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Wetlands share
common and important functions in river catchments
by providing a regular water supply, by filtering
the water naturally, by reducing the effects of
floods and droughts, and by providing a vital
wildlife habitat and superb recreational areas for
people.
Most wetlands are characterised by a high water
table, water-carrying soil and hydrophytes
(water-loving plants), but in semi-arid Southern
Africa there are numerous pans that support few if
any hydrophytes and that may contain shallow water
only once in five or more years.
Wetlands play an important role in maintaining
biodiversity since they support an extraordinary
variety of plant and birdlife e.g. the red bishop (Euplectes
orix), the South African shelduck (Tadorna cana),
insects, mammals, reptiles, amphibians, e.g. the
striped stream frog (Strongylopus fasciatus), fish
and invertebrate species.
Wetland plants such as the bulrush (Typha
capensis), play an important role in the healthy
functioning of a wetland ecosystem by generating
organic matter, the primary element for any foodweb.
They also provide the soil and water with oxygen,
prevent erosion and serve as a filter that purifies
the water.
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These plants provide food, shelter and
breeding sites for many birds and aquatic
animals such as the hippopotamus. Attractive
plant species such as the arum lily (Zantedeschia
aethiopica) and the red-hot poker (Kniphofia
caulescens) are common to wetlands.
Wetlands are likely to occur in the
catchment of all river systems in South
Africa, but their form and abundance vary
considerably owing to regional differences
in topography, climate, vegetation, soil,
land use and hydrological conditions. South
African wetlands, being at the southern tip
of the continent, host a number of endemic
and highly isolated bird species, e.g. the
Cape shoveller (Anas smithii).
A number of paleoarctic migrants visit
Southern African wetlands during the
northern hemisphere's winter, some of which
come all the way from the Taimyr Peninsula
in Siberia (a distance of approximately 15
000 km). South Africa extends into the
tropics, providing the southern limits to a
number of tropical species such as the
pink-backed pelican (Pelecanus rufescens),
the rufous-bellied heron (Butorides
rufiventris), the dwarf bittern (Ixobrychus
sturmii), the open-billed stork (Anastomus
lamelligerus) and the pygmy goose (Nettapus
auritus).
(Source: South Africa
Department of Environmental Affairs and
Tourism)
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