A Review of the Mires of Lesotho: Bogs or Fens?

The highlands of Lesotho form part of the Great Escarpment of Southern Africa and comprise largely of mountains (2000–3482 m a.s.l). These mountains contain many wetlands which, though small in extent, together could exceed thousands of hectares. These wetlands are peat-forming, therefore, mires. They form the headwaters of the Senqu River, a major tributary of the Orange-Senqu River basin that includes parts of Botswana, Lesotho, Namibia and South Africa. Earlier research described these wetlands as raised bogs based on high rainfall in the Maloti Mountains. More recent studies recognised the importance of groundwater as the driving force behind the hydrology of these mires. The present study attempts to review the contradictory information and classification of these mires in the literature and to establish an understanding on the functioning of these mire types in order to inform their protection and management. Second, this review aimed to explore the hydrology, chemical composition and morphology of the mires and revise their subsequent characterisation. Results indicated that these mires are dependent on surface and groundwater flows, and their water pH, varying between 5.0 and 7.0. Exchangeable cations (Ca 2+ , Mg 2+ , K + , and Na + ) are generally high, supporting vegetation that is highly productive and comprises of herbs and sedges. The weight of evidence would suggest that the mires of Maloti Mountains are fens and not bogs.