Nwambia Sandveld Between Shingwedzi and Pafuri. Numerous Pans & Waterholes
Location and Geomorphology
After the formation of the Malvernia System was completed (Shutte 1974), there was a period of dry desert-like conditions under which sand was deposited. The colour of this sand is either red or yellow and can be present up to a depth of 30 metres. These sands are widely spread in Mocambique, but in the KNP they only occur in a small area on the western boundary between shingwedzi and Pafuri. It is a flat landscape and the altitude varies between 474 and 530 metres.
A characteristic of the geomorphology is the absence of well defined drainage channels and the presence of a variety of pans. Good examples are Mathlakuza, Shirombe, Nwambia, Machayi, Masokosa and Klawer pans. The landscape covers 139 km/2 or 0.8 percent of the area of the KNP.
There are no weather stations near Nwambia Sandveld and according to Gertenbach (1980) the rainfall probably varies between 450 and +/- 500 mm per year. If it is taken into consideration that this landscape lies at almost the same altitude as does Punda Maria, then it can be speculated that the rainfall may possibly be higher and the temperatures are also comparable to that of Punda Maria (Table 7).
The soils are deep, sandy, from yellow to red in colour and the pH varies between 4.3 and 5.5. Soil Forms are Hutton and Clovelly, with Gaudam and Sandspruit respectively as the dominant Series. Red sandy soils occur mainly in the eastern part of the landscape while yellow soils occur in the western parts. Heavy structured soils are present next to the pans with Valsrivier and Sterkspruit being the common Forms.
This is a tall shrubveld with very few trees. The crown cover of the woody species range up to 80 percent and the shrubs are mostly between two and four metres high. The structure of the vegetation, however, depends mainly on the plant communities as described by Van Rooyen (1978). There are three basic communities:
1. The Baphia massaiensis/Guibourtia conjugata-thickets.
2. Th Xeroderris stuhlmanii/Combretum apiculatum-tree savanna.
3. The Terminalia sericea/Pogonarthria squarrosa-tree savanna.
The Baphia massaiensis/Guibourtia conjugate-thickets (Fig. 72) occur in the eastern parts of the landscape on the red soils. It is a dense tall shrubveld with no trees. Dominant woody species are: Baphia massaiensis, Guibourtia conjugate, Xylia torreana, Combretum celastroides, Hugonia orientalis, Pteleopsis myrtifolia, Vitex amboniensis, Alchornea laxiflora, Grewia microthyrsa, Vangueria infausta, Hexalobus monopetalus, Spirostachys africana, Dichrostachys cinerea, Ptaeroxylon obliquum, Pavetta catophylla, Heinsia erinata, Zygoon graveolens, Combretum zeyheri and Strychnos madagascariensis. The following rare species also occur in this landscape: Pterocarpus antunesii, Drypetes mossambicensis, Cleistanthus schlechteri, Croton steenkampiana, Dalbergia nitidula and Uvaria lucida subsp.virens.
The field layer is weakly developed and the following species contribute the most towards the cover: Eragrostis pallens, Digitaria eriantha var. pentzii, Panicum maximum, Perotis patens, Brachiaria nigropedata, Tricholaena monachne, Aristida argentea, Pogonarthria squarrossa, Phyllanthus burchelli, Merremia tridentata, Indihofera vicioides, Vigna unguiculata, Commelina erecta and Borreria scabra. From the list of plants above it can be deduced that this community is unique in the KNP, but it is also unique in South Africa. It gives great priority to the conservation status of this area.
Fig. 72. Landscape 32. Nwambia Sandveld Baphia massaiensis thickets. – page 109
Fig. 73. Landscape 32. Nwambia Sandveld. Xeroderris stuhlmanii tree savanna. – page 109
The Xeroderris stuhlmannii/Combretum apiculatum-tree savanna (Fig.73) occurs on the yellow sands west of the previous community. It is a tree savanna with moderately high and low shrubs and a better developed field layer. Dominant trees and shrubs are: Xeroderris stuhlmannii, Sclerocarya caffra, Combretum apiculatum, Adansonia digitata, Afzelia quanzensis, Terminalia sericea, Combretum collinum subsp. suluense, Dalbergia melanoxylon, Strychnos madagascariensis, Balanites maughamii, Guibourtia conjugata, Zygoon graveolens, Vangueria infausta, Cissus cornifolia, Combretum mossambicense, Grewia monticola, Pteleopsis myrtifolia, Grewia bicolor and Boscia albitrunca. Spirostachys africana is the dominant plant species around the pans where brackish soils occur.
Other plants that occur in the same habitat are: Dichrostachys cinerea, Combretum imberbe, Euphorbia ingens, Diospyros mespiliformis, Ehretia amoena, Lochocarpus capassa, Gardenia spatulifolia, Boscia albitrunca, Berchemia discolor, Dalbergia melanoxylon and Crossopteryx febrifuga. The field layer of this community is better developed and the following species are present: Aristida stipitata, A. junciformis, Digitaria eriantha var. pentzii, Panicum maximum, Schmidtia pappophoroides, Tricholaena monachne, Eragrostis pullens, Aristida congesta subsp. congesta, Pogonarthria squarrosa, Tephrosia polystachya, Vigna unguiculata, Merremia tridentate, Ipomoea magnusiana, Borreria scabra, Commelina africana, Rhynchosia resinosa, Euphorbia tettensis, Monechma monechmoides and Melhania forbesii.
The Terminalia sericea/Pogonarthria squarrosa-tree savanna occurs in the south-western part of this landscape but is more characteristic of Landscape 16, viz. the Punda Maria Sandveld on Cave Sandstone and was discussed in more detail in that landscape. This community is dominated by Terminalia sericea with kirkia acuminata, Lannea stuhlmannii, Sclerocarya caffra, Xeromphis obovata, Combretum zeyheri and Strychnos madagascariensis as constant species.
The pans in the Nwambia area (Fig.74) are characterised by the following plant species: Nymphaea capensis, N. caerulea, Ottelia exserta, Paspalidium obtusifolium, Convolvulus mauritanicus, Neptunia oleracea, Bergia salaria, Epaltes gariepina, Marsilea macrocarpa, Potamogeton schweinfurthii, Lagarosiphon crispus, Cyperus difformis, Fuirena ciliaris, Vahlia capensis and Buchnera longespicata.
The Nwambia Sandveld is the only area in the KNP where there is a confirmed evidence of the occurrence of the soeni (Nesotragus livingstonianus zuluensis). This area is also the only habitat for the Limpopo golden mole (Calcohloris obtusirostris limpopoensis) in the KNP (Pienaar, Rautenbach & De Graaff 1980). In addition to the uniqueness of this habitat it is also the only place where a variety of the lower vertebrates are to be found. Larger mammals occur in relatively smaller numbers. Of these kudu and grey duiker are certainly the most important. Other species which occur are elephant, buffalo, sable antelope, nyala, zebra, eland, steenbok, Sharpe’s grysbok and giraffe (Pienaar 1963). The crested guineafowl (Guttera edouardi) occur in large numbers in this Nwambia Sandveld where, with the exception of Punda Maria and areas in the Lebombo range, they are relatively scarce in the KNP. The small fish Nothobranchius orthonotus and N. rachovii occur only in this and the Pumbe vicinity (Pienaar 1978).