
Definition:
Wetlands play an essential part in the regulation of river flow, they filter pollutants and fertilizers, they are spawning zones for some species of fish (pike in particular). They also provide a habitat for plants, insects, batrachians and birds… “
“The expanse of groundwater in these deposits when they are well developed can constitute a large reserve which absorbs the variations of water flow. Alluvial deposits act rather like sponges which absorb surplus water before releasing it later. In these alluvial areas part of the water follows the course of the river: this drainage can represent a large volume. This water has been filtered, has a more constant temperature and constitutes a reserve of good quality water.”
A wetland is wet land (i.e. land which is wet) ! But not all wet land results in a wetland. Why is this so? A wetland is found where the land is wet enough (i.e. saturated or flooded) for long enough to be unfavourable to most plants but are favourable to plants adapted to anaerobic soil conditions. As soil becomes increasingly wet, the water starts to, fill the space; between the soil particles. When all the spaces are filled with water the soil is said to be saturated. In areas which are not wetlands, water drains away quickly and the soil does not remain saturated. However, in wetlands the water persists or drains away very slowly and the soil remains saturated or flooded for long periods. Soil in these conditions is said to be waterlogged. Depending on factors such as temperature, it usually takes a week or so for the plant roots and other living organisms in the soil to use up the oxygen, causing anaerobic conditions to develop in the waterlogged soil. (Rennies Wetland Project)
- Wetlands are ecosystems or habitats for specific plants and animals that are saturated with water. The presence or absence of water determines their formation, processes and characteristics.
- Wetlands are characterised by specific vegetation, particular soils and the presence of water at least for a period of time in the year. A wetland may have all of these characteristics or only one or two of them.
- Floodplains, marshes, bogs, deltas, swamps, peatlands, estuaries, river catchments and lakes are all types of wetland.
- Wetlands occur in areas ranging from higher altitude mountain ranges (seeps), through to mid-catchment areas (marshes), through to estuaries at the coast.
- Some wetlands are constantly wet but others temporarily dry up.
- The type of wetland present depends on the soils, the rainfall, climate and the topography. -( Endangered Wildlife Trust)
Importance of Wetlands
“Wetlands play an essential part in the regulation of river flow, they filter pollutants and fertilizers, they are spawning zones for some species of fish (pike in particular). They also provide a habitat for plants, insects, batrachians and birds… “
“The expanse of groundwater in these deposits when they are well developed can constitute a large reserve which absorbs the variations of water flow. Alluvial deposits act rather like sponges which absorb surplus water before releasing it later. In these alluvial areas part of the water follows the course of the river: this drainage can represent a large volume. This water has been filtered, has a more constant temperature and constitutes a reserve of good quality water.”
“Wetlands associated with streams and rivers slow floodwaters by acting as giant, shallow bowls. Water flowing into these bowls loses speed and spreads out. Plants in the wetland play an important role in holding back the water. The wetland acts as a sponge as much of the flood water is then stored in the wetland and is slowly released to downstream areas, instead of it all rushing to the sea within a few days. This greatly reduces flood damage, particularly erosion, and ensures a more steady supply of water throughout the year.”
“Wetlands improve water quality as they are very good natural filters, trapping sediments, nutrients (e.g. nitrogen and phosphorus), and even pathogenic (disease-causing) bacteria. In addition, pollutants such as heavy metals (e.g. mercury, lead) and pesticides, may be trapped by chemical and biological processes. In other words, the water leaving the wetland is cleaner than the water entering it.”
“Wetlands are filters where sediments and nutrients accumulate, so many plants grow there, e.g. bulrushes, grasses, reeds, waterlilies, sedges and trees. The plants, in turn, provide food and a place for attachment and shelter for many creatures. There is more life, hectare for hectare, in a healthy wetland than in almost any other habitat. These productive places support huge numbers of insects, fish, birds and other animals. Some animals are completely dependant on wetlands, whilst others use wetlands for only part of their lives. The wattled crane, for example, is dependant on wetlands for breeding. The rich diversity of waterbirds in southern Africa (totalling 130 species) is possible because of the many wetlands spread across the sub-continent. The wetlands of southern Africa are of international importance as they are the southern destination for many migratory wading birds.”
“Wetlands have been used for centuries as grazing for domestic stock, and as a source of reeds used for thatching, hut construction and basket weaving. They are provide fishing, hunting and the opportunity to observe wildlife, especially birds. Wetlands are appreciated for their beauty as open spaces and also for their educational value.”