Autecological aspects of the African timber tree Pterocarpus angolensis in support of its sustainable management

Pterocarpus angolensis (Kiaat, Muninga, Mukwa) is the most widely harvested timber species within the African Miombo ecoregion. Relatively little is known about the ecology and productivity of the species that grows only in natural mixed forests. The study aims to contribute to its sustainable management by modelling the occurrence and productivity in function of environmental factors and forest structure. Autecological methods are applied on a large dataset – both recent and historical - for southern Africa and a study area in the open forests of northern Namibia and southern Angola. The dissertation demonstrates that P. angolensis is a long-living, late successional species with weak competitive abilities during the juvenile phase. Its productivity in the study area compares well to that in other parts of the distribution range because of a relative high abundance and growth rate, however the limited amount of natural regeneration and the sensitivity of the species to climate change give causes for concern. Forest managers aiming for an improved and sustainable yield need to focus on more strict fire prevention measures, on increased firefighting, and on introducing silvicultural treatments such as assisted regeneration and thinning during the juvenile phases, especially in the most productive stands.The most widely harvested timber species within the Miombo ecoregion of Africa is Pterocarpus angolensis, also known as Kiaat and Mukwa. Relatively little is known about the ecology and productivity of the species that grows in natural mixed forests where forest management interventions rarely take place. The study aims to contribute to its sustainable management by modelling the occurrence and productivity in function of environmental factors and forest structure. A biographical model for the southern African region shows how the distribution is mainly influenced by rainfall amount and seasonality and hence is sensitive to climate change. Productivity, measured both by abundance and growth, is however much less influenced by climate but rather by forest structure and anthropogenic disturbances. In a study area in the Baikiaea - Pterocarpus forests of northern Namibia and southern Angola, the species is common and characterises one of the tree communities. Stem diameter growth in the study area is about 5.5 mm per year for all diameter classes. The dissertation demonstrates that P. angolensis is a long-living, late successional species that has weak competitive abilities, especially during the juvenile phase. It therefore performs well in the open, dry Baikiaea – Pterocarpus forests. Sustainable forest management needs to focus on fire prevention measures, assisted regeneration and silvicultural treatments such as thinning during the juvenile phases in the most productive stands.nrpages: 136status: publishe