Abstract Gradient, which is largely considered to be related to water level in mires, is referred to as a microtopographic mud bottom to carpet to lawn to hummock level gradient or the hummock level to intermediate level (lawn) to flark level gradient. The relationship of this vegetation gradient to various physical water level characteristics was studied. The general classification used in the present summary paper divides the aro vegetation of the inland of Northern Ostrobothnia into two main groups: (a) treeless fen aro vegetation (Juncus supinus, Carex lasiocarpa, Rhynchospora fusca, Molinia caerulea) and (b) heath aro vegetation (Polytrichum commune). The first group (a) was divided into fen aro wetlands with an approximately10 cm peaty layer at most and into aro fens with a peat layer thicker than 10 cm. The treatment of the water level gradient was divided into three main groups. (1) The mean water level correlated with mire surface levels (microtopographic gradient) within mires with slight water level fluctuations and partly within mires with considerable water level fluctuations. (2) Three habitat groups could be distinguished on the basis of the range of water level fluctuation i.e. mires with slight water level fluctuations, mires with considerable water level fluctuations and the aro vegetation with extreme water level fluctuations. (3) The timing of water level fluctuations indicated that there are different types of patterns within aro wetlands, the seasonal pattern being mainly a response to yearly snow melt and the several-year-fluctuation pattern being related to the regional groundwater table fluctuation in mineral soils (heath forests). A link was suggested between the stability of the water regime and peat production in local aapa mire – aro wetland environments. From the point of view of peatland plants the direction of variation from a stable to an unstable water regime in aapa mire – aro wetland environments represents a transition towards more and more harsh ecological conditions, partly forming a gradient through natural disturbance. A qualitative functional model was provided for the mire – aro wetland systems of Northern Ostrobothnia. The model supposes differences in the characteristics of peat between two functional complexes within a mire system. Finally, the model for local mire – aro wetland systems was converted to a general from: diplotelmic (acrotelm) mires were divided into two subtypes (diplotelmic water stabilization mires, diplotelmic water fluctuation mires) and the relationship of those subtypes to percolation mires and seasonal wetlands was considered.

Wetlands within South Africa are an important source of water and nutrients necessary for biological productivity and often the survival of the local people. In a country where the rural communities depend on wetlands for their day to day provision of water, food and materials it has become necessary to understand the functions within wetland systems, so that proper conservation measures can be applied in order to protect and ensure the sustainable use of wetlands. Due to the fact that South Africa has a semi arid climate, thereby affecting the availability of water it is sensible that studies are under-taken in which, more is explored about the water resources, the protection as well as the sustainable use of the wetlands within the region. Despite the fact that the total area which wetlands cover in South Africa is relatively small, the functions which they provide is of fundamental magnitude not only to wildlife but also as an essential part of the human life support system. Wetlands have the ability to regulate regional flow regimes and are often situated in areas of impeded drainage, which may contribute to the regulation of water. It is thus plausible that if headwater/palustrine wetlands are destroyed, many of the streams and rivers which under normal circumstance are perennial, would not only become non- perennial but the consequence of a drought would be far more severe, as well as increasing the risk in flood damage further down the river. In Giants Castle Game Reserve, situated in the KwaZulu-Natal Drakensberg, several palustrine wetlands where studied to identify the geomorphic attributes which contribute to the origin and maintenance of these wetlands. An added motive for the study was the fact that, according to Ramsar, one of the reasons for conserving the Drakensberg wetlands is to ensure the maintenance and production of water quality to KwaZulu-Natal. Seven wetlands within the Boesmans river upper catchment were identified and studied. Soil investigations were undertaken in an effort to determine the driving forces behind the origin and maintenance, as well as to improve the understanding relating to the functioning of the wetlands. The geomorphic attributes which were identified as being important to the genesis and maintenance of wetlands were found to be the following: low relief, soil piping within wetlands, sediment trapping ability of wetlands, the surface roughness of wetlands, channeling within wetlands, organic matter accumulation as well as geological barriers within wetland system. The adaptability of Longmore’s (2001) Hydro-Geomorphic classification to different catchment areas was also tested and was found suitable for these wetlands, although the influence of piping on wetlands evidently requires further investigation and incorporation into classifications. / Dissertation (MA)--University of Pretoria, 2006. / Geography, Geoinformatics and Meteorology / MA / Unrestricted