Dissertations / Theses on the topic 'Dissertations – Forest and wood science'

Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2009.
ENGLISH ABSTRACT: Wood waste, when used for gasification is commonly pressed into briquettes, especially if no uniform particle size is available. This densification reduces problems of handling, storage and transportation and improves the combustion performance because of a more uniform fuel size. Briquettes have to be mechanically strong enough to be handled. Cohesive strength is provided by residual moisture and lignin present in the wood. The lignin acts as a natural binder. However, the briquetting process becomes more complicated if one wants to add other agricultural waste products that do not necessarily contain lignin as binders,, In this study we have investigated various briquetting process parameters, such as mixing ratios of briquettes containing wood chips, grape skins and chicken litter, moisture content and press time. The aim was to determine the optimum process parameters that allow the production of briquettes, containing a blend of biomaterials that are mechanically stable to allow further handling but yield high energy content at the same time.
AFRIKAANSE OPSOMMING: Wanneer houtafval vir vergassing gebruik word en die partikelgrootte daarvan varieer, word die materiaal normaalweg in ’n brikket gedruk. Brikketvorming vergemaklik opberging, hantering en vervoer. Weens die meer uniforme grootte en vorm van die brikkette is verbranding daarvan heelwat meer doeltreffend. Brikkette moet egter meganies sterk genoeg wees om hanteer te kan word. Die kohesiewe sterkte word deur residuele vog en lignien, wat as natuurlike bindmiddel in hout aanwesig is, verskaf. Indien ander materiale soos landbouafval, wat noodwendig geen lignien bevat nie egter gebruik word, word die brikketvormingsproses meer kompleks. In hierdie ondersoek is verskeie brikketvormingsparameters evalueer. Mengverhoudings van brikkette wat houtspaanders, druiwedoppe en hoendermis bevat, asook invloed van materiaalvoggehalte en druktyd is bestudeer. Die doel was om die optimale materiaal- en prosesparameters vas te stel wanneer ’n mengsel van biomateriale gebruik word om brikkette te lewer wat meganies sterk genoeg is maar steeds die hoogste energieopbrengs lewer.
Centre for Renewable and Sustainable Energy Studies

Thesis (PhD(For))--Stellenbosch University, 2014.
ENGLISH ABSTRACT: Pinus patula is the most intensively planted conifer in the tropics and sub‐tropics. In South Africa Pinus patula plantations are the main saw‐log resource for structural lumber production. Improved intensive silvicultural practices and tree breeding have resulted in marked increases in the rate of growth. To reap the financial benefits of the faster growth, plantation managers are more and more inclined to reduce rotation ages, which inevitably results in the production of higher proportions of juvenile wood at final harvest, and lumber which often does not meet the minimum requirements for stiffness for structural lumber. Knowledge of the variation and the accurate prediction of the mechanical properties of the timber of standing trees can have various benefits for growers and processors of trees. It can be used for tree allocation to different processing facilities, for processing production planning, and to assist tree breeders to screen and select for superior breeding material. The objectives of this study were (1), to examine the within‐ and between‐tree variation in wood properties of young South African grown Pinus patula trees known to have important impacts on the suitability of sawn lumber for structural purposes and (2), to develop empirical prediction models for the flexural lumber properties from standing Pinus patula, based on variables that could be assessed non‐destructively from standing trees. Sample material was obtained from 170 trees (16‐20 years old) established in 17 compartments along the Mpumalanga escarpment of South Africa. A large number of variables which could be obtained non‐destructively from the trees while they were still standing, were measured. The trees were subsequently felled and two logs, 2.1 m in length, were extracted from each tree at two height positions. The 340 logs were processed into 1402 pieces of lumber for further measurements and destructive testing. Results showed that the mean modulus of elasticity measured on edge (MOEedge) was far below the limits set for structural grade softwood timber in South Africa. All the desirable properties for structural lumber improved with distance from the pith with the exception of the 5th percentile value for modulus of rupture (MOR), which was higher at the pith than for the boards processed adjacent to the pith. Boards processed from the lower part of the stem were superior in most of the important properties compared to those higher up in the stem. Separate multiple regression models for predicting the average dynamic MOE (MOEdyn) of individual boards, trees and compartments were developed. The models managed to explain 68%, 60% and 95% of the variation in MOEdyn respectively. The models developed for MOR explained 40% and 42% of variability at board and tree level respectively. At compartment level, 80% of the variation in the 5th percentile MOR value could be explained by the model. Sensitivity analyses showed that site index at base age of 10 years, acoustic time‐of‐flight, wood density and ring width were the most influential variables in the MOE models. The models indicated that tree slenderness during early growth seems to play a major role in determining the dynamic MOE and MOR of lumber. This is in agreement with Euler’s buckling theory and the bending stress theory. Microfibril angle (MFA) and density were measured on radial strips taken from a sub‐sample of trees with the Silviscan 3 technology. The mean microfibril angle per year ring in Pinus patula varied between 7o and 29o. In general MFA decreased with distance from the pith and height above ground level. A multiple regression model including microfibril angle, density and ring width explained 71% of the variation in the dynamic MOE of boards. Sensitivity analysis on the model showed that microfibril angle and density had roughly equal influences on predicting the MOEdyn of Pinus patula boards.
AFRIKAANSE OPSOMMING: Pinus patula is die mees aangeplante naaldhoutspesie in die tropiese en sub‐tropiese areas van die wêreld. Dit is die grootste bron van saagblokke vir die produksie van strukturele hout in SA. Intensiewe boskultuurpraktyke en boomteling het gelei tot ‘n merkbare verhoging in die groeitempo van die spesie. Plantasiebestuurders is gevolglik geneig om rotasie‐ouderdomme te verlaag, wat lei tot ‘n groter persentasie jeughout wat nie aan die minimum styfheidvereistes van strukturele hout voldoen nie. Kennis van die variasie en die akkurate voorspelling van die meganiese eienskappe van staande bome kan voordele inhou vir beide die verbouers en verwerkers van bome. Dit kan byvoorbeeld van hulp wees met die toewysing van bome aan verwerkingsfasiliteite, vir produksiebeplanning, en vir ondersteuning met die keuse van teelmateriaal vir boomtelers. Die doelwitte van hierdie studie was (1), om die binne– en tussenboomvariasie in die houteienskappe, wat ‘n bepalende invloed het op die geskiktheid van jong Suid Afrikaanse Pinus patula bome vir strukturele hout produksie, te ondersoek en (2), om empiriese modelle vir die voorspelling van die buigeienskappe van planke te ontwikkel, gebaseer op veranderlikes wat niedestruktief op staande Pinus patula bome ge‐evalueer is. Monsters vir die studie is verkry vanaf 170 bome (16‐20 jaar oud), geplant in 17 vakke op die Mpumalanga platorand van Suid Afrika. ‘n Groot aantal veranderlikes is nie‐destruktief gemeet op die staande bome waarna die bome gevel is en twee saagblokke, 2.1m in lengte, is op twee hoogte posisies uit elke boom verwyder. Die 340 blokke is verwerk tot 1402 planke vir verdere metings en destruktiewe toetse. Resultate het getoon dat die gemiddelde modulus van elastisiteit gemeet op die dwarskant (MOEedge) aansienlik laer was as wat vereis word vir strukturelegraad hout in Suid Afrika. Al die gewenste eienskappe het toegeneem met afstand vanaf die murg behalwe die 5de persentiel breekmodulus (MOR), wat hoër was vir murgplanke as vir aangrensende planke. Planke afkomstig van die laer dele van die stam het oor die algemeen beter eienskappe gehad as planke afkomstig van die hoër dele. Veelvuldige regressiemodelle kon 68%, 60% en 95% van die variasie in die gemiddelde dinamiese MOE (MOEdyn) op die vlak van onderskeidelik individuele planke, bome en vakke verklaar. Die modelle vir MOR kon 40% en 42% van die variasie op onderskeidelik plank‐ en boomvlak verklaar. Die model vir 5de persentiel MOR van vakke kon 80% van die variasie verklaar. ‘n Sensitiwiteitsanalise het aangetoon dat groeiplekindeks op ouderdom 10, akoestiese vlugtyd, digtheid en jaarringwydte die belangrikste veranderlikes was wat MOEdyn beïnvloed het. Die modelle het aangetoon dat die slankheid van bome tydens vroeë groei vermoedelik ‘n belangrike invloed op die MOEdyn en MOR van planke het. Dit is in ooreenstemming met Euler se knikteorie en die buigsterkteteorie. Die mikrofibrilhoek en digtheid van ‘n steekproef van die bome is gemeet met die Silviscan 3 apparaat. Die gemiddelde mikrofibrilhoek per jaarring het tussen 7 o en 29o varieer. Hierdie variasie was hoofsaaklik afhanklik van boomhoogte en aantal jaarringe vanaf die murg. ‘n Veelvuldige regressiemodel wat mikrofibrilhoek, digtheid en jaarringwydte insluit, kon 71% van die variasie in MOEdyn verklaar. ‘n Sensitiwiteitsanalise op die model het aangetoon dat mikrofibrilhoek en digtheid ongeveer ewe belangrik was wat betref hulle invloed op die voorspelde MOEdyn van Pinus patula planke.

Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2009.
jfl2010
ENGLISH ABSTRACT: The past forest management strategies in Zambia did not allow participation of local communities in the management of Forest Reserves and sharing of benefits. The Zambia forest sector was reviewed between 1987 and 1997 culminating into the National Forestry Policy of 1998 and Forests Act of 1999, which provided for joint or participatory forestry management and share of derived benefits. In 2000, the Forestry Department initiated a pilot project to develop and implement JFM. This study was conducted in Dambwa JFM area in Livingstone to evaluate local people’s participation in JFM; perceptions on the effect of JFM on local livelihoods; and the impact of JFM on forest condition. The study was conducted through the use of household questionnaires, interviews with key informants, focus group discussions, field observation, and vegetation assessment. The results showed that more than half (68%) of the respondents were aware of JFM and almost the same number (64%) participated in JFM project. Participation of men in JFM activities was higher than women, although more women attended meetings than men. The results further showed that local management structures existed at district, forest area and village levels for coordination of JFM activities. Forest User Groups (FUGs) were also established in the area. The prominent FUG was the Mungongo oil pressing and was the only FUG functional at the time of the study. Forest Management Committee, Village Resources Management Committee and FUG members were found to be more involved in JFM activities than other members of the local community. Only a small number (8%) of local people reported improvement in household socio-economic conditions after the introduction of JFM, while the majority (79%) perceived the Forestry Department to be the major beneficiary in the JFM. The study revealed that there was a loss of enthusiasm in JFM among local people largely due to the absence of economic benefits and limited decision-making powers. However, the relationship between local people and Forestry Department was reported to have improved. The overall forest stocking was found to be low (219 SPH) with nearly all (90%) of the stems below 30 cm DBH, including the selected valuable tree species of Baikiaea plurijuga, Pterocarpus angolensis, Guibourtia coleosperma, Afzelia quanzensis and Colophospermum mopane. This implies that the forest area was previously overexploited rendering it uneconomical for commercial exploitation to provide benefits to local people on sustainable basis. However, the results showed a lot of saplings (10,000 SPH) in the Forest Reserve signifying adequate regeneration, including that of the valuable species, except for Afzelia quanzensis and Guibourtia coleosperma. The abundant natural regeneration implies that there was adequate forest protection and management following the introduction of JFM, which enhances regeneration. It is recommended that the Forestry Department should continue with public awareness on JFM to increase understanding and stakeholders’ involvement. The Forests Act of 1999 should be commenced and amended to support full implementation of JFM. The value of the forest also needs to be enhanced to increase benefit for local people and long-term conservation.

Thesis (MScFor) -- Stellenbosch University, 2003.
ENGLISH ABSTRACT: Fire is a threat to all forest plantations. As a result, growers are forced to take active measures to reduce the incidence and extent of fires in their plantations. This thesis is an attempt to collate 846 fire records for eight Komatiland Forests (KLF) plantations in Mpumalanga North for the period 1950 to 1999. Up to now, these reports and the information therein, were not utilised by KLF for planning or for evaluating fire management practices. The only other studies in South Africa, using similar data, were conducted by LeRoux (1988) and Kromhout (1990). A brief background of the forestry industry in South Africa, and in particular Mpumalanga is presented. The main text of the report covers a presentation on fire causes, extent of damage (both in area and in Rand value) and various aspects related to time of ignition and response times. A detailed analysis was done to identify possible relationships between the variables related to compartment, climate and different fire suppression activities. A cause and frequency prediction model was developed that will assist fi re managers in identifying and determining probabilities of fires per cause. Statistical guidelines regarding the planning of fire management around fires caused by honey hunters, lightning, work-related factors, and the activities of people (public, own labour, contractors) are presented. Conclusions were drawn from the results of the analyses of the fire data, which covered a period of 47 years. Recommendations regarding guidelines for strategic fi re management for the Mpumalanga North plantations were made. The main conclusions are: • Statistics on previous fires are very useful in fire management planning as it supplies valuable information on fire causes, time of ignition , past performance related to response times, fire fighting times and damaged caused. • • • • The average area lost due to fires in the study area is 209.9 ha or 0.43% of the plantation area per annum. People-related fires (arson, smokers, picnickers, children and neighbours) caused most of the wild fires (48%), followed by lightning (22%). Some plantations performed poorly, with the occurrence of up to double the number of fires per 1 000 ha of plantation compared to other plantations in the same geographic area. There are definite patterns in the frequency of fires per cause with month of the year. These patterns are valuable for the development of strategies to manage fires caused by honey hunters, lightning fires and work-related fires.
AFRIKAANSE OPSOMMING: Brande is 'n bedreiging vir aile bosbou plantasies. Dit is dus noodsaaklik dat kwekers maatreeHs tref om die voorkoms en omvang van brande in plantasies te beperk. Hierdie tesis poog om 846 vuurverslae se inligting te ontleed ten opsigte van agt Komatiland Forests (KLF) plantasies in Mpumalanga Noord vir die tydperk 1950 tot 1999. Tot op hede is min van die inligting wat in die verslae vervat is deur KLF vir beplanning- en evalueringsdoeleindes ten opsigte van brandbestuur gebruik. Die enigste soortgelyke studies wat op brandverslagdata in Suid-Afrika gedoen is, is gedoen deur Le Roux (1988) en Kromhout (1990). 'n Kort agtergrond oor die bosbouindustrie in Suid-Afrika en spesifiek Mpumalanga word gegee. Die tesis gee 'n oorsig oor brandoorsake, skade wat deur brande veroorsaak word (oppervlakte sowel as finansieHe waarde) en verskeie aspekte rakende brandbestuur soos tyd van ontstaan en reaksietye. Data is volledig ontleed om moontlike verwantskappe te probeer vind tussen vak-, klimaat- en brandbestuursveranderlikes. 'n Oorsaak- en frekwensievoorspellingsmodel is ontwikkel wat brandbestuurders sal help om waarskynlikhede van brande per oorsaak te identifiseer. Statistiese riglyne ten opsigte van bestuursbeplanning vir weerligvure, brande deur heuninguithalers, brande as gevolg van plantasiewerksaamhede en ook brande deur mense (publiek, eie arbeid en kontrakteurs) is daargestel. Brandrekords wat oor 'n periode van 47 jaar gestrek het, is ontleed. Afleidings wat uit die resultate gemaak is, kan benut word om riglyne daar te stel vir strategiese brandbestuur in Mpumalanga Noord plantasies. Die hoof gevolgtrekkings is: • Statistiek van vorige vure is baie nuttig in brandbestuursbeplanning aangesien dit waardevolle inligting verskaf oor brand oorsake, tyd van ontstaan, historiese werkverrigting rakende reaksietye en blustye, sowel as skade wat veroorsaak is. Die gemiddelde oppervlakte beskadig in die studie area is 209.9 ha, of 0.43% van die plantasie oppervlakte per jaar. Menslike aktiwiteite (brandstigting, rakers, piekniekvure, kinders en vure van bure) het die meeste brande veroorsaak (48%), gevolg deur weerlig (22%). Sommige plantasies het swak gevaar en het tot soveel as dubbel die aantal vure per 1 000 ha plantasie gehad in vergelyking met ander plantasies in dieselfde geografiese gebied. Daar is duidelike patrone gevind in die frekwensie van brande per oorsaak oor maande van die jaar. Hierdie patrone is nuttig vir die ontwikkeling van bestuurstrategie vir brande wat veroorsaak word deur heuningversamelaars, weerlig en werkverwante aktiwiteite (plantasieaktiwiteite).

Assignment (MFor)--Stellenbosch University, 2001.
ENGLISH ABSTRACT: The ongoing environmental destruction that results from the continuous use of the woodland resources for economic purposes has caused extensive changes in the original vegetation of Goba area of southern Mozambique. Developing alternative sources of income for communities can reduce their dependence on the production of charcoal, building materials and wood carvings. The lack of infrastructure and remoteness of these localities from the markets make alternatives economically unfeasible and thus unsustainable for rural development. Ineffective policy planning that does not address the problem in a holistic way causes the dilemma of local people in remote areas. The challenge at Goba is to develop alternative livelihoods that are economically, socially and ecologically sustainable. Nature-based tourism has been identified as such an alternative to realize this goal. However, this development requires incentives for sustainable resource use, which can be created either by expanding the benefits accruing from the efficient use of the resource or by changing the distribution of the benefits and cost in favor of the users. In many cases, local communities have developed tourism initiatives in ecologically fragile, remote areas, without sound planning based on detailed ecological and socio-economic information. Uncontrolled flows of tourists in unplanned tourist destinations degrade these areas. These destinations lose their aesthetic appeal; tourism flow decreases and consequently new attractions are opened. This study is of a land use planning nature and follows a combination of existing framework tools. The primary aim of this study was to develop simple guidelines for nature-based tourism that contribute to the conservation and management of the rural woodland areas as well as to the improved socio-economic welfare of rural communities in the Goba area. The study used baseline information for planning, focusing on the tourism market and on the ecological and socia-economical aspects of the siudy area. Two strategies were used to obtain the information, namely market research and attraction resources analysis. The market research in the southern part of Mozambique shows that: International tourist flows are at present from Southern African countries mostly South Africa (more than 50%), North America, Europe and Australia or Asia. Mozambique is perceived mainly as a sunny beach destination for vacations and weekends though most of the tourists were engaged in multi-destination itineraries that included safari, wildernesses, bird watching, touring and curiosity. There was no evidence from any tourist that nature tourism was the reason to visit Mozambique, but many of them said that they would visit ecotourism and nature tourism destinations if available. The average daily expenditure per tourist was found to be US$47. Tourists from long-haul distances had higher disposable expenditures and stayed longer in both attraction assets and in the country. Sixty nine per cent (69%) of surveyed tourists were over 50 years of age and they were mostly males (57%). The results show clearly that many issues must be taken into consideration where the development of ecotourism and nature-based tourism, especially in rural areas, is concerned. Such considerations should include (i) careful planning of the destinations based on the local developmental policy; (ii) developing saleable tourist products and packages and (iii), promotional strategies to expand the market to capture tourists with high average daily expenditure. The rural communities can then have a chance to develop nature-based tourism that uses outstanding natural resources. The resources analysis study results revealed that: The rugged topographic, climatic conditions of Goba water catchment area and the distance from settlements have naturally preserved local forest resources from human utilization. The area has well conserved and differentiated natural scenic landscape. These scenic landscapes have recreational values as well as environmental contrast, scientific discovery potential and retention of vanishing biological species. To preserve or improve the management of these landscapes, it is essential to consider recreation use in relation to all other potential values. Few existing landscapes showed a relative ability to absorb impacts produced by facility development with a minimum negative effect on the visual and ecological quality of the landscape. The majority of the landscapes have some potential for primitive and sensitive recreational spectrum. All these results are consistent with results from similar studies on watershed and water catchment ecology. Given the constraints on the environmental settings of the Goba landscapes, it is recommended that the basic and logic framework development should attract tourists interested in the more primitive portion of the recreational spectrum and should have fewer facilities of small-scale building. These facilities should be rustic in character with less service and more emphasis on self-reliance. Improved management of the Goba ecosystem is needed to maintain the ecological functions of the catchment and local culture and rurality. In conclusion, this study suggests that, if on these remote fragile ecosystems local communities can protect and market attractive quality-of-life-amenities, maintain a relatively low cost of living, and offer serviceable links to global telecommunication infrastructures in order to attract tourists and retirees, these communities can survive and may even thrive as local economies. An incentive planning method and sustained extension outreach effort in rural development, which focuses on nourishing local action at the grassroots level, will complement such a policy strategy.
AFRIKAANSE OPSOMMING: Omvattende verandering van die natuurlike plantegroei in die Goba area van suiderlike Mosambiek is teweeg gebring deur die deurlopende bentting van die omgewing deur die misbruik van die natuurlike hulpbronne vir ekonomiese wins. Die ontwikkeling van alternatiewe inkomstebronne vir plaaslike gemeenskap kan hul afhanklikheid van hout vir die produksie van houtskool, boumateriaal en houtsneewerk verminder. Die gebrek aan infrastruktuur en die groot afstande na markte maak die verkoop van die houtprodukte in stedelike gebiede onprakties en dus nie 'n volhoubare oplossing vir landelike ontwikkeling nie. Oneffektiewe beleidsbeplanning wat die probleem nie holisites benader nie veroorsaak 'n dilemma vir inwoners in afgeleë gebiede. Die uitdaging in Goba is om alternatiewe bronne van inkomste te ontwikkel wat ekonomies, sosiaal en ekologies volhoubaar is. Natuurgebaseerde toerisme is geïdentifiseer as 'n moontlike alternatief wat aan die doel kan beantwoord. Die ontwikkeling van eko-toerisme sal egter net slaag indien die plaaslike bevolking genoegsaam aangemoedig word om die natuurlike hulpbronne op 'n volhoubare basis te benut. Dit kan gedoen word óf deur winste terug te ploeg in die omgewing en so die toerisme basis te vergroot óf deur winsdeling op 'n gebruikersgunstige voordele- en kostebasis te behartig. In baie gevalle het plaaslike gemeenskappe toerisme inisiatiewe in sensitiewe, afgeleë gebiede ontwikkel, sonder deeglike beplanning wat op uitgebreide ekologiese en sosio-ekonomiese inligting berus. Die onbeheerde toeriste aanloop na onbeplande areas lei tot die stelselmatige vernietiging daarvan. Hierdie bestemmings verloor hul estetiese waarde en het tot gevolg dat toeriste ander ongerepte areas gaan soek. Hierdie studie handeloor die beplanning van grondgebruik en volg 'n kombinasie van bestaande raamwerk prosedure. Die primêre doel van hierdie ondersoek is om eenvoudige riglyne vir natuurgebaseede eko-toerisme te ontwikkel wat 'n bydra kan lewer tot die bewaring en bestuur van die natuurlike wonde en wat die sosioekonomiese welvaart van die plaaslike bevolking van Goba sal bevorder. Die studie maak gebruik van basiese inligting vir beplanning, en fokus op die toeristemark sowel as op die ekologiese en sosioekonomiese aspekte van die studie-area. Die twee strategieë wat gevolg is om inligting in te win is marknavorsing en die analise van toeriste-attraksie hulpbronne. Marknavorsing in die suide van Mosambiek toon dat die meerderheid internasionale besoekers aan Mosambiek afkomstig is van lande in Suidelike Afrika (Suid-Afrika alleen 50%), en daarna uit Noord- Amerika, Europa and Australië/Asië. Mosambiek word hoofsaaklik as 'n sonnige strandoord-bestemming vir vakansies en naweke beskou, hoewel die meeste toeriste 'n multi-bestemming reisplan volg wat safaris, ornitologie, reis en besoeke aan besienswaardighede insluit. Daar is geen bewys gevind dat enige toeris Mosambiek besoek het met eko-toerisme as doel nie, maar baie sou belangstelom dit te doen indien ekoen natuurgebaseerde toeriste-betemmings beskikbaar was. Die gemiddelde daaglikse uitgawe per toeris was US$47. Toeriste wat groot afstande moes aflê om hul bestemming te bereik het meer beskikbare fondse en bly langer, beide in die land en by verskillende attraksies. Van die toeriste by wie die opname gemaak is 69% ouer as 50 jaar en die meerderheid (57%) was mans. Die resultate toon dat daar talle faktore is om in ag te neem by die ontwikkeling van 'n landelike area vir natuurgebaseede en eko-toerisme. Daar moet aandag gegee word aan (i) deeglike beplanning van die bestemming gebaseer op die plaaslike ontwikkelingsbeleid; (ii) die ontwikkeling van verkoopbare toeriste produkte en pakkette;en (iii), promosie strategieë om die mark uit te brei om toeriste wat meer spandeer te lok. Die landelike gemeenskappe word sodoende die geleentheid gebied om hul besondere natuurlike hulpbronne te ontwikkel vir natuurgebaseerde toerisme. Die hulpbron-analise toon dat die afgeleë en bergagtige topografie en die klimaatsomstandighede van Goba se wateropvangsgebied as natuurlike beskerming vir inheense woude teen die benutting deur die plaaslike bevolking gedien het. Die area is goed bewaar met skouspelagtige natuurtonele. Die skouspelagtige landskap beskik oor rekreasiewaarde sowel as omgewingskontras, potensiaal vir wetenskaplike ontdekkings en vir bewaring van seldsame fauna en flora. Om hierdie landskap te bewaar of die bestuur daarvan te verbeter, moet gebruik vir rekreasie in verhouding tot die ander potensiële waardes beskou word. Daar is beperkte areas wat die vermoë besit om ontwikkeling te absorbeer en waar die verbouing van fasiliteite slegs 'n minimale negatiewe effek op die visuele en ekologiese kwaliteit sal hê. Die potensiaal bestaan egter vir alle areas om op 'n beperkte skaalontwikkel te word vir die primitiewe en sensitiewe sektor van die rekreasie spektrum. Die resultate van die vavorsing stem ooreen met soortgelyke studies van waterskeiding- en wateropvangsgebied-ekologie en ontwikkeling. Vir die gegewe omgewingsbeperkings van Goba word dit aanbeveel dat ontwikkeling op 'n basiese vlak geskied om daadie proporsie van die toeriste te lok wat in die sogenaamde wildernis-ervaring belangstel. Geboue en beperkte fasiliteite moet slegs op klein skaal opgerig word. Die fasiliteite moet by die omgewing inpas en die klem moet op selfvoorsiening eerder as op dienstelewering val. Die bestuur van die Goba ekosisteem moet egter verbeter om die ekologiese funksie en die plaaslike kultuur en landelikeid te behou. Die bevinding van die studie is dat indien ver-afgeleë en sensitiewe ekosisteme deur die plaaslike bevolking bestuur en beskerm word, dit tot ekonomiese welvaart van die landelike gebiede kan lei. Hierdie areas moet bestuur word sodat die landelike karakter as toeriste aantreklikheid behou word, dat die lewenskoste relatief laag bly en dat verbindings met die buitewêreld op telekommunikasie vlak ingestel word. Beplanning moet op 'n aansporingsbasis gegrond wees met uitreikingsprogramme met landelike ontwikkeling as doel. Aanmoediging van plaaslike aksie op grondvlak behoort so 'n beleidstrategie te versterk.

Thesis (MScFor (Forest and Wood Science))--Stellenbosch University, 2008.
The characterization of soils in Nzara District of Southern Sudan in comparison to other tropical teak growing countries (Tectona grandis) – in respect of extensions to existing and/or the establishment of new teak plantations – were done by firstly considering the soils of three existing plantations: Yoboa, Mabarizinga and Nagondi, and secondly by considering soils outside and inside the existing teak plantations in respect of land uses. From these soil characterizations, it emerged that considerable positive returns can be expected from teak plantings in the area as an investment, provided that appropriate site management is implemented. Climatic data of the Nzara area compared favorably with the climatic range of areas where teak grows naturally and the world’s dominant producers: mean annual rainfall 1350-1600 mm with a distribution over 6-8 months compares well with that of Myanmar (1250-3750 mm) and Indonesia (1511-2108 mm) both with at least 3 months of dry season. The mean annual temperature of 28-350C compares well with 15-410C and 30-320C of Myanmar and Indonesia respectively. The Yoboa and Mabarizinga sites should be prioritized as they appear slightly more suitable than the Nagondi site. All three sites have a dominant soil texture of Sandy Clay Loam similar to Sandy Loam of most areas of other tropical countries where teak is growing well (such as India, Indonesia and Nigeria). Yoboa and Mabarizinga however distinguish themselves by having the highest soil pHwater values range from 6.4±0.56 and 6.04±0.7 in top soils; 5.91±0.5 and 5.46±0.61 in subsoils at Yoboa and Mabarizinga respectively; the highest soil organic matter content 1.8±0.34% and 1.92±0.43% in topsoil 0.89±0.16% and 1.13±0.19% in subsoils; as well as the highest P content in both available (0.09±0.04% and 0.03±0.04% for topsoils) and total forms (1.19±0.26% and 0.9±0.3% also on topsoils). These values though very low in absolute terms, are not much different from those of other tropical teak-growing countries. Management strategies intended to preserve and improve the present status, particularly the protection of top soil horizons against mainly water erosion, would be able to boost the site productivity.

Thesis (MFor ) -- University of Stellenbosch, 2003.
ENGLISH ABSTRACT: The bulk of paper grades destined for the printing industry are produced on modern paper machines which continuously become wider and faster. In order to improve printability, print quality and dimensional stability, such papers contain a large percentage of mineral pigments either in the form of internal loading or external coatings. Although mineral pigments exercise a substantial beneficial effect on paper surface quality, unfortunately these minerals do not contribute towards sheet strength and machine runnability. Today's papermakers are faced with the dilemma of producing highly filled and coated printing papers with low grammages on faster running paper machines, but often lacking the required quality of fibre resources to secure a smooth runnability of such at high speeds. Standard fibre furnishes will have to be upgraded with special types of reinforcing fibres in order to meet the demands of sheet strength and machine runnability. The investigation had succeeded to identify a new suitable fibre resource, which would satisfy the demand of a reinforcing type natural material.
AFRIKAANSE OPSOMMING: Die oorgrootte meerderheid tipes papier wat vir die drukkersbedryf bestem is, word op moderne papiermasjiene vervaardig wat steeds breër en vinniger word. Om die drukbaarheid, drukkwaliteit en dimensionele stabiliteit te verbeter, bevat sulke papiere groot hoeveelhede minerale pigmente wat in die vorm van interne ladings of as eksterne bestrykings teenwoordig is. Alhoewel minerale pigmente -n merkbare voordelige effek op die papier oppervlakte-kwaliteit uittoefen, dra sulke pigmente ongelukkig nie by tot die sterkte en loopvermoë van die papier nie. Die hedendaagse papiervervaardiger word konfronteer met die dilemma om swaar gevuldeen bestrykte drukpapiere met lae oppervlaktegewig op vinniger lopende papiermasjiene te vervaardig. Dit gebeur dikwels sonder die beskikbaarheid van die nodige hoëkwaliteit veselbronne om te verseker dat die loopvermoë van die papier teen hoë spoed nie benadeel word nie. Standaard veselsamestellings salopgegradeer moet word met spesiale tipe versterkingsvesels om aan die uitdaging van hoë velsterkte en masjien-Ioopvermoë te voldoen. Hierdie ondersoek het daarin geslaag om 'n nuwe geskikte veselbron te dentifiseer en wat aandie behoeftes van 'n versterkingsvesel sal voldoen.

Thesis (PhD (Forest and Wood Science))--Stellenbosch University, 2007.
ENGLISH ABSTRACT: There has been a reported reduction in the durability of creosote treated, wooden utility poles in South Africa in recent years. Several factors could have been responsible for this. In this study, Eucalyptus grandis pole drying schedules currently used, methods of measurement of moisture content (MC) after drying and drying defects were investigated. Relationships involving drying defects and MC gradient before treatment which may help in the development of simple nondestructive methods of assessing defects such as surface checking, honeycomb and collapse, and MC gradient were also explored. The long term goal of this study was to increase the durability of treated poles by avoiding unacceptable drying defects and MC values before treatment. The results of this investigation are presented in the following chapters: an introduction motivating the aims of the investigations (Chapter 1); a review of literature relevant to MC and drying defects in sawn or round wood (Chapter 2); ready for press manuscripts on MC and drying defects in kiln-dried E. grandis poles (Chapters 3 to 7) and a general conclusion that links up chapters 3 to 7, and recommendations (Chapter 8). The auger drill method gave reliable MC values when samples in increments of 25 mm depths into the pole were taken. However, when single samples of 50 mm and 75 mm depths were considered, the auger drill MC measurements were unreliable. It was concluded that SABS SM 983 (2000), which specifies taking single radial auger drill samples of depth 70±5 mm at pole mid length, is not a reliable method of measuring MC in a kiln-dried E. grandis pole. Correlation results indicated that tree growth factors such as sapwood depth, green MC and heartwood percentage were related to final drying defects and may be used as criteria for pole sorting before kiln drying. Also, the number of valleys per unit length (VPUL) of the circumference at the theoretical ground line (TGL) was positively correlated with honeycomb and closed surface checks, implying that VPUL as a parameter of the pole circumference profile can be used to assess invisible, internal defects. The dry bulb temperature (Tdb) of 80oC, used to dry poles in industry, was too high and resulted into unacceptable levels of drying defects in kiln dried E. grandis poles. In addition, the drying period of 8 days was too short to attain an acceptable MC gradient in poles. It is, therefore, recommended that: To use the auger drill method to reliably determine the moisture content of a pole, samples in increments of 25 mm should be taken. MC measurements should be made at the most critical zones of a pole such as the TGL and not higher up since there is normally considerable MC variation in the longitudinal direction. It is also important to consider sampling more than one position on the pole circumference to cater for the MC variation in the tangential direction. For poles with large sapwood depths i.e. >15mm, mild drying conditions at the beginning of a drying run should be used, since such poles may be more susceptible to surface checking. Poles with large heartwood percentages should also be dried with suitable kiln schedules, i.e. with low Tdb to minimise honeycomb and collapse. In general, Tdb lower than 80oC should be considered in order to reduce the defects to acceptable levels. Poles should be dried for longer than 8 days even at Tdb as high as 80oC to reduce the MC to acceptable values and gradients. Since only three schedules were tested, more drying schedules should be investigated to make reliable conclusions about the effect of schedule on drying defects. In addition, more poles per schedule should be considered in order to obtain statistically reliable results. The relationship of pole diameter and drying defects also requires further investigation. Since a limited sample was used to test for the effect of source of poles and drying schedules on defect correlations, further studies should be done on sufficient samples to come up with more reliable conclusions. It is also necessary to further investigate the possible variation in correlation of VPUL and internal defects on a large sample of poles from specific sources and drying schedules.
AFRIKAANSE OPSOMMING: Die afgelope paar jaar is waargeneem dat kreosootbehandelde transmissiepale 'n afname in duursaamheid toon. Verskeie faktore kan hiervoor verantwoordelik wees. In hierdie studie is huidige Eucalyptus grandis oonddrogingskedules en voggehalte- (VG) bepalingsmetodes vóór en na droging asook drogingsdefekte ondersoek. Verwantskappe tussen drogingsdefekte en VG-gradiënt vóór behandeling wat kan meehelp om nie-destruktiewe metodes te ontwikkel om defekte soos oppervlaktekrake, interne barste en instorting en VG-gradiënt te bepaal, is ook bestudeer. Die langtermyn doelwit van hierdie studie is om die duursaamheid van behandelde pale te verbeter deur onaanvaarbare drogingsdefekte en voggehaltes vóór behandeling te vermy. Die resultate van hierdie ondersoek word in die volgende hoofstukke bespreek: 'n inleiding waarin die doelwitte van die onderskeie ondersoeke motiveer word (Hoofstuk 1); 'n oorsig van die literatuur relevant tot VG en drogingsdefekte in gesaagde en rondehout (Hoofstuk 2); persklaar manuskripte oor VG en drogingsdefekte in oondgedroogde E. grandis pale (Hoofstukke 3 tot 7) en 'n algemene gevolgtrekking wat bevindings uit hoofstukke 3 tot 7 saamvat gevolg deur aanbevelings (Hoofstuk 8). Die augerboor-metode kon betroubare VG-waardes lewer indien monsters van 25mm diepteinkremente in die paal geneem is. Augerboor-voggehaltemetings met enkel 50mm en 75mm monsters was egter onbetroubaar. Daar is bevind dat SABS SM 983 (2000), wat 'n enkel radiale augerboormonster tot op 'n diepte van 70±5 mm in die middel van die lengte van die paal spesifiseer, nie 'n betroubare VG-bepalingsmetode vir oondgedroogde E. grandis pale is nie. Die resultate het aangetoon dat boomgroeifaktore soos spinthoutdiepte, groen voggehalte en die persentasie kernhout aan drogingsdefekte verwant is en as basis vir sortering van pale vóór oonddroging gebruik kan word. Ook kon die aantal valleie per eenheidslengte (e. VPUL) van die omtrek by die teoretiese grondlyn (TGL) positief met interne barste en geslote oppervlaktekrake korreleer word wat impliseer dat VPUL as parameter van die omtrekprofiel van die paal gebruik kan word om onsigbare, interne defekte mee vas te stel. Die droëbaltemperatuur (Tdb) van 80oC wat in die industrie gebruik word, was te hoog omdat dit onaanvaarbare vlakke van drogingsdefekte in oondgedroogde E. grandis veroorsaak het. Daarbenewens was die drogingsperiode van 8 dae by 'n Tdb van 80oC te kort om 'n aanvaarbare VG-gradiënt te lewer. Die volgende word derhalwe aanbeveel: Om betroubare VG-resultate d.m.v. die augerboormetode te verkry, behoort monsters in inkremente van 25mm geneem te word. VG-metings behoort in die mees kritiese dele van 'n paal gedoen te word byv. by TGL en nie hoër nie omdat daar normaalweg beduidende VG-variasie in die longitudinale rigting is. Dis ook belangrik om op meer as een posisie op die omtrek te meet om vir die variasie in die tangensiale rigting voorsiening te maak. Ligte drogingstoestande behoort aan die begin van die drogingsproses by pale met groot spinthoutdieptes, bv. > 15mm, gebruik te word omdat sulke pale meer geneigd tot oppervlaktekrake is. Pale met hoë kernhoutpersentasies moet ook met geskikte drogingskedules, bv. met lae Tdb, gedroog word om interne barste en ineenstorting te verminder. Oor die algemeen behoort Tdb laer as 80oC oorweeg te word om die omvang van defekte by aanvaarbare vlakke te hou. Selfs by Tdb so hoog as 80oC behoort pale langer as 8 dae te droog om die VG tot by aanvaarbare waardes en 'n gradiënt te bring. Omdat slegs drie skedules evalueer is, behoort meer skedules ondersoek word om betroubare gevolgtrekkings oor die effek van skedule op drogingsdefekte te verskaf. Addisioneel behoort meer pale per skedule oorweeg word om statisties betroubare resultate te verkry. Die verwantskap tussen paaldeursnee en drogingsdefekte benodig ook verdere ondersoek. Aangesien 'n beperkte aantal pale gebruik is om die herkoms en drogingskedule met defekte te korreleer, behoort verdere studie op genoeg pale gedoen te word om meer betroubare gevolgtrekkings te kry. Dit is ook noodsaaklik om die moontlike variasie in die korrelasie tussen VPUL en interne defekte op 'n groot aantal pale van spesifieke herkoms en drogingskedules vas te stel.

Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2005.
Like in many developing countries, forest and woodland resources contribute significantly to ensure the sustainability of livelihoods of rural people of Eritrea. However, the contribution made by forest and woodland resources has been masked due to the inability of the traditional economic valuation methods to reveal the hidden values of forest resources. As a result they do not reflect in GDP accounting, development planning and conservation policymaking. The underestimation of the importance of forest and woodland resources to the rural subsistence economy results in both market and policy failures. These in turn lead to escalated forest degradation, livelihood insecurity, value conflicts and ineffective conservation programmes. The forest and woodlands of administrative sub-zone Dighe were selected as a case study as they comprise trees, shrubs and other non-woody plants of outstanding importance both in terms of socio-economics and biodiversity richness. However, these resources are being rapidly depleted as a result of clearing for commercial agriculture and are under growing pressure due to resettlement of returnees and needs of other social actors. The study was carried out in three representative administrative areas of the sub-zone. A literature survey was carried out to identify the best of traditional neo-classical economic valuation methods to use in this study. Complementary methods from various streams of economics, ethnobotany, ecological anthropology and rural sociology were reviewed. The sub-set of selected marketable items were quantified and monetised based on market-based valuation approaches; and compared with non-marketable roles to indicate the magnitude of full values of the forest and woodland resources. Values that could not be quantified were described qualitatively. A production-consumption analysis of dom palm scrub leaf harvesting for household utensils was carried out. Forest health was investigated based on observation, semi-structured interviews and secondary information. The study revealed that local forests and woodlands provide essential goods and services for subsistence use, to generate income and to reduce vulnerability during times of hardships. Riverine forests, acacia woodlands and scattered trees and shrubs of grassland are the three vegetation types found in the study area. The riverine forest, dominated by dom palm, is a most valuable resource as it provides for multiple uses. Among the many marketable and non-marketable benefits, forests and woodlands provide wild food, construction material, livestock feed, household utensils, firewood, traditional medicine, shade, climate amelioration, erosion control, cultural heritages and scenic values. All members of rural households regardless of age, gender and wealth extract forest products, which minor variation between households and administrative areas. Variability of consumptive use values between households and between administrative areas and other non-marketable values are determined by relative wealth status, seasonality, resource availability and distribution, market outlets and local institutions. The study revealed that the riverine forests and woodland values of the Dighe administrative sub-zone alone have contributed economical values many times greater than US $ 1.43 million per annum for selected quantifiable items only. This would be higher if the other non-marketable forest values were monetised including the livestock grazing and access to watering points. Beyond any doubt, the high local values of forest and woodlands and consequently the contribution to the national economy justify the conservation of the remaining forest. Moreover, the production-consumption analyses showed that the present level of dom scrub leaf harvesting is sustainable. Forest health situation analysis indicates, however, that the entire forest is under immense pressure. Moreover, the findings of this study suggest that conserving forest resource for local values is compatible with the millennium global development agendas.

Thesis (MFor (Forest and Wood Science))--University of Stellenbosch, 2009.
The aim of this study was to develop biomass prediction models for the determination of total aboveground biomass for mopane at three (3) study sites in Botswana. Thereafter, based on the pooled data from the three (3) study sites, recommend one cross-site biomass prediction model that could be used for the indirect estimation of the total aboveground biomass for mopane in Botswana. All the data were collected by destructive sampling from three (3) study sites in Botswana. Stratified random sampling was based on the stem diameter at breast height (1.3 m from the ground). A total of 30 sample trees at each study site were measured, felled and weighed. The 30 sample trees were distributed equally between six DBH classes (Five sample trees per DBH class). Thereafter, using the data from these sample trees, site-specific biomass prediction models for the indirect estimation of total aboveground biomass for mopane were developed as a function of the following independent variables: stem diameter at 0.15 m from the ground; stem diameter at 1.3 m from the ground; stem diameter at 3 m from the ground; crown diameter; and total tree height. The data from the sites were pooled together to develop cross-site biomass prediction models as a function of the given independent variables. The biomass prediction model that provided the best fit at Serule was a linear equation estimated by means of the stem diameter at 1.3 m, while in Sexaxa the biomass prediction model that provided the best fit was estimated by means of the stem diameter at 0.15 m. The biomass prediction model that provided the best fit at the Tamacha site was estimated by means of the stem diameter at 1.3 m. On the basis of the collected data, cross-site biomass prediction models were developed. The cross-site biomass prediction model that provided the best fit was developed from the stem diameter at 1.3 m. This relationship was adopted as the prediction model for the indirect biomass estimation of Colophospermum mopane (mopane) in Botswana.

Thesis (MSc)--Stellenbosch University, 2000.
ENGLISH ABSTRACT: The aim of the study was to extract elevation information (such as tree height) from stereo satellite imagery (IRS-I C), to scrutinise the performance of the DTM (Digital Terrain Model) tools as provided by the LH (LeicalHelava) Systems' softcopy system, and subsequently to perform a feasibility study on the application of a practically viable forest inventory design. A softcopy photogrammetry workstation (LH Systems DPW 770), IRS-I C stereo panchromatic satellite imagery, and digital aerial photography at a scale of 1:30000 (scanned at 15 micrometers) was used. The study was conducted over various sites in the Sabie area (province of Mpumalanga) in South Africa, where extensive man made forests with pine and eucalypts are to be found. The extraction of stand parameters such as tree height was performed manually, semi-automatically, and automatically. In addition, the compartment area was determined using a GIS tool. The Digital Surface Models (DSM), representing the canopy structure of the stands, was extracted from the IRS-I C imagery and validated through a comparison of the resulting contours with the corresponding contours generated by aerial photogrammetric methods. Due to the coarse spatial resolution of the IRS-IC imagery (5m) and the suboptimal BIH (BaselHeight) ratio (0.57), only objects featuring a height exceeding 20m could be manually measured with confidence. Furthermore, only the edges of the compartments proved to be suitable for the determination of tree heights (i.e. with a sufficiently large parallax difference and image contrast). The manual determination of tree heights in the IRS-I C imagery yielded accuracies of about 95% compared to the height values of the aerial photographs and the ground data. The application of image enhancement techniques had severe effects on the accuracy of the IRS-IC stereo model, resulting in deviations of about -57m from the 'true' value. It was observed that image matching was only a problem where features changed their appearance (e.g. clearfelled or burnt areas) during the acquisition period of the stereo pair of the satellite imagery. LH Systems' Adaptive Automatic Terrain Extraction (AATE) tool performed very well for the creation of digital terrain and surface models when using digital aerial photography with a high scanning rate. In contrast, the automatic creation of canopy surface models from various forest compartments did not yield any useful results when applied to IRS-l C imagery. AATE could not model the canopy structure properly. The coarse spatial resolution of the satellite imagery in conjunction with the sparse post spacing (20m) and matching errors are most likely to be responsible for this poor performance. Two-phase sampling and the Hugershoff method were chosen for automatically derived height values to be evaluated for possible application in forest inventory. Unfortunately, neither for the determination of the regression estimator for the first method, nor for the calculation of timber volume after application of the Hugershoff method could any useful result be obtained. This is mostly due to the fact that image matching errors and blunders (resulting in tree heights of -885m) were not properly accounted for in the terrain extraction software. However, the outcomes for the manual measurement of tree heights performed on the satellite imagery show that under optimal conditions accuracies can be achieved similar to those for the height determination in small scale aerial photographs, but at lower cost. The obtained height values can then be used for the calculation of timber volume according to Eichhorn's law. Keywords: AATE, blunders, digital photogrammetry, DPW770, forest inventory, Hugershoff IRS-l C, matching error, remote sensing, satellite imagery, two-phase sampling
AFRIKAANSE OPSOMMING: N GANGBAARHEIDSTIIDIE VIR BOSINVENTARIS MET BEHULP VAN STEREO SATELLIETBEELDE MET GEBRUIK VAN SAGTEKOPIE FOTOGRAMMETRIESETEGNOLOGIE: Die doel van hierdie studie was om elevasie inligting (soos boomhoogtes) uit stereo satellietbeelde (IRS-I C) te ontrek, en die DTM (Digitale Terrein Modelle) funksies van die LH Systems se sagtekopie sisteem te evalueer en 'n ondersoek in te stel na praktiese toepassing van die tegnologie in bosvoorraadopname. 'n Sagtekopie fotogrammetriese werkstasie (LH Systems DPW 770), IRS-I C stereo panchromatiese satellietwaarneming en digitale lugfotografie is gebruik. Die studie is uitgevoer oor verskeie areas in die Sabie omgewing (Mpumalanga, Suid-Afrika), waar daar ekstensiewe mensgemaakte woude voorkom met denne en Eucalyptus soorte. Die ekstraksie van opstandparameters soos boomhoogte is uitgevoer met die hand, as ook met semi-outomatiese en outomatiese metodes. Die digitale oppervlakmodelle (wat die kroondakstrukture van die opstande voorstel) was vanaf die IRS-I C beelde onttrek en gevalideer deur vergelyking van die resulterende kontoere met die korresponderende kontoere wat deur lugfotogrammetriese metodes gegenereer is. As gevolg van die growwe ruimtelike resolusie van die IRS-IC waarneming (Sm) en die suboptimale BIH verhouding (0.57) kan slegs voorwerpe met 'n hoogte van meer as 20m met vertroue met die hand gemeet word. Slegs die rande van die vakke is bruikbaar vir die berekening van boomhoogtes (d.w. s. met 'n voldoende paralaksverskil en 'n sterk beeldkontras ). Boomhoogtes wat met die hand bepaal is vanaf IRS-I C beelde is 95% akkuraat in vergelyking met die hoogtewaardes verkry vanaf die lugfoto's en die veldmetings. Die toepassing van beeldverbeteringstegnieke het duidelike invloede op die akkuraatheid van die IRS-IC stereomodel met afwykings van ongeveer -57m vanaf die "werklike" waardes. Daar is ook waargeneem dat beeldooreenstemming slegs 'n probleem is waar terreinvorme se voorkoms verander het (weens afkappings of brande) gedurende die verkrygingsperiode waarin die stereo paar van die satellietbeelde verkry is. LH Systems se Aanpassende Outomatiese Terrein Onttrekkings (Adaptive Automatic Terrain Extraction - AATE) instrument het goed gevaar tydens die gebruik van digitale lugfotografie met Inhoë skanderingstempo. In kontras hiermee het die outomatiese skepping van kroondakoppervlakmodelle van verskeie plantasievakke geen nuttige resultate gelewer wanneer dit op IRS-I C beelde toegepas is nie. Die growwe ruimtelike resolusie van die satellietbeelde tesame met die wye paalspasïering (20m) en passingsfoute is waarskynlik vir hierdie swak resultate verantwoordelik. Twee-fase proefueming en die Hugershoff metode was gebruik vir die bepaling van outomaties afgeleide hoogtewaardes vir evaluering van moonlike toepassing in bosvoorraadopnames. Geen bruikbare resultate kon verkry word vir die vasstelling van die regressieskatter vir die eersgenoemde metode of vir die berekening van die houtvolume volgens die Hugershoff metode nie. Dit is meestal as gevolg van beeld-- ooreenkomsfoute en flaters, (wat tot boomhoogtes van -885m gelei het) wat nie voldoende in ag geneem word in die terreinekstraksie sagteware nie. Die resultate vir die handgemete ('manual') boomhoogtebepaling wat uitgevoer is op die satellietbeelde (op die sagtekopie werkstasie DPW 770), toon dat akkuraathede soortgelyk aan daardie vir hoogte bepaal op klein-skaal lugfotos onder optimale toestande verkry kan word, maar goedkoper. Die hoogtewaardes wat verkry is kan gebruik word vir die berekening van houtvolume volgens die wet van Eichhorn. Sleutelwoorde: AATE, afstandswaarneming, bosvoorraadopnames, digitale fotogrammetrie, DPW770, flaters, Hugershoff, IRS-! C, satellietbeelde, twee-fase proefueming

Thesis (MscFor)--Stellenbosch University, 2004.
ENGLISH ABSTRACT: The state owned and managed forest and woodland resources during the colonial and postindependence periods in Mozambique. However, the centralised government forestry policies failed to stop the continual loss of natural forest and woodland resources under the state control. This study is concerned with the sustainability of a cimbirre (Androstachys johnson iidominated) woodland in a rural part of Mozambique. A. johnsonii trees are the major source of subsistence and income generation in southern Mozambique. Nevertheless, the exploitation of the species is running illegally because the diameters used for poles are below the harvestable diameter limit defined by the forestry legislation. This study is part of the research activities of a community-based natural resources management project being implemented in the Mabote District. The study focuses on the four villages covered by this project funded by the Government of Finland. It intends to develop guidelines for sustainable management of the woodland which is of a great concern to the rural woodland-dependent communities. The study examines the socio-economic context of commercial harvesting of A. johnsonii trees for poles by local communities, as well as the sustainability of the woodland resources concerned, especially with respect to the setting of minimum harvestable diameter limits. It is assumed that the current deliberate burning of cimbirre woodlands to kill the desired species would cease once a sustainable diameter limit is established. Three methods are used to respond to the objectives of the study, namely: (1) Semi-structured interviews and group discussions with key informants; (2) Structured questionnaire surveys submitted to households randomly selected within the four villages being studied; and (3) Forest resource assessment. The literature review documents the theoretical issues of sustainable management of natural resources and forest in particular, both past and present. It indicates that a state-community partnership should be considered for sustainable management of the area. It is also valid for communal areas in Mozambique in general, where the government legally controls forest resources. The implementation of the structural adjustment programme that Mozambique currently pursues, allied to the retrenchments in the gold mining industry in South Africa and the abolishment of recruitment of Mozambican labourers in the South African mining industry, have transformed the traditional forms of rural livelihoods. These measures provide rather large incentives for private interests to exploit poles for commercial purposes. Findings of this study based on the forest resource assessment provide an ecological basis for allowing harvesting of juvenile trees of A. johnsonii for poles by local communities, because the current level of harvesting trees does not lead to woodland degradation. Besides, the centralised policies that governed the allocation of forest resources both in colonial and postindependent Mozambique have transformed traditional authorities. This has led to a confusion of roles and conflicting power in forest management. Key words: Community involvement, deforestation, sustainable natural forest management.
AFRIKAANSE OPSOMMING: Gedurende die koloniale en post-onafhanklike periode in Mosambiek is die woude en bosland hulpbronne deur die staat beheer en besit. Dié gesentraliseerde regeringsbeleide het egter nie die voortdurende verlies aan natuurlike hulpbronne onder staatsbeheer gestop nie. Hierdie studie handle oor die volhoubaarheid van 'n cimbirre (Androstachys johnson ii-dominated) inheemse bos in 'n landelike deel van Mosambiek. A. johnsonii bome is die hoofbron van bestaan en inkomstegenerering in die suidelike deel van Mosambiek. Nogtans word dié spesie onwettiglik uitgebuit omdat die deursnee vir pale onder die oesbare minimum deursnee is, soos bepaal deur bosbouwetgewing. Dié studie vorm deel van die navorsingsaktiwiteite van 'n gemeenskapsbeheerde, natuurlike hulpbron bestuursprojek wat tans geïmplementeer word in die Mabote Distrik. Die fokus van dié studie is vier dorpies wat gedek word deur die projek. Die doelwit is om riglyne te ontwikkel vir die volhoubare bestuur van die bosgebied wat 'n groot bron van bekommernis is vir die landelike gemeenskappe wat van die bos afhanklik is. Die studie ondersoek die sosioekonomiese konteks vir die kommersiële oes van A. johnsonii bome vir pale deur die plaaslike gemeenskappe, sowel as die volhoubaarheid van die bosebied se hulpbronne hier betrokke, veral met die oog op die bepaling van 'n minimum deursnee beperking vir oesdoeleindes. Dit word aanvaar dat die huidige doelbewuste brand van cimbirre boslande, om die gewenste spesies dood te maak, beeïndig sal word as 'n volhoubare deursnee limiet vasgestel word. Dit sal gedoen word met behulp van insette deur die afhanklike gemeenskappe. Drie metodes is gebruik om die doelwitte van die studie te behaal; (1) Semigestruktureerde onderhoude en groepbesprekings met kerninformante; (2) Getruktureerde vraelys opname wat aan lukraak geselekteerde huishoudings binne die vier dorpies (wat deel maak van studie) gegee is; en (3) Hulpbronwaardering in die bos. Die literatuurstudie dokumenteer die teoretiese kwessies oor die volhoubare bestuur van natuurlike hulpbronne en dan spesifiek woude, beide in die verlede en in die huidige situasie. Die gevolgtrekking is dat 'n staatgemeenskapsvennootskap oorweeg moet word vir die volhoubare bestuur van die area. Dit geld ook in die algemeen vir die kommunale areas in Mosambiek, waar die regering wettiglik woudhulpbronne beheer. Die implementering van strukturele aanpassings programme tans in Mosambiek, asook die afdankings in die goudmynindustrie in Suid-Afrika en die beeïndiging aan die werwing van Mosambiekse arbeiders deur Suid-Afrika, het tradisionele vorms van landelike broodwinning getransformeer. Dit lei weer tot die misbruik van pale vir kommersiële doeleindes, deur die privaat sektor. Bevindings uit dié studie, gebaseer op die woudhulpbron waarderings, verskaf 'n ekologiese basis vir die oes van jong A. johnsonii bome vir pale deur die plaaslike gemeenskappe, want die huidige vlak van oes van dié bome lei nie tot boslandagteruitgang nie. Boonop het die gesentraliseerde beleide wat die toekenning van woudhulpbronne beheer, in beide 'n koloniale Mosambiek en 'n post-onafhanklike Mosambiek, tradisionele gesagsstrukture getransformeer. Dit het gelei tot 'n verwarring in rolle en 'n konflik in mag in inheemse bosbestuur. Key words: Deforestasie, gemeenskapsbetrokkenheid, volhoubare natuurlike bosbestuur.

Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: The objective of this study was to develop and assess a methodology of using pruning information (age and height) and ring width measurements on increment core samples taken at breast height from standing pruned Pinus patula trees for modeling the knotty core sizes in the pruned section of a tree. A total of 170 trees from 17 compartments, representing a wide variety of growth sites from the Mpumalanga escarpment, were selected and destructively sampled. Sample trees were selected to represent the productive timber volume available from the compartments using stratified sampling. Sample discs were removed at breast height (1.3m) and at six meter height. After drying and sanding, the cross-sectional surfaces of one surface of each of the discs were scanned on a document scanner and the ring widths measured, using an image analysis program. A preliminary study, using 30 discs, was undertaken to ascertain the appropriate number of radii per disc to measure. A comparison between results of two opposite radii, as opposed to four radii, showed that the difference in mean ring width resulting from the two approaches was statistically not significant. In practice this means that for ring width assessment, sampling of increment cores opposite to one another at breast height would be sufficiently accurate to study average ring width variation across the radius of a tree. A study was also conducted to determine to what accuracy ring widths at six metre height could be predicted from breast height measurements. It was shown that cumulative growth at six metre height can be predicted from cumulative growth at breast height, site index and cambial age at breast height as independent variables (R2 = 0.96). Ring width measurements at breast height can, therefore, be used to predict incremental growth throughout the pruned section. Combined with available information on the pruning history of a stand (pruning heights and pruning age), this study proved that quantitative knowledge on incremental growth can be used as a basis for estimating changes in knotty core sizes along the entire pruned section of the stem. Analysis of variation for the entire data set from ring width measurements showed that there was far greater variation in knotty core percentages (the percentage of diameter occupied by knotty core) between different compartments than within compartments. Within a tree, the knotty core percentages between three stem sections, 0-2.4m, 2.4–4.8m, and 4.8-7m, were found to increase significantly from the bottom section (49.1%) to the top section (65.4%). A single 2.4m log from the pruned section of each tree was removed and processed into sawn timber at a sawmill. After drying of the boards, a sub-sample of sawn boards from 17 logs, one log from each compartment, was selected and reconstructed into log form. From the reconstructed log (reconstructed to represent their original position in the log) the actual knotty core size was estimated by measuring the distance from the pith to the end of the branch stub. A comparison of the actual knotty core sizes and the modelled knotty core sizes of a sub-sample of trees showed only a modest relationship (R2 = 0.62). Reasons for this might be variability in pruning quality, inaccurate pruning records, nodal swellings and the methodology used to measure the actual knotty core sizes. Knowledge of knotty core sizes of standing trees can be used for many different purposes. Two applications that were assessed and found to be useful include decision support for cross cutting logs and for sawmill production planning purposes. Sawmill simulation software was used to evaluate value -and grade recoveries under different scenarios. Results showed that cross-cutting the pruned sections of logs from a compartment with large within-tree knotty core size variation into shorter logs, as opposed to keeping the pruned sections as single logs, result in increases in grade and value recovery. It was also shown that sawing of pruned logs from compartments with relatively small knotty cores, results in much better grade recoveries than logs from compartments with relatively large knotty cores (this information will be useful for production planning purposes). It can be concluded that the methodology proposed to reconstruct knotty cores from tree ring measurements has the potential to be used as a decision aid in the forest and forest products industry.

Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: Mid rotation fertiliser application is generally practised in forestry to enhance nutrient availability in areas were soils are impoverished and do not provide sufficient nutrients for high productivity. Generally speaking there is great potential for mid rotation fertiliser in pine plantations, but stand and site characteristics such as water availability, soil depth, stand density and available nutrients need to be considered before fertiliser treatments are implemented. Foliar nutrient analyses were used to estimate nutrient availability. These levels were measured throughout the study and were used to implement specific fertiliser treatments that would boost nutrient availability. Treatments consisted of an unfertilised control, a single fertiliser application (1F) and two fertiliser applications over two consecutive years (2F). Leaf area index (LAI) and stem volume increment were measured in order to evaluate its influence on growth efficiency. LAI was estimated using the gap fraction method with the use of a ceptometer. Volume increment was calculated with diameter and height measurements. Basal area was calculated by means of diameter measurements. These growth responses were used to determine the effect of increased nutrient availability and although increases were found in LAI, volume increment, basal area increment and growth efficiency, none were significant. The lack of significance may be due to relatively large variations in other factors such as stand density and initial volume of the experimental plots. The 18 month monitoring period apparently did not allow complete reaction time to increased nutrient availability and limited our understanding of the responses somewhat. Despite this, the magnitude of some growth responses was large as nutrient ratios in the foliage increased to levels within the norms range. Increases in current annual volume increment (CAI) of 3.48 m3 ha-1 a-1 and 3.62 m3 ha-1 a-1 in 1F plots at Grabouw and La Motte plantations indicated that it may be economically feasible to fertilise at mid rotation age as the NPV and IRR increased over a projected 25 year rotation. The Grabouw site had the most significant response with regards to CAI in 2F treatment with a mean volume increment of 5.43 m3 ha-1 a-1. The mechanism of the response was examined further by taking water availability and soil characteristics into account. The seasonal climatic effect (length of the moisture growing season) had a significant influence on the response to fertilisation.
AFRIKAANSE OPSOMMING: Die toediening van mid-rotasie bemesting word algemeen in bosbou toegepas om voedingstofbeskikbaarheid te verhoog in areas waar voedingstowwe onvoldoende is vir hoë produktiwiteit. Daar is oor die algemeen ruim potensiaal vir mid-rotasie bemesting in denne plantasies, maar eienskappe soos waterbeskikbaarheid, gronddiepte, opstanddigtheid en beskikbaarheid van voedingstowwe moet in ag geneem word voor optimum bemestingtoedienings bepaal kan word. Blaaranalise is gebruik om voedingstofbeskikbaarheid in plantasies te skat. Hierdie voedingstofvlakke is deurgans gemeet en is gebruik om spesifieke bemestingsbehandelings te implementeer wat voedingstofbeskikbaarheid kon opstoot. Behandelings het bestaan uit ‘n onbemeste kontrole, ‘n eenmalige kunsmistoediening (1F) en twee kunsmistoedienings in opeenvolgende jare (2F). Blaar oppervlak indeks en toename in stamvolume is gemeet om die invloed daarvan op die effektiwiteit van groei te bepaal. Blaaroppervlakindeks is bepaal deur middel van die gapingfraksie metode met behulp van ‘n stralingsmeter. Toename in volume is bereken met stamdeursnee en hoogte meetings. Basale oppervlakte is bereken deur middel van deursnee metings. Hierdie groeireaksies is gebruik om die effek van verbeterde voedingstofbeskikbaarheid te bepaal. Al die groeireaksies het toegeneem maar was nie statisties beduidend nie. Die gebrek aan beduidende toename kan toegeskryf word aan variasies in opstandsdigtheid en oorspronklike volume van die bome in die navorsingspersele. Die toetstydperk van 18 maande het moontlik nie genoeg tyd gegee vir die bome om op die toename in voedingstofbeskikbaarheid te reageer nie. ‘n Goeie groeirespons is wel waargeneem waar die voedingstofverhoudings in die naalde aanvaarbare norme bereik het. Die toename in volume aanwas van tussen 3.48m3 ha-1 a-1 en 3.62 m3 ha-1 a-1 in 1F persele by Grabouw en La Motte plantasies het aangedui dat dit ekonomies lewensvatbaar is om op mid-rotasie ouderdom bemesting toe te dien aangesien die netto teenswoordige waarde en die interne opbrengs koers toegeneem het op ‘n geprojekteerde 25 jaar rotasie. Die persele op Grabouw plantasie het die mees beduidende respons getoon met betrekking tot huidige jaarlikse aanwas (5.43 m3 ha-1 a-1 in die 2F perseel). Die meganisme van die respons is verder nagevors met inagneming van waterbeskikbaarheid en grondeienskappe. Die seisoenale klimaatseffek (lengte van die vog-groeiseisoen) het ‘n beduidende impak op die respons tot bemesting.

Thesis (PhD (For))--Stellenbosch University, 2002.
ENGLISH ABSTRACT: This study aims to evaluate the effects of forestry policy on the sustainability of forest resources in Southern Africa. However, the study has confirmed that forestry policy does not operate independently of other policies. Its scope is defined by overarching framework legislation and policy, while it functions within a complex mesh of crosscutting and sectoral policies. Therefore, the implications of these external policies for forest conservation have also been assessed. The method used employs predominantly qualitative assessment of documentary data, which constitute the main contents of the three case studies: South Africa, Tanzania and Zambia. This qualitative information has been transformed into quantitative data, using a scoring scale of one to five for certain indicators of sustainable forest management (SFM). The average score for each country makes up a forest conservation index (FCI), which provides a comprehensive insight into the performance of a country's forestry and other resource conservation policies. South Africa's FCI is estimated at 3, while Tanzania and Zambia's indices have been rounded to 2 each. As South Africa's forestry policy and other biological resource conservation policies came into existence as recent as the mid- and late 1990s, this index suggests that these policies will lead to SFM subject to satisfactory implementation. Indeed, South Africa has a congruous forestry legislation whose regulatory mechanisms are appropriately blended with financial and framework incentives. Its overarching framework legislation and policy define forestry policy, while the crosscutting policies reinforce it. However, the country's performance on intergovernmental and intersectoral policy co-ordination is poor, as well as on the economic valuation of its natural forest resources. Furthermore, the formulation of South Africa's forestry policy was not founded on up-to-date forest resource data. Contrary to the South African case, Tanzania and Zambia's indices indicate the likelihood of unsustainable forest use and management. These countries' existing forestry and other resource conservation policy-making processes are narrow-based and gender-insensitive, rendering them unpopular among policyaffected and policy-connected stakeholders. These inappropriate policies and their blunt instruments distort markets for forest resources, i.e., create situations in which benefits are dissociated from costs, prices from scarcities, rights from responsibilities and actions from consequences. Both forestry policies and their governing tools were not founded on contemporary forest resource data, i.e., they are not issue centred. The countries' framework laws have also failed to institutionalise environmental impact assessment, monitoring and evaluation, intersectoral policy co-ordination, participatory approaches to natural resource management and ownership of environmental assets such as land and forest resources by local communities. The administration of forestry policy requires competent professional and technical staff. South Africa has adequate human resources in the forestry sector, although the personnel appear to lack the necessary skills for participatory forest management for poverty reduction. Tanzania has adequate but ineffective forestry personnel, resutting in lack of law enforcement and corruption while Zambia lacks professional staff to interpret and implement the existing forestry policy. The ineffectiveness and the lack of professional and technical staff, inter alia, is reflected in the high rates of deforestation, which have been estimated at 91,000 halannum for Tanzania and 851,000 halannum for Zambia. Unlike South Africa, both Tanzania and Zambia's sectoral policies fail to cultivate concerns for forest conservation. This situation is aggravated further by the pervasive lack of intra- and intersectoral policy coordination among biological resource conservation divisions and departments. The coherence of South Africa's forestry and other resource conservation policies is attributable to the scarcity of natural forests in the country. Approximately, 7.0% of South Africa's landscape is under forest cover, while Tanzania and Zambia have 37% and 42%, respectively. Decreasing supplies of forest coupled with the increasing demands for forest resources causes the value of forest resources to appreciate. Naturally, there is a stronger need for the forest-scarce South Africa to pursue prudent conservation policies to protect its limited forest than Tanzania and Zambia whose governments treat their respective vast land and forest resources as a safety valve for economic hardship without adequate investment in SFM. In summary, forest resource use and management in Tanzania and Zambia are littered by market and policy failures. It is envisaged that the opportunities and constraints identified in each market and policy failure will inform future forestry and related policy-making process, not only in the concerned countries but also in other African countries experiencing similar forest conservation problems.
AFRIKAANSE OPSOMMING: Hierdie studie het ten doel om die effekte te evalueer wat bosboubeleid het op die volhoubaarheid van woudhulpbronne in Suidelike Afrika. Hierdie studie het egter bevestig dat bosboubeleid nie onafhanklik van ander beleidspunte funksioneer nie. Die omvang daarvan word gedefinieer deur oorkoepelende raamwerkwetgewing en beleid, terwyl dit binne 'n komplekse netwerk van oorkruisende en sektorale beleid funksioneer. Daaom is die implikasies van hierdie eksteme beleidspunte vir woudbewaring ook bepaal. Die metode gebruik, wend hoofsaaklik kwalitatiewe beraming van dokumentere data aan, wat die hoofinhoud van die drie gevallestudies, nl. Suid-Afrika, Tanzania en Zambia uitrnaak. Hierdie kwalitatiewe informasie is omvorm na kwantitatiewe data, deur gebruik te maak van 'n skaal van een tot vyf vir sekere indikators van vohoubae bosbestuur (VBB). Die gemiddelde punt vir elke land vorm 'n woudbewaringsindeks (WBI), wat 'n omvatlende insig verskaf van die land se uitvoering van die bosbou- en bewaringsbeleid van ander hulpbronne. Suid-Afrika se WBI is beraam op 3, terwyl Tanzania en Zambia sa indekse elk tot 2 afgerond is. Siende dat Suid-Afrika se bosbou- en bewainqsoeleld van ander biologiese hulpbronne eers so onlangs as die middel- en laat 1990's in werking getree het, stel hierdie indeks voor dat die beleid sal lei tot VBB, onderhewig aan bevredigende uitvoering daarvan. Suid-Afrika het inderdaad 'n gepaste bosboubeleid, waarvan die regulerende meganismes toepaslik vermeng is met finensiele en raamwerk aansporings. Die oorkoepelende raamwerkwetgewing en beleid definieer bosboubeleid, terwyl oorkruisende beleidspunte dit versterk. Die land se uitvoering van interregerings- en intersektorale beleidkoordinasie, is egter swak, asook in die ekonomiesa waardering van sy natuurlike woudhulpbronne. Verder, is die formulering van Suid-Afrika se bosboubeleid nie gegrond op woudhulpbrondata wat op hoogte was nie. In teenstelling met die Suid-Afrikaanse geval, toon die indeksa van Tanzania en Zcrnbia die waCl'skynlikheid van onvomoubae bosbenutting en -bestuur. Hierdie lande se bestaande beleidvormingsprosasse vir bosbou en bewaring van ander hulpbronne, is eng-gebaseer en geslags-onsensitief, wat dit onpopulsr maak onder beleidgeaffekteerde en beleidverbonde insethouers. Hierdie ontoepaslike beleidspunte en stomp instrumente verdraai markte vir woudhulpbronne, d.i. skep situasies waarin voordele gedissosieer is van kostes, pryse van skaashed, regte van verantwoordelikhede en aksies van nagevolge. Beide bosboubeleidspunte en die leidingsinstrumente is nie gegrond op kontemporere woudhulpbrondata nie, d.w.s. hulle is nie rondom die kwessie gesentreer nie. Die lande se raamwerkwette het ook gefaal daarin om omgewingsimpakberamings, monitering en evaluering, intersektorale beleidkoordinering, deelnemende benaderings tot natuurlike hulpbronbestuur en plaaslike gemeenskappe sa eienaaskai van omgewingsbates, SODS grond en woudhulpbronne in te stel. Die administrasie van bosboubeleid verg bevoegde professionele en tegniese personeel. Sui-Afrika het voldoende menslike hulpbronne in die bosbousektor, hoewel dit voorkom of die personeel nie die nodige vaadiqhede het vir deelnemende bosbestuur vir die veligting van arnoede nie. Tanzanie het voldoende, maa oneffektiewe bosboupersoneel, wat 'n gebrek aan wetstoepassing en korrupsie tot gevolg het, terwyl Zambie 'n tekort het aan professionele personeel om die bestaande bosboubeleid te interpreteer en te implementeer. Die oneffektiwiteit en die gebrek aan professionele en tegniese personeel, onder andere, word gerefiekteer in die hoe tempo van ontbossing, wat beraam is op 91,000 ha/jaCl'vir Tenzenie en 851,000 ha/jaCl'vir Zembie. Anders as Suid-Afrika, faal beide Tanzanie en Zambia se sektorale beleidspunte daain om belange vir woudbewaring te kweek. Hierdie situasie word verder vererger deur die deurdringende gebrek aan intra- en intersektorale beleidkoordinering onder afdelings en departemente van biologiese hulpbronbewaring. Die verband tussen Suid-Afrika se bosbou- en bewaringsbeleid van ander hulpbronne word toegeskryf aan die skaarsheid van natuurlike woude in die land. Ongeveer 7.0% van die Suid-Afrikaanse landskap is bedek met woude, terwyl Tanzanie en Zambia onderskeidelik 37% en 42% bedek is. Verlaagde voorraad van woude, gepaard met die toenemende vraag na woudhulpbronne, het tot gevolg dat die waade van woudhulpbronne styg. Natuurlik is daar 'n groter behoefte vir die woud-arm Suid-Afrika om verstandige bewaingsbeleid na te streef om sy beperkte woude te beskerm as Tanzanie en Zambie, waa hulle regerings hul onderskeie ge\Yeldigegrond en woudhulpbronne behandel as 'n veiligheidsklep vir ekonomiese ontbering, sonder voldoende belegging in VBB. As opsomming, is die benutting en bestuur van woudhulpbronne in Tanzania en Zambia met mark- en beleidsmislukking besaai. Dit word beoog dat die geleenthede en beperkinge wat met elke mark- en beleidsmislukking ge'identifiseer is, toekomstige bosbou en verwante beleidvormingsproses kan inlig, nie net in die betrokke lande nie, maar ook in ander Afrika lande wat soortgelyke woudbewarings probleme ondervind.

Thesis (MScFor)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: The study aims at developing models for predicting aboveground biomass for selected drought tolerant Eucalyptus (E) species (E. cladocalyx, E. gomphocephala and E. grandis x camaldulensis) from the dry west coast. Biomass models were fit for each of the species and a cross-species model was parameterised based on pooled data for all the three species. Data was based on destructive sampling of 28 eucalypt trees which were 20 years of age and additional five five-year old E. gomphocephala trees. Preliminary measurements on diameter at breast height (dbh), height (h) and crown height were recorded in the field. The sampled trees were then felled and samples of discs, branches and foliage were collected. Density of the wood discs and the bark was determined by a water displacement method and computer tomography scanning (CT-scanner). Stem biomass was reconstructed using Smalian’s formula for volume determination and the calculated densities. Upscaling of the crown was carried out by regression equations formulated by employing the sampled branches. Further assessment was carried out on a sub-sample by subjecting the samples to different drying temperatures in a series between 60 and 105ºC. Linear models were parameterised by a simultaneous regression approach based on Seemingly Unrelated Regression (SUR) using the “Systemfit” R statistical package. The predictor variables employed in the study were dbh, d2h and h in which the coefficient of determination (R2), Mean Standard Error (MSE) and Root Mean Standard Error (RMSE) were used to determine the goodness of fit for the models. Akaike Information Criteria (AIC) was also used in the selection of the best fitting model. A system of equations consisting of five models was formulated for each Eucalyptus species. The biomass prediction models had degrees of determination (R2) ranging from 0.65 to 0.98 in which dbh and d2h were the main predictor variable while h improved the model fit. The total biomass models were the best fitting models in most cases while foliage biomass had the least good fit when compared to other models. When the samples were subjected to different drying temperatures, stem wood had the largest percentage change of 6% when drying from 60ºC to 105ºC while foliage had the lowest percentage change of less than 2%.
AFRIKAANSE OPSOMMING: Die doel met hierdie studie is om modelle vir die voorspelling van die bogrondse biomassa van drie droogte-bestande Eucalyptus (E) spesies (E. cladocalyx, E. gomphocephala en E. grandis x camaldulensis), gekweek op die droë kusvlakte in Wes-Kaapland, te ontwikkel. Biomassa modelle vir elk van die spesies is gepas en ’n model gegrond op die gekombineerde data van al drie die spesies, is geparameteriseer. Verder is die biomassa variasie onder verskeie droogingstemperature vasgestel. Die data versameling is uitgevoer gegrond op die destruktiewe mostering van 28 Eucalyptus bome wat 20 jaar oud was en ’n bykomende vyf vyfjarige E. gomphocephala bome. Die aanvanklike mates, naamlik deursnee op borshoogte (dbh), boomhoogte (h) en kroonhoogte is in die veld opgemeet. Die gemonsterde bome is afgesaag en monsters van stamhout skywe, takke en die bas is versamel. Die digtheid van die skywe en die bas is deur die waterverplasing metode, en Rekenaar Tomografie skandering (“CT-scanning”) vasgestel. Stam biomassa is rekonstrukteer deur gebruik te maak van Smalian se formule vir die vasstelling van volume en berekende digtheid. Die opskaal van die kroon biomassa is gedoen met behulp van regressie vergelykings van gekose takmonsters. Submonsters is onderwerp aan ’n reeks van verskillende drogingstemperature tussen 60 en 105ºC. Lineêre modelle is deur ’n gelyktydige regressie benadering gegrond op die Seemingly Unrelated Regression (SUR) wat ’n“Systemfit” R statistiese pakket gebruik, parameteriseer. Die voorspeller veranderlikes wat in hierdie studie gebruik is, is dbh, d2h en h waarin die koëffisient van bepaling (R2), gemiddelde standaardfout (MSE) en vierkantswortel van die gemiddelde standaardfout (RMSE) gebruik is om vas te stel hoe goed die model pas. Akaike Inligting Kriteria is gebruik vir die seleksie van die gepaste model. ’n Reeks vergelykings wat bestaan uit vyf modelle is vir elke Eucalyptus spesie geformuleer. Die biomassa voorspelling model het waardes vir die koëffisiente van bepaling (R2) opgelewer wat strek van 0.65 to 0.98% en waarin dbh en d2h die hoof voorspelling veranderlikes is, terwyl h die pas van die model verbeter. Die totale biomassa model het in die meeste gevalle die beste gepas en die blaarbiomassa die swakste as dit met die ander modelle vergelyk word. Tydens droging vind die grootste persentasie verandering van 6% by stamhout plaas tussen temperature van 60ºC tot 105ºC, en die kleinste persentasie verandering van minder as 2% by blare.

Thesis (PhD (For))--Stellenbosch University, 2012.
ENGLISH ABSTRACT: A primary reason for the existence of the forest industry is to provide a renewable and natural resource for much needed timber and fibre products. Substantial improvements in management practices are required to increase forest volume and pulp yields for increased demand. Eucalyptus grandis clonal trees of age 6.75 years, grown in a Nelder 1a spacing experiment, were sampled and analysed to describe the effect of planting density on i) growth and yield, ii) wood properties and iii) pulp and paper quality. The main objective was to populate a fibre productivity index (FPI) which would be suitable from technical and economical perspectives. A material study was conducted on the wood and in addition, two methods were developed to further describe the variability of the forest resource to i) separate growth rings by means of wood density peaks from gamma-ray densitometry and ii) calibrate near infrared (NIR) prediction models. The results indicated that planting density did not influence the variability of wood density but mechanisms affecting available soil water are important. NIR prediction models were developed to rapidly and reliably assess wood properties on a non-destructive basis. The validation models for wood density, total pulp yield, kappa number and insoluble lignin returned high predictive ability. When applied to predict chemical properties from an independent data set, the outcomes were accurate in comparison with measured data. Growth and yield functions were developed for tree survival, dominant height and basal area. They accurately predicted outcomes as demonstrated by the goodness of fit and their logical behaviour tested over the range of planting densities. When the most extreme stand density treatments, 6809 and 275 trees per hectare (TPH) were evaluated for wood and fibre properties, the larger trees grown at 275 TPH, produced wood of better quality for pulp processing; basic wood density at 0.520 g cm–3 (21 % higher), fibre cell wall thickness at 2.10 μm (18.6 % thicker) and fibre lumen diameter at 8.16 μm (9.9 % lower) than for 6809 TPH. Intra-specific tree variability of wood and product properties increased from diameter at breast height (DBH) to 35 % and then decreased to 65 % of tree height. The effect of planting density was carried throughout the product value chain up to the paper manufacturing phase. Paper with higher bulk mass and thickness and more porous sheets is most likely to be made from lower planting densities (801 and 275 TPH), and stronger, smoother and denser paper is most likely to be made with trees at high planting densities (6809 or 2336 TPH). From the growth and yield and materials investigation, technical indicators identified to populate a fibre productivity index were: i) mean annual increment (MAI) as a forestry growth indicator, ii) wood density, summarising the composition of wood and, iii) pulp yield, the indicator of the amount of fibre processed through a chemical cooking process. Delivered cost of timber to the mill, was identified as the most suitable economic indicator which included fixed costs elements, variable costs and aspects of mill efficiency. The product of the technical and economic indicators concluded in a profit/loss scenario of producing 1 ton of pulp was deemed the best index to describe the entire and integrated value chain. This index, termed the Fibre Productivity Index (FPI) at the Mill, denoted as FPMill, is an integrated index that is easy to interpret in the realms of a forestry - pulp manufacturing, and can be used for differential pricing of timber for wood quality.
AFRIKAANSE OPSOMMING: 'n Primêre rede vir die bestaan van die bosbouindustrie is om ‘n hernubare, natuurlike hulpbron vir hout en vesel te voorsien. Aansienlike verbeterings in bestuurspraktyke is nodig om die houtvolume en pulpopbrengste vir die toename in aanvraag te verhoog. Eucalyptus grandis klonale bome met ‘n ouderdom van 6.75 jaar en wat in 'n Nelder 1a spasiëring eksperiment gegroei is, is versamel en ontleed om die effek van opstandsdigtheid te beskryf op a) groei en opbrengs, b) houteienskappe en c) pulp- en papiergehalte. Die hoofdoel was om 'n veselproduktiwiteitsindeks (FPI), wat geskik sou wees in terme van tegniese en ekonomiese perspektiewe, te ontwikkel. 'n Materiaalkundigestudie is op hout uitgevoer. Twee metodes is ontwikkel om die variasie in hout as natuurlike hulpbron te beskryf deur a) vroeëhout- en laathoutdigtheidspieke deur gammastraal-densitometrie van mekaar te skei en variasie in groeiringe te beskryf en b) daarstelling van naby-infrarooispektroskopiese (NIR) voorspellingsmodelle. Die resultate het aangedui dat aanplantingsdigtheid nie ‘n invloed het op die variasie van houtdigtheid nie, maar dat meganismes wat beskikbare grondwater bepaal, belangrik is. NIR-voorspellingsmodelle is ontwikkel om houteienskappe op 'n nie-destruktiewe manier betroubaar te kan evalueer. Die validasiemodelle vir houtdigtheid, pulpopbrengs, kappanommer en onoplosbare lignien, openbaar akkurate voorspellingsvermoë. Wanneer dit toegepas word om chemiese eienskappe van 'n onafhanklike datastel te voorspel, was die resultate akkuraat in vergelyking met gemete data. Groei- en opbrengsfunksies is ontwikkel vir mortaliteit, dominante boomhoogte en basale area. Akkurate voorspellingsuitkomste is verkry soos gedemonstreer deur die logiese gedrag wat getoets is vir alle plantdigthede. Toe die mees ekstreme opstansdigtheidbehandelings vir hul hout- en veseleienskappe geëvalueer is, was die hout van die groter bome, teen 275 stamme per hektaar (SPH), van beter gehalte. Dit was veral prominent vir houtdigtheid van 0.520 g cm-3 (21 % hoër), veselselwanddikte van 2.10 μm (18.6 % dikker) en vesellumendeursnit van 8.16 μm (9.9 % laer) as by die hoër (6809) SPH. Intra-spesifieke boomvariasie van hout- en produkeienskappe het toegeneem van deursnee op borshoogte (DBH) tot 35 % en dan weer afgeneem tot 65 % van die boomhoogte. Die effek van plantdigtheid is regdeur die produkwaardeketting tot by die papiervervaardigingstadium sigbaar. Papier met hoër basismassa en dikte, en meer poreuse papiervelle kan meer waarskynlik van laer aanplantdigtheid (801 en 275 TPH) bome gemaak kan word. Papier wat sterker, gladder en digter is, kan waarskynlik gemaak word van hout van bome teen hoë aanplantdigthede (6809 of 2336 SPH). Die veselproduktiwiteitindeks wat ontwikkel is uit die materiaalondersoek en tegniese aanwysers wat geïdentifiseer is sluit in i) gemiddelde jaarlikse aanwas, as 'n bosbou groei-indikator, ii) houtdigtheid, wat ‘n opsomming van die samestelling van hout is, en iii) pulpopbrengs; die aanduiding van die hoeveelheid vesel verwerk deur 'n chemiese verpulpingsproses. Gelewerde koste van hout by die pulpmeul is geïdentifiseer as die mees geskikte ekonomiese aanwyser wat vaste kosteelemente, veranderlike koste en aspekte van die meul se doeltreffendheid insluit. Die produk van die tegniese en ekonomiese aanwysers is saamgevat in 'n wins / verlies opsie vir die vervaardiging van 1 ton pulp, en is beskou as die mees geskikte indeks om die geïntegreerde waardeketting te beskryf. Dié indeks, die sogenaamde Vesel Produktiwiteitsindeks (VPI) by die Pulpmeul, aangedui as VPMeul, is 'n geïntegreerde indeks wat maklik is om te interpreteer in 'n bosbou - pulpvervaardigingsopset, en kan gebruik word in die differensiële prysbepaling van hout waarby die kwaliteit in ag geneem word.

Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2006.
Producing high quality end products, rather than focusing on volume production, is slowly but surely becoming the main driving force in the wood processing industry of South Africa. Drying defects such as surface checks and discolouration by yellow stain and kiln brown stain are major factors in softwood timber downgrades when selecting furniture grade timber. Previous efforts to control these defects have focused on schedule adaptation, but as the industry is still mainly concerned with volume production, and because of the varying lumber price, longer schedules to control these drying defects have not yet been that attractive for the larger sawmills. In ongoing research in this laboratory, a dip treatment of freshly sawn softwood boards in an aqueous solution containing a surfactant called sodium lauryl sulphate (SLS) was used to try to influence the mechanism involved in the development of these stains. Further, complementary research is reported in this study. Firstly, the possibility of using SLS solutions to control surface mould development and bluestain was investigated. Results showed that SLS did control the development of blue stain and mould growth in open-stacked boards for up to three weeks, using concentrations as low as 0.1%, and up to two weeks in closed-stacked timber when using concentrations of 0.2%. Secondly, it was investigated whether SLS treatment would have a detrimental effect on downstream product quality; in particular, kiln dried boards and glued components for furniture manufacturing. Since SLS influenced fluid water flow during kiln drying, the treatment could have exacerbated the occurrence of surface checking due to altered moisture distribution profiles. Results of this investigation showed that the SLS treatment did not result in increased surface checking. Thirdly, as furniture quality timber treated with SLS would be glued, (and also finished with surface coatings), it was further considered important to determine if SLS treatment influenced adhesion properties of wood surfaces. Based on shear test results, it was established that SLS did not influence the adhesion properties of wood when glued with two most commonly used glues in the furniture industry i.e. polyvinyl acetate (PVAc) and urea formaldehyde (UF).

Thesis (PhD (Forest and Wood Science))--University of Stellenbosch, 2006.
This study aims at examining technical and institutional capacity in local organisations to manage decentralised forest resources in Uganda. Specifically the study assessed the roles, responsibilities, powers and legal instruments, incentives, facilities and human and fiscal resources of local organisations to undertake decentralised forest governance. Semistructured and key informant interviews were conducted in local organisations and legal and policy documents reviewed to ascertain strategies for implementing decentralised forestry. An inventory of selected forests was conducted to assess effect of decentralisation policy on the condition of forests in Uganda. Chi-square tests were used to show the factors that motivate local organisations to participate in decentralised forest governance. Tree species diversity and richness, density, diameter at breast height and basal area and sings of human disturbance were used to compare the condition of forests under local government and those under private and central government ownership. Similarity between the forests was assessed using a Two Way INdicator SPecies Analysis, while the differences in the composition and structural characteristics of trees among forest ownership categories were compared by oneway analysis of variance. Multiple regression analysis was used to show the influence of household pressure, forest size, the distance of the forest from roads and forest administrative office, and the market demand of the forest produce on the capacity of forest agencies to regulate timber harvesting. The findings reveals that local organisations supported devolved forest management functions such as forest monitoring, tree planting, environmental education, networking, collaborative and integrated planning, resource mobilisation and formulation of byelaws. The role of forestry in the livelihoods of the people, the desire to control forest degradation and access to forest revenue, donor and central government fiscal support were the most important incentives in decentralised forest management. However, limited capacity in terms of qualified staff, funds, facilities and equipment and inadequate decision-making powers over fiscal resources from forestry, inequitable distribution of forest revenue and unclear forest and tree tenure hindered decentralised forest management. The diversity and richness indices, density, diameter at breast height and basal area of trees were significantly higher in central forest reserves, intermediate in private and lower in local forest reserves. The frequency of human disturbances was significantly higher in local forest reserves than in private and central forest reserves. The variation in composition and structure of the local forest reserves is partly attributed to human disturbances. The capacity of the forest agencies to regulate forest resources use in the Mpigi forests was significantly affected by the size of forest, and its location in relation to the well-maintained roads, forest administrative office and the number of households in close proximity and the market demand of the forest produce. Large forests in close proximity to densely populated areas and far a way from roads and the forest administrative office were more affected by timber harvesting. The results demonstrated that local governments are not yet efficient in monitoring and regulating forest use and maintaining the condition of forests in Uganda. Local organisations need to play an increased role in the implementation of the Forest Policy, the National Forestry and Tree Planting and the Local Government Acts for successful decentralisation of forest management and to recruit more technical staff, strengthen internal sources of revenue and develop integrated forestry work plans. There is also a need for the central government to integrate and co-ordinate local and central interests, and facilitate a working relationship with local governments, civil society and the private sector involved in forestry. Forest owners and managers in the Mpigi forests and Ugandaâ s tropical forests in general need to manage human impacts so as to balance utilisation and conservation forest resources. There is need for longterm studies to fully understand the real significance of ownership on the composition and structure of the Mpigi forests and forests in other districts of Uganda.

Thesis (PhD)--Stellenbosch University, 2004.
ENGLISH ABSTRACT:Six experiments, five in the glasshouse and one in the field near Nelspruit, were carried out to ascertain the effect of factors related to shoot die-back, and of water treatments on the growth and physiological responses of Pterocarpus angolensis seedlings. The study was undertaken to broaden the knowledge and understanding of the phenomenon of shoot die-back in order to enhance our ability to regenerate the species. The following experiments were carried out (a) Assessment of biomass accumulation; anatomical characteristics of the shoot apical meristem; foliar, stem and root concentration of micro- and macronutrients associated with each phenophase, (b) Effect of seedling age and seed source on the occurrence of shoot die-back under field conditions; (c) Water treatment effects on ChI. afluorescence traits of£'. angolensis seedlings obtained by assessing the fluorescence yield of photosynthetic samples subjected to dark- and light-adaptation; (d) Genetic variation in shoot die-back and other traits of sixteen halfsib families of £.. angolensis from Malawi, Namibia and Zambia grown over two die-back seasons. Experiments conducted revealed the following 1. Patterns of growth observed in phenophases are indicators of seasonal changes in annual biomass allocation to the shoot and root. Phenophases such as leaf loss and stem senescence, whether shoot die-back occurs completely or not, are directly related to the decline in above-ground biomass and declined rate of increase in root biomass respectively. Leaf flush, expansion and maturation result in increased biomass accumulation whilst shoot die-back has a minimal downregulatory effect on root biomass accumulation compared to the shoot. Shoot dieback is not sudden, therefore from the first day of germination, seedlings synchronise growth and development with the occurrence of shoot die-back. 2. Phenophasic concentration of foliar N, Ca and Mg, stem Fe and Cu and root concentrations of P, K, Mg, Fe and B are associated with shoot die-back. Patterns of mineral nutrient concentration obtained in foliage and roots but to a lesser extent in the stem, may be related to nutrient remobilisation during shoot dieback. Higher relative mineral nutrient changes during leaf yellowing and shoot die-back may be an indication of the removal of significant volumes of mobile nutrients from senescing tissues. 3. The volume of the shoot apex of E. angolensis remains constant during different phenophases which points to seasonal uniformity in the size of the apical dome. Changes in phenology associated with declined growth, or shoot die-back, is revealed through declined cell number in the tunica which is a reflection of declined mitotic activity. 4. Shoot die-back occurs in all seedlings from nursery stock planted under field conditions and all seedlings of up to two years experience complete shoot dieback. Shoot die-back takes place irrespective of seed source or the age of nursery stock that is planted. Survival after the first shoot die-back is normally low. Water treatments had no significant effect on the function of PSIJ reaction centres of P. angolensis nursery seedlings. In the case of both dark- and light-adapted leaves, water treatment had no significant effect on the measured Chi. a fluorescence parameters or the calculated parameters (specific activities, phenomenological fluxes, structure-function and performance indexes and drivingforces). 5. Water treatments affect the shape of ChI. a fluorescence transients of lightadapted compared to that of dark-adapted photosynthetic samples of E. angolensis. No significant water treatment effect was obtained for extracted and technical Chi. afluorescence parameters, specific fluxes, quantum efficiencies and phenomenological fluxes. Quantum yield, relative electron transport and quantum yield limitation, de-excitation rate constants, structure-function, performance indexes and driving forces were also not significantly different across water treatments.6. Genetic variation was observed to exist among 16 halfsib families from Malawi, Namibia and Zambia. High heritabilities were obtained for shoot die-back and other traits, indicating that shoot die-back is genetically controlled. The trait is passed from parents to offspring and it is highly probable that it occurs, throughout its natural range, in all seedlings. Since shoot die-back is genetically programmed, it remains crucial to the ability of a seedling to regenerate in the following rainy season
AFRIKAANSE OPSOMMING:Ses eksperimente, vyf in die glashuis en een in die veld naby Nelspruit, is uitgevoer om die effek van faktore wat verwant is aan die terugsterwing van lote op saailinge, sowel as om die effek van waterstres op die groei en fisiologiese responsies van Pterocarpus angolensis saailinge, te ondersoek. Die studie is ondemeem om die kennis en begrip aangaande die regenerasie-dinamika van die spesies te verbeter. Die volgende eksperimente is uitgevoer: (a) Evaluering van die effek van jisiologiese veranderings op biomassa; blaar-, stam- en wortelkonsentrasies van spoor- en makro-voedingselemente, en anatomiese eienskappe van die apikale meristeem van die lote. (b) Effek van saailingouderdom en saadbron op die voorkoms van lootterugsterwing onder veldtoestande. (c) Waterbehandelingseffekte op Chi. ajluorisensie eienskappe van ,e. angolensis saailinge wat verkry is deur die jluorisensie te evalueer van fotosintesemonsters wat aan donker- en lig-adaptasies onderwerp is. (d) Genetiese variasie in loot-terugsterwing en ander groei-eienskappe van 16 halfsib families van ,e. angolensis vanaf Malawi, Namibia en Zambia wat gekweek is oor twee terugsterj-seisoene. Die eksperimente het die volgende aan die lig gebring: 1. Groeipatrone waargeneem gedurende die fenofases is indikatore van seisoenale veranderings in jaarlikse biomassa allokasies aan die loot en die wortels. Fenofases soos blaarverlies en lootafsterwing, ongeag of loot-terugsterwing volledig is of nie, is direk verwant aan die afname in bogrondse biomassa en afnemende tempo van toename in wortelbiomassa respektiewelik. Bottende blare, vergroting en rypwording van blare lei tot toenemende biomassa akkumulasie terwyl loot-terugsterwing 'n minimale afskalende effek op akkumulasie van wortelbiomassa het in vergelyking met die van die loot. Loot-terugsterwing is nie skielik, met ander woorde vanaf die eerste dag van ontkieming sinchroniseer saailinge groei en ontwikkeling met die voorkoms van loot-terugsterwing. 2. Fenofase konsentrasies van en veranderings in blaar N en Ca en loot Fe, asook veranderings in waargenome wortel N, K, Ca, Mn, Cu, Zn en B is sterk geassosieer met loot-terugsterwing. Patrone van minerale voedingselementkonsentrasies wat in blare en wortels, en in minder mate in die loot, verkry is, mag direk verwant wees aan hermobilisering van voedingselemente gedurende loot-terugsterwing. Hoe relatiewe minerale voedingselementveranderings gedurende die vergeling van blare en lootterugsterwing mag 'n indikasie wees van die verwydering van betekenisvoUe hoeveelhede mobiele nutriente vanaf sterwende weefsel. 3. Die volume van die groeipunt van r. angolensis bly konstant gedurende verskillende fenofases wat dui op seisoenale uniformiteit in die grootte van die apikale koepel. Veranderings in fenologie ge-assosieer met afnemende groei, of loot-terugsterwing, word gerejlekteer deur afnemende selgetaUe in die tunika wat dui op afnemende mitotiese aktiwiteit. 4. VoUedige loot-terugsterwing kom voor in aUe saailinge vanaf die kwekery wat in die veld geplant word tot op die ouderdom van twee iaar. Dit kom voor angeag van saadbron of ouderdom van saailinge ten tye van planting. Oorlewing na aanvanklike loot-terugsterwing is normaalweg laag. 5. Water behandelings het geen beduidende effek op die funksie van PSII reaksiesentra van r. angolensis kewekery-saailinge gehad. Vir beide donker- en lig-aangepaste blare is geen beduidende waterbehandelingseffek verkry vir waargenome ChI. a jluoresensie parameters of die berekende parameters (spes ifieke aktiwiteite, jenomenologiese jlukse, struktuur-funksie-indekse, "perjormance-indekse oj" driving forces" ). 6. Genetiese variasie tussen 16 halfsibfamilies vanaf Malawi, Namibie en Zambie is verkry vir loot-terugsterwing en ander groei-eienskappe. Dit dui op genetiese beheer van terugsterwing en dat die eienskap oorerjbaar is, en waarskynlik in die hele natuurlike verspreidingsgebied van die spesies in aUe saailinge voorkom. Aangesien loot-terugsterwing gene ties geprogrammeer is, is dit noodsaaklik vir die vermoe van die plant om in die volgende reenseisoen te regenereer.

Thesis (MSc (Forest and Wood Science))--University of Stellenbosch, 2011.
ENGLISH ABSTRACT: The percentage yield of sawn timber recovered from logs has a large influence on the profitability of a sawmill. The positioning of the log as it is fed into the primary breakdown saw is one of the factors that impacts on the volume recovery percentage. The log’s position can be adjusted by changes in rotation, offset and skewness and depending on the ranges and increments used for these variables, the number of possible combinations can become substantial. In a sawmill the time available to assess possible log positions is limited and different strategies can be followed to arrive at an optimal or close‐to‐optimal positioning solution without an exhaustive evaluation of solutions. Meta‐heuristics are sometimes used to arrive at solutions for combinatorial optimisation problems in a limited time. The effectiveness of this approach on the optimisation of timber volume recovery based on log form is evaluated in this study using sawmill simulation data of sixty SA pine logs. A new meta‐heuristic, for convenience named the Tentacle algorithm, was developed specifically for the problem of log positioning optimisation. The results obtained with the Tentacle algorithm was compared with results from three existing meta‐heuristics i.e. the Simulated Annealing algorithm, the Population Based Incremental Learning algorithm and the Particle Swarm Optimisation algorithm, in terms of its efficiency and effectiveness in finding good log positioning solutions in a limited time. A fifth method, that of exhaustively searching smaller, high quality areas around the centered and “horns‐up” and “horns‐down” positions in the search space was compared to that of using the meta‐heuristic algorithms. In terms of volume recovery, the Tentacle algorithm performed, on average, the best of the four algorithms evaluated. However, exhaustive searches in the smaller, high quality areas in the search space, outperformed the algorithms.
AFRIKAANSE OPSOMMING: Die herwinningspersentasie van gesaagde planke uit saagblokke het ‘n groot invloed op die winsgewendheid van ‘n saagmeul. Die posisionering van die blok in die primêre saag is een van die faktore wat die herwinningspersentasie beïnvloed. Die blok se posisie kan verstel word deur veranderinge in rotasie, oplyning en skeefheid. Afhangend van die veld ‐en inkrementgrootte kan die hoeveelheid moontlike kombinasies beduidend wees. In ‘n tipiese saagmeul is die beskikbare tyd om moontlike posisies te evalueer beperk en verskeie strategieë kan gevolg word om optimale of nabyoptimale kombinasies te bereik sonder om alle moontlike kombinasies te evalueer. Meta‐heuristieke word soms gebruik om in ‘n beperkte tyd oplossings te vind vir kombinatoriese optimeringsprobleme. Die doeltreffendheid van hierdie metode by die optimering van herwinningspersentasie gebaseer op blokvorm is in hierdie studie ondersoek. Dit is met behulp van saagmeulsimulasiedata soos van sestig SA dennehoutblokke verkry, uitgevoer. ‘n Nuwe meta‐heuristiek, genaamd die Tentakelalgoritme, is tydens hierdie studie spesifiek vir die probleem van blokposisie‐optimering ontwikkel. Die resultate verkry met die Tentakelalgoritme is vergelyk met drie bestaande meta‐heuristieke, nl. die “Simulated Annealing”‐algoritme, die “Population Based Incremental Learning”‐algoritme en die “Particle Swarm Optimisation”‐algoritme in terme van doeltreffendheid om goeie blokposisies in ‘n beperkte tyd te vind. ‘n Vyfde metode, die gebruik van ‘n volledige ondersoek van verkleinde versamelings, rondom hoë‐kwaliteit areas in die soekarea, is vergelyk met die gebruik van die meta‐heuristieke. Hierdie hoë‐kwaliteit areas word gevind rondom die gesentreerde “horns‐up” en “horns‐down” posisies. Die Tentakelalgoritme het gemiddelde die beste herwinningsresultate van die vier meta‐heuristieke wat ondersoek was gelewer. Die volledige ondersoek van verkleinde versamelings in die hoë kwaliteit areas het egter die meta‐heuristieke oortref.

Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2011.
ENGLISH ABSTRACT: A lab scale combustion unit was designed, in order to characterise the performance of various woody and wood-based biofuels commonly used for energy production, cooking and heating. The unit was constructed in a way that it could be repeatedly reused and provide similar testing conditions, such as airflow for all samples. The requirements were that it was big enough to contain a fire large enough to yield good time/temperature profiles and at the same time easy to handle, operate and clean. It also had to allow the insertion of the thermocouples and flue gas probe. Time / temperature profiles were obtained and O2, CO2 and CO levels in the flue gas determined for each biofuel. The samples consisted of the five most commonly used fuel wood species in the Western Cape, namely Rooikrans, Camelthorn, Bluegum, Black wattle and vine stumps and five processed products, namely wood pellets, wood briquettes, commercial charcoal, commercial briquettes and handmade briquettes. Combustion time/temperature profiles were obtained for all samples and characteristic values, such as the maximum temperature and coal temperature compared. This allowed an indication of which product performed better than others in the different combustion phases and is more suitable for different requirements, such as industrial heating, or domestic cooking. Even though Bluegum and Camelthorn performed best overall they were not necessarily suited, for example, for large scale industrial use. It was found that wood pellets and charcoal were the best biofuel for industrial purposes, whereas Rooikrans was found to be the best option for small scale use.
AFRIKAANSE OPSOMMING: ‘n Laboratoriumskaal verbrandingseenheid was ontwerp vir die toets en karakterisering van verskeie houtgebaseerde biomassa soorte algemeen in gebruik vir energie opwekking, kook en verhitting. Daar was besluit om ‘n eenheid te bou vir herhaalde gebruik wat die omstandinghede vir elke toets konstant kan hou, bv. ‘n damper om lugvloei deur die sisteem the beheer. Die eenheid moet groot genoeg wees om veilig ‘n groot genoeg vuur the bevat waarmee ‘n goeie tyd/temperatuur profiel verkry kan word, maar terselfdetyd klein genoeg wees om te hanteer, operateer en skoon te maak. Die eenheid moes ook voorsiening maak vir die insteek van die termostate en gas peilstif. Tyd/temperatuur profiele is verkry en O2, CO2 en CO vlakke in die uitlaatgas is bepaal vir elke bio-brandstof. Die monsters was saamgestel uit vyf van die mees algemeen gebruikte brandhout spesies in die Wes Kaap, naamlik Rooikrans, Kameeldoring, Bloekom, Swartwattel en wingerdstompies, asook vyf geprosesseerde produkte naamlik houtpille, houtbrikette, kommersiële steenkool, kommersiële brikette and handgemaakte brikette. Verbranding tyd/temperatuur profiele is verkry vir al die monsters en verteenwoord waardes is daarvan afgelees, bv. die maksimum temperatuur wat bereik is of die temperatuur waar die vlamme uitgesterf het en slegs koolhitte gemeet word. Hierdie profiele het dit moontlik gemaak om te identifiseer watter produk het beter gevaar as ander gedurende die verskillende verbrandingsfases en is beter gepas vir verskillende gebruike, bv. huishoudelike kook en verhitting. Resultate het gedui dat die Bloekom en Kameeldoring die beste gevaar het oor all die toetse heen, maar was nie noodwendig ideaal vir elke spesifieke doel nie. Dit was bevind dat die steenkool en houtpille die beste gepas is vir industriele gebruik en dat die Rooikrans beter geskik is vir huishoudelike en kleinskaalse gebruik.

Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2009.
In this study, a multi-stem harvesting operation was observed and time studies carried out on its machines. A stump-to-mill simulation model (System 1) of this system was subsequently built using a commercial simulation software package (Arena 9) and data from the time studies were incorporated into the model. Following this, another two stump-to-mill multistem models (Systems 2 and 3) were built using the same simulation software package and parameterised input data. These two models represented hypothetical systems which were tested against System 1 and against one another in terms of machine balance within the system, production rate and cost. System 2 used identical equipment to System 1, but practised alternative operating methods. Some of System 3’s machines and operating methods differed from those in Systems 1 and 2. The objectives of the study were to: 1. Determine whether or not commercial simulation software can be used to adequately model forest harvesting operations. 2. Gauge potential system balance, production and/or cost improvement/s achievable through application of simulation-based operation adjustments. 3. Define beneficial equipment operation and application practises for multi-stem systems. 4. Through construction and use of the commercial software package in producing forest harvesting operation models, evaluate the software’s usability in terms of its applicability to and ease of use in such models, as well as its ability to meet forestrybased user requirements.

Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: The discussion on climate change is leading to a re-evaluation of tree plantations in South Africa; prompting the adoption of forest bioenergy system as one of the cost effective ‘carbon mitigation options’. In an analysis of this changing paradigm, emphasis was placed on the socio-economic aspects of integrated commercial tree plantations and forest bioenergy systems with special attention to harvest residues recovery for bioelectricity production and construction and operation of a bioelectricity plant. The study also explored the direct and indirect benefits that adjacent communities derive from tree plantations in South Africa in order to determine the potential impact of integrated timber and bioelectricity production on rural livelihood and conventional forestry operations. Structured questionnaires and in-depth interviews were used in randomly sampling twelve villages on Mondi tree plantations in the Piet Retief and Iswepe areas of South Africa. Six villages from each area were selected; and a systematic random sampling of ten households per village was carried out. The possibility of using harvest residues from final clear felling from these plantations for bioelectricity production was examined. The study developed and described a scenario for a five megawatt bioelectricity generation facility, requiring an annual volume of 19,569.85 dry tonnes of residues as feedstock for its operation. The study revealed that adjacent rural communities to Mondi plantations in Piet Retief and Iswepe areas enjoy direct benefits such as employment opportunities, utilization of harvest residues, utilization of non-timber resources, and free accommodation. Indirect benefits that these communities enjoy include: free farmland and graze-land and various social benefits. Issues of concern and dislike such as: lack of electricity; poor health and sanitation and transportation problems were also identified. Using NPV and IRR, the study estimated the economic impacts of integrated pulpwood and bioelectricity production, compared to conventional pulpwood production operation. The study concluded that integrated pulpwood and harvest residue recovery for bioelectricity production is a profitable means of producing renewable energy. The approach was found to increase the profitability of conventional forest operations.
AFRIKAANSE OPSOMMING: Besprekings rondom klimaatsverandering lei tot ‘n her-evaluasie van boom plantasies in Suid Afrika wat aanleiding gee tot die aanvaarding van bio-energie stelsels as een van die koste effektiewe “koolstof versagtende opsies”. In ‘n ontleding van hierdie paradigma verandering, is klem geplaas op die sosio-ekonomiese aspekte van die integrasie van boom plantasies en bos bio-energie stelsels. Spesiale aandag is gegee aan onginningsafval herwinning vir bio-energie produksie en die konstruksie en werking van ‘n bio-elektriese kragsentrale. Die studie ondersoek ook die direkte en indirekte voordele wat gemeenskappe, aangrensend aan boom plantasies in Suid Afrika verkry, om sodoende die potensiële effek van geintegreerde hout en bio-elektriese produksie op landelike lewensbestaan en konvensionele bosbou operasies te bepaal. Gestruktureerde vraelyste en indiepte onderhoude is gebruik om ‘n lukraakte steekproef van twaalf dorpies op Mondi boom plantasies in die Piet Retief en Iswepe areas van Suid Afrika uit te voer. Ses dorpies in elke area is gekies en ‘n sistematiese lukraakte steekproef van tien huishoudings per dorpie is uitgevoer. Die moontlikheid om ontginningsafval van finale kaalkap van hierdie plantasies vir bio-elektrisiteit te gebruik is ook ondersoek. Die studie het ‘n senario ontwikkel en beskryf van ‘n vyf megawatt bio-elektriese kragsentrale wat ‘n jaarlikse volume van 11,708 droë ton ontginningsafval benodig as voermateriaal vir kragopwekking. Die studie het getoon dat aangrensende landelike gemeenskappe langs Mondi plantasies in die Piet Retief en Iswepe areas direkte voordele soos werksgeleenthede, gebruik van ontginningsafval, gebruik van nie-hout hulpbronne en gratis akkommodasie geniet. Indirekte voordele wat gemeenskappe geniet sluit in gratis toegang to landbou grond en weiding, sowel as sosiale voordele. Probleemfaktore waarmee hulle saamleef is ‘n gebrek aan elektrisiteit, swak gesondheids en sanitasie dienste en vervoerprobleme. Deur die gebruik van NPV en IRR analitiese metodes is die ekonomiese impak van geintegreerde pulphout en bio-elektrisiteits produksie bepaal en vergelyk met konfensionele pulphout produksie. Die gevolgtrekking is dat geintegreerde pulphout en ontginningsafval herwinning vir bio-elektrisiteit produksie ‘n winsgewende manier van hernubare energie produksie is. Die benadering kan die winsgewendheid van konfensionele bosbou operasies verbeter.

Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: Balau, a group consisting of 21 Shorea species, is widely used for outdoor application. In South Africa, Balau is one of the most popular materials used for decking. Due to the increasing scarcity of Balau, it is of economic importance to investigate the possibility of a substitute timber for decking material. One possible timber could be Colorado, a mixture containing one or more of the following: Eucalyptus camaldulensis, Eucalyptus tereticornis and their hybrids. These two species and their hybrids are extensively cultivated in countries such as Australia, India and parts of South America because of their short rotation period and easy adaptability to a wide variety of soil and climatic factors. The timber was initially utilized as raw material for the pulp and paper industry but is now gaining importance in structural uses like furniture, flooring and decking. The aim of this exploratory study was to investigate relevant material properties and to examine the natural and accelerated weathering behaviour of Colorado and Balau to predict Colorado’s suitability as decking material. It was found that Colorado had smaller vessel lumina, fewer vessels/m2 and smaller rays than Balau and had a higher density than Balau. Although both timbers had a relatively low FSP, Colorado’s FSP was 2.3 percentage points higher than Balau’s. The swelling coefficients (radial and tangential) of Colorado were slightly higher than Balau’s but Colorado’s lower swelling anisotropy can result in a lower tendency to twist in service. Colorado had a higher water soluble extractive content than Balau, which can lead to the rapid initial colour changes when the timber is exposed uncoated. The weathering performance of Colorado and Balau was investigated by exposing samples in a QUV accelerated weathering apparatus and to natural weathering at an inland and a marine location. During weathering Colorado showed a slightly higher colour change ( E*) than Balau. Balau showed a higher increase in roughness (Rz), surface checking and check formation than Colorado. Colorado showed slightly more cup than Balau, however, Balau showed much larger amounts of twisting than Colorado. No statistically significant differences were found between the hydrophobicity of the two timbers. A coating was effective in increasing the initial hydrophobicity of samples and could maintain a relatively hydrophobic surface during weathering. No statistically significant differences were found in the effect of sample cut on timber species surface wettability. Although only long term exposure studies and using substantially more samples can confirm its weathering performance, the results of this exploratory weathering study indicated that Colorado can successfully be used as a substitute decking material for Balau.
AFRIKAANSE OPSOMMING: Balau, ‘n houtsoort wat ongeveer 21 Shorea-spesies verteenwoordig, word wyd in buitenshuise aanwendings benut. In Suid-Afrika is Balau een van die mees gewilde materiale wat vir dek-doeleindes gebruik word. As gevolg van die toenemende skaarsheid van Balau, is dit van ekonomiese belang om die gebruik van ‘n moontlik plaasvervangende houtsoort vir dek-materiaal te ondersoek. Colorado, ‘n mengsel van een of meer van die volgende: Eucalyptus camaldulensis, Eucalyptus tereticornis en hibriede daarvan, kan as ‘n moontlike plaasvervanger gebruik word. Hierdie twee spesies en hulle hibriede word op groot skaal in lande soos Australië, Indië en dele van Suid-Amerika gekweek vanweë hul kort rotasieperiode en goeie aanpasbaarheid by ‘n wye verskeidenheid grond- en klimaatsfaktore. Die spesies is aanvanklik as grondstof in die pulp- en papierbedryf gebruik maar word tans al hoe belangriker in strukturele aanwendings soos byv. meubels, vloer- en dek-materiaal. Die doel van hierdie verkennende studie was om relevante materiaaleienskappe te ondersoek en om die versnelde en natuurlike verweringsgedrag van Colorado en Balau vas te stel om sodoende ‘n aanduiding van die geskiktheid van Colorado as dek-materiaal te kan kry. Daar is gevind dat Colorado kleiner vat-lumina, minder vate/m2 en kleiner strale as Balau besit en dat Colorado ‘n hoër digtheid het as Balau. Alhoewel beide houtsoorte relatiewe lae veselversadigingspunte (VVP) besit, is Colorado se VVP 2.3% persentasiepunte hoër as dié van Balau. Die swellingskoëffisiente (radiaal en tangensiaal) van Colorado is effens hoër as dié van Balau, maar Colorado se laer swellingsanisotropie kan op ‘n kleiner neiging tot skeeftrek dui. Colorado het ‘n hoër wateroplosbare ekstrakstofinhoud as Balau bevat, wat tot aanvanklik vinnige kleurveranderings kan lei wanneer die hout sonder oppervlaktemiddel blootgestel word. Die verweringsgedrag van Colorado en Balau is ondersoek deur monsters aan versnelde en natuurlike verwering bloot te stel. Eersgenoemde is in ‘n QUV versnelde verweringsapparaat uitgevoer en laasgenoemde in ‘n binnelandse en ‘n mariene lokaliteit. Tydens verwering het Colorado ‘n effens hoër kleurverandering ( E*) as Balau getoon. Balau het ‘n hoër toename in rofheid (Rz), oppervlaktekrake en kraakvorming as Colorado getoon. Colorado het effens meer kromgetrek terwyl Balau meer skeefgetrek het as Colorado. Geen statisties beduidende verskille kon tussen die waterwerende eienskappe van die twee houtsoorte vasgestel word nie. ‘n Oppervlakbedekking was effektief om die aanvanklike toename in waterwerende vermoë te verhoog en gedurende verwering te kon behou. Geen statisties beduidende verskille kon tussen die invloed van snit van die monster op die oppervlaktebenatbaarheid van die houtsoorte vasgestel word nie. Alhoewel slegs langtermyn blootstellingstudies en die gebruik van beduidend veel meer monsters die verweringsgedrag kan bevestig, dui die resultate van hierdie verkennende ondersoek aan dat Colorado suksesvol as ‘n plaasvervangende dekmateriaal vir Balau gebruik kan word.

Thesis (MSc (Forest and Wood Science))--University of Stellenbosch, 2011.
ENGLISH ABSTRACT: The Saasveld solar kiln, valued at US$ 10,000 (R 70,000), is a greenhouse-type solar kiln requiring no additional heating. A unique auto-regulated process of natural dehumidification at night controls the humidity, and uses no venting system, nor any human/controller intervention. The natural dehumidification is achieved by circulating the humid kiln air through an air jacket on the periphery of the solar kiln. Diurnal temperature fluctuations allow condensation in the air jacket when air is cooled to below its dew-point temperature. The process is simple as colder night temperatures are a certainty. Almost no research has been done on similar kilns. The purpose of this thesis was to study the operation and performance of a solar drying kiln to dry high density hardwoods utilising natural dehumidification. The kiln load consisted of 20.1m 3 of a high density hardwood, Eucalyptus diversicolor, with air-dry density of 893kg/m 3 . The ZA Dry Q drying quality assessment indicated outstanding moisture distribution with little drying stress, a few surface checks and no internal checks, collapse, short bow or surface discolouration. The results conformed to the ZA Dry Q softwood appearance grade specification, except for end checks – remarkable for the drying of any hardwood. The final moisture content (MC) distribution was extremely tight with MC average of 11.5 per cent (%), standard deviation of 0.97% and the moisture gradient averaged 1.49%, standard deviation of 0.5%. The MC and MG were equally distributed in all three geometric directions throughout the load. The timber dried in 130 days. The kiln operation was analysed by temperature and humidity parameters at five positions inside and outside the kiln while monitoring the MC. The extent of moisture evaporation from the timber and the dehumidification of air were derived from this data. The results showed that the average of the daily kiln temperature, independent from the external temperature, increased from 18.0°C initially to 25.7°C. A maximum temperature of 38.1°C was recorded at the end of drying. Cell collapse did not occur under these low temperatures. Evaporation occurred generally from 07h30 to 16h45. The rate reduced at lower moisture contents. There was no effect of stack width. Natural dehumidification by condensation happened generally from 17h00 to 07h30. The equilibrium moisture content (EMC) decreased automatically from an initial daily average of 18.1% (variation 5%) to 8% (variation 2%) finally. It was similar to a smoothed T3C2–schedule. The mild drying conditions, with EMCs above 7.3%, ensured minimal moisture gradients and drying stresses. This reduced surface and internal checks. Nocturnal equalising and conditioning, comparable to intermittent schedules, resulted from: no evaporation, improved diffusion of heated timber and adsorption of moisture on the wood surface. The kiln protected the timber in extreme climatic conditions. It was found that the main circulating fan could be switched off from 17h00 to 07h30. A 30-minute manual venting at noon was permitted once fibre saturation point had been reached. Beneficiaries to this study can include hardwood processors who need to dry high density hardwoods within a reasonable time to an excellent drying quality. Processors in developing countries or who have little drying expertise could also benefit.
AFRIKAANSE OPSOMMING: Die Saasveld sondroër, met ‘n beraamde waarde van US$ 10,000 (R70,000), is ‘n groentetonneltipe sondroër met geen addisionele verhitting nie. ‘n Unieke auto-reguleerder beheer die humiditeit snags deur natuurlike dehumidifikasie. Dit gebruik geen ventileerder of enige menslike/kontroleerder inmenging nie. Die natuurlike dehumidifikasie word verkry deur die vogtige lug te sirkuleer deur ‘n lugkussing op die omtrek van die tonnel. Dag-en-nag temperatuur skommelings laat kondensasie toe binne-in die lugkussing sodra die lug benede die doupunttemperatuur afkoel. Dit is ‘n eenvoudige proses aangesien kouer nagte ‘n gegewe is. Byna geen navorsing is nog op soortgelyke sondroërs gedoen nie. Die doel van die tesis was om die werking en werkverrigting van ‘n sondroër wat hoë digtheid loofhout met behulp van natuurlike dehumidifikasie droog, te bestudeer. Die houtvrag het bestaan uit 20.1m 3 van hoë digtheid loofhout, Eucalyptus diversicolor, met ‘n gemiddelde lug-droë digtheid van 893 kg/m 3 . Die ZA Dry Q drogingskwaliteit toets het uitstaande resultate getoon. Daar was min drogingspannings, ‘n paar oppervlak krake en geen interne krake, sel-ineenstorting, kort-boog of oppervlak-verkleuring nie. Die resultate bevredig die ZA Dry Q naaldhout voorkomsgraad spesifikasie, behalwe vir end-krake – merkwaardig vir die droging van enige hoë digtheid loofhout. Die finale vogverspreiding was nou-verspreid met ‘n gemiddelde voggehalte van 11.5%, standaard afwyking van 0.97% en ‘n gemiddelde vog-gradiënt van ‘n 1.49%, standaard afwyking van 0.5%. Die voggehalte en vog-gradiënt was eweredig verspreid in al drie geometriese rigtings van die houtvrag. Die hout het in 130 dae gedroog. Die werking van die sondroër is geanaliseer deur temperatuur- en humiditeits-parameters by vyf posisies binne- en buite die droogkamer tegelykertyd met die voggehalte te monitor. Die omvang van vogverdamping uit die hout en dehumidifikasie van die lug is afgelei van hierdie data. Die gemiddelde daaglikse sondroër-temperatuur, wat onafhanklik van die buite temperatuur was, het verhoog van 18.0°C aanvanklik tot 25.7°C. Die maksimum temperatuur van 38.1°C is gemeet aan die end van droging. Sel-ineenstorting het nie voorgekom by hierdie lae temperature nie. Verdamping het algemeen voorgekom vanaf 07h30 tot 16h45, teen ‘n vertragende verdampingstempo by laer voggehaltes. Die stapelwydte-effek was van geen belang nie. Natuurlike dehumidifikasie deur kondensasie het gereeld voorgekom vanaf 17h00 tot 07h30. Die ewewigsvoggehalte (EVG) het outomaties verminder vanaf ‘n aanvanklike daaglikse gemiddelde van 18.1% (variasie van 5%) na 8% (variasie van 2%). Dit was soortgelyk aan ‘n gelykmatige T3C2 –drogingskedule. Die matige drogingskondisies, met EVG bokant 7.3%, het minimale vog-gradiënte en drogingspannings verseker wat oppervlak-krake en interne-krake verhoed het. Nagtelike houtvog egalisasie en kondisionering, vergelykbaar met puls-humiditeit skedules, was die gevolg van: geen verdamping, verbeterde diffusie in verhitte hout en adsorpsie van vog op die hout oppervlak. Die droogkamer het die hout beskerm teen buitengewone klimaatstoestande. Daar is gevind dat die hoof-waaier afgeskakel kan word vanaf 17h00 tot 07h30 en dat ‘n 30-minute nie-outomatiese ventilering smiddae kan plaasvind sodra veselversadigingspunt bereik is. Hierdie studie sal van nut wees vir die loofhout verwerkers wat hoë-digtheid loofhout moet droog binne ‘n redelike tydperk met ‘n uitstekende drogings-kwaliteit, asook houtverwerkers in opkomende lande of met gebrekkige drogingsvaardighede.

Thesis (MScFor)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: Individual tree models, as opposed to stand models, have the potential to greatly improve sensitivity of forest growth models to changing conditions such as silvicultural amendments, irregular stand structures, etc. It was the purpose of this study to extend two sub-components of a European individual tree growth model to introduce individual tree growth modelling concepts in South Africa using Pinus elliottii as a study species. Two main objectives were established: Modelling the potential height of stands across different site qualities and modelling diameter increment using a potential modifier approach with a combination of competition indices that change in importance according to the edaphic conditions of the site. Potential height modelling used three steps in order to achieve this objective. The first was to compare site index models based on different model fitting techniques, namely nonlinear least squares, generalised nonlinear least squares and nonlinear mixed effects models. The nonlinear mixed effects model proved to be superior in terms of achieving the principles of regression assumptions and model fit for the data range observed. The second step was to fit potential height using nonlinear quantile regression on observed spacing trial height measurements. This proved to be a robust technique able to capture potentials according to the defined Chapman-Richards model structure. The final step was to use the predicted site index as a site classification variable in order to predict potential height. While some small deviation occurred, potential height seems to be well correlated to site index and validation on selected sites suggested that site index can be used to model potential height until a more sophisticated site classification model is used for future improvement of the model. Diameter increment modelling followed six major steps in order to apply the full parameterisation methodology of an age-independent diameter increment model dependent on tree diameter and competition. Diameter increment potentials were fit using site index as a predictor of the potential height curves. Multiple competition indices were tested on two sites to obtain a combination of two indices, which can capture overtopping and local crowding effects. Principle components analysis and variance inflation factors calculation were applied to test for collinearity between indices. Suitable combinations were tested resulting in a combination of the KKL and Local Basal Area competition indices. Changing importance of the two indices were observed on the two sites tested indicating a shift in the mode of competition according to a water gradient. These were combined in a deterministic potential modifier model, which mimicked competitive stages over age; however the validation showed a skewed distribution, which was not sensitive to stand density gradients. A stochastic model was constructed to model variance from observed residual plots using linear quantile regression to determine bounds for a truncated normal distribution which generates random deviates for a predicted increment. The stochastic element significantly improved the performance and sensitivity of the model, however the model was still not sensitive enough at very high and very low spacing densities. All in all two key models for an adaptation of an individual tree growth simulator to South African conditions were successfully demonstrated. The two main objectives were achieved; however some indicated improvements could be made, especially for the competition indices where the sensitivity of competition to changing resource limitation according to site and temporal scales needs to be further investigated. Furthermore, the full set of models for simulating individual tree growth still needs to be applied. Overall, as a methodological approach, the study outlined problems and future improvements, introduced new concepts and can serve as a guideline for future parameterisation of an individual tree growth model.
AFRIKAANSE OPSOMMING: In vergelyking met vakgroeimodelle, het individuele-boomgroeimodelle die potensiaal om die sensitiwiteit van plantasiegroeimodelle vir veranderende omstandighede soos aanpassings in boskultuur, onreëlmatige vakstrukture, ensovoorts, drasties te verbeter. Die doel van hierdie studie was om twee subkomponente van ‘n Europese individuele-boomgroeimodel uit te brei om sodoende individuele-boomgroei modelleringskonsepte in Suid-Afrika bekend te stel. Pinus elliottii is gebruik as studiespesie. Twee hoofdoelstellings is bepaal. Eerstens, die modellering van hoogtegroei potensiaal van opstande oor verskeie vlakke van groeiplek kwaliteit. Tweedens, die modellering van deursnee-aanwas deur gebruik te maak van ‘n potensiaal matigingsbenadering “potential modifier approach“ met ‘n kombinasie van kompetisie-indekse waarvan die belangrikheid verander volgens die edafiese toestande van die groeiplek. Die hoogtepotensiaalmodellering bestaan uit drie stappe. Tydens die eerste stap word groeiplek bonniteitsmodelle vergelyk op grond van verskillende modelpassingstegnieke, naamlik nie-lineêre minimum kwadrate, algemene nie-lineêre minimum kwadrate en nie-lineêre gemengde effek modelle. Laasgenoemde het die beste gevaar in terme van die beginsels van regressiemodelle asook die mate waarin die model die waargeneemde data pas. Tweedens is hoogtegroei potensiaal gemodelleer deur nie-lineêre kwantielregressie op waargeneemde hoogtes van spasiëringseksperimente toe te pas. Die metode is robuust en in staat om potensiale volgens die gedefinieerde Chapman Richards modelstruktuur vas te vang. Laastens is die voorspelde bonniteits indeks as ‘n groeiplek klassifasie veranderlike gebruik om sodoende die hoogtegroei potensiaal te voorspel. Alhoewel klein afwykings voorgekom het, blyk hoogtegroei potensiaal goed gekorreleer te wees met bonniteits indeks. Uit validasie op geselekteerde groieplekke blyk dit dat bonniteits indeks gebruik kan word om hoogtegroei potensiaal te modelleer totdat ‘n meer gesofistikeerde groeiplek klassifikasiemodel beskikbaar is wat die model verder sal kan vebeter. Die volledige parametriseringsmetodiek van ‘n ouderdoms-onafhanklike deursnee-aanwas model wat afhanklik is van boomdeursnee en kompetisie bestaan uit ses hoof prosesse. Nie-lineêre kwantielregressie is gebruik om deursnee-aanwaspotensiale te pas vir verskeie groeiplekke. Dié is gekombineer met ‘n bonniteits indeks om ‘n nuwe model te vorm waarmee hoogtegroeipotensiaal kurwes voorpel kon word. Daar is met veelvuldige kompetisie-indekse op twee groeiplekke geëksperimenteer om ‘n kombinasie van slegs twee indekse te vind wat die effekte van oorskaduwing en plaaslike verdringing kan vasvang, te vind. Hoof komponent analise “Principle components analysis” en variansie inflasie faktore berekening “variance inflation factors calculation” is gebruik om vir kollineariteit tussen die indekse te toets. Gepaste indekskombinasies is getoets. ‘n Kombinasie van die KKL en plaaslike basale oppervlakte “Local Basal Area” kompetisie-indekse het die beste resultate gelewer. Die twee indekse is as volg geselekteer. Veranderings in die belangrikheid van elk van die indekse is waargeneem op die twee toetspersele. Dit dui op ‘n verskuiwing in die modus van kompetisie afhangend van ‘n watergradiënt. Die twee indekse is gekombineer in ‘n deterministiese potensiaal matigings model wat die kompeterende stadiums oor ouderdom naboots. Validasie het egter ‘n skewe verdeling wat nie sensitief vir opstandsdigtheidsgradiënte is nie, gewys. ‘n Stogastiese model is ontwikkel om variansie in die residuele grafieke te modelleer. Lineêre kwantielregressie is gebruik om grense vir ‘n afgestompte normaalverdeling wat ewekansige afwykings vir ‘n voorspelde aanwas te bepaal. Die stogastiese element het die prestasie van die deterministiese model merkbaar verbeter. Selfs met die stogastiese element, is die model egter steeds nie sensitief genoeg vir baie hoë en baie lae opstandsdigthede nie. Ter opsomming is twee modelle vir ‘n aanpassing van ‘n individuele-boomgroeisimuleerder vir Suid- Afrikaanse toestande suksesvol gedemonstreer. Die twee hoofdoelstellings is bereik. Daar is egter steeds ‘n paar aangeduide verbeterings wat aangebring kan word. Die sensitiwiteit van die kompetisie-indekse op hulpbronbeperkings wat verander op grond van die ruimtelike en temporale skale moet veral verder bestudeer word. Verder moet die volle stel modelle wat benodig word om individuele-boomgroei te modelleer nog toegepas word. As ‘n metodologiese benadering, het die studie probleme uitgewys en toekomstige verbeterings aangedui, nuwe konsepte bekendgestel en kan dus dien as ‘n riglyn vir toekomstige parametrisering van individuele-boomgroeimodelle.

Thesis (MScFor (Dept. of Forest and Wood Science)--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: This study aims to quantify the benefits of implementing an operational harvesting plan in forest harvesting operations. This is to be achieved by comparing productivity and costs from unplanned and planned harvesting operations. The study was conducted on a Pinus radiata plantation owned by Mountain to Ocean Forestry Company (Pty) Ltd (MTO) located near the town of Grabouw in the Western Cape Province of South Africa. MTO conducts harvesting operations using semi-mechanised tree-length harvesting systems. A wheeled H67 Clark Ranger cable skidder is used to extract tree-lengths from infield to the landing. Data was obtained both manually (work study) and from GPS tracking. Choking and dechoking data was obtained through time and method studies. GPS tracking was used to measure travel loaded and travel empty times, as well as travel distances and travel speeds. The aim of using both manual techniques and GPS tracking was to obtain detailed and spatially accurate information about the operation. The operating costs were estimated using South African Harvesting and Transport Costing Model. Productivity of the newly introduced tagline system (45.97 m³/pmh) exceeded that of mainline system (37.85 m³/pmhh) by 26%. The unit production cost of using tagline system (R20.21/m³) was 10% lower than the unit production cost of using mainline system (R22.54/³3). There were no benefits to be gained from improving the level of skid trail construction by removal of logging residue or cutting down stumps to as near the ground level as possible. A combination of manual (time and method studies) data collection and GPS tracking provided more detailed and accurate information on the semi-mechanised harvesting system.
AFRKAANSE OPSOMMING: Hierdie studie beoog om die voordele van die uitvoering van 'n operasionele inoestingsplan te kwantifiseer. Dit word bereik deur produktiwiteit en kostes van beplande en onbeplande inoestingswerksaamhede te vergelyk. Die studie is gedoen in Pinus radiata opstande van Mountain to Ocean Forestry Company (Pty) Ltd (MTO) naby Grabouw in die Wes-Kaap provinsie van Suid Afrika. MTO gebruik semi-gemeganiseerde boomlengte inoestingstelsels in hul inoestingswerksaamhede. . H67 Clark Ranger wielsleeptrekker met kabel en wenas is gebruik om boomlengtes van die veld na die pad te sleep. Data is versamel deur van beide hand (werkstudie) en GPS-opsporing gebruik te maak. Afhaak en aanhaak data is verkry deur van tyd- en metodestudies gebruik te maak. Gelaaide en ongelaaide tyd, spoed en afstande is met behulp van die GPS gemeet. Deur van beide hand en GPS versamelingsmetodes gebruik te maak, kon omvattende sowel as ruimtelik akkurate inligting oor die werksaamhede verkry word. Die bedryfskostes is verkry van die South African Harvesting and Transport Costing Model. Produktiwiteit van die nuut ingestelde verbindingslynstelsel (45.97 m³/pmh) het die hooflynstelsel (37.85 m³/pmh) met 26% oorskry. Die eenheidsproduksiekoste van die verbindingslynstelsel (R20.21/m³) was 10% laer as die eenheidsproduksiekoste van die hooflynstelsel (R22.54/m³). Daar was geen voordeel in die verbetering van die sleeppad konstruksie deur afval te verwyder of stompe nader aan die grondvlak af te sny nie. 'n Kombinasie van hand (tyd- en metodestudies) dataversameling en GPS-opsporing het meer akkurate en omvattende inligting oor die semi-gemeganiseerde inoestingstelsel verskaf.

Thesis (PhD (Dept. of Forest and Wood Science))--University of Stellenbosch, 2009.
ENGLISH ABSTRACT: This study aimed to analyze under which conditions the structure, organization and integration of knowledge systems can provide the implementation of adaptive collaborative management of natural resources under conditions of high biodiversity in the humid forest zone of southern Cameroon. The study specifically did the following: characterized sustainable slash-and-burn agriculture innovations; examined the influences of local perceptions of nature and forest knowledge management systems on adaptive slash-and-burn agriculture practices; analyzed the influences of the social representation of land use patterns and their local indicators on agro-ecological sustainability; characterised the biophysical dimensions of local management of agricultural biodiversity knowledge systems; analyzed how local agricultural biodiversity knowledge is used to adapt and to satisfy household consumption needs, market preferences, and sustainable livelihoods; examined the influences of local perceptions of climate variability for the ability and adaptive capacity of people to use local knowledge to deal with the effect of pests-diseases on crop yield, corrective management actions, and adaptive slash-and-burn agriculture management. The study was conducted in three blocks within the humid forest zone of southern Cameroon along a gradient of natural resource use management intensification and population density. Data were collected via structured and semi-structured interviews, multi-disciplinary landscape assessment and a review of secondary information. Chisquare tests were used to show how local knowledge influences - natural resource management at the forest-agriculture interface, while binary logistic regressions were used to understand the influences of biophysical and socio-economic factors on farmers’ decisions to domesticate tree species and to cultivate several crop cultivars. Fourteen research and development (R&D) themes were identified and found to be equally distributed among blocks but unequally distributed across technical, marketing and socio-organisational types of innovation. There was a gap between social demand and innovation offer. Innovations offered covered more technical issues, such as crop variety development, indicating their agricultural focus rather than the integration of forest and agriculture issues. The local perceptions of nature and forest resources are based on social representation of the vital space into components having a specific function for the social, physical and spiritual life of people. Needs of the human world determine the role of local forest knowledge systems in the interpretation and responses of the natural environment, and guide the trajectories of natural resource management practices. The management of agro-ecological sustainability is based on the local definition of well-being, social representation of space and on a multi-criteria approach combining bio-indicators such as plants, earthworm activities, age of vegetation or forest cover, soil colour and quality but it is also positively influenced by land use history, the use value of wild plant and crop species, the knowledge of crop qualities, the knowledge of interactions between crops, and between crops and other wild plant species, the tree size of tree species used, the future use of a current land use, the estimated land use for own use and market access.
AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om te bepaal onder watter omstandighede die struktuur, organisasie en integrasie van kennissisteme kan bydra tot die implementering van aanpasbare deelnemende bestuur van natuurlike hulpbronne onder toestande van hoë biodiversiteit in die vogtige woudsone van suidelike Kameroen. Die studie het spesifiek die volgende gedoen: volhoubare kap-en-brand landboukundige ontwikkelinge gekarakteriseer; die invloede van plaaslike persepsies van die natuur en woudkennisgebaseerde bestuursisteme op aanpasbare kap-en-brand landboupraktyke ge-evalueer; die invloede van die sosiale verteenwoordiging van grondgebruikspatrone en hul plaaslike indikatore op agro-ekologiese volhoubaarheid ontleed; die biofisiese dimensies van die plaaslike bestuur van landboukundige biodiversiteitskennissisteme gekarakteriseer; geanaliseer hoe die plaaslike landboukundige biodiversiteitskennis gebruik word om aan te pas by en bevrediging te verkry vir huishoudelike gebruiksbehoeftes, marksvoorkeure en volhoubare bestaansbehoeftes; die invloede en gebruik van plaaslike kennis en persepsies van klimaatsvariasie beoordeel in die vermoë en aanpassingskapasiteit van mense om die effekte van siektes-peste op gewasproduksie, regstellende aksies en aanpasbare kap-enbrand landboubestuur te hanteer. Die studie is uitgevoer in drie blokke binne die vogtige woudsone van suidelike Kameroen langs ‘n gradient van natuurlike hulpbrongebruiksbestuursintensiteit en populasiedigtheid. Data is versamel deur gestruktureerde en semi-gestruktureerde onderhoude, multi-dissiplinere landskapsevaluering en ‘n oorsig van sekondere inligting. Chi-kwadraat toetse is gebruik om te wys hoe plaaslike kennis die bestuur van die woudlandbou konneksie beinvloed asook binêre logistiese regressies om die invloede te verstaan van biofisiese en sosio-ekonomiese faktore op die boere se besluite om boomsoorte te domestikeer en om verskeie gewaskultivars te kweek. Veertien temas in navorsing en ontwikkeling (N&O) was gelyk versprei tussen die blokke en ongelyk versprei tussen tegniese, bemarking en sosio-organisatoriese tipes innovering. Daar was ‘n gaping tussen sosiale aanvraag en innoveringsaanbieding. Innoverings het meer tegniese aspekte gedek, soos ontwikkeling van ‘n verskeidenheid gewasse, wat wys op ‘n landboukundige fokus eerder as ‘n integrasie van woud en landboukundige aspekte. Die plaaslike persepsies van die natuur en woudhulpbronne was gebaseer op sosiale verteenwoordiging van lewensbelangrike ruimte in komponente met ‘n spesifieke funksie vir die sosiale, fisiese en geestelike lewe van die mense. Behoeftes van die menslike wereld bepaal die rol van plaaslike woudkennissisteme in die interpretasie van en reaksie op die natuurlike omgewing, en rig die gebruik van hulpbronbestuurspraktyke. Die bestuur van agro-ekologiese volhoubaarheid is gebaseer op die plaaslike definisie van geluk, sosiale verteenwoordiging van ruimte en op ‘n multikriteria benadering wat bio-indikatore kombineer soos plante, erdwurmaktiwiteite, ouderdom van plantegroei- of woudbedekking, grondkleur- en kwaliteit, maar is ook positief beinvloed deur grondgebruiksgeskiedenis, die gebruikswaarde van natuurlike en gewassoorte, die kennis van gewaskwaliteite, die kennis van die interaksie tussen gewasse en tussen gewasse en natuurlike plantsoorte, die boomgrootte van boomsoorte wat gebruik word, die toekomstige gebruik van ‘n huidige grondgebruik, die beraamde grondgebruik vir eie gebruik en vir toegang tot die markte.

Thesis (PhD (Forest and Wood Science))--University of Stellenbosch, 2006.
The discolouration of South African softwood during kiln drying can reduce the value of furniture grade lumber. Thermal discolouration of wood, as found due to heat treatment, produces a homogeneously browner colour in wood than is normally expected. This type of discolouration is attributed to reactions of the macromolecules present in wood and is found in both hard- and softwoods. Yellow stain and kiln brown stain can severely alter the colour of the outer few millimeters of a wooden board and is attributed to the reaction of water-soluble sugars and nitrogenous compounds, present in the wood sap, after deposition at the wood surface due to liquid or capillary water flow during drying. A discussion of the mechanism of discolouration due to yellow stain and kiln brown stain would be incomplete without a good understanding of the liquid flow of water during drying above fibre saturation point. This thesis brings the two concepts of liquid water flow and discolouration in context and is presented in four chapters: • an introduction motivating the aims of the investigation (Chapter 1); • a literature review of factors which may influence discolouration and liquid water flow during drying (Chapter 2); • original manuscripts describing the discolouration of South African softwood and liquid water flow in hard- and softwood (Chapter 3); and • a final conclusion that links up the results from the investigations (Chapter 4). The investigations into the occurrence of yellow stain and kiln brown stain showed that the intensity of these types of discolouration was influenced by geographical origin (and/or climate), tree species, planing depth of dried lumber, and kiln schedule parameters like dry- and wet bulb temperature and time. The characteristic discolouration pattern of yellow stain and kiln brown stain indicated that this stain type was related to the wetline phenomenon that is found during the liquid water flow phase of drying wet wood. Thermal discolouration, on the other hand, occurred homogeneously throughout the volume of lumber and is, therefore, not related to free water flow, but to chemical changes of the macromolecules in wood. The results of the liquid water flow investigations support the invasion percolation theory of drying that states that the largest meniscus will retract into a drying liquid-filled capillary network until it is not the largest meniscus anymore. Fluctuations in the rate of moisture loss from the cores of wood pieces above fibre saturation point were also found. The pattern of fluctuation differed appreciably between Betula verrucosa and Pinus radiata. In both cases, the start of the last phase in rate of moisture loss from the core coincided with a reduction in the cross-sectional area of the drying wood piece. This behaviour is explained by the hypothesis that distinct capillary size classes are emptied of free water, in order, from large to small. As smaller capillaries are emptied, the capillary forces become greater, to the point where the forces are great enough to cause permanent or temporary deformation of the remaining water-filled capillaries. Classification and regression tree analysis was a useful statistical technique to analyse a large multivariate dataset. The importance of kiln schedule temperatures and planing depth to control yellow stain and kiln brown stain was clearly pointed out by the technique, which can help to simplify the control of colour quality during the industrial processing of wood.

Thesis (MScFor)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: One of the major objectives in plantation forestry is to achieve a high level of homogeneity of distribution and dimension of trees within the stand. Precise planting geometries, intensive silviculture and genetic selection are used to achieve this homogeneity. However, a natural variability is still introduced by micro-­‐site conditions and disturbances. A substantial source of variation is caused by edge effects of neighbouring stands or other land use forms. The edge effect causes trees at the stand edge to develop differently from trees in the interior of the stand. The overarching objective of this study is to simulate the edge effect based on average stand interior variables as typically received from an enumeration and spatial information on the current and historic stand neighbourhood. With re-­‐introducing this natural variance as well as its spatial pattern, we expect to derive improved planning information. A major aim is thus separating the effect of the edge interaction from the other factors contributing to stand variance and quantifying the result in terms of stand output. A methodology is introduced for quantifying interaction at stand edges between a given stand and its neighbouring stands over its lifetime. Transferring the edge interaction value from the edges to all the trees within the stand is then done by applying inverse distance weighting interpolation from the edges to the tree position within the stand. Once an edge interaction value has been calculated for each point, the extent of the edge effect is quantified. The spatial extent of the edge effect is derived empirically from an existing fully spatially mapped stand by means of breakpoint regression. The expected variance as a result of edge influence is then quantified by producing a set of models, which can reproduce the effect of the edge interaction on tree height, diameter and volume. The edge effect is treated as a dynamic interaction for which the temporal aspect needs to be considered, because the current spatial structure of a stand is influenced by its current neighbourhood, but also by the historic development of the neighbourhood in relation to the stand in question. Each stand therefore undergoes an edge effect which is completely unique to that stand, within a given time period. For this reason the presented methodology is a spatial-­‐temporal one, aimed at providing a way in which growth and yield forest modelling can be augmented by the inclusion of the edge effect in a practical way. To explicitly quantify edge effects, the natural variance had to be separated into a component explained by edge effect and a second component introduced by other factors such as micro site conditions and disturbance. The second component is treated as an unexplained residual variance. In order to provide a realistic simulation of a stand output at a finer, tree level, this second stand variance needs nonetheless to be quantified. The variance attributable to factors other than the edge effect is mimicked by generating a random number by means of a parameterised stochastic process based on the variance of the inner stand region, which is beyond the reach of the edge effect. In this way, a realistic spatial pattern of a plantation forest stand, taking into account the edge effect and combining it with the natural stand variance is achieved. This study, within the field of plantation forest management, aspires to land use optimization both in terms of productive capacity estimation and for the provision of information for effective land use management planning. It makes use of open source software resources namely the R framework and QGIS and explores aerial stereophotogrammetry as an option for data collection.
AFRIKAANSE OPSOMMING: Een van die hoofdoelwitte in plantasie bosbou praktyk is hoё vlakke van homogeniteit met betrekking tot die verspreiding en die dimensies van die bome in die plantasie opstand. Simetriese aanplantings, intensiewe bosboupraktyk en genetiese seleksie word gebruik om hierdie homogeniteit te verkry. Natuurlike verskille word egter nog steeds gevind as gevolg van groeiplek mikro toestande en ander versteurings in die opstand. Een van die hoofbronne van hierdie variasie is die randeffekte van buurplantasies en ander gebruike van grond. Hierdie randeffekte veroorsaak dat bome aan die rand van die opstand anders ontwikkel as die bome binne in die opstand. Die oorhoofse doelwit met hierdie navorsing is om die randeffekte te simuleer. Hierdie randeffekte is gegrond op die gemiddelde binneopstand boom veranderlikes soos afgelei uit die opmeting en uit ruimtelike inligting oor die huidige en geskiedkundige toestande in die omgewing. As hierdie natuurlike variasies asook die ruimtelike patrone weer in berekening gebring word, verwag ons om beter beplanningsinligting te bekom. ’n Belangrike doelwit tydens hierdie navorsing is dus om die effek van die rand-­‐interaksie te skei van die effek van ander faktore wat bydra tot variasies binne-­‐in die opstand en om die resultaat in terme van plantasie produksie te kwantifiseer. ’n Metodiek word voorgestel vir die kwantifisering van die interaksie op die rande tussen die opstand en die buuropstande tydens die leeftyd van die opstand. Die oorplasing van die rand interaksie waarde van die rand af na al die bome in die plantasie word dan gedoen deur om geweegde inverse afstand interpolasie vanaf die rand tot by die ligging van die boom, toe te pas. As die rand interaksie waarde vir elke punt bereken is, kan die omvang van die randeffek gekwantifiseer word. Die ruimtelike omvang van die rand effek is, met die gebruik van breekpunt regressie, empiries afgelei van ’n bestaande ten volle karteerde plantasie. Die verwagte variasie as gevolg van die randeffek word dan met die gebruik van ’n stel modelle gekwantifiseer, wat dan die effek van die rand interaksie op boomhoogte, deursnit en volume kan weergee. Die randeffek word as ’n dinamiese interaksie beskou waarvan die tydsaspek in ag geneem moet word, want die huidige ruimtelike struktuur van die plantasie word beïnvloed deur die huidige omgewing asook deur die historiese ontwikkeling van die omgewing met betrekking tot die opstand onder bespreking. Elke opstand ondergaan ’n randeffek wat uniek is aan daardie plantasie op die gegewe tydstip. Die doelwit is om ’n wyse te vind waarvolgens groei-­‐en-­‐opbrengs plantasie modellering deur die insluiting van randeffek op ’n praktiese wyse, aangevul kan word. Om hierdie rede is die aanbevole metodiek ruimtelik-­‐tydelik en gerig daarop om ’n wyse te vind waarvolgens groei-­‐en-­‐opbrengs modellering deur die insluiting van die randeffek, op ’n praktiese wyse aangevul kan word. Om randeffek eksplisiet te kwantifiseer, moes die natuurlike afwyking gedeel word in die komponent wat die gevolg is van die randeffek, en ’n tweede komponent wat die gevolg is van ander faktore soos mikroligging toestande en versteurings. Die tweede komponent word behandel as ’n onverklaarde oorblywende afwyking. Hierdie tweede plantasie afwyking moet nogtans kwantifiseer word om sodoende ’n realistiese simulasie van plantasie opbrengs op ’n fyner boom vlak te verkry. Die afwyking wat toegeskryf kan word aan faktore buiten die randeffek, word nageboots deur om ’n lukrake nommer (wat gebaseer word op die afwyking van die binne-­‐plantasie gebied wat buite die strekwydte van die randeffek is) deur middel van ‘n geparameteriseerde stogastiese proses te genereer. Sodoende word ’n realistiese ruimtelike patroon van ’n plantasie opstand verkry, wat die randeffek in ag neem en dit kombineer met die natuurlike plantasie afwyking.

Thesis (MScFor) (Forest and Wood Science)--University of Stellenbosch, 2007.
While the contribution of non-timber forest products (NTFPs) in sustaining livelihoods of the poor is gaining global attention, the importance of woodcarving trade in sustaining the livelihoods of the poor people has been poorly researched. A study was conducted in Cape Town area of the Western Province, South Africa to assess the contribution of woodcarving trade to the livelihoods of the traders and the dynamics of the trade, and institutional constraints impacting on the development of the trade. A total of 61 traders in wood carving, as well as municipal authorities and key informants, were interviewed using structured questionnaires; note taking, personal observations, and in-depth interview based open-ended questions. The findings of the study revealed that the woodcarving trade is a highly male (69%) dominated activity. Most traders were married (55%) and most of the respondents (63%) fell within the active age group of 21-35 years. The wood carving trade was dominated by highly literate people with 66% and 25% having reached secondary and tertiary education, respectively. The study also revealed that “earning a living” represented the single most important factor (70%) that pushed people into the wood carving trade. Most traders (85%) did not own property but for those who owned property, 56% were South Africans followed by Zimbabweans (22%). The study showed that most of the woodcarving products arriving in the Western Cape come from the SADC region accounting for 78% of the products. Malawi (36%), Zimbabwe (30%) and Kenya (13%) are the main sources of the wooden crafts curio into the Western Cape woodcraft market. The study also found that Dalbergia melanoxylon from Zimbabwe (47%) and Malawi (16%) and Brachylaena huillensis from Kenya (47%) and Afzelia quanzensis from Zimbabwe (27%) represent the most traded wood species. The wood for carving was mainly accessed through intermediate agents (48%) and on site purchase (43%); and polishing represented the most important process (80%) of value adding compared to painting and shining. Personal cars (38%) and buses (36%) were the main means of transportation used compared to other forms of transport. It was shown that cost (48%) and customer based price (33%) represented the main pricing methods used by traders. Shop owners had an average income estimated at R 6, 450 and R 2, 692 in good and lean month sales, respectively. In addition, seasonality represented the single most important factor (56%) threatening the woodcarving industry and the livelihood of urban traders compared to factors such as quality of wood product (18%) and scarcity of the resource (10%). This study found that traders had difficulties accessing physical infrastructures (87%); social assets (50%) and human capital (74%). On the other hand, 62% of the traders did not seem to have problems accessing natural assets. As a livelihood strategy, traders also undertook multiple activities including sale of minor products as well as soliciting extra help from companions and/or hiring extra help during peak seasons. For the sustainability of the woodcarving trade in the Western Cape, there is a need for sustained, long-term management of wood species used for carving through domestication and use of alternative wood species. In addition, policies should promote: (i) integrated resource use that will ensure maximum utilisation of the wood from a single tree e.g. timber and wood carving, (ii) the culture of association and cooperation among traders, (iii) collaborative mechanisms involving all players from the forest and the tourism sector as well as the traders, (iv) secure traders’ livelihood assets, (v) an environment favourable to business venture’s expansion and growth through micro-finance and micro-credit schemes.

Thesis (MScFor)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: The practice of combining row and selective thinning in commercial pine plantation silviculture carries the risk of unwanted irregularities in tree distribution within the stand. This situation is aggravated with poor tree selection during marking. The potential consequences of poor tree selection are gaps created along row removals, which are necessary for access to harvesting operations. These gaps lead to spatially asymmetric growing space among adjacent trees. The effect of irregular stand structures on tree morphology and growth are investigated in this study, and are based on two stands of Pinus patula, (Schiede ex Schlechtendal et Cham.) in Langeni plantation, South Africa. This study focuses on two aspects. Firstly, a comparison between trees grown in all-sided and one-sided spatial competition situations in order to assess if there are differences in growth and selected quality parameters. Secondly, the mitigation of irregular structures using a simulation based study on changing the planting geometry in order to investigate the effect on harvesting in terms of stand impact, simulated harvesting productivity and harvesting system costs. Results showed that trees grown in an irregular competitive status have significantly larger crown diameters, crown lengths, longer and thicker branches, disproportionately one sided crown growth and a reduction in space-use efficiency. Simulations indicated that changing planting geometry from the current 2.7m x 2.7m to 2.3m x 3.1m and 2.4m x 3m would result in up to a 20% reduction of machine trail length and fewer rows being removed for machine access. The simulation of harvesting thinnings showed that various planting geometry alternatives increased harvesting productivity by 10% to 20% and reduced overall thinning harvesting cost by up to 11%. This study successfully investigated the factors that potentially negatively affect saw timber quality and volume production of the stand at final felling. It also illustrated the applicability of simulation methods for testing harvesting scenarios and developing economically viable alternatives.
AFRIKAANSE OPSOMMING: Die praktiese kombinasie van ryuitdunning en seleksiedunning in kommersiële denneplantasies dra die risiko van ongewensde onreelmatighede in die verspreiding van bome in die opstand. Hierdie situasie word vererger deur swak boomseleksie tydens die merk van dunnings. Die potensiële gevolge van swak boomseleksie is die ontstaan van onreelmatige gapings tussen boomkrone, veral langs die rydunnings, wat nodig is vir toegang tydens die ontginning van die hout. Dit lei daartoe dat die bome langs die dunningsrye asimmetriese ruimtes het om in te groei. Die effek van onreelmatige opstandstrukture op boom-morfologie en -groei word in hierdie studie ondersoek in twee Pinus patula, (Schiede ex Schlechtendal et Cham.) vakke te Langeni plantasie, Suid-afrika. In die studie word daar gefokus op twee aspekte. Eerstens word bome wat onder toestande van eweredige ruimetlike kompetisie groei vergelyk met die wat onder toestande van eensydige ruimtelike kompetisie groei om sodoende vas te stel of daar verskille is in die groeipatroon aan die hand van geselekteerde gehalteparameters. Tweedens word daar gefokus op die verbetering van onreelmatige opstandstrukture deur gebruik te maak van ’n simulasie-gebasseerde studie om veranderinge in die aanplantingsgeometrie te ondersoek met die doel om die effek van plantspasieering op ontginningsimpakte, gesimuleerde ontginningsproduktiwiteit en -sisteem koste te bepaal. Die resultate het getoon dat bome wat onder toestande van onreelmatige spasieering en kompetisie groei krone met groter deursnee asook langer lengtes ontwikkel, langer en dikker takke het, disproporsionele, eensydige kroongroei en ’n reduksie in ruimte-gebruik toon, wat die groeidoeltreffendheid nadelig beinvloed. Simulasies met betrekking tot die verandering in boomaanplantgeometrie vanaf die huidige 2.7m x 2.7m na 2.3m x 3.1m en 2.4m x 3m het gedui op ’n reduksie van 20% in die masjienpadafstand en na minder rye wat uitgehaal moes word om die toegang van masjiene moontlik te maak. Die simulasie van die ontginning van dunnings het getoon dat verskillende aanplantgeometriealternatiewe die ontginningsproduktiwiteit met 10% tot 20% verbeter het, en die algehele dunningsoeskoste met tot 11% verminder het. In hierdie studie is die faktore, wat die gehalte van saaghoutkwaliteit en volume tydens die finale oes van die plantasie potensieel negatief mag beinvloed, suksesvol ondersoek. Dit illustreer ook die geskiktheid van simulasietoepassings vir die toets van ontginningsalternatiewe en die ontwikkelling van meer ekonomies voordelige praktyke .

Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2005.
This study is about marketing of Uapaca kirkiana fruit in Zambia, a fruit that has great economic value especially among the rural and urban poor. It contributes to general food security. In southern Africa, farmers and other stakeholders have identified Uapaca as a priority species for domestication. Current agroforestry initiatives are promoting integration of indigenous trees into farming systems to provide marketable products for income generation. Domestication of trees however, depends on expanding the market demand for tree products. There is considerable evidence that expanding market opportunities is critical for the success of domestication innovations but farmers have been introduced to domestication with little consideration for marketing. The existing market potential can be achieved through sound knowledge on markets and marketing. Information on the marketing of Uapaca fruit is inadequate. This study, therefore, aimed at generating information on the marketing of Uapaca kirkiana fruit, including the basic conditions of demand and supply of the fruit. The main study was conducted in Chipata and Ndola districts in the Eastern and Copperbelt provinces respectively, while fruit pricing was conducted in Lusaka district in Lusaka Province. Questionnaires and participatory research methods were used to collect the data. A total of 37 markets involving 49 collectors, 59 retailers, 189 consumers and 20 government forest workers are included in the study. The study reveals that there is demand for the fresh and secondary products of the fruit and hence substantial fruit trading exists in Zambia. However, the marketing system is characterised by underdevelopment. There is insufficient capacity to satisfy the demand for the fruit and institutional /policy support to Uapaca fruit market expansion. Currently, only basic technology for product development exists. The results suggest a need to address policy and capacity development for expansion of Uapaca kirkiana fruit industry. To improve the Uapaca trade industry, the study proposes developing and scaling up policy strategies, fruit processing sector, research-extension-trader-agribusiness linkages, infrastructure development and knowledge generation for improved understanding of the Uapaca fruit markets.

Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2009.
ENGLISH ABSTRACT: Access to secure energy supplies is widely acknowledged as a critical foundation for sustainable development. Rural households are highly dependent on forest resources for their livelihoods including energy needs. Fuelwood is a non-timber forest product (NTFP) that accounts for one of the main uses of forests and woodlands. Despite substantial household electrification programmes in South Africa, the use of fuelwood as a source of energy continues. This study aimed to analyze fuelwood use patterns of two rural villages situated in Keiskammahoek in the Eastern Cape Province of South Africa in order to understand the perceptions of the community members regarding communal tree planting. The study was conducted in two rural villages, namely, Cata and Tshoxa. A total of 120 respondents from both villages were interviewed using semi-structured questionnaires to collect data on the use of fuelwood and evaluate their perception on tree planting. The study revealed that up to 77% of the people living in Keiskammahoek used fuelwood as a major source of energy and that women were the main collectors and users of fuelwood. In the rural Cata, food is cooked in three-legged pots over open fires while in Tshoxa food is mainly cooked over paraffin and electric stoves. The respondents from both villages did not have energy conservation measures in place and improved wood stoves have not been introduced in this region. The local community of Cata was also involved in tree planting on a community level, while both villages were also involved in tree planting at a household level. The study concluded that fuelwood was the most important product from the forests in both rural areas and natural forests were a valuable source of other NTFPs; most notably indigenous fruit products. In addition most of the fuelwood was used for cooking and heating purposes but that there was no deliberate use of energy efficient methods. On tree planting, the study showed that communities from both rural villages have an interest in planting trees around their households; with preference for fruit and shade trees.
AFRIKAANSE OPSOMMING: Toegang tot betroubare energieverskaffing word algemeen erken as 'n uiters belangrike grondslag vir volhoubare ontwikkeling. Plattelandse huishoudings is hoogs afhanklik van bosbronne vir hul bestaan, met inbegrip van energiebehoeftes. Brandhout is 'n nie-hout bosproduk (NHBP) wat beskou word as een van die hoofgebruike van woude en boslande. Nieteenstaande wesenlike elektrifiseringsprogramme vir huishoudings in Suid-Afrika, duur die gebruik van brandhout as 'n bron van energie voort. Hierdie studie het beoog om die gebruikspatrone van brandhout van twee plattelandse dorpe in Keiskammahoek in die Oos-Kaapse Provinsie van Suid-Afrika te ontleed en om die begrip van die gemeenskap aangaande die gemeenskaplike plant van bome te verstaan. Die studie is in twee plattelandse dorpe, naamlik Cata en Tshoxa, uitgevoer. Onderhoude is gevoer met 'n totaal van 120 respondente van beide dorpe deur die gebruik van halfgestruktureerde vraelyste om gegewens oor die gebruik van brandhout in te samel en die respondente se begrip van die plant van bome te evalueer. Die studie het aan die lig gebring dat tot 77% van die mense wat in Keiskammahoek woon, brandhout as 'n hoofbron van energie gebruik en dat vrouens die hoofgaarders en gebruikers van brandhout is. In die landelike Cata word kos in driepootpotte op oop vure gekook terwyl kos in Tshoxa hoofsaaklik op paraffien- en elektriese stowe gekook word. Die respondente van beide dorpe het nie energiebesparingsmaatreëls in plek gehad nie en verbeterde houtstowe is nog nie in hierdie streek ingebring nie. Die plaaslike gemeenskap van Cata was ook betrokke by die plant van bome op 'n gemeenskapsvlak, terwyl beide dorpe ook betrokke was by die plant van bome op 'n huishoudelike vlak. Die studie het tot ’n gevolgtrekking gekom dat brandhout die belangrikste produk van die woude in beide plattelandse gebiede is en dat die natuurlike woude 'n belangrike bron van ander NHBP’s is; veral inheemse vrugteprodukte. Daarbenewens is meeste van die brandhout gebruik vir kook- en verhittingsdoeleindes, maar daar was geen doelbewuste gebruik van energiedoeltreffende metodes nie. Op die gebied van die plant van bome het die studie getoon dat die gemeenskappe van beide plattelandse dorpe belange het in die plant van bome rondom hulle huishoudings; met voorkeur aan vrugte- en skadubome.

Thesis (MScFor)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: The role that forestry plays in climate change mitigation is well recognized by countries that ratified the Kyoto protocol agreement. Though climate change mitigation strategies provide a strong incentive to quantify current patterns of forest carbon sources and sinks, this exercise (carbon accounting) is not as simple as it sounds. This is proven by the vast number of techniques and methodologies available, from models to softwares programmes created in response to the need to estimate carbon sequestration. The study aimed at gaining an understanding of the current carbon sequestration estimation methodology and models in use by the South African Forestry Industry. A survey was undertaken amongst forestry industry stakeholders in which 77% of respondents agreed to the need for a carbon sequestration model for South Africa. This model should have qualities that the forestry industry and all stakeholders agreed with. . A search of freely available models and software was conducted. The aim was to find freely available model(s) that would be readily applicable and adoptable to South African conditions. A Multi Criteria Analysis was carried out using “ideal qualities” for a carbon model as weighting. This resulted in the selection of two models, CASMOFOR and CBM CFS 3, which obtained the highest sum product total from the analysis. These together with FICAT, which came as a recommendation from the questionnaire survey, were compared in the analysis. Carbon values were calculated from yield table volumes by Kotze et al. (2012). A conversion of these volumes to biomass and carbon was done using Dovey (2009) biomass expansion factors and a biomass to carbon conversion value of 0.5 g C/g dry matter, following procedures by Matthews (1993). The first comparison was made on how the model results related to the yield table estimates from Kotze et al. (2012). When carbon values were compared per hectare, it was found that the FICAT model differed significantly from the rest. A second comparison looked at the models’ prediction of the carbon accumulated in NCT’s Enon plantation outside Pietermaritzburg. The Hungarian model, CASMOFOR, was the better predictor as it produced the lowest Mean Squared Error (MSE). Based on the results from the survey and model analysis a number of recommendations can be made regarding the current carbon accounting situation in South Africa. One of the main recommendations is that information sharing among the industry’s stakeholders should improve if the industry is to reach consensus on which methodology to adopt in their business practices.
AFRIKAANSE OPSOMMING: Die rol wat bosbou speel in klimaatsverandering-bekamping is welbekend onder lande wat die Kyoto protokol ooreenkoms onderteken het. Alhoewel klimaatsverandering-bekamping strategieë ‘n sterk aansporing bied om huidige patrone van woudkoolstof bronne en sinkte te kwantifiseer, is hierdie oefening nie so maklik soos dit klink nie. Die bewys hiervan is die groot aantal tegnieke en metodes, wat wissel van modelle tot sagteware programme wat ontwikkel is om koolstofsekwistrasie te meet. Die doelwit van die studie was om die huidige koolstofsekwistrasie metodes en modelle wat deur die Suid Afrikaanse Bosbou Bedryf gebruik word, beter te verstaan. ‘n Vraelysopname is onderneem onder bosbou-industrie deelnemers, waarin 77% van respondente saamgestem het dat dit nodig is dat Suid Afrika ‘n koolstofsekwistrasie model moet hê. Die model moet eienskappe hê waarmee die bosbou-industrie en alle deelnemers saamstem. ‘n Soektog na vrylik beskikbare koolstofmodelle en sagteware programme is onderneem. Die doelwit was om modelle te vind wat geredelik aangepas kan word vir Suid Afrikaanse toestande. ‘n Multi-kriteria analise is uitgevoer met die “ideale eienskappe”vir ‘n koolstofmodel as gewigte. Die resultaat was die seleksie van twee modelle, CASMOFOR en CBM CFS 3, wat die hoogste telling in die ontleding behaal het. Hierdie modelle, tesame met FICAT, wat aanbeveel is deur respondente van die vraelys opname, is vergelyk in ‘n ontleding. Koolstofwaardes is bereken vanaf opbrengstabelle wat deur Kotze et al. (2012) ontwikkel is. Die omsetting van hierdie volumes na biomassa en koolstof is gedoen deur Dovey (2009) se biomassa uitbreidingsfaktore en ‘n biomassa na koolstof omsettings faktor van 0.5 g C/g droëmassa te gebruik (Matthews, 1993). In die eerste vergelyking van die modelle is gekyk hoe die modelle vergelyk met koolstof berekeninge vanaf die Kotze et al. (2012) opbrengstabelle. Wanneer koolstofwaardes per hektaar vergelyk word is gevind dat FICAT beduidend verskil van die ander modelle. In ‘n tweede vergelyking is gekyk na hoe die modelle die koolstof wat in NCT se Enon plantasie buite Pietermaritzburg versamel is, voorspel. Die Hongaarse CASMOFOR model was die beste voorspeller. Anders as die FICAT en CBM CFS 3 modelle het dit die laagste Gemiddelde Vierkante Fout gehad. Na gelang van die resultate van die vraelysopname en die modelontleding kan ‘n aantal aanbevelings gemaak word oor die huidige koolstofberekening situasie in Suid Afrika. Een van die hoof aanbevelings is dat die uitruil van inligting tussen industrie deelnemers moet verbeter as die bedryf eenstemmigheid oor die metode van koolstofberekening wil bereik.

Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2009.
ENGLISH ABSTRACT: This thesis assesses the livelihoods of rural households in a proposed green field forestry area, located in Sanga District of Niassa province, Mozambique. The livelihood analysis was used to analyze potential socio-economic impacts of introducing forest plantations to rural households located within the proposed afforestation area. The study made use of household interviews, key informant interviews and secondary data. The sustainable livelihoods framework was used in the research process to develop the household questionnaire and to identify livelihood strategies. Data was analyzed using 331 household questionnaires collected throughout the proposed afforestation area in various communities in the study area. Findings from the study indicated that there is minimal wealth gaps between rural households; but that the introduction of the forestry industry and the subsequent employment created thereof may result in larger wealth gaps between wage earning and non-wage earning households. The study further concludes by linking the potential socio-economic impacts with mitigation recommendations that could be harmonized with FSC Standard requirements for forestry companies interested in developing a forest industry in the study area.
AFRIKAANSE OPSOMMING: Hierdie tesis ontleed die lewensbestaan van landelike huishoudings in ‘n voorgestelde nuwe bosbou area, gelee in die Sanga distrik van die Niassa provinsie, Mosambiek. Die lewensbestaan ontleding was gebruik om die potensiele sosio-ekonomiese impak van die vestiging van bosbou plantasies op landelike huishoudings in die voorgestelde bebossings area te analiseer. Hierdie studie het gebruik gemaak van huishoudelike onderhoude, sleutel informant onderhoude asook sekondere data. Die volhoubare lewensbestaan raamwerk was gebruik in die navorsings proses om die huishoudelike onderhoude te ontwikkel en om die huishoudelike strategiee te identifiseer. Data was geanaliseer van 331 huishoudelike onderhoude afgeneem in verskeie gemeenskappe binne die studie areas. Bevindinge van die studie het aangetoon dat daar minimale inkomste gapings is tussen landelike huishoudings, maar met die vestiging van kommersiele bosbou en geassosieerde werskeppings moontlikhede, mag groter inkomste gapings ontwikkel tussen huishoudings wat inkostes uit bosbou verdien en huishoudings daarsonder. Verder het die studie aangetoon dat daar ‚n potensiele sosiale impak is van mense wat na die area migreer en dat sulke impakte deur FSC sertifisering beheer kan word.

Thesis (MScFor)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: Wood scarcity remains the main challenge for many rural households who still rely on natural resources for energy needs. This study aimed to investigate the relationship between fuel use and quality and quantity of fuel in two rural villages (Ongulumbashe and Onaitembu) in the Omusati Region of Namibia. It investigated the impact of fuel quality and quantity and the corresponding sales of firewood on households’ energy consumption. Data was collected between April and June 2012 from the two villages by means of questionnaire surveys, biomass assessment and laboratory assessment. Interviews were conducted with seventy-seven households, four firewood sellers, government officials, and local leaders. The study quantified the amount of fuelwood consumed and collected per household per week using user-recall and physical measurement, respectively. The most preferred fuel species or fuel materials were identified and their physical properties, calorific value, moisture content, ash content and density were measured under laboratory conditions. Differences between the two villages in terms of fuelwood collected and consumed were found. Due to wood scarcity households from Onaitembu village used other alternatives (buying fuelwood and cutting live firewood) rather than collecting dead firewood. The study found a link between fuelwood use, quality and quantity, with households changing their consumption and harvesting based on season, fuelwood demand and availability of fuelwood. The average weekly fuelwood consumption per household ranged from 66 kg to 79 kg for a firewood abundant area and from 59 kg to 67 kg for an area with a shortage of firewood. Mopane was the most preferred species due to its ability to burn efficiently and its abundance. Wood scarcity affected households economically, culturally and nutritionally. The study found that households in degraded areas spend an average of N$ 50 per week on fuelwood, and many households depended on government grants and small cash income activities. The study found that the government, through the Ministry of Agriculture, Water and Forestry, is trying to improve rural households’ energy use by constructing firewood outlets. The study concluded that there is a high level of illegal trade in firewood that will require government to increase the number of staff in the region as well as to strengthen its policy on cross-border trading. There is an imbalance in fuel species use in areas of rich biomass and over-utilization of resources in degraded areas. These require the Directorate of Forestry to educate the community about the value of other possible fuel species and the impact of harvesting live firewood on households’ livelihood and on the environment.
AFRIKAANSE OPSOMMING: Houtskaarsheid bly die grootste uitdaging vir baie landelike huishoudings, wat nog steeds staatmaak op natuurlike hulpbronne vir energie behoeftes. Hierdie studie het gepoog om die verhouding tussen brandstof gebruik en kwaliteit en kwantiteit van brandstof in twee plattelandse dorpies (Ongulumbashe en Onaitembu) in die Omusati-streek van Namibië te ondersoek. Die impak van brandstof kwaliteit en kwantiteit en verkope van brandhout op huishoudings se energie gebruik is ondersoek. Data is ingesamel in April en Junie 2012 in die twee dorpe deur middel van vraelys opnames, biomassa assessering en laboratorium ontledings. Onderhoude is gevoer met 77 huishoudings, vier brandhoutverkopers, regeringsamptenare, en plaaslike leiers. Die studie het die hoeveelheid vuurmaakhout verbruik en versamel per huishouding per week gekwantifiseer deur gebruik te maak van gebruikergeheue en fisiese meting van vuurmaakhout. Die mees gewilde brandstof spesies of brandstof materiaal is geïdentifiseer en hul fisiese eienskappe, kaloriewaarde, voginhoud, asinhoud en digtheid is onder laboratorium toestand gemeet. Verskille tussen die twee dorpe in terme van brandhout versamel en verbruik is gevind. As gevolg van houtskaarsheid gebruik huishoudings in ONA ander alternatiewe energiebronne, soos om brandhout te koop of om vars hout te saag, in plaas van om dooie hout te versamel. Die studie het ‘n skakel gevind tussen brandhout gebruik en die gehalte en hoeveelheid wat beskikbaar is. Huishoudings het hulle brandhout verbruik aangepas by die seisoen, aanvraag en beskikbaarheid van brandhout. Die gemiddelde weeklikse brandhout verbruik per huishouding het gewissel tussen 66 kg tot 79 kg vir 'n area met ‘n oorvloed van brandhout en 59 kg tot 67 kg vir 'n gebied met 'n tekort aan brandhout. Mopanie was die mees gewilde spesie as gevolg van sy besikibaarheid en vermoë om doeltreffendheid te brand. Houtskaarstes beinvloed huishoudings op ekonomies, kulturele en voedings vlakk. De studie het bevind dat huishoudings in ’n area met ‘n houtskaarste gemiddeld N$50 per week spandeer om brandhout te koop en dat baie huishoudings afhanklik is van staatstoelaes en klein kontant inkomste-aktiwiteite. Die studie het gevind dat die regering, deur middel van die Ministerie van Landbou, Water en Bosbou, probeer om landelike huishoudings se energie gebruik te verbeter deur die bou van brandhout afsetpunte. Die studie het tot die gevolgtrekking gekom dat daar 'n hoë vlak van onwettige handel in brandhout is wat sal vereis dat die regering die aantal amptenare in die streek moet vermeerder en sy beleid rakende handel oor landsgrense heen moet verbeter. Daar is 'n wanbalans in die gebruik van brandstofspesies in 'n gebied met baie biomassa, en oorbenutting van hulpbronne in gedegradeerde gebiede. Die Direktoraat van Bosbou moet die gemeenskape oplei oor die waarde van ander moontlike brandstofspesies en die impak van die oes van lewendige bome op huishoudings se lewensbestaan en op die omgewing.

Dissertation (PhD (For))--University of Stellenbosch, 2001.
ENGLISH ABSTRACT: The objective of this study is to develop a new method which can be used to forecast the Forest Engineering value chain. The method is then applied in the South African context in order to validate the use thereof. Finally, the South African results are used to propose strategies, which the industry should pursue in the future. To forecast the future an understanding of the past is required. To this end, the historical development of Forest Engineering is discussed, both globally and in South Africa. The current status quo in Forest Engineering in South Africa was determined through a national survey of plantations larger than 200 ha. The results are reflected in Chapter 2. Because of the importance of globalisation and technology, Chapter 3 gives a literature review of relevance of technology in today's business world, including various forecasting techniques that are relevant to the study. These techniques are a combination of traditional forecasting methods, technology forecasting methods and strategic planning methods. Various approaches to financial analysis have also been discussed, in order to determine the soundest method of comparing various forest engineering systems with each other. This includes an overview of traditional machine cost calculations. The core of the study lies in the combination of these methodologies into a useful method, which is particularly suited to forecasting the Forest Engineering value chain. Such a method is developed in Chapter 4, based on the literature review of forecasting methodologies. The method is then validated in Chapter 5, through the application thereof in the South African forestry industry. Global trends are established with the use of a Delphi study. This technique uses a panel of experts who give their views on future developments on a multiple round basis. The study then evaluates 14 Forest Engineering systems for pine sawtimber, pine pulpwood and Eucalyptus pulpwood, based on various scenarios of the future. The scenario matrix is based on the future cost of labour vs. the future cost of machinery. Finally, a strategy is proposed on how the South African forestry industry should prepare itself for the future.
AFRIKAANSE OPSOMMING: Die doelwit van die studie is om 'n nuwe metode te ontwikkel waarmee 'n vooruitskatting van die Bosingenieurswese waardeketting gemaak kan word. Die metode word dan in die Suid-Afrikaanse konteks toegepas om die geldigheid daarvan te beproef. Die Suid-Afrikaanse resultate word voorts gebruik om 'n nasionale Bosingenieurswese strategie voor te stel vir die bedryf. Dit is nodig om die verlede te verstaan, voor die toekoms vooruitgeskat kan word. Om dié rede is die historiese ontwikkeling van bosingenieurswese bespreek, in beide 'n internasionale, sowel as 'n Suid Afrikaanse konteks. Die huidige status quo van Bosingenieurswese in Suid Afrika is vasgestel deur 'n nasionale opname waarby plantasies van groter as 200 ha ingesluit is. Die resultate van die opname word weergegee in Hoofstuk 2. As gevolg van die belangrikheid van beide globalisering en tegnologie, is 'n literatuur studie ingesluit in Hoofstuk 3 oor die relevansie van tegnologie in die besigheidswêreld van vandag, asook en 'n bespreking van verskeie vooruitskattingstegnieke wat in die studie gebruik kan word. Hierdie vooruitskattinge is 'n kombinasie van tradisionele vooruitskattings tegnieke, tegnologie vooruitskattingstegnieke en tegnieke wat gebruik word vir strategiese beplanning. Verskeie benaderinge tot finansiële analise is ook bespreek. Dit sluit tradisionele masjienkoste berekening in. Die rede hiervoor is om vas te stel watter metode die mees geskikte sou wees om verskeie Bosingenieurswese sisteme met mekaar te vergelyk. Die kern van die studie lê in die kombinasie van hierdie metodes om 'n bruikbare metode te ontwerp om die Bosingenieurswese waardeketting vooruit te skat. Hierdie ontwerp word in Hoofstuk 4 bespreek. Die metode word in Hoofstuk 5 beproef, deur die toepassing daarvan op die Suid Afrikaanse bosbedryf. Internasionale bosingenieurswese tendense is vasgestel deur middel van 'n Delphi studie. Hierdie vooruitskatting maak gebruik van 'n paneel van kundiges wat hulle siening oor die toekoms uitspreek deur verskeie rondtes van vrae wat aan hulle gestel word. Die studie evalueer hierna 14 Bosingenieurswese sisteme vir denne saaghout, denne pulphout en Eucalyptus pulphout, gebaseer op 'n scenario-analise van die toekoms. Die scenario matriks is gefundeer op die toekomstige koste van arbeid teenoor die toekomstige koste van masjinerie. As 'n finale stap word voorgestel hoe die Suid Afrikaanse bosbedryf kan voorberei om die toekoms tegemoet te gaan.

Thesis (MScFor)--Stellenbosch University 2002.
ENGLISH ABSTRACT: One of the greatest .limitations to the productivity of a plantation forest is poor nutrient status of the soil. Empirical application of corrective treatments are marginally successful in some cases, but because of limited understanding of the soiltree system, most nutritional problems go unnoticed or are accepted as a conceivable growth constraint. The aim of this investigation was to identify nutrient growth problems through field observations and to determine means of confirming these nutrient imbalances. Poor and abnormal growth of pine trees in the following areas were investigated: (i) The North Eastern Cape: Ugie and Maclear Districts (ii) The Natal Midlands: Mooi River area (iii) Mpumalanga: .Graskop and Kaapsche Hoop areas (iv) Southwestern Cape: Jonkershoek Plantation The study was conducted as nursery trials at the University of Stellenbosch and field trials at the various locations. Soils from the different regions were collected and used as growing media to test the growth response of five timber species (Pinus patula, P. elliottii, P. taeda, P. greggii and Eucalyptus nitens) under controlled conditions to various nutrient treatments. Indicator plants (cauliflower and soya) were included in these bio-assays. In the field trials nutrients were applied to seedlings and established stands of various ages by means of foliar and soil application. In the nursery trials and the trials where seedlings were planted in the field, plant performance was measured by quantitative means. The reaction of established stands to nutrient treatments were however less vigorous and qualitative means (e.g. colour changes) were used for assessment. Field observations in the North Eastern Cape and the Natal Midlands indicated possible boron, iron and molybdenum deficiencies and thus the work concentrates on these elements. Foliar and soil analyses reinforced these observations with marginal to deficient levels for boron and molybdenum being detected. The yellowing of foliage during the dry season was symptomatic of ineffective nitrogen assimilation and pointed to a molybdenum deficiency while seasonal growth tip dieback, resm exudation, sinuous tree limbs and bushy trees were classical boron deficiency symptoms. Potted trials indicated positive reaction to the application of boron and molybdenum deficiency symptoms were observed on indicator plants. Conclusive evidence of a boron deficiency in some of the pot trials, the planted field trials and the tree evaluation field trials remain elusive due to toxicity experienced as a result of an over-application of the nutrient. The occurrence of multiple deficiencies (phosphorous and calcium) further complicated the findings. The Mpumalanga observations indicated severe nutrient imbalance due to manganese toxicity (strong iron antagonism). The discolouring of the foliage on some sites towards the end of the winter was thought to be an induced molybdenum deficiency on the weathered and acidic red soils. Positive reaction to molybdenum application occurred in a single. tree evaluation trial, but because of soil oxidisation during collection, the effect of manganese toxicity was diluted in the pot trials. Foliar analyses indicated that foliar application of iron was unsuccessful and that other means should be considered to ensure uptake of this nutrient.
AFRIKAANSE OPSOMMING: Die lae vrugbaarheid van grond is een van die grootste beperkings tot die produktiwiteit van plantasie bosbou. Empiriese toedienings van kunsmisstowwe is in sekere gevalle suksesvol tot die bekamping van onvrugbaarheid. Weens gebrekkige kennis t.o.v die grond-boom sisteem word baie van die voedingstof probleme egter onkundig oorgeslaan' of word dit as natuurlike beperking in die produksie konteks aanvaar. Die doel van hierdie ondersoek was om swak boomgroei in die veld waar te neem en om bevestigende metodes te vind waarmee hierdie probleme as voedingstoftekorte geëien kan word. Swak en abnormale boomgroei van denne is in die volgende gebiede ondersoek: (i) Die Noordoos Kaap: Ugie- en Maclear Distrikte (ii) Die Natal Middelande: Mooirivier area (iii) Mpumalanga: Graskop- en Kaapsche Hoop areas (iv) Suidwes Kaap: Jonkershoek Plantasie Die ondersoek is uitgevoer as kwekery proewe by die Universiteit van Stellenbosch en as veldproewe in die onderskeie areas. Grond is uit die verskilende gebiede versamel en as groeimeduim gebruik om die groei-reaksie van vyf verskillende houtspesies (Pinus patula, P. elliottii, P. taeda, P. greggii en Eucalyptus nitens) onder beheerde klimaatsomstandighede te ondersoek. Daar is ook gebruik gemaak van indikator spesies (blomkool en soya) vir diagnose van visuele tekort simptome. Beide saailinge en reeds gevestigde bome is in die veldproewe gebruik. Voedingstowwe is by aanplanting toegedien, of in die geval van groter bome, as blaar- of grondtoedienings. Waar dit moontlik was (meestal in die geval van die saailinge) is die reaksie op die toegediende voedingstowwe met kwantitatiewe metodes bepaal. Daar moes egter van alternatiewe kwalitatiewe metodes gebruik gemaak word om die reaksie by die ouer en groter bome te bepaal. Gevolglik is verandering in bladkleur t.o.v. 'n basiskleur onder andere as maatstaf gebruik. Waarnemings van swak boomgroei in die Noordoos Kaap en die Natal Middelande het gedui op moontlike boor, yster en/of molibdeen tekorte. Lae vlakke van hierdie elemente in blaar- en grondanalises het hierdie waarnemings bevestig. Die geel verkleuring van die naalde gedurende die droë seisoen is simptomaties van oneffektiewe stikstof assimilasie en dui op 'n molibdeen tekort. Die waarneming van seisoenale terugsterwing van groeipunte, gebuigde stamme en takke, gomuitskeiding en bome met bosagtige voorkoms is eienskappe van 'n boor tekort. In die potproewe was daar positiewe reaksie op die toediening van boor en tekort simptome van molibdeen is in die indikator plante waargeneem. In van die potproewe, die saailing veldproewe en ander veldproewe kon daar egter nie uitsluitsel tot die effektiwiteit van boor gevind word nie aangesien toedienings te heftig was en toksisiteit ervaar is. Diagnose van enkel element voedingstof tekorte word bemoeilik deur van die proewe wat ook dui op veelvoudige voedingstoftekorte (veral fosfaat en kalsium). In Mpumalanga is daar waargeneem dat drastiese voedingstof wanbalanse a.g.v. mangaan toksisiteit aanwesig is (veral 'n sterk Fe antagonisme). Die bladverkleuring op sekere proefopstande aan die einde van die winter is ook 'n aanduiding van geïnduseerde molibdeen tekorte wat op die verweerde en suur rooi gronde van die omgewing verwag kan word. Daar was dan ook positiewe reaksie op die toediening van molibdeen, hoewel slegs byeen proefopstand. Die inherente nadeel van potproewe is op die mangaanryk gronde geopenbaar deurdat belugting (gedurende grond versameling) die effek van mangaan toksisiteit verminder het. Die gebruik van blaaranalises is ook voordelig aangewend om te bepaal dat die toediening van yster as blaartoediening onsuksesvol was en dat ander metodes ondersoek moet word om opname van die element te verseker.

Thesis (MScFor)--Stellenbosch University, 2000.
ENGLISH ABSTRACT: Grobbelaar, F.R. 2000. A methodology to aid in appropriate technology decision-making for developing countries. M.Sc thesis. University of Stellenbosch. In the process of selecting what we believe to be suitable technology for timber harvesting and transport, economics are usually the determining factor, whether in the form of capital investment or personnel cost. Internationally we see a move towards mechanisation in forestry for various reasons: e.g., high wages, labour shortage, and occupational safety. The realities of South Africa highlights other issues requiring attention: e.g., high unemployment, skills' shortage, global competition, rampant AIDS pandemic, and a poor safety and security record. This should focus our attention on finding local solutions to the problem of finding suitable or appropriate technology to support South Africa's quest for sustainable development. This thesis attempts to establish a methodology for the objective evaluation of alternative technologies for a specific timber harvesting situation, considering the economic, social and environmental implications.
AFRIKAANSE OPSOMMING: Grobbelaar, F.R. 2000. A methodology to aid in appropriate technology decisionmaking for developing countries. M.Sc tesis. Universiteit van Stellenbosch. Tydens die keuse van sogenaamde toepaslike tegnologie vir houtinoesting en -vervoer is ekonomie meestal die deurslaggewende faktor, hetsy verteenwoordig deur kapitaal belegging of personeelkoste. Internasionaal is daar tans In neiging na meganisasie in bosbou vir In verskeidenheid redes: bv., hoë arbeidskoste, arbeidtekort, en beroepsveiligheid. Die werklikhede van Suid-Afrika beklemtoon egter ander sake wat daadwerklike optrede vereis: nl., hoë werkloosheid, gebrek aan vaardighede, internasionale mededinging, ernstige VIGS pandemie, en In swak veiligheid-en sekuriteit rekord. Dit behoort ons aandag te fokus op die vind van plaaslike oplossings tot die probleem met die keuse van geskikte of toepaslike tegnologie ter bevordering van Suid Afrika se strewe na volhoubare ontwikkeling. Hierdie tesis poog om In metodiek te ontwikkel vir die objektiewe beoordeling van alternatiewe tegnologieë vir houtinoesting binne bepaalde omstandighede, met inagneming van ekonomiese, sosiale en omgewings implikasies.

Thesis (MScFor)--Stellenbosch University, 2002.
ENGLISH ABSTRACT: Deforestation in Malawi is said to reach 2.3% per annum and negatively affects agricultural production, the backbone of the country's economy. High dependence on indigenous wood for sale as fuelwood or charcoal by rural communities due to poverty largely contributes to this deforestation. Women and children suffer most because they spend more time collecting firewood than men, affecting other activities like child-care and education. The study, aimed at investigating ways to alleviate deforestation by increasing rural people's economic benefits from non-destructive indigenous fruit utilisation, was conducted in Mwanza District from February to June 2001. The district's customary forests which contain a wide variety of wild fruit species are currently deforested due mainly to charcoal production. Five out of 16 villages facing deforestation were randomly chosen by the lottery method. Group, individual and key informant interviews focused on the utilisation of preferred fruit species by communities while participatory resource assessment was used to determine availability and distribution of fruit trees. A market survey to assess fruit trade in the country was conducted in Balaka, Blantyre, Mangochi, Mwanza and Zomba Districts in early June 2001. Twenty-six wild fruit species were found to be utilised by villagers in the study area but Adansonia digitata (Baobab) was the most commonly found near villages and the most preferred fruit by 90% of respondents. Other preferred species were Tamarindus indica (Tamarind), Diospyros kirkii, Flacourtia indica and Vangueria infausta. Most fruit trees except for baobab were found to be of small size classes because of being young stems regenerating while others were shrubs. The poor largely depended on fruit as a meal and for sale. Mainly children and women sold baobab and tamarind within the villages while only men sold fruit at distant markets for more income. Middlemen largely benefited from fruit sales compared to villagers who sold at low prices and lacked marketing information. Fruit rot affected retailers outside the study area. Tree climbing to harvest fruit was mainly done by boys and destructive harvesting methods were associated with commercial use. Large, sweet tasting fruit were mainly chosen by rural communities for subsistence use. Land clearance, mast fruiting, perishability and seasonality of fruit seemed to have affected harvest both for subsistence and for sale. However, 89% of households owned fruit trees in homesteads and agricultural fields, said to be more protected than in communal lands with open access. Preferred wild fruit trees were rarely cut by the communities. Local fruit processing, mainly by women, included porridge and juice making and fruit drying while careful storage enabled baobab fruit to be stored for up to a year. Wild fruit plays an important role in the lives of rural communities mainly the poor. Communities attach value to the preferred fruit species but it is difficult to convince most of them to sell wild fruit unless value is added and price incentives are initiated. Regular marketing information could be provided to rural communities and policy makers should set fruit pricing guidelines to create price incentives. Domestication of the preferred fruit trees should be encouraged for continuous fruit supply. Simple fruit processing technologies for commercial purpose could be initiated for women mostly. Research is needed to determine sustainable harvesting levels of wild fruit and ways for participatory monitoring of the levels and harvesting methods used.
AFRIKAANSE OPSOMMING: Ontbossing in Malawi beloop 2.3% per jaar, wat beteken dat landbouproduksie, die ruggraat van die land se ekonomie, negatief geaffekteer word. Wat grootliks bydra tot hierdie ontbossing is dat die plattelandse gemeenskappe as gevolg van armoede hoogs afhanklik is van inheemse hout wat as brandhout of as houtskool verkoop word. Vroue en kinders ly die meeste omdat hulle meer tyd as mans spandeer om vuurmaakhout bymekaar te maak. Dit affekteer ander aktiwiteite soos kindersorg en opvoeding. Hierdie studie het ten doelom maniere te ondersoek waarvolgens ontbossing verlig kan word deur mense op die platteland se ekonomiese voordele uit die benutting van inheemse vrugte te vermeerder sonder dat daar enige omgewingskade aangebring word. Die studie is uitgevoer in die Mwanza Distrik vanaf Februarie 2001 tot Junie 2001. Die distrik se inheemse bosse wat 'n wye verskeidenheid wilde vrugtespesies bevat, word tans ontbos - hoofsaaklik as gevolg van die produksie van houtskool. Vyf uit die 16 dorpies wat ontbossing in die gesig staar, is op 'n lukrake wyse met die loterymetode gekies. In die onderhoude met groepe, individue, en sleutelinformante is gefokus op die benutting van vrugtespesies wat deur die gemeenskappe verkies word. Hulpbronevaluering is gebruik om die beskikbaarheid en verspreiding van vrugtebome te bepaal. Die gemeenskap is by hierdie evaluering betrek. Marknavorsing om vrugtehandel in die land te evalueer, is vroeg in Junie 2001 in die Balaka, Blantyre, Mangochi, Mwanza en Zomba distrikte gedoen. In die studie is bevind dat die inwoners van die area wat bestudeer is 26 wilde vrugtespesies benut. Adansonia digitata (Baobab/Kremetartboom) is egter die meeste naby die dorpies aangetref, en is deur 90% van die respondente as hulle gunsteling vrug aangedui. Ander gewilde spesies is Tamarindus indica (Tamarinde/Suurdadelboom), Diospyros kirkii, Flacourtia indica en Vangueria infausta. Die meeste vrugtebome, behalwe die baobab, val in die laer klasse wat grootte betref, omdat dit die jong lote is wat regenereer, terwyl ander struike is. Die arm mense is grootliks afhanklik van vrugte as 'n maaltyd en as verkoopsartikels. Hoofsaaklik kinders en vroue verkoop baobab- en tamarindevrugte in die dorpies, terwyl vrugte by verafgeleë markte slegs deur mans vir 'n groter inkomste verkoop word. Die middelman trek grootliks voordeel uit vrugteverkope, in vergelyking met die inwoners van die dorpies wat vrugte teen lae pryse verkoop as gevolg van 'n tekort aan bemarkingsinligting. Kleinhandelaars buite die studie-area is deur vrugteverrotting geaffekteer. Dit is hoofsaaklik seuns wat die bome klim om vrugte te oes, en destruktiewe oesmetodes is met kommersiële gebruik geassosieer. Plattelandse gemeenskappe verkies hoofsaaklik groot, soet vrugte vir bestaansgebruik. Dit wil voorkom of grondopruiming, die vrugvorming van byvoorbeeld akkers (mast fruiting), die bederfbaarheid en seisoensgebondenheid van vrugte, die oes affekteer vir bestaansgebruik sowel as vir verkope. Vrugtebome word egter deur 89% van die huishoudings besit en die bome by hierdie huise en in landbouvelde word beter beskerm as dié in gemeenskaplike lande met vrye toegang. Die gemeenskappe kap selde hulle gunsteling wilde vrugtebome uit. Plaaslike vrugteverwerking, hoofsaaklik deur vroue, sluit in die maak van pap en sap, asook die droog van vrugte, terwyl sorgvuldige bewaring daartoe kan lei dat baobabvrugte vir tot 'n jaar lank gebêre kan word. Wilde vrugte speel 'n belangrike rol in die lewens van plattelandse gemeenskappe, veral vir die armes. Die gemeenskappe heg waarde aan hulle gunstelingvrugtespesies, maar dit is moeilik om die meeste te oortuig om wilde vrugte te verkoop - behalwe as waarde bygevoeg word en prysaansporings ingestel word. Gereelde bemarkingsinligting kan aan plattelandse gemeenskappe voorsien word, en beleidbepalers behoort riglyne vir vrugtepryse daar te stelom prysaansporings te skep. Die mense behoort aangemoedig te word om hulle gunstelingvrugtebome by hulle huise te plant om 'n voortdurende vrugtevoorraad te verseker. Eenvoudige vrugteverwerkingtegnologie kan vir kommersiële doeleindes vir hoofsaaklik vroue ingestel word. Navorsing is nodig om volhoubare oesvlakke van wilde vrugte te bepaal, sowel as maniere vir die deelnemende monitering van hierdie vlakke en die oesmetodes wat gebruik word.

Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: The purpose of the study was to investigate the potential tree taxa that could be grown as a source of biomass in the Cape Winelands region. The trials comprises of two different aspects. The first being the estimation of potential volume, density and biomass of a pair of six year-old stands of E. gomphocephala and E. cladocalyx families at two climatically different sites within the study region. The second part of the study was the early growth assessment of alternative taxa that could be planted in the region compared to the regional mainstay E. cladocalyx. The volume of families was estimated using appropriate volume equations and using the form height were none were available. The best volume yield varied from 4.6 to 11.2 m3 ha-1a-1, at the dry and sub-humid sites, respectively. Wood density, estimated from non-destructive samples at both sites, varied from 620 (sub-humid) to 588 kg m-3 (dry site). The estimated biomass production rate of the top producing families yielded 2.7 and 6.9 t ha -1a -1 at the dry and sub-humid sites, respectively. In terms of estimated biomass and survival, E. gomphocephala was more suited to the dry site, while E. cladocalyx displayed superior yield than E. gomphocephala on the sub-humid site, but not significantly so. Early growth assessment of the trial of alternative taxa found that the hybrid E. grandis × camldulensis and E. grandis × urophylla had superior biomass indices, but were more susceptible to infestation by Thaumastocoris peregrinus and Gonipterus scuttelatus.
AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om potensiële boom taksa vir gebruik as ’n bron van biomassa in die Kaapse Wynlandstreek te ondersoek. Die proewe behels twee aspekte: eerstens die beraming van die potensiële volume, digtheid en biomassa van sesjaaroue opstande met families van E. gomphocephala en E. cladocalyx by twee klimatologies verskillende groeiplekke in die studiegebied; tweedens die beoordeling van die vroeë groei van alternatiewe taksa wat in die streek geplant kan word in vergelyking met die streek se historiese staatmaker-spesie E. cladocalyx. Die volume van die families is beraam deur gebruik te maak van toepaslike volumevergelykings, en met behulp van ’n vormfaktor waar vergelykings nie beskikbaar was nie. Die volume aanwas by die droë en sub-humiede groeiplekke was onderskeidelik 4.6 en 11.2 m3 ha-1j-1. Houtdigtheid is beraam deur nie-destruktiewe monsters uit die opstand te neem. Gemiddelde digthede het variëer van 588 (sub-humied) tot 620 kg m-3 (droë groeiplek). Die beraamde biomassaproduksie van die top-families beloop onderskeidelik 2.7 en 6.9 t ha -1j -1 vir die droë en sub-humiede groeiplekke. In terme van beraamde biomassa en oorlewing, is E. gomphocephala meer geskik vir droër groeiplekke , terwyl E. cladocalyx by die sub-humiede groeiplek ’n hoër opbrengs as E. gomphocephala getoon het, hoewel nie betekenisvol nie. Beramings van die vroeë groei by die proef met alternatiewe taksa het getoon dat die basters E. grandis × camldulensis en E. grandis × urophylla hoër biomassa-indekse het, maar meer vatbaar is vir besmetting deur Thaumastocoris peregrinus en Gonipterus scuttelatus.
Centre for Renewable and Sustainable Energy Studies

Thesis (PhD (Forest and Wood Science))—University of Stellenbosch, 2006.
Experiments carried out in this study sought to contribute to the understanding of the ecological interactions involved in Uapaca kirkiana seedling establishment and growth in a natural woodland ecosystem. These include soil pH reactions, plant root surface pH change, root exudates that affect the chemical behaviour of the soil in the vicinity of the root, and microbial effects. Although it was difficult to determine which of these factors play a dominant role in the soil-plant relationship, the study contributed to the understanding of the mycorrhizal fungi-host plant association. It revealed the diversity of mycorrhizal fungal species occurring in the different ecological sites, and also analysed the relationship between soil factors. Soil pH and K had significant influences on the fungi population diversity. K was considered important in its role in the translocation of auxins to the root sites where they enhance root susceptibility to mycorrhizal fungal infection. More work needs to be undertaken to establish the role of soil pH.

Thesis (MSc (Forest and Wood Science))--University of Stellenbosch, 2011.
ENGLISH ABSTRACT: This study investigated the use of carbon isotopes as a potential measure for water availability and drought stress in Pinus radiata in the Western and Southern Cape, South Africa. An understanding of water availability and its variation in space is fundamental to the implementation of increasingly site-specific management regimes that have the potential to greatly improve productivity across sites in the region. Fifteen plantation compartments situated on water shedding sites were identified where good weather data existed and a water balance model could be run. In addition, late wood samples were analysed from four co-dominant trees in the same stand to determine the δ13C values of five tree rings, each representing a specific growth year before first thinning. Detailed water balances were constructed for each trial site and drought stress indicators (a) relative canopy conductance (after Granier et al., 2000) and (b) the ratio of actual to potential evapotranspiration (supply / demand ratio), were related to δ13C values in latewood. Maximum available soil water ranged from 52 to 313 mm across trial sites. The water balance model used adequately described soil water availability throughout each growing season and indicated that stand stress due to the lack of available soil water mainly occurred during the summer months of the study period (November to April). The supply / demand ratio for this period as well as the relative canopy conductance proved to be good measures of drought stress. The six-month supply demand ratio (calculated for the period November to April) ranged from 0.04 to nearly 1 (winter rainfall zone) and 0.35 to 1 (all-year rainfall zone) and were strongly related to δ13C values (p < 0.001; r2 = 0.7822). It appears that using δ13C values, it may be possible to classify sites into three water availability classes. This classification may assist in the implementation of intensive silvicultural operations on an increasingly site-specific basis. Where sites are enriched with water from lateral flow or upslope positions, δ13C may be the only reliable technique to quantify soil water availability.
AFRIKAANSE OPSOMMING: Hierdie studie ondersoek die gebruik van koolstof isotope as 'n moontlike maatstaf vir die beskikbaarheid van water en droogtestremming in Pinus radiata in die Wes-en Suid-Kaap, Suid-Afrika. 'n Begrip van die beskikbaarheid van water en die ruimtelike variasie daarvan is fundamenteel vir die implementering van groeiplek-spesifieke bestuur sisteem wat die potensiaal het om baie verbeterde produktiwiteit oor persele in die streek teweeg te bring. Vyftien plantasievakke, geleë op waterskeidingsterreine is geïdentifiseer waar goeie weer data bestaan en 'n water balans model uitgevoer kon word. Daarmee saam is laathout monsters vanuit vier ko-dominante bome in dieselfde kompartement geanaliseer en die δ13C waardes van laathout in vyf jaarringe bepaal wat elk 'n spesifieke jaar van groei voor die eerste dunning verteenwoordig. Gedetailleerde water balanse is vir elke proef perseel bereken en aanwysers van droogtestremming, nl.: (a) relatiewe kroon geleiding (na Granier et al., 2000) en (b) die verhouding van die werklike teenoor potensiële evapotranspirasie (vraag / aanbod verhouding) is gekorreleer met 13C waardes in laat hout. Die maksimum hoeveelheid water beskikbaar op die verskeie proefpersele wissel van 52 tot 313 mm. Die water balans model wat gebruik is beskryf die beskikbare grondwater met genoegsame akkuraatheid. vir die hele groeiseisoen. Die model dui ook aan dat die kompartemente droogtestremming as gevolg van die gebrek aan beskikbare grond water ervaar gedurende die somer maande van die studie tydperk (November tot April). Die vraag / aanbod verhouding vir hierdie tydperk, asook die relatiewe kroon geleiding is geskik om as maatstawwe van droogtestremming gebruik te word. Die vraag / aanbod verhouding (bereken vir die tydperk November tot April) het gewissel van 0,04 tot byna 1 (Winter reënval gebied) en 0,35 tot 1 (die heel jaar reënval sone) en is sterk verwant aan 13C waardes (p <0,001; r2 = 0,7822). Dit blyk dat met die gebruik van δ13C waardes, dit moontlik kan wees om kompartemente te klassifiseer in drie klasse van water beskikbaarheid. Hierdie klassifikasie kan help met die implementering van intensiewe boskultuur bedrywighede op 'n meer vak-spesifieke basis. Waar vakkeverryk is met water vanuit laterale vloei of hoër liggende posisies, mag δ13C dalk die enigste betroubare tegniek wees om die beskikbaarheid van water te kwantifiseer.