Browsing by Author "Ham, H."

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    Climate as possible reproductive barrier in Pinus radiata (D. Don) interspecific hybridisation
    (Marin Dracea National Research-Development Institute in Forestry, 2017) Ham, H.; Botha, A. M.; Kanzler, A.; Du Toit, B.
    Historically, interspecific hybridisation with Pinus radiata D. Don had limited success. The effect of environmental conditions and position of pollination bags in the tree were investigated as possible hybridisation barriers. The study was conducted in a P. radiata seed orchard in the Southern Cape (South Africa). Field data were compared to the climatic conditions at natural and commercial provenances of seven Mesoamerican Pinus species identified as possible hybrid partners. In vitro pollen studies were used to confirm whether interspecific crosses with P. radiata might be feasible within predefined climatic parameters. The temperature ranges for both top and northern side of P. radiata pine trees in the seed orchard was similar to the natural distribution of P. radiata, P. elliottii Engelm. and P. taeda L. in the USA. Results suggested that pollen of P. elliottii and P. taeda might be more suited to result in the successful pollination of P. radiata than the other Mesoamerican pine species tested in this study. Furthermore, the combination of minimum temperature and precipitation also showed a closer correlation to successful hybridisation with P. radiata for both P. elliotii and P. taeda. However, pollen tube elongation studies did not support these results, suggesting that mean temperature might not be the only determining factor of hybridisation success. Three circadian temperature models that mimic natural conditions were developed for Karatara and Sabie (Tweefontein, Witklip and Spitskop). These models will be tested in future in vitro studies to further evaluate temperature fluctuations between day and night regimes as a possible reproductive barrier limiting hybridisation success between P. radiata and other Mesoamerican pine species.
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    IUFRO Precision Forestry Symposium
    (2010) Ackerman, P. A.; Ham, H.; Lu, C.
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    Sustainable forest management in Africa : some solutions to natural forest management problems in Africa
    (Stellenbosch University, 2008-11) Geldenhuys, C. J.; Ham, C.; Ham, H.
    The bulk of African forests occur in the countries of Central Africa (37%) and Southern Africa (28%). The forests vary from tropical rainforests to warm-temperate forests (at higher altitudes and latitudes) to tropical-subtropical deciduous woodlands and wooded savannas. The forests constitute an immense value but are under severe pressure for harvesting of diverse timber and non-timber forest products for sustainable livelihoods and for clearing for agricultural production and infrastructure. Much information deal with the negative aspects of forest cover loss through degradation and deforestation but more information surfaces on other aspects of forest cover changes, including forest gains, and positive issues of forest management. Relatively little information is available on the assessment of forest productivity and stand dynamics (recruitment, growth and mortality). This knowledge gap is compounded by the practicing of little to no sustainable forest management, and little to no integration between management for forestry, agriculture and nature conservation, for timber and non-timber products, or for industry and rural livelihood needs. The growing population and recent upturn of many African economies provide rapidly growing domestic markets for forest products and services, but there is no assessment of the capacity of the African forests to produce them. Climate change scenarios for Africa and its forest ecosystems add new challenges with great implications for the forests, household livelihoods, and national and economic development; these need to be incorporated into planning climate change response strategies, nationally and internationally. Perspectives on the role of forests in development have evolved significantly since the Rio Summit in 1992. In many African countries, there is a growing recognition of the need to address the issues of poverty in national development programs, such as Poverty Reduction Strategies to meet the Millennium Development Goals and objectives of the New Economic Partnership for Africa’s Development (NEPAD). Some global initiatives include Tropical Forest Action Plans (TFAPs), National Forestry Programmes (NFPs), the Intergovernmental Panel on Forests (IPF), Intergovernmental Forum on Forests (IFF), and the United Nations Forum on Forests (UNFF). However these initiatives have had little impact on reversing the declining capacity to manage African forests. In part, this has been ascribed to the low participation of Africa in international dialogues on relevant forestry issues and the lack of a forum on the African continent that could facilitate African stakeholders to dialogue on these and other issues. Technical and scientific exchanges in Africa on both the implications and applications of sustainable forest management for adaptation to climate change without compromising forest ecosystem resilience, and their critical mitigation activities, are therefore important. An Africa-wide dialogue on issues of sustainable forest management needs to be pursued to find African solutions to African problems in the context of sustainable management of the African natural forest ecosystems. What is the true state of African forests and their management? Do the African forest ecosystems have unique features that need to be incorporated into sustainable forest management strategies? Are there scientific and traditional knowledge systems of the African forest ecosystems to guide the world on sound multiple-use, multi-disciplinary and integrated forestry-agriculture-conservation strategies and actions? The International Symposium on Sustainable Forest Management in Africa was hosted in Stellenbosch, South Africa, from 3 to 7 November 2008, to facilitate a discussion of these issues. It was organized by the Department of Forest and Wood Science, Stellenbosch University, and the Commercial Products from the Wild Group, in collaboration with the Copperbelt University (Zambia), Eduardo Mondlane University (Mozambique), the Research Institute in Tropical Ecology of the National Centre for Scientific and Technological Research (Gabon), the Centre for International Forestry Research (CIFOR), the International Union of Forest Research Organisations (IUFRO), and the Food and Agricultural Organization of United Nations (FAO). The objectives for the symposium was to • bring together national, regional and international policy- and decision-makers, forest scientists, forest ecologists, planners and resource managers (public and private sectors), rural communities, farmers and individuals, the education community, consumers of forest/tree-derived products, NGOs with forest, environment, social and other foci of work, and others; • share information, concepts and ideas on a broad range of topics (papers and posters); • facilitate networking among diverse stakeholders in forestry in Africa; • facilitate development of specific programs, projects and activities that address priority issues, and facilitate coordination, collaboration, dialogue and funding; • facilitate advocacy activities with the potential to raise the profile of forestry, to highlight threats to forest resources and the environment, and to champion better management of African forests. The symposium was attended by 102 participants from 23 countries representing 41 institutions. A total of 53 oral papers were presented. This collection of symposium papers includes the four keynote presentations, and 38 papers presented in seven themes. The mid-symposium excursion took participants to the Newlands urban forest within the Table Mountain National Park on the Cape Peninsula, managed by the South African National Parks. Today 3.4 million people live in and around Cape Town, with associated pressures on the natural areas with their very small patches of natural forest. The forests are affected (positively and negatively) by commercial timber plantations, controlled and uncontrolled fires, outdoor recreation, and illegal plant and bark collection mainly for traditional medicine. The visit focused on options to use the stands of plantation and invader plant species to rehabilitate natural forest, and thereby recover the regeneration and population status of the tree species negatively impacted by bark harvesting. The post-symposium tour visited the Southern Cape Afrotemperate Forests, the largest natural forest area in South Africa, in collaboration with South African National Parks, who manages most of those forests. The visit focused on forest ecological research and the sustainable multiple-use forest management in which ecosystem conservation (species and processes) remains the overriding management objective. Secondary objectives included the utilization of timber, ferns and medicinal plants, outdoor recreation, research and community development through participatory forest management (PFM). Management of these areas received international recognition through FSC certification in December 2002. We hope that the enthusiasm with which participants took part in the deliberations and discussions will continue to stimulate research and sustainable forest management in Africa, with more regular dialogue within Africa to find African solutions for African problems in sustainable management of the African forests for the benefit of African Society.