Impacts of local-level utilization pressure on the structure of mopane woodlands in Omusati region, Northern Namibia

Abstract

A comparative analysis of mopane woodland structure under different utilization pressure was done in Omusati region, northern Namibia. Heights, basal area, biomass and densities of trees, shrubs and stumps were compared between a game park, densely-populated (central) and sparsely-populated (western) areas. Heavy utilization significantly reduced tree basal area, biomass and plant densities in central Omusati, leading to an unsustainable situation. Woodland recovery from previous disturbance in the game park has been slow. Contrary to expectation, there were fewer dead stumps in central area because of continual harvesting due to firewood scarcity. Height structure differed significantly with more than expected numbers of plants in the ≤ 1 m, 1.1 to 2 m and less than expected plants in the 3.1 to 4 m and 4.1 to 5 m height classes in central Omusati. More than expected numbers of trees were recorded in 4.1 to 5 m height class in western area and in 2.1 to 3 m and 3.1 to 4 m height classes in Game Park. This indicates over-harvesting of medium-sized trees in central Omusati. Mopane regenerates profusely through coppicing. However, no relationship existed between stump size and number of shoots due to continual harvesting of shoots, especially in central area. Proper coppice management and pollarding strategies should be implemented to improve the situation. Key words: Colophospermum mopane, coppicing, Omusati, woodland structure, woodland utilization.