziland System and to a lesser degree granite and gneiss mixed with weathered material from gabbro and dolerite (Shutte 1974). It is a relatively flat landscape in comparison with the adjacent undulating terrain on granite. This area is situated north of the old Letaba / Phalaborwa tourist road and south of the Letaba River, excluding the direct southerly drainage to the Letaba River. It is drained by the Ngwenyeni, Malopene and Nwanedzi spruits, and is situated between 300 and 380 metres above sea level. This landscape occupies 546 km/2 or 2.8 percent of the KNP.

Climate

There is no reason to believe that the climate of this landscape differs much from Landscapes 8 and 10. Surrounding weather stations and their annual average rainfall are Mahlangene 490 mm, Phalaborwa 481 mm, Letaba Ranch 487 mm and Letaba 471 mm (Gertenbach 1980). As a result of the flat terrain the possibility of frost in winter is poor (See Table 5 for temperature data).

Soil Pattern

Considering that this landscape is reasonably flat, there is no great variation in soil types. There is a gradation in the clay content of the soil from the uplands to the bottomland areas with the more clayey soils occurring in the latter. The soil is normally red in colour and the following soil Forms and series can be expected: Glenrosa/Dunvegan – Lomondo – Dothole – Archterdam – Ponda and Hutton/- Malonga – Vergenoeg – Shigalo – Hardap. A characteristic of this landscape of this landscape is the presence of small pans which once again indicates that the landscape is reasonably flat. It sometimes happens that weathered granite mix with material originating from the great gabbro sills that intersect the landscape. In such cases soils of the Mayo Form can be expected.

Fig. 22. Landscape 9. Colophospermum mopane Savanna. – page 42

The woody vegetation is dominated by Colophospermum mopane. Combretum apiculatum occurs commonly where the soil is more sandy, but disappears completely on clayey soils. Other associated woody species are: Acacia nigrescens, Cissus cornifolia, Combretum imberbe, Ozoroa engleri, Maerua parvifolia, Albizia harveyi, Lannea stuhlmannii, Grewia bicolor, Ncorautanenia amboensis and Commiphora africana. The vegetation of this landscape shows similarity to the vegetation on granite bottomlands and also with vegetation of dolerite instrusions. The field layer is dense with the following dominant grasses: Bothriochloa radicans, Themeda triandra, Digitaria eriantha var. pentzii and Heteropogon contortus. Other associated grass species are Pogonarthria squarrosa, Schmidtia pappophoroides, Panicum coloratum, P. maximum, Urochloa mosambicensis, Eragrostis suoerba and Aristida congesta subsp. Barbicollis. The following forbs occur regularly: Seddera capense, Cassia mimosoides, Crotalaria virgulata, Rhynchosia totta, Phyllanthus asperulatus, Corchorus asplenifolius, Hibiscus micranthus and cucumis hirsutus. The riverine vegetation is comparable to that of Landscape 6.

Vegetation

The vegetation of this landscape is an open savanna with a sparse shrub layer and a relatively dense grass cover (Fig.22). The structural analysis of the woody component of the landscape is approximately as follows:

Fauna

This landscape provides ideal habitat for game preferring plains. The only herd of roan antelope in the central KNP occurs in this landscape and on the adjacent gabbro intrusions. Eland (Taurotragus oryx), another relatively rare game species in the KNP is also encountered here. Quite a few groups of wildebeest are present and zebra are common and usually found in larger groups. Browsers such as kudu and giraffe are not well represented and impala may be sporadically found in this landscape close to water. This landscape is ideal for buffalo but elephant are generally less common. As a result of a large number of veld pans, water is reasonably available until late into the dry season and therefore warthog are very common in this landscape. Interesting to note is that sable antelope which are plentiful in the adjoining landscapes are not present here.