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Peat resources in northern
KwaZulu-Natal wetlands:
Maputaland

P-L Grundling, H Mazus & L Baartman.

1998

Department of Environmental Affairs and Tourism. Pretoria

ISBN 0-621-27960-9


Managment Summary

The objectives of this project were to map, characterise and document the peat resources of Maputaland in terms of:

Peat is a natural organic resource presently being deposited in certain wetlands in South Africa. It forms an active part of the filter and storage capabilities of wetlands and plays a vital role, in the daily lives of local communities, as a water and horticultural resource. Peat is formed when decaying organic matter accumulates in moist, reducing and low energy environments, as in swamps.

The research was conducted in Maputaland, northern KwaZulu-Natal. This region was chosen as it hosts the most extensive wetlands and best developed peat deposits in South Africa. It is an underdeveloped region and rates as a RDP priority in terms of determining natural resources and has an apparent potential for peat mining.

Maputaland is part of the southern area of the Mozambique Coastal Plain (MCP), and is an area of high bio-diversity. It has a high concentration of endemic species, and has been classed as typical southern African Coastal Bushveld/Grassland Biome.

The Holocene peat deposits of Maputaland on the MCP are controlled by the underlying coastal dune topography of late Pleistocene age. This results in elongated peat bodies being deposited in interdune valleys, which parallel the current coastline. Wetlands are mainly ground water fed, with perched aquifers within the dunes draining to the interdune valley floors. Previous research by the Council for Geoscience (CGS) showed that peatlands occur in areas where the rainfall exceeds 600 mm/year and at elevations between sea level and 50 m above mean sea level.

266 peatlands occur within the MCP. Their thickness varies from 0.5 to 10 m and wetlands vary in size from a few hectares up to 8 800 ha. The peat resource is inferred to be 158 million m3, moist peat and it comprises 60% of South Africa's peat. Present estimates of peat volumes are as much as 30 - 50 % lower than previously reported.

More than 70% of Maputaland's peatlands are located in proclaimed conservation areas. Most peatlands outside and even some inside conservation areas are utilised by local inhabitants as a water, horticultural and biomass resource. Peat forms an active part of wetlands. In turn wetlands are an important source of fresh water, fodder and biomass for the local communities.

Uncontrolled commercial and domestic afforestation poses a threat to peatlands by disturbing the ecological balance. The manifestation of this disturbance is the drying out of wetland areas, which has a direct result on the viability of peat accumulation and preservation.

The physical characteristics and the ash content found throughout the peatland at Majiji, as well as at Lake Mgobezeleni indicate that in the past significant variations in environmental conditions did prevail. These variations are ascribed to long-term climatic changes. The observed trends suggest that variations in proximate analyses could be a common feature of all peatlands of the MCP. The conclusion drawn is that if too little sampling is done on a individual peatland, this could result in incorrect resource estimations and inaccurate classification of the commodity.

More than 50% of the peatlands have a high ash content (more than 30% ), about 30% have a medium content (15 - 30%) and 15% a low content. (less than 15%). This implies that the bulk of Maputaland peat has a low calorific value when compared to the low ash peats exploited in the Northern Hemisphere. Thus, compared to wood, South African peat does not really represent an alternative energy resource. This is especially true as Maputaland has an abundance of indigenous and exotic wood (woodlots).

Twenty-eight C14 ages at various depths have been determined for a selection of these peatlands. Maximum ages for individual peatlands vary from 770 years before present (BP) for the Mseleni peatland to 45 000 years BP for the Mfabeni peatland. Linear curves of depth v/s time for Mfabeni and Maputaland do not indicate compaction. Average accumulation rates for Maputaland and Mfabeni over the past 7 000 and 45 000 years are 1.06 and 0.45 mm/year respectively. If it is accepted that these two values are representative of the range of accumulation rates, a Maputaland peat layer of a certain depth can be dated roughly.

The linear curves of depth v/s time for Mfabeni indicate a clear break point at 10 000 years, which corresponds with the Holocene-Pleistocene boundary. This also corresponds with a sandy peat layer of 4 - 5 m, indicating a higher energy flow during the development of this wetland.

Botanical studies on twelve selected sites indicate that peat-forming flora tends to be monospecific. No uniformity exists in the vegetation cover of the selected peatlands and each site exhibits its own character. The most common peat-forming species are reed and/or papyrus with bulrush, sedges and ferns, swamp forest, grasses and sedges, mangroves and raffia palms. No endemics were noted on the peatlands. Papyrus/reed/sedge peatlands comprise 55%, swamp forests 30% and grass/sedge mires only about 15% of the peatlands of Maputaland.

The pollen-based generation rates vary from 0.26 - 18.5 mm/year and compare relatively well with the minimum and maximum C14 accumulation rates of 0.22 and 6.54 mm/year. These rates differ significantly with previously indicated current accumulation rates. This current finding on accumulation rates implies that the renewable resource potential of the Maputaland peatlands is negligible.

Pollen and spores of the examined profiles indicate that at the beginning of the Holocene hydromorphous forests existed and expanded in Maputaland. The forests were composed of Podocarpus, Celtis, Olea, Syzigium, Myrica and other trees and shrubs. These forests attained their maximum expansion about 5 000 BP. Since then the forests retreated northwards out of the area. The retreat of the forests possibly corresponds with climatic and hydrological fluctuations in the coastal region. The pollen data of the Mfabeni peatland show that a similar, hydromorphous forest occupied the area in the Pleistocene, about 43 000 BP. Forest retreats are noted in the dry and cold climatic phase between 33 000 and 20 800 BP.

The assemblages of pollen and spores of peat-forming plants in the examined profiles show successions from open water conditions through reed/sedge vegetation to swamp forest.

The following management guidelines are recommended:

The peat in South Africa occurs in ecologically sensitive wetland areas. Peat as a resource for clean drinking water is probably much more important than any of the other uses, especially in remote rural parts. Its value, in terms of commercial exploitation, must be weighed up against the value of permanent and clean water.


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Home This page is maintained by the South African Wetlands Conservation Programme and was last updated on 12 January 1999.