Mires & Peatlands
Author: Rehana Dada ~ Producer & presenter: SAfm and 50/50 Environmental TV Programme
( Article Type: Explanation )
Mires are wetlands where a special type of soil called peat grows. In South Africa, they are rare and unique, occurring mainly in narrow stretches on the bottoms of river valleys and between dunes. They play a vital role in storing and purifying water and supporting biodiversity. Mires or peatlands, comprise a wide variety of ecosystems, including the coastal swamp forests of Maputaland and the river-valley vleis of the highveld.
Peat is partly decomposed, compressed organic material such as reeds and sedges. It is like a giant sponge, and is able to store a thousand times its weight in water. Wetlands, in general, are important water stores but peat holds up to ten times more water than other wetland soils, making it an extremely valuable resource in a water-scarce country.
Mires are also commonly known as bogs or fens and occur in broad, extensive stretches in the northern hemisphere where rainfall, temperature and landscape are more suitable for their formation. In the southern hemisphere, with its higher rates of evaporation and transpiration, mires are uncommon and usually occur as narrow ribbons along rivers. About 50% of the world’s wetlands are actually mires, but less than 1% of mires occur in the southern hemisphere. The peat of the southern hemisphere forms mostly from reeds and sedges, and in northern hemisphere it usually forms from sphagnum moss.
Research on southern African mires is limited and only the Maputaland mires are well researched. In this region, the role of peat in supporting biodiversity is complex. The lakes of this region owe their clear water to the purification function of peat along the streams, and the rare coastal swamp forests are also closely associated with the occurrence of peat. Some significant mires include Mfabeni, which runs alongside Lake St Lucia and plays an important water storage and supply role for the lake, Botswana’s Okavango Delta as well as Lake Fundutsi in Venda.
Threats to mires include changes in land use, pollution, increased development, dams, excessive water abstraction for urban use and agriculture, industrial timber and mining.
Threats – Farming in coastal swamp forests
The conflict between nature and people is most stark in the Maputaland region where the only soils in this sandy land that are suitable for vegetable gardening are in wetlands and on the edges of swamp forests. Most subsistence farmers in this high-poverty node rely on farming and fishing as their main source of food. HIV/Aids has added to the impacts on communities in the region and, in combination with the return of retrenched workers from the Gauteng mines and resurfaced tensions with the regional conservation body, the pressure on the natural system has increased dramatically since the early 1990s.
The incursion into swamp forests has been severe, with people employing slash-and-burn agricultural practices that would only have been acceptable a century ago when population pressures were smaller. Also, commercial farmers have made inroads into the swamps. All farming is prohibited in the swamp forests, but while there have been some prosecutions, the local authorities are concentrating more on finding alternative livelihoods and farming techniques. Various options are being investigated to ensure that both the swamp forests and the livelihoods of the Maputaland peoples are protected.
Threats – Peat mining
On the highveld, peat plays a particularly important role in water quality by removing heavy metals from water that is released from the mining industry, yet currently 45 000 cubic metres of peat is removed annually to supply the mushroom and horticulture industries. The soil is considered to be an ideal growing medium because of the very properties that make it valuable in nature – its ability to absorb water and release it slowly. While the horticultural industries in certain European countries depend on standardised peat-containing products, in South Africa the horticultural use of peat is unncessary and a host of alternatives exist, including byproducts of other industries, such as sugar-cane bagasse, tree bark and peanut shells. In the mushroom industry, tree bark has proven to be aneffective alternative and produces better mushrooms than peat at the same cost, with only marginally increased labour input.
The Peat Working Group, a co-operative governance effort between the national and provincial departments of water, agriculture, environment and conservation is responsible for making decisions around the issuing of permits for peat mining, but ultimately it is the national Department of Agriculture that has final responsibility. Although the activity has, for the most part, been overlooked over the past decade, recent media attention and a rapidly growing understanding about the importance of healthy wetlands for a healthy water resource (especially in the dry North West Province) has lead to growing public concern and support for an end to peat use in South Africa.
