Coert J. Geldenhuys

Managing forest complexity through application of disturbance–recovery knowledge in development of silvicultural systems and ecological rehabilitation in natural forest systems in Africa

How can we accommodate the diversity in tree species and sizes in mixed-species/size/age stands in the sustainable management of natural forests and woodlands in Africa for diverse timber and non-timber forest products and services, and during rehabilitation of degraded forests? The evergreen moist tropical to warm-temperate forests, from the equator to 34°S, generally function through relative shade tolerance. The tropical, strongly seasonal, drier deciduous woodlands generally function through adaptation to fire and/or grazing/browsing. Silvicultural systems, when implemented, are often not aligned with the ecological characteristics of the particular forest systems or the specific targeted species. This paper presents the concept of using the basic disturbance–recovery processes, with recovery development via stand development stages, as the basis for the development of silvicultural systems suitable for maintenance of forest complexity. Grain analysis and stem diameter distributions, analysed from resource inventories, are used to determine the specific shade- or fire-tolerance characteristics of key economical and ecological tree species. The gained knowledge of the ecosystem and species characteristics (including modes of regeneration, i.e. from seed or vegetative regrowth) and processes is used to simulate the ecological disturbance–recovery processes through the development of mixed silvicultural systems, such as a single-tree selection system, a group felling system and a coppice management system in the same forest. Very similar concepts are used to develop rehabilitation strategies to recover the processes towards regrowth stands of diverse species and structure: through stands of introduced plantations and invader tree species; and through early regrowth stages in deciduous woodlands and evergreen forests, after fire, slash-and-burn traditional agriculture, charcoal production or open-cast mining.

Response of Ocotea bullata, Curtisia dentata and Rapanea melanophloeos to medicinal bark stripping in the southern Cape, South Africa: implications for sustainable use

Tree bark is commonly used for traditional medicine in southern Africa and further afield. Increasing demand and commercialisation have resulted in the overexploitation of many species, posing a major challenge to forest managers to develop mechanisms for sustainable resource use. An experimental bark harvesting research project was initiated in the southern Cape, South Africa, to inform best practices for bark harvesting based on tree response to bark stripping. The species selected for the study, Ocotea bullata, Curtisia dentata and Rapanea melanophloeos, are much sought after and well represented in southern Cape forests. The treatment entailed removing vertical strips of bark, 1 m in length and of different strip widths, covering the full range of tree size classes ≥10 cm DBH. The treatments were applied during two seasons, winter and summer. Evaluations were done every six months to assess tree response to bark stripping in terms of bark regrowth through phellogen edge and sheet development, and susceptibility to insect and fungal damage. The results show a differential response of tree species in terms of phellogen edge and sheet growth, as well as susceptibility to fungal and insect attack. Rapanea melanophloeos was the most vulnerable to fungal and insect damage and displayed little bark regrowth following wounding. Curtisia dentata showed best bark regrowth through sheet development. Only O. bullata, though, showed adequate bark regrowth (through edge development) to allow for sustainable strip harvesting. Bark regrowth is influenced by season of stripping, although this is difficult to define considering the wide range of environmental and other factors affecting tree response to bark removal. Smaller trees are more vulnerable to bark stripping, especially with a wide strip, with poorer bark regrowth than bigger trees.

The use of species-stem curves in sampling the development of the Zambian miombo woodland species in charcoal production and slash-and-burn regrowth stands

The use of fixed-area plot methods was considered unsuitable to compare the responses and recovery over time of different miombo woodland species to different land-use practices (i.e. charcoal production and slash-and-burn agriculture). Young regrowth stages have many stems and the older more advanced stages have fewer stems. Different land-use practices in miombo woodland impact on the recovery potential of the woodlands. Timber harvesting does not result in significant change in stocking of the woodland compared to changes in regrowth after vegetation clearing for either charcoal production or slash-and-burn agriculture. After such clearing the woodland regrowth changes from an initial high stocking to a much lower stocking over time. This study in Zambian Copperbelt miombo woodland assessed the feasibility to use species–stem curves to determine the optimum number of stems or plants to record at a sampling point in order to compare species recovery over time in regrowth stands 2–15 years after ending the slash-and-burn and charcoal production activities. The results show that 34 and 31 stems or plants for slash-and-burn and charcoal production regrowth stands, respectively, would adequately capture the representative number of species to describe the plant community of these regrowth stands. The research has also revealed that the use of fixed-area methods would result in the measuring of too many plants in one category (younger stands) with too few in the other category (advanced stands). Therefore, the study explains why, and concludes that, variable plot size is an appropriate method for sampling species recovery in regrowth stands.

Managing Southern African Woodlands for Biomass Production: The Potential Challenges and Opportunities

This chapter defines what extensively managed woodlands are and presents the general distribution of southern African woodlands highlighting the important forest types and species. Potential productivity is presented with available data from both long term permanent sample plots and space-for-time experiments; highlighting the paucity of data due to limited research in biomass estimates and therefore productivity; and problems associated with the estimation of biomass due to lack of standard methods for assessment in extensively managed woodlands. The chapter therefore points to the importance of using modeling to develop methods for whole woody biomass estimates in extensively managed woodlands. In addition, the increased demand for biomass energy may impact negatively on the environment due to over-harvesting; and so this chapter further highlights the link to the sustainable management of the biomass especially with respect to non-timber forest products in extensively managed woodlands.

Linking forest tenure and anthropogenic factors with institutions and the effectiveness of management in Mpigi forests, central Uganda

This paper reveals the investigated effects of forest tenure and physical and socioeconomic correlates on conservation and management of forests in the Mpigi District, central Uganda. Tree diversity was surveyed in 156 nested plots of 20 m × 50 m. Tree density, mean diameter at breast height (dbh) and evidence of illegal forest use were used as indicators of forest conditions and the efficacy of forest management. The stand structure characteristics (i.e. tree density, mean dbh and basal area of trees) were higher in private forests than in Central Forest Reserves (CFRs) and Local Forest Reserves (LFRs) due to effective regulation and monitoring measures by private forest owners. Diameter size for all species combined followed the inverse J-shape, typical of mixed-age stands. Forests in close proximity to a dense human settlement and far from roads were heavily used, suggesting a high likelihood of population pressure on forest resources and limited capacity of forest owners and managers to effectively control and halt degradation in forests far away from agencies. A high proportion of plots in LFRs (81%) had signs of illegal forest use compared to CFRs (67%) and private forests (45%), even in LFRs and CFRs that were located closer to forest management institutions. Tenure alone did not ensure that forest condition is maintained but other factors such as distance to maintained roads and human pressure on the resource were also important. Management of forests in Mpigi needs to recognise and adequately address human impacts and improve the capacity of forest agencies and owners to monitor and regulate harvesting of forest produce.

The socioeconomic status of the non-timber forest product subsector in Swaziland

A wide spectrum of non-timber forest products (NTFPs) generally has a remarkable contribution to the household economy in rural areas. Most communities make a living either through their domestic or commercial use. The objective of this study was to review the current status of the NTFP sector and further compile an up-to-date list of major use categories of NTFPs. The review of the national study on the NTFP sector indicate an average annual value of the selected NTFPs groups of between US

Miombo Woodland Utilization and Management, and Impact Perception among Stakeholders in Zambia: A Call for Policy Change in Southern Africa

19.8 million and US

Spatial changes in forest cover on the KwaNibela Peninsula, St Lucia, South Africa, during the period 1937 to 2008

79 million with a median value of US

Die-back of kiaat (Pterocarpus angolensis) in southern Africa: A cause for concern?

49.38 million. The most important group from an economic point of view is medicinal plants with an average annual value of US

Variation in seed rain from Widdringtonia whytei growing in different conditions on Mulanje Mountain in Malawi

32.1 million, followed by fuel wood with an estimated annual value of US