Thesis (MSc) -- Stellenbosch University, 1996. / ENGLISH ABSTRACT:Principle objectives of this study were to investigate the ecological feasibility of sustained utilization of mopane, using Venetia Limpopo Nature Reserve as a pilot study area. The study was limited to three different mopane dominated vegetation types on the reserve with most research being conducted in C.mopane woodland. Results can be summarized as follows: 1. Colophospermum mopane is ubiquitous on VLNR. 2. C.mopane woodland has the deusest mopane growth of the three vegetation types and highest densities are found on soils (OaB, VaB, Du, SwB & VaA) in association with C.mopane woodland. There seems to be a correlation between mopane density and soil type. 3. Largest mopane trees according to height and circumference were found in C.mopane/C.apiculatum open woodland. There is no significant difference between height and circumference on different soil types. 4. Most senility occurs in C.mopane shrubland and there is a significant difference in senility between mopane associated with different soils on which this vegetation type occurs. 5. Oldest average ages per tree were fo•.md in C.mopane woodland while growth rates were fastest in C.moparse!C.apiculatum open woodland. 6. There is a significant positive correlation between total and charcoal weights for mopane. Total and charcoul weights per tree were highest for C.mopane/C.apiculatum open woodland, while weights per hectare were highest for C.mopane woodland. Soils could not positively be associated with this trend. 7. Mopar.e lends itself to harvesting, especially C.mopane ••10odland in the Endora, Lizzulea and Hilda areas. Winter months seem to be most desirable for harvesting activities. Hand felling in elongated patches (increases ecotone boundary) is recommended where labour is cheap. A harvesting strategy of between 25% and 50% would make the operation economically viable and ecologically acceptable. An optimum harvesting rate of 27% is suggested by a harvesting model developed specifically for this mopane data. 8. Total herbivore densities, distribution and species proportions can be expected to change following bush clearing. Habitat for grazers should increase due to an increased grass production. Habitat for browsers should not be influenced much. Effect of noise and human disturbance during harvesting, especially for elephants is negligible, as hunting activities already take place on VLNR. 9. Grass production would increase but quality should decrease after harvesting, due to an increase in low quality opportunistic species, especially if soil disturbance takes place. Grass quality is best in association with herbaceous species such as Salvadora angustifolia. Carrying capacity for grazers should increase after harvesting as a result of habitat change and grass biomass increase. 10. Total browse production would decrease but leaf biomass should increase on remaining trees as they have improved water availability due to Q lack of intra­ specific competition. Higher seed production and more flowering takes place at lower tree densities. Greatest advantages for browsers after harvesting, is the fact that leaves become senescent later in autumn and that spring leaf flush takes place earlier thus prolonging bro\'se availability. / AFRIKAANSE OPSOMMING:Die hoof doelwitte van hierdie studie was om te bepaal wat die invloed van die oes van mop nie op die ekologie sou wees as dit op 'n volgehoue basis plaasvind en tot w•atter mate mopanie geskik is vir hou skoolvervaardiging. Die navorsing is op die Venetia Limpopo Natuureservaat in slegs drie van die belangrikste mopanie veldtipes uitgevoer met die oorgrote meerderheid van die navorsing in die C.mopane bosveld. Die resultate van die studie kan soos volg opgesom word: 1. Colophospermum mopane is alomteenwoordig op die VLNR. 2. Die C.mopane bosveld het die hoogste digtheid van al drie veldtipes en word ook geassosieer met sekere grondtipes (OaB, VaB, Du, SwB & VaA) wat eie is aan hierdie spesifieke veldtipe. Daar blyk 'n korrelasie te wees tussen die digthede van mopanie en grondtipes. 3. Die grootste mopanie borne, ten opsigte van hnogte en omtrek, word in die C.mopane/C.apiculatum oop bosveld aangetref. Daar is nie 'n beduidende verskil tussen die hoogte en omtrek van mopanie op die verskillende grondtipes nie. 4. Die C.mopane struikveld toon die meeste seniliteit ten opsigte van die persentasie kruin dood. Daar is 'n definitiewe aanduiding dat seniliteit ooreenstem met sekere grondtipes veral met betrekking tot die mopanie struikveld. 5. Die C.mopane bosveld het gemiddeld die oudste borne terwyl die C.mopane/C.apiculatum oop bosveld die vinnigste groeikoers toon. Die bogenoemde feite het 'n ver0and met die grondtipes. 6. Daar is 'n posltiewe korrelasie tussen die totale gewig en die houtskoolgewig van mopanle. Die S\vaarste borne is in die C.mopane!C.apiculatum oop bosveld aangetref, terwyl die swaarste gewig per hektaar in die C.mopane bosveld aangetref is. Gewig kon nie met grondt pes gekorreleer word nie. 7. Die mopanie in die C.mopane bosveld is geskik vir die oes vir houtskool, veral in die Endora, Lizzulea en Hilda gebiede. Dit is raadsaam om die borne in verlengde stroke per hand af te kap (vergroot die ekotoongebied), veral waar arbeid goedkoop is. 'n Oesstrategie van tussen 25% en 50% vir mopanie word aanbeveel om dit ekonomies en ekologies aanvaarbaar te maak. 'n Optimum oesstrategie van 27% word aanbeveel deur 'n oes model wat spesifiak vir hierdie mopane data opgestel is. 8. Daar kan verwag word dat na die oes van mopanie die getalle asook verspreidingspatrone van alle hoefdierspesies kan verander. 'n Voordeel van lae mopanie digthede is dat die verspreiding van die blaarbiomassa ewerediger oor die seisoene sal geskied. Grasvreters word bevoordeel vanwee die verandering in habitat. Die effek van geraas en ander oesbedrywighede op olifante behoort klein te wees aangesien jagaktiwiteite alreeds op diereservaat toegepas word en hulle redelik gewoond daaraan behoort te wees. 9. Grasproduksie behoort toe te neem terwyl die kwaliteit daarvan afneem as gevolg van opportunistieslae kwaliteit grasspcsies wat toeneem na die oes van mopanie, veral as die grand tydens oesaktiwiteite versteur word. Die beste kwaliteit gras word in assosiasie met kruidagtige spesies, veral Salvadora angustifolia, gevi.nd. As gevolg van die verandering in habitat asook die toename in grasbiomassa neem die drakrag vir grasvreters na die oes an mopanietoe. 10. Di.e totale blaarbi.)massa behoort na die oes van mopanie af te neem, maar behoort terselfdertyd op die oorblywende borne as gevolg van die afname in kompetisie vi= watr en anrler natuurlike hulpbronne toe te neem. Hoer persentasies blomvorming en saadproduksie vind by laer boomdigthede plaas. Die grootste enkele voordeel vir blaarvreters, na die oes van mopanie, is die feit dat die blare later in die herfs afval en vroeer in die lente uitbot en dus die voedselbeskikbaarheid vir blaarvreters verleng.

Thesis (MScFor)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: In South Africa fertilizer applications at establishment is a common practice in the forestry industry. Recommendations are based on past research with conventional sources (CV) and as a result there have only been slight improvements in additional plantation production over recent years. The objective of this study was to investigate initial stand responses in terms of leaf are index (LAI), foliar nutrient content, biomass index (BI) and volume growth to the application of controlled release fertilizers (CRF) at re-establishment. Nitrogen (N), phosphorus (P) and potassium (K) were applied in a three way factorial combination to Pinus radiata at planting on a site in the Western Cape. The design was replicated five times across the study area. N (CRF) and P (CV) were applied in a two way factorial combination at planting to two Eucalyptus grandis x urophylla hybrids and Eucalyptus dunnii across three sites, one ex-agricultural and two re-establishment sites, on the Zululand coastal plain and the Midlands region. The design was replicated nine times on each study site. Harvesting residues were burnt on the eucalypt sites prior to establishment and may have had an impact on the responses found. An outbreak of Fusarium circinatum on the P. radiata site resulted in unexpected and extremely variable responses. An attempt to quantify the effect of the disease had limited success. The mean BI of the control treatment reached 25. The best CV and CRF treatments yielded improvements of 42 % and 83 % in BI over the control respectively, with only the CRF treatment difference being significant. Foliar analysis results revealed marginal to deficient concentrations of P and Mg being alleviated by the treatments in question. On the KZN Zululand sites there was a marked response of the hybrids to N with P having an additive effect on volume growth, LAI and foliar N content. Application of 120 g N and 20 g P per tree on the ex-agriculture site produced a volume of 8 m3 ha-1 at one year of age, a significant increase of 118 % and 80 % over the control and best CV treatment respectively. Application of 80 g N and 20 g P per tree, on the re-establishment site, yielded a volume of 24.6 m3 ha-1 at one year which equates to a significant 39 % and insignificant 7 % additional volume at one year over the control and best CV treatment respectively. A non-significant suppressive effect was found with 20 g CV P application only. At the KZN Midlands site, the major early response in height were to P application. Applications of 20 g CV P per tree, resulted in a mean height of 162.6 cm at seven months of age, a significant 28 % higher than the control. There was no significant effect of 80 g CRF N and 20 g CV P per tree respectively. CRF N applications up to 120 g per tree provide additional growth over recommended CV applications on coastal Zululand sites with low organic carbon (OC) content. On the KZN Midlands site with higher OC and clay content, early responses were limited to P fertilization only regardless of the fertilizer source. / AFRIKAANSE OPSOMMING: Dit is algemene praktyk in die Suid Afrikaanse bosbou industrie om kunsmis tydens aanplanting toe te dien. Hierdie aanbeveling is gebasseer op navorsing resultate met konvensionele bronne (CV), gevolglik was slegs ‘n klein toename in bykomende plantasie produksie gemeet die afgelope paar jaar. Die doelwit tydens hierdie studie is om die aanvanklike reaksie van die bome in terme van blaar oppervlak indeks (LAI), blaar-voedingstof inhoud, biomassa indeks (BI) en volume op die toediening van beheerde vrylating kunsmis (CRF) tydens aanplanting vas te stel. Stikstof (N), fosfor (P) en kalium (K) is in drie-ledige kombinasie aan Pinus radiata op ’n plantasie in die Weskaap toegedien. Die ontwerp is vyf keer in die studiegebied herhaal. N en P is in twee-ledige kombinasie aan twee Eucalyptus grandis x urophylla hibriede en Eucalyptus dunnii op drie groeiplekke, een eks-landbou en twee eks-bosbou, op die Zoeloeland kusvlakte en in die Natalse Middellande toegedien. Die ontwerp is nege keer in elke studiegebied herhaal. Oesreste is voor aanplanting op die Eucalyptus groeiplekke verbrand. Die voorkoms van Fusarium circinatum op die P. radiata groeiplek het onverwagte en hoogs uiteenlopende reaksies tot gevolg gehad. ’n Poging om die effek van die siekte te kwantifiseer, was slegs gedeeltelik suksesvol. Die gemiddelde BI van die kontrole behandeling, was 25. Die beste CV en CRF behandeling het onderskeidelik 42 % en 83 % hoër BI as die kontrole groep gehad, waarvan slegs die CRF behandeling beduidend was. Blaarontleding het gewys dat daar marginale of ontoereikende konsentrasies van P en Mg was. In Zoeloeland het die Eucalyptus hibriede ’n beduidende reaksie op N en P getoon met meer volume groei, LAI en N inhoud. Die toediening van 120 g N en 20 g P per boom op die eks-landbou groeiplek het ’n volume van 8 m3 ha-1 op eenjarige ouderdom tot gevolg gehad. Dis beduidend beter met 118 % en 80 % onderskeidelik vir die kontrole en beste CV behandeling. Die toediening van 80 g N en 20 g P per boom op die hervestigde eks-bosbou groeiplek, het ’n volume van 24.6 m3 ha-1 op eenjarige ouderdom tot gevolg gehad. Dit is 39 % beduidend en 7 % onbeduidend addisionele volume op eenjarige ouderdom vir onderskeidelik die kontrole groep en beste CV behandeling. ’n Onbeduidende depressie effek is met die alleen toediening van 20 g CV P gevind. In die Natalse Middellande groeiplek het die toediening van P ‘n vroeë reaksie in hoogte groei veroorsaak. Die toediening van 20 g CV P per boom, het ’n gemiddelde hoogte van 162.6 cm op die ouderdom van sewe maande tot gevolg gehad. Dit is 28 % beduidend hoër as die kontrole. Die toediening van 80 g CRF N en 20 g CV P per boom was onbeduidend. Toedienings van CRF N tot en met 120 g per boom het in die kusgebiede van Zoeloeland met ‘n lae organiese koolstof (OC) inhoud, groter groei as die aanbevole CV toedienings gehad. Die Middellande groeiplek met ’n hoër OC en klei inhoud, was die vroeë reaksie alleenlik beperk tot P bemesting.

Thesis (MScFor)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The aim of this project was to determine the site effect- especially water availability - and the effect of cambial age on selected anatomical properties of Pinus radiata, in order to be able to predict possible changes in wood quality due to an expected change in climate. A second objective was to correlate ring and fibre properties, in order to determine, if ring properties could be used as a proxy to describe wood quality. The samples consisted of 12 trees, sampled at an age of 1 to 16 from six selected sites in the Western Cape, which ranged from water stressed to moist. Apart from the water availability all other external factors, such as elevation etc. were kept as equal as possible. Anatomical wood properties such as fibre length and fibre diameter, lumen diameter, cell wall thickness, ring width and earlywood/latewood ratio were determined and their change with cambial age and water availability was evaluated. Fibre length, fibre diameter and cell wall thickness increased with increasing cambial age, and ring width and earlywood/latewood ratio decreased with increasing cambial age. No significant correlations were found between any of the ring or fibre properties and water availability. Most of the fibre properties were significantly correlated with ring width and earlywood/latewood ratio when age was not considered as covariate, but showed no correlation when the age effect was excluded. / AFRIKAANSE OPSOMMING: Die doel van die projek was om die perseel se effek te bepaal, veral water beskikbaarheid, ten opsigte van die effek van kambium ouderdom en geselekteerde anatomiese eienskappe van Pinus radiata, om sodoende die moontike verandering in hout kwaliteit as gevolg van verwagte klimaatsverandering te voorspel. ‘n Tweede doelwit was om die ring en vesel eienskappe te korreleer en ook te bepaal of ring eienskappe gebruik kan word om hout kwaliteit te beskryf. Die monsters het bestaan uit bome van ses geselekteerde persele in die Wes Kaap en het gevarieer van ‘n water tekort na klam. Behalwe vir water beskikbaarheid is al die ander eksterne faktore, soos hoogte ens., konstant gehou waar moontlik. Anatomiese hout eienskappe soos vesel lengte en deursnee, sel deursnee, selwand dikte, ring wydte en E/L verhouding was bepaal asook die verandering met kambium ouderdom en water beskikbaarheid. Vesel lengte , vesel deursnee en selwand dikte het toegeneem met toename in kambium ouderdom, en ring wydte en E/L verhouding het afgeneem met toename in kambium ouderdom. Toename in water beskikbaarheid het gelei to afname in vesel lengte en selwand dikte, waar vesel deursnee, sel deursnee, E/L verhouding en ring wydte toegeneem het. Meeste van die vesel eienskappe het betekenisvol gekorrelleer met ring wydte en E/L verhouding wanneer ouderdom nie as ko-variant gebruik is nie.

Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: For wood manufacturers around the world, the single biggest cost factor is known to be its raw material. Thus maximum utilisation, specifically volume recovery of this raw material, is of key importance for the industry. The wood products industry consists of several interrelated manufacturing steps for converting trees into logs and logs into finished lumber. At most primary and secondary wood processors the different manufacturing steps are optimised in isolation or based on operator experience. This can lead to suboptimal decisions and a substantial waste of raw material. The objective of this study was to determine the optimal machine settings for two interrelated operations, namely the sawing and ripping operations which have traditionally been optimised individually. A model, having two decision variables, was developed which aims to satisfy market demand at a minimal cost. The first decision was how to saw the log supply into different thicknesses by choosing specific sawing patterns. The second was to decide on a rip saw’s settings, namely part priority values, which determines how the products from the primary sawing operation are ripped into products of a certain thickness and width. The techniques used to determine the machine settings included static simulation with the SIMSAW software to represent the sawing operation and mixed integer programming to model the ripping operation. A metaheuristic, namely the Population Based Incremental Learning algorithm, was the link between the two operations and determined the optimal settings for the combined process. The model’s objective function was formulated to minimise the cost of production. This cost included the raw material waste cost and the over or under production cost. The over production cost was estimated to include the stock keeping costs. The under production cost was estimated as the buy-in cost of purchasing the under supplied products from another wood supplier. The model performed well against current decision software available in South Africa, namely the Sawmill Production Planning System package, which combines simulation (SIMSAW) and mixed integer programming techniques to maximise profit. The model added further value in modelling and determining the ripping priority settings in addition to the primary sawing patterns. / AFRIKAANSE OPSOMMING: Die grootste enkele koste vir houtprodukvervaardigers wêreldwyd is dié van hulle roumateriaal. Die maksimale gebruik van rou materiaal, of volume herwinning, is dus van primêre belang vir hierdie industrie. Die vervaardigingsproses in die houtprodukte-industrie bestaan uit ‘n verskeidenheid interafhanklike stappe om bome na stompe te verwerk en stompe na eindprodukte. By meeste primêre -en sekondêre houtvervaardigers word die verskillende vervaardigingsstappe in isolasie ge-optimeer. Hierdie praktyk lei tot sub-optimale besluite en ‘n vermorsing van roumateriale. Die doelwit van hierdie studie was om die optimale masjienverstellings vir twee interafhanklike prosesse, die primêre -en kloofsaag prosesse, te bepaal. Tradisioneel word hierdie twee prosesse individueel optimeer. ‘n Model met twee besluitnemingsveranderlikes is ontwikkel wat poog om die markaanvraag te bevredig teen ‘n minimum koste. Die eerste besluit was watter saagpatroon gekies moet word om die stompe in die regte dikte produkte te saag. Die tweede besluit was wat die kloofsaagstellings, ook bekend as prioriteitswaardes, moet wees sodat die regte wydte produkte gesaag word. Die tegnieke wat gebruik is sluit statiese simulasie met SIMSAW sagteware in om die primêre saagproses te modelleer en gemengde heelgetalprogammering (“mixed integer programming”) om die kloofsaagproses te modelleer. ‘n Metaheuristiek genaamd die “Population Based Incremental Learning” algoritme,was die skakel tussen die twee operasies om die optimale masjienstellings vir die proses te bepaal. Die model se doelfunksie was geformuleer om die koste van produksie te minimeer. Hierdie koste sluit die roumateriaal afvalkoste en die kostes van oor -en onderproduksie in. Die oorproduksiekoste was ‘n skatting van die voorraadkostes. Die onderproduksiekoste was ‘n skatting van die koste om voorraad van ‘n ander verskaffer aan te koop. Die model het goed opgeweeg teen die beskikbare besluitnemingssagteware in Suid Afrika, die “Sawmill Production Planning System”, wat ‘n kombinasie van SIMSAW en ‘n gemengde heelgetalprogrammeringstegniek is. Die model het verder waarde toegevoeg deur die kloofsaag se prioriteitswaardes te modelleer saam met die primêre saagpatrone.

Thesis (PhD) -- Stellenbosch University, 1990. / ENGLISH ABSTRACT:Bushpig sociology, energetics, reproduction and population dynamics were studied over an 8-year period in the Cape Province, South Africa. The social organization was found to be strikingly different from that known from other suid species. The basic social unit is a unimaternal family group, occupying a resource-based territority, with a monogamous mating system. This form of social organisation is related to the dispersed nature of food resources, to which it provides exclusive access. It is reminiscent of canid social systems. Agonistic behaviour, communication and maternal behaviour were studied as the opportunity arose. The average home range size was 7,2 kmª, ranging from 3,8 to 10.1 kmª. Home ranges were often traversed within 1-4 days, as part of territory patrolling. The average diel ranging distance was 3 km. Bushpig were active during both night and day and exhibited a basic bimodal rhythm. The main phase of intensive foraging occurred from before dusk to midnight, with a secondary activity peak after dawn. Activity schedules were geared to avoid extreme ambient temperatures. Temperature regulation and water use were investigated, with particular reference to thermoregulatory behaviour (nest building). pelage characteristics, body core temperature dynamics, thermoneutral zones and resting metabolic rates. The thermoneutral zone for 10 kg bushpig juveniles was estimated to lie between 13° and 30°C and that for adults between 8° and 25°C. Foraging behaviour, diet and its nutritient content were investigated. Regional differences in the nutritional quality of bushpig diets in the Eastern and Southern Cape were associated with the predominance of nutrient-rich and nutrient-poor substrates respectively. These in turn were reflected by divergent life history features in the populations from the two regions. Patterns of growth and energy storage were described and the value of various parameters (e.g. mass to size ratio, fat depositions, blood composition) to evaluate condition was investigated. In studying reproductive biology, sexual maturation, female reproductive cycles, prenatal litter statistics, foetal development, 1actation, breeding seasonality and reproductive turnover were the main aspects addressed. The role of food quality, body condition and social status in determining reproductive success was discussed. Bushpig population density estimates in the Southern Cape ranged between 0,3 and 0,5 animals/kmª• The dynamics of Southern and Eastern Cape populations were found to differ. The differences are consistent with the hypothesis that social organisation is determined by the distribution and availability of food while diet quality shapes life history tactics. A life history model was developed which links edaphoclimatic environmental conditions with diet quality, metabolic turnover rate and, ultimately, life history features. In the concluding chapter some of the managerial implications of the research findings are discussed. / AFRIKAANSE OPSOMMING:Die sosiologie, fasette van die energiebalans (temperatuurregulasie, voeding). voortplanting en bevolkingsdinamika van bosvarke is in die Kaapprovinsie (Suid-Afrika) oor 'n tydperk van 8 jaar bestudeer. Dit kon bewys word dat die sosiale organisasie van die bosvark van die van ander varksoorte verskil. Die basiese sosiale eenheid bestaan uit 'n familiegroep wat slegs 'n enkele telende moederdier bevat. Ruimtelike organisasie is gebaseer op 'n stelstel van voedingsterritoriums. 'n Monogamiese paringstelsel kom voor. Die yl verspreiding van voedsel word as die onderliggende rede vir die sosiale organisasie beskou. Gedragspatrone (kommunikasie, aggressie, grootmaak van kleintjies) is bestudeer soos die geleentheid voorgekom het. Heelwat ooreenkomste is gevind tussen die sosiale organisasie van die bosvark en lede van die hondefamilie. Die gemiddelde woongebiedgrootte is 7,2 kmª (tussen 3,8 en 10,1 kmª). Woongebiede word gewoonlik binne 1-4 dae deurkruis en dus soos territoria gepatroleer. Die gemiddelde daaglike bewegingsafstand was 3 km. Bosvarke was beide gedurende die nag en die dag aktief en het 'n bimodale aktiwiteitsritme gevolg. Die hoofaktiwiteitsfase van intensiewe voeding het tussen sononder en middernag plaasgevind, met 'n sekondere fase na sonop. Soedoende is temperatuuruiterstes vermy. Temperatuurregulasie en watergebruikpatrone is bestudeer, insluitend temperatuurreguleringsgedrag, haarkleedeienskappe, liggaamskerntemperature, termoneutraliteit en metabolise omset. Voedingsgedrag, voedsel en die voedingswaarde daarvan is ondersoek. Verskille tussen die Oos- en Suid-Kaap in die kwaliteit van voedsel hang saam met die laer vlak van voedingsstowwe in die gronde van die Suid-Kaap. Bosvarkbevolkings in die twee streke toon verskille in populasiedinamika wat hieraan toegeskryf kan word. Groei- en energiestoorpatrone is beskryf. Die moontlikhede is ondersoek om kondisie te evalueer met behulp van parameters soos massa tot grootte-verhoudings, vetneerleggings en bloedwaardes. Aspekte van voortplantingsbiologie, soos geslagsrypheid, vroulike voortplantingssiklusse, voorgeboortelike werpselgroottes, foetale ontwikkeling, laktasie, seisoenaliteit en voortplantingsomset is behandel. Die rol van voedselkwaliteit, kondisie en sosiale status by die bepaling van voortplantingsukses word bespreek. Skattings van die bevolkingsdigtheid van bosvarke in die Suid-Kaap het gewissel tussen 0,3 en 0,5 diere per kmª• Op grond van die verskille in bevolkingsdinamika tussen bosvarke in die Suid- en Oos-Kaap is 'n model ontwikkel om die verband tussen bevolkingsregulering en lewensstrategieeë (life history tactics) te verklaar. Hiervolgens het voedselbeskikbaarheid die tipe sosiale organisasie bepaal terwyl die lewensstrategieë van bevolkings die gevolg is van voedselkwaliteit. Die model stel vaar 'n verband tussen groeipleksomstandighede, voedselkwaliteit, metaboliese omset en bevolkingsdinamika. In die laaste hoofstuk word sommige van die bestuursimplikasies van die navorsingsbevindinge bespreek.

Thesis (MScBosb)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The characteristics and total fuel load of the forest floor (FF) and harvest residue (HR) are needed to develop tools that can be used for fuel load management, fire risk analysis and fire behaviour prediction for P. patula grown in the summer rainfall area of South Africa (SA). Forest floor depth, mass and ash-free mass were measured and there was generally a greater range in depth under sawtimber (ST) stands than under pulpwood (PLP) stands. Forest floor loads, prior to ashing, ranged from 21 - 168 t ha-1 and 27 - 72 t ha-1, for ST and PLP stands, respectively and loads increased linearly with stand age. Sawtimber and PLP stands were analysed together, which resulted in a significant correlation between depth and mass (r2 = 0.78, n = 31). A loss on ignition procedure carried out on sub-samples of the FF improved the relationship between the FF depth and the ash-free mass for the different stands, and provided a more accurate model for the prediction of mass from depth. A multiple regression analysis revealed that age, altitude and mean annual precipitation (MAP) provided the best subset and accounted for 72% of the variation in the FF mass observed. The effect of increasing FF load and increasing moisture content on the fireline intensity (FLI) was examined using the fire behaviour prediction programme, BehavePlus. Harvest residue was quantified and characterised in terms of fuel size classes, under current silvicultural regimes for ST and PLP, for the development of fuel models for this species over its planted range in SA. An investigation into the proportion (by mass) of the 1- (0.0 - 0.6 cm), 10- (0.6 – 2.5 cm), 100- (2.5 – 7.6 cm) and 1000-hr (> 7.6 cm diameter) fuel classes of the total HR mass indicated that there was a significant difference between the mass of the 1-, 10- and 1000-hr fuel classes of the two silvicultural regimes, and no significant difference for the 100-hr fuel class. Two fuel models for P. patula HR and two models for standing timber were developed using the new model (NEWMDL) programme of BEHAVE and tested in BehavePlus. Nutrient concentrations were used with FF layer and HR size class load data to estimate the quantities of nutrients held in the fuel and to describe nutrient distributions in the fuel complex. Significant differences in the nutrient concentration of the FF layers and fuel components were observed which has important implications for fuel management. The concentration of N determined in this study, relative to that determined in other similar studies on P. patula was low. Forest floor loads were predicted and nutrient pools calculated for typical ST and PLP stands at both low and high altitude to provide insight into the nutrient distributions within the fuel complex. / AFRIKAANSE OPSOMMING: Die karaktereienskappe en totale brandstoflading van die bosvloer (FF) en kaalkap oorskot (HR) word benodig om instrumente te ontwikkel wat gebruik kan word vir brandstoflading bestuur, brandgevaar ontleding en brandgedrag voorspelling vir P. patula, wat in die somer reënvalgebied van Suid-Afrika groei. Die bosvloer diepte, massa en asvrye massa is gemeet en daar was oor die algemeen ‘n groter variasie in diepte onder saaghout (ST) opstande as onder pulphout (PLP) opstande. Die bosvloerladings, voor verassing, het varieer van 21 – 168 t ha-1 en 27 – 72 t ha-1 vir ST en PLP opstande respektiwelik. Ladings het linieêr vermeerder met opstand ouderdom. Saaghout en PLP opstande is saam geanaliseer en het tot ‘n betekenisvolle korrelasie gelei tussen diepte en massa (r2 = 0.78, n = 31). ‘n Verliestydens- ontbranding prosedure is uitgevoer op die FF monsters en het die verhouding tussen FF diepte en die asvrye massa van die verskillende opstande verbeter. Dit het ook gelei tot akkurater model vir die voorspelling van massa vanaf diepte. ‘n Veelvoudige regressie analise het aan die lig gebring dat ouderdom, hoogte en gemiddelde jaarlikse reënval (MAP) die beste sub-groep verskaf, en het 72% van die variasie in die FF massa verklaar. Ondersoek is ingestel op die effek van toenemende FF lading en toenemende voginhoud op die brandlyn intensiteit (FLI) deur die brandgedrag program, BehavePlus, toe te pas. Die kaalkap oorskot is gekwantifiseer en gekarakteriseer volgens brandstof grootteklasse, onder die huidige boskultuurstelsels vir ST en PLP, vir die ontwikkeling van brandstofmodelle vir hierdie spesie oor die betrokke groeistreek in SA. ‘n Ondersoek in die verhouding (volgens massa) van die 1- (0.0 – 0.6 cm), 10- (0.6 – 2.5 cm), 100- (2.5 – 7.6 cm) en 1000-uur (> 7.6 cm deursnee) brandstofklasse van die totale HR massa het aangedui dat daar ‘n betekenisvolle verskil is tussen die massas van die 1-, 10- en 1000-uur brandstofklasse van die twee boskultuurstelsels, en geen betekenisvolle verskil vir die 100- uur brandstofklas nie. Twee brandstofmodelle is ontwikkel vir P. patula HR en twee modelle vir staande hout deur gebruik te maak van die nuwe model (NEWMDL) program van BEHAVE en getoets in BehavePlus. Voedingstof konsentrasies is gebruik, tesame met die FF laag en HR klasgrootte ladingdata, om die voedingstof inhoud van die brandstof te skat en om die voedingstof verspreiding te beskryf in die brandstofkompleks. Betekenisvolle verskille is waargeneem in die voedingstof konsentrasies van die FF lae en brandstof komponente wat belangrike implikasies inhou vir brandstofbestuur. Die konsentrasie wat vir N in hierdie studie bepaal is, was laag relatief tot ander soortgelyke studies vir P. patula. Die bosvloer ladings is voorspel en voedingstofpoele bereken vir tipiese ST en PLP opstande vir beide lae en hoë hoogtes om insig te verkry, sodat insig verkry kon word in die voedingstof verspreidings binne die brandstofkompleks.

Thesis (MPhil)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: A thesis undertaken to quantify genotype-by-environment interaction within Eucalyptus grandis clones growing in the eastern portion of South Africa. Thirty one sites were selected to represent the "traditional" E. grandis growing areas of South Africa. Eleven common macro- site variables and twelve common micro- site soil variables were recorded at each site. Twenty seven E. grandis clones and four E. grandis hybrid clones were then evaluated over these 31 sites. An incomplete latin square design was used to evaluate the 31 test clones, and five E. grandis controls were incorporated into the trial design to link the 31 sites. Volume production, stem form, stem defects and survival were assessed at two and five years, as well as the disease infestation of three stem cankers at five years. The analytical methods which were used to evaluate and quantify the GEl portion of the study are the analysis of variance (ANOV A), correlation analysis, and joint regression analysis (IRA) together with the analysis of co-variance (ACOV AR). The growth-site association for volume production, stem form and Endothia disease infestation were investigated using factor analysis (FA), and equations derived for the species and for the individual clones using a stepwise multiple regression approach. GEl, as evaluated through JRA, revealed that an increase in site productivity lead to a positive linear response in productivity on a clonal level, and that there was a diverging or fanning pattern among the regression lines of the clones. This tendency was also observed for both the stem form and the Endothia infestation. Hence, no significant changes in the rankings of the clones were found, and only relevant differences between the clones were found to change significantly. Juvenile-mature genetic correlations for volume production and the stem form showed moderate (rg = 0,66 and rg = 0,70) correlations between the two and the five year assessments. On a species level, rainfall was the main environmental factor responsible for volume production, while latitude was the main influence on stem form and Endothia infestation. On an individual clone basis, some micro-site soil factor interaction within the clones was found for the growth-site response models. Keywords: Eucalyptus grandis, genotype environment interaction, clones, site factors, growth-site response, ANOV A, ACOV AR, GEl, FA, JRA, / AFRIKAANSE OPSOMMING: 'n Studie is ondemeem om die genotipe-omgewingsinteraksie van Eucalyptus grandis klone, wat in die oostelike deel van Suid-Afrika groei, te kwantifiseer. Eenen- dertig groeiplekke is geselekteer om die "tradisionele" E. grandis groeiplekke in Suid-Afrika te verteenwoordig. Elf gemeenskaplike makro-groeiplek veranderlikes en twaalf gemeenskaplike mikro-groeiplek veranderlikes is by elk van die groei areas opgeteken. Sewe-en-twintig E. grandis klone en vier E. grandis basterklone is daama oor hierdie 31 groeiplekke geevalueer. 'n Onvolledige Latynse roosterontwerp is gebruik om die 31 toetsklone te evalueer en vyf kontroles is gebruik om die groeiplekke gemeenskaplik te verbind. Volume produksie, stamvorm, stamdefekte en oorlewing is op twee- en vyfjarige ouderdomme geevalueer terwyl besmetting met drie stamkankers op vyf jaar beoordeel is. Die analitiese metodes wat gebruik was om genotipeomgewingsinteraksie te evalueer en te kwantifiseer is die variansie analise (ANOYA), korrelasie analise, en gesamentlike regressie analise (JRA) tesame met ko-variansie analise (ACOY AR). Die groeiplek assosiasie vir volume produksie, stamvorm en Endothia besmetting is ondersoek deur gebruik te maak van faktor analise (FA), en vergelykings is verkry vir die spesies en individuele klone deur gebruik van 'n stapsgewyse meervoudige regressie benadering. Genotipe-omgewingsinteraksie, soos geevalueer deur JRA, wys dat 'n toename in groeiplek produktiwiteit lei tot 'n positiewe lineere reaksie in produktiwiteit op klonale vlak en dat daar 'n divergerende patroon tussen die regressielyne van die klone is. Hierdie tendens is ook vir beide die stamvorm en Endothia besmetting waargeneem. Gevolglik is nie-beduidende veranderings in die rangorde van die klone gevind en slegs reletiewe verskille tussen klone is gevind. Onvolwasse-volwasse genetiese korrelasies vir volume produksie en stamvorm toon matige korrelasies (rg =0.66 en rg =0.70) tussen die twee- en vyfjaar metings. Op 'n spesiesvlak was reenval die oorheersende omgewingsfaktor verantwoordelik vir volume produksie terwyl die breedtegraad ligging stamvorm en Endothia besmetting bemvloed het. Op individuele kloonvlak het sommige mikro-groeiplek interaksie binne klone bygedra tot die groei en groeiplek reaksie modelle. Sleutelwoorde: Eucalyptus grandis, Genotipe-omgewingsinteraksie, klone, groeiplek faktore, groeiplek reaksie, ANOY A, ACOY AR, FA, JRA

Thesis (MScFor)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: This study investigates how information on plant products can be used to incorporate local users into joint forest management planning by developing guidelines for sustainable collaborative management in Derre miombo woodland in the Zambézia Province in Mozambique. From the participatory appraisal, it was found that 46 woody miombo species were used in the five villages for at least 29 different purposes. Five of these species (Brachystegia boehmii, B. spiciformis, Pterocarpus angolensis, Terminalia sericea and Swartzia madagascariensis) were selected for analysis because of their multiple uses and the unknown impact of their harvesting on the future survival of those hardwood trees species. In order to determine the impact of human resource extraction on the forest and on the dynamics of tree canopy populations an inventory of woody plants was.carried out for two categories of forest land-use, namely selective harvesting and fallow land (approximately 15 years old). This was done for Golombe and Arame villages and for selective harvesting only for Mphoto village, on 23, I-ha random selected plots in the woodland adjacent to the three villages. The population structure of the five species T sericea, S. madagascariensis, P. angolensis, B. boehmii and B. spiciformis showed different trends in each of the three villages. Size class distribution of the first tree species gave evidence that the species were being harvested for building poles. This study has shown that, through plant species products, miombo contribute to the livelihoods of the local communities living in Derre woodlands. In this study it was found that usually more than one species were used for one product as well as most of the species being trees with multiple uses. This study has also provided some evidence that P. angolensis and S. madagascariensis can benefit from shifting cultivation and fire, which encourages coppice regeneration. More research is required to further validate this evidence. / AFRIKAANSE OPSOMMING: Hierdie studie ondersoek die moontlikhede wat inligting oor spesifieke plantprodukte bied, in die betrekking van plaaslike gemeenskappe in die proses van gesamentlike bosbestuurs- en beplanningspraktyke. Verder word riglyne opgestel aangaande die volhoubaarheid van die gesamentlike bestuurs- en beplanningspraktyke in die Derre miombo bosveld, in die Zambézia Provinsie in Mozambique. Inligting verkry vanuit die deelnemende opname dui aan dat in die vyf nedersettings wat ondersoek is, 46 houtagtige miombo spesies vir ten minste 29 verskillende doeleindes aangewend word. Vyf van die spesies (Brachystegia boehmii, B. spiciformis, Pterocarpus angolensis, Terminalia sericea en Swartzia madagascariensis) is geselekteer vir gebruik in analises as gevolg van hul benutbaarheid deur plaaslike inwoners en die feit dat minimale inligting beskikbaar is oor die impak van gebruik van die harde hout spesies op hul volhoubare benutting en voortbestaan. 'n Opname van houtagtige spesies is uitgevoer in areas wat val in een van twee bosgrondgebruiks kategoriee nl. areas wat selektief geoes en benut word, en braaklande (ongeveer 15 jaar oud). Dit is gedoen om die impak wat verwydering van boshulpbronne deur mense op die boomkruin populasies het, vas te stel. Die opname strategie is gevolg in 23 ha persele, uitgelê in die gebiede wat die Golombe, Arame en Mphoto nedersettings omring - in die geval van laasgenoemde nedersetting is slegs die impak van selektiewe benutting ondersoek. Die populasie struktuur van die vyf studiespesies (T sericea, S. madagascariensis, P. angolensis, B. boehmii en B. spiciformis) het verkil vir elk van die drie nedersettings wat ondersoek is. Die verspreiding van grootte klasse vir die eerste spesie, het aangedui dat die spesie vir gebruik as konstruksie pale geoes word. Die miombo bosveld plantegroei-tipe dra by tot die lewensonderhoud van plaaslike gemeenskappe in die vorm van plant produkte, in die Derre omgewing. Daar is verder gevind dat meer as een spesie dikwels vir dieselfde doel aangewend kan word en die meeste van die spesies wat benut word is boomagtig met meer as een gebruik. In die studie is verder aanduidings gevind dat P. angolensis en S. madagascariensis kan baatvind by grondverbouings praktyke wat gereeld verskuif word en ook brande, omdat beide praktyke kreupelhout regenerasie stimuleer. Verdere navorsing word egter benodig om dié bevinding te ondersteun.

Thesis (MScFor )--Stellenbosch University, 2003. / ENGLISH ABSTRACT: Species-rich Renosterveld vegetation does not return to old agricultural fields even after many years (10-20) of abandonment. In most cases the fields are slowly taken over by non-indigenous species, particularly alien pasture grasses and African lawn grass. While poor survival of indigenous seedlings due to competition, grazing or any other establishment constraints, might explain the failure of natural vegetation to colonise old fields, here I am testing the hypothesis that recolonisation by indigenous plant species is limited by seed dispersal. I have quantified changes in seed density with distance from the natural vegetation into old fields using seed traps and soil seed bank assessment. I have also looked at seed dispersal in the dung of large herbivores. Shrubs (with the exception of Eytropappus rhinocerotis) were poorly represented in the seed rain indicating that they might be seed limited. Dicerothamnus rinocerotis (a dominant shrub in Renosterveld) and certain geophytes (that were recovered in the soil bank) have proven that seed dispersal is not the primary constraint to their return to ploughed fields. Dicerothamnus rinocerotis produces a large number of seeds that are dispersed long distances into the old field and a number of geophytes were well represented in the soil bank. Large herbivores are dispersing a lot of herbaceous forbs in their dung but make very little contribution to the dispersal of indigenous tussock grass and shrubs. Seeds of indigenous Renosterveld tussock grasses (e.g Tribolium hispidum) were restricted to the edge of the natural vegetation. My research has shown that some indigenous seeds, particularly those dispersed in wind and through large mammals, do reach the old ploughed field. I therefore conclude that seed dispersal is not the primary constraint to the natural recovery of populations of some indigenous plant species on old fields, but may limit recovery of certain indigenous geophytes, grasses and shrubs. / AFRIKAANSE OPSOMMING: Spesie-ryke Renosterveld plantegroei hervestig nie op ou landerye nie, selfs ná baie jare (l0-20) van verlating. Oor die algemeen word hierdie grond stadig oorgeneem deur uitheemse spesies, veral uitheemse weidingsgrasse en kweekgras. Terwyl swak oorlewing van inheemse saailinge as gevolg van kompetisie, weiding of enige ander vestigingsbeperkinge, die mislukte vestiging van natuurlike plantegroei op ou benutte grond kan verduidelik, toets ek hier die hipotese dat hervestiging deur inheemse plantspesies deur saadverspreiding beperk word. Ek het veranderinge in saaddigtheid oor afstand vanaf die natuurlike plantegroei na ou landerye gekwantifiseer, deur gebruik te maak van saadopvangsvalle en sand saadbank beraminge. Ek het ook gekyk na saadverspreiding in die mis van groot herbivore. Struike (behalwe Eytropappus rhinocerotis) was swak verteenwoordig in die "saadreën", wat mag toon dat struike saadbeperk is. Eytropappus rhinocerotis ('n dominante struik in Renosterveld) en sekere geofiete (wat in die saadbank gevind is) het bewys dat saadverspreiding nie die hoofbeperking is vir hulle terugkeer na geploegde lande nie. Eytropappus rhinocerotis produseer 'n groot hoeveelheid saad wat oor groot afstande oor die ou landerye versprei word en 'n aantal geofiete was goed verteenwoordig in die saadbank. Groot herbivore versprei 'n groot hoeveelheid kruidagtige forbe in hulle mis, maar maak 'n baie klein bydrae tot die verspreiding van inheemse polgras en struike. Saad van inheemse Renosterveld polgrasse (bv. Tribolium hispidum) was beperk tot die some van die natuurlike plantegroei. My navorsing het getoon dat sommige inheemse saad, veral dié wat deur die wind en deur groot herbivore versprei word, wel die ou geploegde landerye bereik. Ek maak dus die gevolgtrekking dat saadverspreiding nie die hoofbeperking is vir die natuurlike herstel van populasies van sommige inheemse plantspesies op ou landerye nie, maar mag die herstel van sekere inheemse geofiete, grasse en struike beperk.

Thesis (MScFor)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Kiaat trees in Namibia are threatened by unsustainable harvesting practice. This study’s aim was to estimate the total value of an average Kiaat tree selected for harvesting with a focus on current timber use value, value of an optimally utilised tree, carbon value, and alternative uses of Kiaat trees. To accomplish this aim, the following specific objectives were set: (1) to estimate the total tree volume and optimum utilisable timber volume of an average Kiaat tree; (2) to estimate the amount and value of carbon stored in the above-ground parts of an average Kiaat tree; (3) to determine timber utilisation levels; and (4) to identify alternative use options to reduce timber losses of Kiaat trees. Previous studies on Kiaat in Namibia and elsewhere focused on growth, development and socio-economical aspects of Kiaat trees. A combination of a socio-economic survey and tree volumes and biomass determination was used to collect data. The survey entailed Kiaat products assessment and face-to-face personal interviews with known key-informants in and around Rundu. Loggers with permits to harvest Kiaat trees were asked to harvest 40 Kiaat trees and data collected from each tree before and after felling included: lower-stem diameter, diameter at breast height (DBH), upper-stem diameter, stem length, stump height, recovered merchantable logs lengths and lower-and-upper diameters and lengths of branches greater than 10 cm in diameter. All canopy parts smaller than 10 cm in diameter were directly weighed, sampled and oven-dried at 105°C until constant weight. Volume of different tree parts was calculated and in combination with basic wood density used to calculate the biomass. It was established that a typically harvested Kiaat tree had an above-ground dry volume of 1.63 m3, of which 1.34 m3 (82%) was utilisable timber volume but that only 0.37 m3 (23%) was used and 0.97 m3 (59%) was left behind in the field. Merchantable logs were mainly cut into planks from which finished products - beds, chairs, doors and tables - were made. An average of 10.7 planks were cut per trunk and the local price of planks was N$45.26 at the time of the study. More income is generated from finished products compared to selling loose planks. Canopy parts were mainly cut into woodcrafts – bowls, music drums, and walking sticks. Current timber use value (N$484.73) surpasses carbon value (N$123.74). A further result of the study was that a significantly higher income could be earned for local livelihoods from Kiaat trees in the Kavango Region if trees were optimally used. Carbon trading is a noble conservation initiative, particularly when trees unsuitable for timber are considered. Use of timber trees exclusively for carbon trading is, however, not a viable option in respect of supporting local people’s livelihoods. / AFRIKAANSE OPSOMMING: Kiaatbome in Namibië word bedreig deur onvolhoubare ontginningspraktyke. Die doelwit van die studie was om die totale waarde van ‘n gemiddelde Kiaatboom, wat gekies is vir ontginning, te bepaal met die fokus op huidige houtwaarde, waarde van ‘n optimaal gebruikte boom, koolstofwaarde en alternatiewe gebruike vir Kiaatbome. Om hierdie doelwit te bereik is die volgende spesifieke sub-doelwitte gestel: (1) bepaal die totale boomvolume en optimale bruikbare houtvolume van ‘n gemiddelde Kiaatboom; (2) bepaal die hoeveelheid koolstof wat in die bogrondse dele van ‘n gemiddelde Kiaatboom gestoor word en bereken die monitêrewaarde daarvan; (3) bepaal die houtgebruiksvlakke en houtvermorsing van Kiaatbome; en (4) identifiseer alternatiewe gebruike om die vermorsing van Kiaatbome te verminder. Vorige studies oor Kiaat in Namibië en elders het gefokus op groei, ontwikkeling en sosio-ekonomiese aspekte van Kiaatbome. ‘n Kombinasie van ‘n sosio-ekonomiese opname en boomvolume en biomassa bepalings is gebruik vir die insameling van data. Die opname het ‘n Kiaat produkbepaling en gesig-tot-gesig persoonlike onderhoude met sleutel informante in en om Rundu behels. Boomkappers met permitte om kiaatbome te ontgin is gevra om 40 Kiaatbome te ontgin en data is versamel van elke boom voor en na ontginning. Die data het ingesluit: lae-stam deursnee, deursnee op borshoogte (DBH), bo-stam deursnee, stamlengte, stomphoogte, herwinde bruikbare stomplengte, bo- en onder- deursnee en lengtes van takke wat 10 cm of groter deursnee het. All kroondele 10 cm en kleiner in deursnee is geweeg en ‘n steekproef versamel wat oondroog gemaak is by 105ºC totdat konstante gewig bereik is. Die volume van verskillende boomdele is bereken en in kombinasie met houtdigtheid gebruik om biomassa te bereken. Dit is bereken dat ‘n tipiese geoeste Kiaatboom ‘n bogrondse droë volume van 1.63 m³ het, waarvan 1.34 m³ (82%) bruikbare houtvolume is. Net 0.37 m³ (23%) van die bruikbare houtvolume is egter gebruik en 0.97 m³ (59%) is agtergelaat in die veld. Bruikbare stompe is meestal opgesaag in planke waarvan finale produkte soos beddens, stoele, deure en tafels gemaak is. ‘n Gemiddeld van 10.7 planke is verkry per stomp en die plaaslike prys van planke was N$45.26 gedurende die studie tydperk. Meer inkomste is verkry van finale produkte as van die verkoop van los planke. Kroondele is meestal opgesaag in houtkunswerke soos bakke, musiekdromme en kieries. Die huidige houtwaarde van N$484.73 is meer as die koolstof waarde (N$123.74) van die bome. ‘n Belangrike resultaat van die studie is dat ‘n beduidende groter inkomste gegenereer kan word vir plaaslike lewensbestaan van Kiaatbome in die Kavangostreek as bome optimaal benut word. Koolstofhandel is ‘n edele bewaringskonsep, veral as bome ongeskik vir houtgebruik is soos in die geval van krom bome en jonger bome. Die eksklusiewe gebruik van houtbome vir koolstofhandel is nie ‘n lewensvatbare opsie om plaaslike mense se lewensbestaan te ondersteun nie.