Vegetation change analysis and ecological recovery of the copperbelt Miombo woodland of Zambia

Syampungani, Stephen (2009-03)

Thesis (PhD (Forest and Wood Science))--University of Stellenbosch, 2009.

Thesis

ENGLISH ABSTRACT: The study aimed at developing a new understanding of the Miombo woodland recovery dynamics when exposed to single tree selection, slash & burn agriculture and charcoal production. Five specific studies were conducted to examine different parts of this overall study: Miombo woodland utilization, management and conflict resolution among stakeholders; speciesstem curves as a tool in sampling the development of Miombo woodland species richness in charcoal and slash & burn regrowth stands over time; the impact of human disturbance on the floristic composition of Miombo woodland; regeneration and recruitment potentials of key Miombo woodland species after disturbance; and age and growth rate determination using selected Miombo woodland species. Different methods were developed for each specific study. The study of woodland utilization and management employed semi-structured and key informant interviews. STATISTICA statistical package version 6.0 was used for data collation and analysis. Chi-square tests were used to show levels of significance in differences that existed between different user groups. Species-stem curves were used to determine the sample size to assess Miombo woodland dynamics in regrowth stands after slash & burn and charcoal production, and a fixed-area method was used for the mature woodland stands. The study sites in each of three study areas were selected to represent ages ranging from 2 to 15+ years since each disturbance was terminated. The undisturbed woodland was chosen to act as a control. Various analyses using the STATISTICA statistical package and CANOCO version 4.0 were conducted to understand responses of Miombo woodland to these different disturbances. The research revealed that single tree selection, slash & burn agriculture and charcoal production are the main forms of Copperbelt Miombo woodland utilization which will always be there. Additionally, the the Miombo woodland stands were characterized based on the size class profile they exhibit on exposure to human disturbance factors through forest utilization. The characterization has revealed that the woodland is dominated by light demanding species. As such single tree selection harvesting does not support the regeneration and establishment of the timber species which are canopy species under shade conditions. This implies that selection harvesting of timber species, although it appears to be a non event in terms of disturbance at stand level may be a disaster at population level. The study also revealed that clearing of the woodland for either slash & burn agriculture or charcoal production results in enhanced regeneration and establishment of the dominant Miombo woodland species. The study concludes that charcoal production and slash & burn agriculture are important components to which the woodland ecosystem is adapted. As such these disturbance factors may be considered as incorporated disturbances. It is recommended from the study that woodland utilization and management should integrate charcoal production and slash & burn agriculture into forest management. Cutting cycles should be based on growth rate of the selected species. Timber species harvesting should go side by side with these disturbance factors so as to open up the canopy in order that maximum sunlight can reach the regeneration stock. The study also brings out the other management and utilization opportunities (such as managing for Uapaca kirkiana and Anisophyllea boehmii fruits) that arise from different development stages of the woodland. Lastly, it is recommended to ascertain the optimum gap sizes for both charcoal production or slash & burn agriculture which would still support the Miombo woodland recovery.

AFRIKAANSE OPSOMMING: Hierdie studie is gedoen om ‘n nuwe begrip te ontwikkel vir die hersteldinamika van Miombo boomveld na onderwerping aan enkelboomseleksie, kap & brand lanbou en houtskoolproduksie. Vyf spesifieke studies is gedoen om verskillende komponente van die total studie te ondersoek: benutting, bestuur en konflikresolusie tussen gebruikers van Miombo boomveld; species-stam kurwes as ‘n instrument in die bemonstering van die ontwikkeling van Miombo boomveld species-rykdom oor tyd na afloop van houtskoolproduksie en kap & brand landbou; die impak van menslike versteuring op die floristiese samestelling van Miombo boomveld; verjongingspotensiaal van sleutelsoorte in Miombo boomveld na versteuring; en bepaling van ouderdom en groeitempo in ge-selekteerde Miombo boomveldsoorte. Verskillende metodes is ontwikkel vir elke spesifieke studie. In die studie van boomveldgebruik en –bestuur is semigestruktureerde en sleutel-informant onderhoude gebruik. Die STATISTICA statistiese packet weergawe 6.0 is gebruik vir dataverwerking en -ontleding. Chi-kwadraat toetse is gebruik om vlakke van betekenisvolheid te toon wat bestaan tussen verskillende gebruikersgroepe. Speciesstamkruwes is gebruik om monstergrootte te bepaal vir die evaluering van Miombo boomvelddinamika in hergroeiopstande na kap & brand en houtskoolproduksie, terwyl vastegrootte persele gebruik is vir volwasse boomveldopstande. Die studieplekke in elk van drie studiegebiede is geselekteer om verskillende ouderdomme tussen 2 en 15+ jaar na be-eindiging van die versteuring te verteenwoordig. Onversteurde boomveld is gebruik as kontrole. Verskeie ontledings, met die STATISTICA statistiese pakket en CANOCO weergawe 4.0 is gedoen om die reaksie van Miombo boomveld op die verskillende versteurings te verstaan. Die navorsing het getoon dat enkelboomseleksie, kap & brand landbou en houtskoolproduksie is die hoof vorme van Copperbelt Miombo boomveld benutting wat altyd daar sal wees. Verder is die Miombo boomveldopstande gekarakteriseer gebaseer op die grootteklasprofiel wat hulle vertoon na menslike versteuringsfaktore in die vorm van boomveldbenutting. Die karakterisering het getoon dat die boomveld gedomineer word deur ligeisende soorte. Daarom ondersteun enkelboomseleksie nie die verjonging en vestiging van die dominante houtsoorte wat kroonsoorte is onder skadutoestande. Dit impliseer dat selektiewe inoesting van houtsoorte, alhoewel dit voorkom as ‘n onbelangrike gebeurtenis in terme van versteuring op opstandsvlak, ‘n ramp is op populasievlak. Die studie het ook getoon dat skoonmaak van die boomveld vir of kap & brand landbou of houtskoolproduksie, lei tot verbeterde verjonging en vestiging van die dominante Miombo boomveldsoorte. Die studie lei tot die gevolgtrekking dat houtskoolproduksie en kap & brand landbou belangrike komponente is waarby die boomveldsisteem aangepas is. Daarom kan hierdie versteuringsfaktore beskou word as ingeslote versteurings. Vanuit die studie word daarom aanbeveel dat boomveldbenutting en –bestuur houtskoolproduksie en kap & brand landbou binne die bosbestuur integreerd moet word. Kapsiklusse moet gebaseer word op die groeitempos van geselekteerde soorte. Inoesting van houtsoorte moet saamloop met hierdie versteuringsfaktore sodat die kroondak oopgemaak kan word sodat maksimum sonlig die verjonging bereik. Die studie bring ook na vore die bestuur en benuttingsgeleenthede (soos bestuur vir die vrugte van Uapaca kirkiana en Anisophyllea boehmii) wat voorkom in verskillende ontwikkelingstadiums van die boomveld. Laastens word aanbeveel dat die optimum openinggroottes vir beide kap & brand en houtskoolbereiding wat herstel van Miombo boomveld ondersteun, bepaal.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/4833
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