Thesis (PhD For) (Forest and Wood Science))--Stellenbosch University, 2012. / ENGLISH ABSTRACT: See full text for abstract / AFRIKAANSE OPSOMMING: Sien volteks vir opsomming

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 (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. / 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 (MSc (Forestry))--Stellenbosch University, 1977. / The social biology and habitat selection of bushbuok, Tragelaphus scriptus, was investigated by ra~io-tracking five bushbuck in the same area, three males and two females. A large degree of over= lap of home ranges was shown to exist. Evidence is advanced to suggest the existence of a time-mechanism to separate individuals whose home ranges overlap. Subadult males have larger home ranges than females. Crepuscular peaks were exhibited in the activity pattern of the study animals. Of 1 380 animals observed in this study, 61% occurred singly and 29% in twos. Breeding is probably throughout the year with peaks in the rate of parturition in April, July-August and November. Bushbuck show a need for canopy cover during the day but will frequent areas with lateral cover or even no cover during the night. Although the indigenous forests are of great importance to bushbuck, evidence was found that they can exist in a very much modified environment such as pinus spp stands. Bushbuck occur at densities of about 3-5 animals!k~ in the Southern Cape. They feed on a wide array of food plants but are mostly browsers with grasses constituting only about five per cent of the diet. A surprisingly high incidence of mushrooms were found in the diet during winter. Some indications exist of the possible presence of sub-optimal feeding conditions during winter. Information is also presented on nutritional element levels, external parasites and morphological data.

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 (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 (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 (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.

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.