Conceptual decision-making framework for the sustainable harvesting of forest and woodland species for medicinal tree bark in southern Africa

Abstract

Tree bark is widely used in traditional medicine in southern Africa. The growing demand for medicinal bark requires scientifically sound harvest systems for sustainable use. A conceptual framework and decision matrix are presented to aid forest managers in selecting the most appropriate system for the sustainable harvesting of particular species. The conceptual framework is based on the results of experimental bark harvesting of selected forest and woodland tree species in southern Africa, where tree response to bark stripping was assessed. The extent and rate of bark regrowth and the susceptibility of the exposed wood to fungal and insect damage, are of particular importance to assess harvest options. The decision matrix groups species based on tree response to bark stripping, and identifies the most appropriate harvest option for a particular species. Species-specific harvest prescriptions are formulated and alternatives to strip harvesting are identified where avoidance is advised. The conceptual framework and decision matrix were applied to forest woodland species on which experimental bark harvesting was conducted in Malawi, South Africa and Zambia. Of the 22 species studied, 10 have the potential for strip harvesting, based on extent of bark regrowth and susceptibility to fungal and insect damage. These were assessed further in terms of prescriptions for strip harvesting. For the remainder, full-tree harvesting in a single-tree selection system would be the most viable harvest option. Alternatives to strip and full-tree harvesting are also discussed.