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Site description (2001 baseline):
Site location and context
Widely known as Bushmanland after the inhabitants of this region, the new name is the Tsumkwe District. The original name has been retained because of its widespread acceptance. This very extensive wetland system in north-eastern Namibia has developed on a broad, flat watershed, on the eastern edge of the Kalahari Basin, situated between the Nhoma and Daneib drainage systems. Here, the geology restricts drainage and, as there are no major drainage lines out of the area, these pans, flooded grasslands and
Acacia woodlands can remain wet throughout the dry season in years of above-average rainfall. The town of Tsumkwe lies in the centre of the area, which is inhabited by the Ju/’hoan Khoi. Livestock, so common in other parts of Namibia, are largely absent from the area, since a hunter-gathering lifestyle was until recently practised by all the inhabitants. However, cattle-farming has been introduced, and will, in time, replace the traditional nomadic lifestyle.
The Bushmanland Pans system is centred on the Nyae-Nyae wetlands, which run in a broad arc south-east of Tsumkwe. The Nyae-Nyae Pan itself consists of a large deflation basin comprising both grassland and open wetlands. Also included are the Pannetjies Veld wetlands 25 km east of Tsumkwe, comprising mainly flooded woodland, the Klein Dobe wetlands (two pans of 30 and 50 ha) 15 km north of Tsumkwe and the CinQo wetlands 40 km north-east of Tsumkwe. The wetland system as a whole is both extensive and variable.
The wetlands are widely interconnected and many wetland-types intergrade into one another, including: (1) Unvegetated open-water pans with highly alkaline evaporite basins; these pans are the last to dry up and can be up to 1.5 m deep. (2) Doline pans appear to be sinkholes formed in areas underlain by calcrete. When full, these are more than 2 m deep and unvegetated. (3) Open-water pans form where the underlying soils are not very alkaline. Vegetation is dominated by floating and submerged macrophytes such as
Persicaria,
Scirpus,
Nymphaea,
Aponogeton,
Elytrophorus,
Eragrostis and species of algae (Characeae). The pans are of medium size and the water in them can persist for three months. A second type of open-water pan develops where shallow calcareous sands make the pans more alkaline. In these, the vegetation is dominated by sedges (Cyperaceae) and floating mats of
Persicaria which form in the deeper parts of the system. (4) Grass pans are small pans where organic clays have impeded the drainage; these are dominated by
Echinochloa or
Diplachne; the latter are the commonest pans in the system. (5) Wet grasslands develop on calcareous sands where the period of inundation is short. (6) During periods of extreme inundation on clay soils, flooded woodland develops. Occasionally scrubby areas of
Grewia and
Croton become periodically flooded in years of very high rainfall. The high-lying areas surrounding the pans hold palms such as
Hyphaene.
See Box and Table 3 for key species. The variety of wetland habitats, ranging from unvegetated open-water systems to wet grasslands, supports a diverse assemblage of flora and fauna. This area holds important numbers of rare and threatened bird species; it regularly holds more than 10,000 waterbirds of 84 species when wet. The most important species include breeding
Egretta vinaceigula, and non-breeding
Grus carunculatus and
Gallinago media; the cranes occur in larger numbers than anywhere else in Namibia. These wetlands are also known to be important for rails (Rallidae), especially migratory Palearctic and intra-African crakes. The pans occasionally support thousands of both
Phoenicopterus ruber and
P. minor (probably on passage between Etosha and Makgadikgadi Pans in Botswana), as well as thousands of
Himantopus himantopus.
Tringa glareola and
Philomachus pugnax may be particularly numerous, with over 1,000 birds present.
The surrounding grassveld holds Palearctic migrants, including large numbers of
Glareola nordmanni and
Charadrius asiaticus. Large mixed breeding colonies of
Podiceps nigricollis,
Chlidonias hybridus,
Fulica cristata,
Porphyrio porphyrio,
Gallinula angulata,
Himantopus himantopus and a handful of
Porzana pusilla form in flooded grasslands around Nyae-Nyae. It is in the top 20 atlas squares for overall avian species richness in Namibia.
Non-bird biodiversity: Among mammals, the temporary wetland system supports the near-endemic Mastomys shortridgei, and threatened species include Acinonyx jubatus (VU), Lycaon pictus (EN) and Loxodonta africana (EN).
Pressure/threats to key biodiversity
Overall threats to temporary wetlands in the area are low since it is used mainly by traditional hunter-gathering Khoi or Ju/’hoan. Developments in the tourism industry and recently introduced subsistence livestock-farming may have negative impacts if they are not adequately controlled. Tourism is on the increase in eastern Bushmanland, and the pans of the Nyae-Nyae area may be heavily utilized. The area was gazetted as a conservancy on 16 February 1998 and land-use plan policies have been initiated. Threats to birds come largely from disturbance of breeding waterfowl, and off-road vehicles driving through the wetland areas. Livestock-farming in the Gautcha area has already led to overgrazing of upland sites which may change drainage patterns, groundwater percolation and vegetation development. Continued monitoring of these wetlands over a long period of time, encompassing both wet and dry phases, could give important insights into arid-zone wetland functioning. Careful assessment of the threats to this system, particularly tourism, is required.
Recommended citation
BirdLife International (2024) Important Bird Area factsheet: Tsumkwe pan system (Namibia). Downloaded from
https://datazone.birdlife.org/site/factsheet/tsumkwe-pan-system-iba-namibia on 23/12/2024.
