Thesis (MScFor)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: Namaqualand has a very unusual diversity of plant life, with many endemic plant species. The fundamental question of this thesis is how this system, damaged by strip-mining activities, can be rehabilitated. The aim was to base the rehabilitation methods on ecological processes. In order to answer this question an overview of the relevant literature was needed in order to identify possible research needs and also to evaluate the work that has been done in the field of strip-mine rehabilitation in arid areas. An understanding of community and ecosystem dynamics would help to establish aims and methods for site-specific rehabilitation. In Namaqualand, South Africa, there is also a need for experimentation to establish which of the many factors is most limiting to long-term ecosystem recovery. It is important to have a good knowledge of the successional processes and disturbance history of the land which needs to be rehabilitated. The vegetation on unmined areas and mined areas of different ages and treatments after mining, were sampled. It was shown that some areas could be expected to show a large degree of recovery in the space of a few years, whilst others would show little or no recovery over a period of decades. It is important to recognise rehabilitation as a gradual process that takes place at different rates in different areas and in different years. The planting of Atriplex nummularia and sowing of Atriplex semibaccata did not facilitate the return of indigenous, perennial species, but rather seem to inhibit their return. In view of the importance of topsoil in terms of the fertility of the soil and the seed bank present in the topsoil, the influence of topsoil removal and stockpiling due to strip-mining activities were tested. The soil fertility was tested by means of radish bioassays and soil laboratory analysis, whilst species diversity and richness were tested with seedling emergence trials. As expected a higher plant species diversity was found on the unmined soils and radishes grew larger on these soils. The topsoil deteriorated in terms of plant species richness, diversity and soil fertility whilst it was stockpiled. Direct replacement of topsoil would ensure a planting medium closer to the pre-disturbance level that could lead to fairly rapid and successful recolonization of the mined area. Successful plant recruitment also depends on the microsites to which seeds are dispersed. The effect that different microsites had on seed germination, seedling growth and survival was tested. It was found that micro catchments always yielded the highest numbers. The establishment and survival of seedlings in the other microsite types (under single shrubs, under clumped shrubs and in the open) varied, depending on the amount of rainfall received in the particular year. Lastly, I experimented with the translocation of three local, indigenous, succulent plant species. These plants were transplanted either in clumps of three together or alone, since I hypothesized that planting them together would facilitate their survival. However, it was found that it depended largely on the morphology of the plant and the amount of rainfall received in a particular year, whether these plants will compete with each other for limiting resources or facilitate each other's survival. The thesis contributes to the understanding of vegetation dynamics in the Succulent Karoo after strip-mining has taken place. Guidelines are provided based on ecological processes, for strip-mine rehabilitation in the Succulent Karoo. / AFRIKAANSE OPSOMMING: Namakwaland is bekend vir sy ongewone diversiteit van plante, met baie endemiese spesies. Die fundamentele vraag wat deur hierdie tesis gevra word is hoe hierdie sisteem, wat beskadig is deur oppervlak mynbou, gerehabiliteer kan word. Die doel is om die rehabilitasie metodes te baseer op ekologiese prosesse. 'n Oorsig van die relevante literatuur was nodig om moontlike areas van verdere navorsing te identifiseer en ook die navorsing wat reeds gedoen is oor rehabilitasie van oppervlak myne in ariede gebiede, te evalueer. 'n Goeie begrip van gemeenskap en ekosisteem dinamika sal help om doelwitte en metodes daar te stel vir die rehabilitasie van spesifieke areas. Dit is ook nodig om in Namakwaland, Suid -Afrika, uit te vind watter van die baie faktore, die lang-termyn herstel van 'n ekosisteem, die meeste verhinder. Dit is baie belangrik om In goeie kennis te hê van die versteurings geskiedenis van die area wat gerehabiliteer moet word, asook die suksessionele prosesse wat werksaam is. Plantegroei van areas wat op verskillende tye gemyn en verskillend behandel is, asook ongemynde areas is ondersoek. Sekere areas het In groot mate van herstel gewys in 'n tydperk van 'n paar jaar, terwyl ander, min of geen hersteloor 'n periode van dekades getoon het nie. Dit is belangrik om rehabilitasie as 'n geleidelike proses te sien, wat teen verskillende tempos plaasvind tydens verskillende jare en in verskillende areas. Daar is bevind dat die plant van Atriplex nummularia asook die saai van Atriplex semibaccata nie die terugkeer van inheemse, meerjarige spesies bevoordeel nie, maar dit eerder inhibeer. Aangesien die bo-grond so belangrik is in terme van die grondvrugbaarheid en ook die saadbank wat teenwoordig is, word die invloed van die verwydering en opberging van die bogrond getoets. Die grondvrugbaarheid was bepaal deur groei-toetse op radyse en laboratorium analise op die grond te doen. Die plant spesie diversiteit en rykheid was bepaal met In saad ontkieming studie. In ooreenstemming met die verwagte uitkoms, was die plant spesie diversiteit hoër op die ongemynde bo-grond en die radyse het groter geword op dieselfde grond. Dit kom voor asof die plant spesie diversiteit en rykheid, asook die grond vrugbaarheid afneem met tyd wat die bo-grond geberg word. Die direkte verspreiding van die bo-grond nadat dit verwyder is, sal In medium vir die plante verseker wat nader is aan die vlak voordat die grond versteur is. Dit sal oak sorg vir redelike vinnige en suksesvolle terugkoms van plante op die gemynde grond. Die suksesvolle vestiging van plante hang ook af van die mikro areas (klein areas in terme van die grootte van 'n saad, wat In eie mikro-klimaat vorm), waarna saad versprei word. Die effek van sulke mikro-gebiede op die ontkieming van saad, die groei van die saailinge en die oorlewing van die saailinge was bepaal. Mikro-water- opvanggebiede het in al drie bogenoemde gevalle die hoogste syfers getoon. Die vestiging en oorlewing van saailinge in die ander mikro-gebiede (die area onder enkel struike, die area onder groepe struike en oop areas) het gevarieer afhangend van die hoeveelheid reënval wat ontvang is in die spesifieke jaar. Laastens, is daar ge-eksperimenteer met die oorplant van drie plaaslike, inheemse, sukkulente spesies. Hierdie plante was alleen geplant of in groepies van drie, bymekaar. Die hipotese was dat huloorlewingskanse beter sal wees as hulle saam geplant word. Dit was egter bevind dat die hoeveelheid reënval in 'n spesifieke jaar en die morfologie van die plant, bepaal of hulle sal kompeteer vir die beperkte bronne en of hulle deur saam te groei huloorlewingskanse sal verhoog. Hierdie tesis dra by tot die verstaan van die plantegroei dinamika in die Sukkulente Karoo nadat oppervlak mynbou plaasgevind het. Riglyne vir die rehabilitasie van oppervlak myne, gebasseer op ekologiese prosesse, word ook voorgestel.

Thesis (MScFor)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: The invasive Australian acacia, A. sa ligna, is widespread in the Western Cape, South Africa, and is widely used by local communities. Not surprisingly, the introduction of the biological control agent, the fungus Uromycladium tepperianum in 1987 was received with mixed emotions. In an effort to determine the socio-economical and ecological impact of the fungus, the Department of Water Affairs and Forestry has commissioned a study, of which this thesis forms part. For this thesis, a number of parameters, environmental as well as biological, were sampled, analyzed and compared with existing data from previous studies. The goal was to obtain a comprehensive estimation of the effect of A. saligna on a Sand Plain Fynbos community near Atlantis and to assess whether or not, the detrimental effect A. saligna has on plant biodiversity, has reached the stage where it has become irreversible. The floristic data confirmed results from earlier studies, that invasion of A. saligna in Fynbos communities induces a decline in plant diversity, especially in dense acacia thickets. This study mainly revealed structural changes rather than community shifts. The enrichment of the soil as noted by others authors was also confirmed for the study area. However, it was outside the scope of this study to determine the long-term effects of this enrichment on the Sand Plain Fynbos communities. Soil moisture content was sampled on three different occasions, in densely invaded and uninvaded study plots. The aim was to see if A. saligna had any influence on the availability of water in the upper soil. Contrary to expectations, moisture content under acacia stands was higher in spring and early summer in the top soil than in pristine fynbos. Pitfall traps were used to sample the arthropods that dwell the surface of the study area. For arthropods in general, the survey did not produce conclusive data, but spider species seem to be positively affected by the presence of A. saligna, probably due to the structural diversity they add to the fynbos. This study revealed that the full ecological impact of A. saligna on its environment is far from understood, mainly due to the richness and complexity of the fynbos communities and a lack of research about faunal aspect of the Fynbos ecosystem. / AFRIKAANSE OPSOMMING: Die Australiese akasia, A. saligna, is wydverspreid in die Wes-Kaap, Suid-Afrika, en word dikwels gebruik deur die plaaslike gemeenskap. Dit is dan nie verbasend dat die invoering van die biologiese bestrydingsmiddel, die swam Uromycladium Tepperianum in 1987, met teenstrydige emosies ontvang is nie. In 'n poging om die sosio-ekonomiese en ekologiese impak van die swam te bepaal, het die Department van Waterwese en Bosboukunde 'n ondersoek aangevra waarvan die tesis deel vorm. Vir die tesis word 'n aantal parameters, omgewings sowel as biologies, geproef, geanaliseer en vergelyk met bestaande data van vroeër navorsing. Die doel van die studie is om te bepaal watter effek A. saligna op 'n sandpleinfynbos gemeenskap naby Atlantis het en om sodoende vas te stelof die nadelige effek van A. saligna op die biodiversiteit onomkeerbaar is. Plantaardige data bevestig resultate uit vroeër studies dat A. saligna 'n afuame in plant diversiteit, veral in digte akasiabosse, veroorsaak. In die studie word getoon dat die toename van A. saligna strukturele veranderings in plaas van gemeenskaplike verskuiwings tot gevolg het. Die verryking van die grond, deur ander navorsers genoteer, word ook in die studie bevestig. Dit is egter buite die veld van studie om die lang termyn gevolge van die verryking van die grond op die sandpleinfynbosgemeenskap te beslis. Op drie verskillende geleenthede word die watergehalte van die grond getoets onder die akasiabosse en die fynbos. Die doel van die toetse is om vas te stel hoe A. saligna die beskikbaarheid van water in die boonste grondlaag beïnvloed. In teenstelling is hoër vogtigheidsvlakke in die boonste grondlaag onder die akasiabosse as onder die fynbos gevind gedurende lente en vroeë somer. Lokvalle is gebruik om monsters te neem van die antropodieë woonagtig op die oppervlak van die studiearea. Oor die algemeen is die opname vir die antropodieë onvoldoende. Dit is egter insiggewend dat die spinnekopspesies voordeel trek uit die aanwesigheid van A. saligna. Dit is waarskynlik omdat die akasia strukturele diversiteit aan die fynbos verleen. Die studie onthul dat die volle ekologiese impak van A. saligna op sy omgewing moeilik verstaanbaar is as gevolg van die diversiteit en kompleksiteit van fynbos asook 'n gebrek aan navorsing.

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 (Dept. of Forest and Wood Science)--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: In this study 1345 pieces of 38x114 mm timber sawn from 16-20 year-old Pinus patula trees were obtained from a wide variety of sites along the Mpumalanga escarpment in South Africa. The samples were tested for various mechanical and physical properties. The objectives of this study were (1) to determine the variation in the bending strength, tension strength, and stiffness of the sawn timber, (2) to assess the efficiency of the current visual and mechanical grading rules on this sample, and (3) to evaluate the potential of some indicator properties to be used as structural grading parameters on this resource. A large number of non-destructive measurements were performed on all the samples, including scanning of the boards with a commercial X-ray density scanner, moisture content measurement, growth ring measurements, warp measurement, acoustic frequency measurement and measurement of the stiffness using a mechanical grader. The data from the X-ray density scanner was used to calculate a number of knot-related variables for each board. Visual grading according to the SANS 1783-2 (2005) specifications for structural timber was performed by a certified grader on all the boards. The timber was divided into two groups for destructive testing, one group each for bending and tension tests. Tests were conducted according to the SANS 6122 (1994) method for in-grade testing. Due to the sampling method followed, the destructive tests effectively used a random placement of defects with regard to the load application position. From the destructive tests the modulus of elasticity (MOEedge), bending strength (MOR) and tensile strength were determined. The study showed that the MOEedge of the sawn timber was far below the requirements of the current national standard (SANS 10163-1) for all of the visual and mechanical grades. The mean MOEedge of the visually graded S5 timber was about 30% lower than required. The 5th percentile values for bending strength of all the visual and mechanical grades were above the required values of SANS 10163-1. The 5th percentile values for tensile strength of all the visual and mechanical grades were similar to that required by the SANS 10163-1 standard. Correlations between flatwise measured MOE (MOEflat) and edgewise measured MOE (MOEedge) were smaller than expected, as well as the correlations between both MOEedge and MOEflat with MOR. Dynamic MOE (MOEdyn), calculated from acoustic frequency tests on the timber, was found to be the best single predictor of MOEedge, MOR and tension strength. Multiple regression analysis showed that a combination of MOEdyn, density and knot parameters can be used to improve the predictability of some of the strength and stiffness characteristics of the timber. It is recommended that a comprehensive study on the structural grading of SA Pine be performed which includes (1) an analysis of market requirements in terms of strength and stiffness properties of timber, (2) in-grade testing of a representative sample of structural timber in South Africa, and (3) a review of the standards used in South Africa to regulate the structural grading of timber. / AFRIKAANSE OPSOMMING: In hierdie studie is 1345 stukke 38x114 mm 16-20 jaar-oue Pinus patula planke, afkomstig van ‘n wye verskydenheid groeiplekke teen die Mpumalanga platorand in Suid Afrika, gebruik. Die planke is getoets vir verskeie meganiese sowel as fisiese eienskappe. Die doelwitte van hierdie studie was om (1) die variasie in buigsterkte, treksterkte en styfheid van die gesaagde planke te bepaal, (2) die effektiwiteit van die huidige visuele -en meganiese graderingsreëls op hierdie monster planke vas te stel, en (3) die potensiaal te evalueer van sommige eienskappe wat gebruik kan word as strukturele graderingsparameters. ‘n Groot hoeveelheid nie-destruktiewe toetse is op alle planke uitgevoer, wat ingesluit het skandering van planke met ‘n kommersiële X-straaldigt-heidskandeerder, metings van voginhoud, groeiringwydtes, deformasie, akoestiese frekwensie en die bepaling van styfheid met behulp van ‘n meganiese gradeerder. Die data van die X-straalskandeerder is gebruik om ‘n aantal kwasverwante veranderlikes vir elke plank te bereken. Visuele gradering is op alle planke uitgevoer ooreenkomstig met die SANS 1783-2 (2005) spesifikasies vir strukturele hout deur ‘n gesertifiseerde gradeerder. Die hout is in twee groepe opgedeel vir destruktiewe toetse, een vir buigtoetse en een vir trektoetse, ooreenkomstig met die SANS 6122 (1994) metode vir binnegraadse toetse. As gevolg van die monsternemingsmetodiek wat gevolg is, is daar effektief gebruik gemaak van ‘n lukrake plasing van defekte met betrekking tot die las-aanwendingsposisie. Die modulus van elastisiteit (MOEedge), buigsterkte (MOR) en treksterkte is deur middel van destruktiewe toetsresultate bepaal. Die studie het aangetoon dat die MOEedge van gesaagde hout aansienlik minder as die vereiste van die huidige nasionale standaard (SANS 10163-1) is vir al die visuele en meganiese grade. Die gemiddelde MOEedge van die visueel-gegradeerde S5 planke was omtrent 30% laer as vereis. Die 5de persentiel waardes vir buigsterkte van alle visuele en meganiese grade was hoër as die vereiste waardes soos voorgeskryf deur SANS 10163-1. Die 5de persentiel waardes vir treksterkte van alle visuele en meganiese grade was gelykstaande aan wat vereis word deur SANS 10163-1. Korrelasies tussen MOE, gemeet op die wydte sy (MOEflat), en MOE, gemeet op die diktesy (MOEedge), asook die korrelasies van beide MOEedge en MOEflat met MOR van die planke was laer as verwag. Dinamiese MOE (MOEdyn), wat bereken was vanaf die akoestiese frekwensie resultate, is vasgestel as die beste enkele indikator van MOEedge, MOR en treksterkte. Meervuldige regressie analise het aangetoon dat ‘n kombinasie van MOEdyn, digtheid en kwasparameters gebruik kan word om die voorspelbaarheid van sommige van die sterkte- en styfheids eienskappe van die hout te verbeter. Daar word aanbeveel dat ‘n omvattende studie gedoen word op die strukturele gradering van SA Dennehout, wat insluit (1) ‘n analise van die markbehoeftes in terme van die sterkte- en styfheids eienskappe van hout, (2) binnegraadse toetsing van ‘n verteenwoordigende monster strukturele hout in Suid Afrika, en (3) die hersiening van standaarde in gebruik in Suid Afrika om die strukturele gradering van hout te reguleer.

Thesis (MSc)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: Today there is renewed interest in using soil improvers with fertilising capability as the use of inorganic fertilisers results in ground water pollution through leaching and formation of nitrates in plant materials. Lignin is an important precursor of humic material in soils and with modification, can be used as a raw material for producing slow release nitrogenous fertilisers. This project focussed on the use of industrial residues such as technical lignins which are produced by the South African pulping industry as well as low grade coals such as lignite occurring in South Africa, for the production of high-grade humic substances like Novihum TM, using the special technology developed by the Institute of Plant and Wood Chemistry of the Technical University of Dresden in Germany. Technicallignins derived from kraft lignin, sugar cane baggase, autohydrolysis lignin with a trade name Sucrolin, a calcium lignosulphonate and South African lignites mined in the Kraaifontein and BraekenfeIl areas as well as German brown coal were subjected to oxidative ammonolysis with the aim to produce slow release nitrogenous fertilizers. Curie Point Pyrolysis GCIMS was used to determine the structural composition of the raw materials and products. Oxidative ammonolysis reactions were carried out on a laboratory and a pilot plant scale. Highest nitrogen contents were obtained with Sucrolin lignin followed by the lignite from Germany. The amount of nitrogen that could be fixed with oxidative ammonolysis varied between 1.44 - 10% for the various raw materials. The CIN ratios obtained were in the range between 5 - 34. Marginal differences were observed between the materials modified on lab and pilot plant scales. There were improvements in the total incorporated nitrogen when the raw materials were pre-activated with oxidising agents such as hydrogen perxide and a fungal species, Phanaerochateae chrysosporium prior to oxidative ammonolysis. Variable amounts of differently bonded nitrogen forms were obtained for the materials tested due to their structural differences. / AFRIKAANSE OPSOMMING: Daar is deesdae hernude belangstelling in die gebruik van grondverbeteringsmiddels wat ook 'n bemestingsfunksie het, aangesien die gebruik van anorganiese kunsmis besoedeling van grondwater deur uitlogingen insypeling veroorsaak, wat weer tot die vorming van nitrate in plantmateriaallei. Lignien is 'n belangrike voorloper van humiese materiale in grondstowwe en kan dmv modifisering gebruik word as 'n grondstof vir die produksie van stadigstikstof vrystellende nitro gene kunsmisstowwe. Die huidige projek het gefokus op die gebruik van industriële residue en tegniese ligniene wat deur die Suid- Afrikaanse pulpnywerheid geproduseer word, sowel as lae-graad steenkool soos ligniet wat in Suid-Afrika aangetrefword, vir die produksie van hoë-graad humiese stowwe soos Novihum TM. Hierdie produk is mbv spesiale tegnologie deur die Instituut van Plant- en Houtchemie van die Tegniese Universiteit van Dresden in Duitsland ontwikkel. In hierdie ondersoek is verskeie Suid-Afrikaanse tegniese ligniene soos Kraft lignien, suikerriet bagasse, 'n outohidrolise lignien met die naam van Sucrolin en 'n kalsiumlignosulfonaat sowel as SA ligniete, afkomstig van Brackenfell en Kraaifontein, gebied en Duitse bruinkool, aan oksidatiewe ammonolise onderwerp om sodoende verskillende, stadigvrstellende, stikstofryke kunsmisstowwe te vervaardig. Curie Punt Pirolise GC/MS is gebruik om die chemiese struktuur van die grondstowwe en produkte vas te stel. Oksidatiewe ammonolise reaksies is op 'n laboratorium en loodsaanlegskaal. uitgevoer. Die hoogste stikstofinhoud is met Sucrolin lignien verkry, gevolg deur die ligniet van Duitsland. Die hoeveelheid stikstof wat dmv oksidatiewe ammonlise bereik kon word, het tussen 1.44 en 10% gewissel. Die CIN verhoudings wat verkry was, het varieer tussen 5 en 34. Marginale verskille is tussen laboratorium - en loodsaanlegsskaal gemodifiseerde grondstowwe waargeneem. Daar was verhogings in stikstofinhoud wanneer die grondstowwe vooraf met oksiderende middels soos waterstofperoksied of swamkultur soos Phanaerochatae chrysosporium, aktiveer is. Stikstof is op verskillende maniere en in verskillende hoeveelhede gebind.

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.

Thesis (MScFor)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: South Africa is a timber scarce country that will most probably experience a shortage of structural timber in the near future. In this study the concept of using young finger‐jointed Eucalyptus grandis timber was evaluated for possible application in roof truss structures while the timber is still in the green, unseasoned state. 220 finger‐jointed boards of cross‐sectional dimension 48 x 73 mm and 36 x 111 mm timber, cut from 5‐18 year old Eucalyptus grandis trees were obtained from Limpopo province, South Africa. The boards were manufactured using a polyurethane (PU) adhesive at moisture content levels above fibre saturation point and no drying was performed. The objectives of this study were to determine various mechanical and physical properties of this finger‐jointed product. More specifically (1) to determine the strength and stiffness potential of the product in the wet and the dry condition, (2) to evaluate physical properties such as density, warp, checking and splitting, (3) to evaluate potential indicator properties to be used as structural grading parameters, and (4) to compare the flexural properties to the current SA pine resource and SANS structural grade requirements. The boards were divided into two groups of the same size, which constituted the wet and the dry samples. Each sample was further separated into six different groups for testing the different strength and stiffness properties. The dry group was stacked in a green‐house for nine weeks until equilibrium moisture content was reached. Afterwards selected physical properties such as warp, checking and splitting were assessed. Destructive testing was conducted on the boards and the results were used to determine various mechanical properties. Finally, each board was assessed for density and moisture content (MC) values. The study showed that the young finger‐jointed Eucalyptus grandis timber had very good flexural properties. Both mean modulus of elasticity (MOE) and modulus of rupture (MOR) 5th percentile strength values for wet and dry boards complied with the current SANS 10163‐1 (2003) requirements for grade S7.The values of tensile perpendicular to grain and compression perpendicular to grain strength did not conform to SANS requirements for grade S5. The other strength properties for the wet and dry groups complied with one of the three SANS structural grades. The 5 year old (48 x 73 mm) boards’ showed significantly higher levels of twist and checking compared to 11 year old boards of the same dimension. Only 46.3% of the finger‐jointed products conformed to the density requirements in SANS 1783‐2 (2004) for grade S7. There was a significant difference in density between the three age groups (5, 11 and 18 years) presented in this study. The variation in both MOE and MOR values of the fingerjointed product proved to be significantly lower in comparison to currently used SA pine sources. Based on the results from this study the concept of producing roof trusses from wet, unseasoned and finger‐jointed young Eucalyptus grandis timber has potential. However, additional research on a number of issues not covered in this study is still required for this product including full scale truss evaluations, proof grading, PU adhesive evaluation at elevated temperatures, nail plate load capacity, and the possible need for chemical treatment of the product against Lyctus beetles. / AFRIKAANSE OPSOMMING: Suid Afrika is ‘n land wat waarskynlik ‘n tekort aan strukturele hout sal ervaar in die nabye toekoms. In hierdie studie word die gebruik van jong gevingerlasde Eucalyptus grandis hout vir die moontlike gebruik in dakstrukture, terwyl nat en ongedroog, ondersoek. 220 gevingerlasde planke van deursnit 48 x 73 mm en 36 x 111 mm gesaag van 5‐18 jaar‐oue Eucalyptus grandis bome en afkomstig van die Limpopo provinsie in Suid Afrika, is gebruik. Die produk is vervaardig met poli‐uretaan (PU) lym uit planke met vog inhouds vlakke bo veselversadigingspunt. Die doelwit van hierdie studie was om verskeie meganiese en fisiese eienskappe van die vingerlas produk vas te stel. Meer spesifiek (1) om die sterkte en modulus van elastisiteit (MOE) potensiaal van die vingerlas produk in die nat en droë toestand te analiseer, (2) om die fisiese eienskappe soos digtheid, vervorming, oppervlakbarse en spleting te ondersoek, (3) om potensiële graderingsparameters te evalueer, en (4) om die buigeienskappe van die produk te vergelyk met SA dennehout asook die SANS strukturele graad vereistes. Die planke is verdeel in twee groepe, ‘n nat groep en ‘n droë groep. Elke groep is verder verdeel in ses kleiner groepe soos buig, trek en drukmonsters. Die droë groep was in ‘n kweekhuis geplaas vir nege weke totdat veselversadigingspunt bereik is. Daarna is geselekteerde fisiese eienskappe soos vervorming, oppervlak barse en spleting gemeet. Destruktiewe toetsing is uitgevoer op die planke en die resultate was gebruik om verskeie meganiese eienskappe vas te stel. Laastens is elke plank se digtheid en voggehalte gemeet. Die studie het getoon dat die jong gevingerlasde Eucalyptus grandis hout goeie buigeienskappe het. Beide die gemiddelde MOE en buig sterkte 5de persentiel waardes van die nat en droë groep het voldoen aan die huidige SANS 10163‐1 (2003) vereistes vir graad S7. Die sterkte‐eienskappe van loodregte trekkrag en loodregte druk het nie die vereistes vir SANS graad S5 gemaak nie. Die ander sterkte‐eienskappe van die nat en droë groep het voldoen aan een van die drie SANS strukturele graadvereistes. Die 5 jaar‐oue (48 x 73 mm ) planke het beduidend hoër vlakke van draai‐trek en oppervlakbarste getoon as die 11 jaar‐oue planke van dieselfe dimensie. Slegs 46.3% van die vingerlas produk het voldoen aan digtheidsvereistes vir SANS graad S7. Daar was ‘n beduidende verskil in dightheid tussen die drie ouderdomsgroepe (5, 11 en 18 jaar). Die MOE en buigsterkte‐waardes van die Biligom produk het beduidend laer variasie as huidige SA denne houtbronne getoon. Die resultate verkry in die studie toon dat die konsep om dakkappe te vervaardig van nat, gevingerlasde jong Eucalyptus grandis hout die potensiaal het om suksesvol toegepas te word. Bykomende navorsing oor ‘n aantal faktore wat nie in hierdie studie ingesluit is nie word steeds benodig. Dit sluit in ‘n volskaalse dakkap evaluasie, proefgradering, PU lym evaluasie by hoë temperature, spykerplaat ladingskapasiteit en die moontlike noodsaaklikheid van chemiese behandeling van die produk teen Lyctus kewers, insluit.

Thesis (MScFor)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Information on the external shape and internal properties of a tree such as the branch structure, tree ring widths and formation, and defects such as resin pockets is important for many forest –and wood science researchers as well as for the forest and wood processing industries. Resin pockets are internal defects associated with some softwood species, and are undesirable in some wood applications such as furniture and veneer. A tool that is often used in research to obtain this information is the Computed Tomography scanner. The high cost of the scanner, as well as the cost of transporting logs to the scanner, limits the application range of this equipment. An alternative, lower cost method would be beneficial for many researchers interested in tree shape and macroscopic internal tree characteristics. The objectives of this study were to: - Design, construct and test a mobile system that can be used in field to obtain a three‐dimensional model of a log or tree stem indicating selected macroscopic internal characteristics and, - Interpret results to explain the occurrence and causes of resin pockets in Pinus patula from the Mpumalanga escarpment, South Africa. A system for dissecting and measuring trees in field was designed, constructed and tested. The metal frame was used to cut a stationary, fixed log into discs and obtain digital images of crosssections along the stem axis. The frame was capable of processing logs with maximum dimensions of 3 m in length and 45 cm in diameter. Software was developed to convert the digital images into three‐dimensional models of logs and trees to demonstrate properties such as the external shape of the trees, branch structure and pith location. Properties such as ring width were measured from the images obtained. The study was conducted in the Mpumalanga escarpment to obtain three‐dimensional models of Pinus patula trees and to establish the reason for formation of resin pockets in these trees. Four 3 m logs from twenty‐four trees from three compartments were dissected and digitally reconstructed into three‐dimensional models. A total of 61 cross sections with resin pockets were identified from the 2750 cross cut images taken 20 cm apart along the longitudinal axis of the log. It was not possible to accept or reject conclusively any of the existing hypotheses for the cause of resin pocket formation. The formation of Type 2 resin pockets was most probably due to felling damage during thinning operations. It seems likely that wind damage and possibly insects might be responsible for the formation of Type 1 resin pockets. / AFRIKAANSE OPSOMMING: Kennis in verband met die interne eienskappe van ‘n boom soos takeienskappe, jaarringwydte en vorm, en harsholtes is belangrik vir sommige bos ‐en houtkundige navorsers. Die toerusting wat huidiglik algemeen gebruik word om inligting van hierdie aard te bekom is ‘n CT skandeerder. Die metode is egter duur as gevolg van hoë kapitale koste van die toerusting sowel as die vervoerkoste van stompe na die CT‐fasiliteit. ‘n Meer ekonomiese alternatief sal vir baie navorsers van waarde wees. Harsholtes in hout lei tot afgradering van hout en fineer. Die doel van die studie was twee‐sydig: - Om ‘n stelsel te ontwerp en bou wat ‘n drie‐dimensionele model van ‘n boom kan skep wat sommige makroskopiese, interne eienskappe weergee, en - Om die voorkoms en oorsaak van harsholtes in Pinus Patula van die Mpumalanga platorand te ondersoek. ‘n Raam is ontwerp en vervaardig wat in die plantasie gebruik word. Die raam kan stompe van tot drie meter lengte met ‘n maksimale diameter van 45 cm hanteer. Die raam is gebruik om snitte deur die stompe te maak, ‘n afstandmeting tot by die gesaagde oppervlak word deur ‘n lasermeter geneem en ‘n kamera neem ‘n foto. Sagteware word dan gebruik vir die uitkenning van sekere dele in elke beeld sowel as die samestelling van ‘n drie‐dimensionele model. Data‐insameling met die raam is in Mpumalanga gedoen. Die raam is in die tydperk getoets en het goed gefunksioneer. Vier stompe elk vanaf vier‐en‐twintig bome vanuit drie afsonderlike kompartemente is verwerk op die raam en volledige drie‐dimensionele modelle geskep vir hierdie bome insluitend hul eksterne vorm, takeienskappe en pitvorm (“pith location”). Ongeveer 2750 foto’s van dwarssnitte is tydens data‐insameling geneem. Net 61 van die foto’s het harsholtes bevat. Geen definitiewe oorsaak van harsholtes kon bepaal word nie. Tipe 2 harsholtes word waarskynlik as gevolg van skade tydens uitdunning van bome gevorm. Wind en insekte lyk na die mees waarskynlike oorsake van Tipe 1 harsholtes.

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)--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.