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Eucalyptus grandis was introduced into South Africa in the 19th century, and has since become the most important of the hardwood plantation tree species grown for pulp. Until the late 1980's E. grandis was virtually the only eucalypt species grown. In order to meet the increasing demand for pulpwood in South Africa, forestry companies need to increase their timber output from an existing land base (Brown and Hillis, 1984; Kimmins, 1994 and Little and Gardner, 2003), or alternatively extend the planting of favourable alternative tree species into areas previously considered unsuitable for forestry due to unfavourable climatic conditions. From 1984 the major timber companies expanded their plantation forestry into the colder, frost-prone highland areas of western KwaZulu-Natal, the northeastern Cape and southeastern Mpumalanga Highveld. As E. grandis was not tolerant to severe frost, E. macarthurii amd E. nitens were planted in these areas as alternatives (Schonau and Gardner, 1991). As much of the earlier research had been centered around the development of silvicultural standards for E. grandis, it became necessary to test these for the different eucalypt species. Two trials were therefore established to E. marcarthurii and E. nitens with the following objectives: - to extend current recommendations to include different species, - to determine the degree of interaction between different silvicultural standards (genetic improvement, fertilisation and weed control), - to determine the effects of weeds, fertilisation, genotype and regeneration method (seedling vs coppicing) on the initial and long term growth, uniformity, tree straightness and survival of cold tolerant eucalypts, - cost effectiveness of various methods for re-establishing E. nitens and E. macarthurii. Genetic improvement played an important role in the establishment and initial growth of E. macarthurii and E. nitens. The improved treatments outperformed the unimproved treatments in terms of tree growth until canopy closure. At the last measured date when the trees were six years of age, the E. nitens improved seedlings were still significantly better in terms of basal area when compared to unimproved seedlings. The initial positive effect of genetic improvement of E. macarthurii seedling however, was not sustained. Genetic improvement of E. macarthurii and E. nitens also had a positive effect on tree straightness and survival when the trees were assessed at five years of age. The genetic improvement of both species also showed to be a viable option to produce an optimum timber output at a lower cost when regeneration is carried out by means of replanting with seedlings. Fertilisation also showed positive effects in terms of the establishment and initial growth of E. macarthurii and E. nitens. At six years after planting, the basal area of E. macarthurii seedlings without fertiliser was still significantly lower than any one of the other treatments. However, the initial positive effect fertiliser had on the growth of E. nitens seedlings decreased to a non-significant level at six years after planting. Fertilisation of E. macarthurii and E. nitens had a positive effect on tree straightness and survival when the trees were assessed at five years of age. The fertilisation of E. macarthurii seedlings also produced an adequate amount of timber at a relatively low cost. The controlling of weeds did not have an impact on tree performance initially or after canopy closure for either E. macarthurii or E. nitens. This is due to the lack of weed growth at these high altitudes at which the sites were planted. Little and Schumann (1996) found that eucalypts could tolerate an aboveground weed biomass of up to 2000 kg ha (-1) before there were any severe losses in growth due to competition. At both these trials, the weed load did not reach these levels in order to compete with the trees. No significant interactions between any of the treatments were detected at both these sites at any stage. At the last measured date, there were no significant differences in terms of tree growth between the coppice and seedling treatments for either E. macarthurii or E. nitens. Regeneration by means of E. macarthurii and E. nitens coppice had a positive effect on tree straightness and survival when the trees were assessed at five years of age. Re-establishment by means of coppice for both E. macarthurii and E. nitens was also shown to be by far the most cost-effective way at present to produce an adequate amount of timber. Coppicing was shown to be the least costly way to produce a m2 ha(-1) of timber provided the right species are coppiced, and optimum density levels are obtained. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

In order to determine if weed control as practised during the establishment phase of tree growth had a beneficial and long term (over a six to eight year rotation) impact on tree performance, a Eucalyptus hybrid clone (GC304) was planted in a field trial in 1990. The trial was situated in the coastal Zululand region near the KwaZulu-Natal town of Mtunzini. Nine different vegetation management treatments were imposed from establishment. These included a weedy control, a manually weeded treatment, a chemically weeded treatment, a 1.2 m row and 1.2 m inter-row weeding, a 0.5 m radius ring weeding, a complete weeding except for a 0.5 m radius ring around the tree, and the use of two legume cover-crops, Mucuna puriens (cowpea) and Vigna sinensis (velvet bean). Initial improvements in tree performance from these competition control treatments were detected from 60 days after planting, and were maintained over seven growing seasons. This occurred despite the absence of competitive vegetation after the first growing season due to reduced light, following crown canopy closure. There were strong indications that initial competition was mainly for moisture and possibly also for nutrients, rather than competition for light. Initially those trees that had weeds within their immediate vicinity were most affected (weedy control, inter-row weeding and the complete weeding except for a 0.5 m radius around the tree). With time, tree performance was more closely related to an increase in the percentage of the area kept free of weeds. The best performing treatment at felling, the manually weeded control, produced 17.1 % and 38.5 % more merchantable timber than the 1.2 m row weeding and the weedy control, at an increased profit of 8 % and 27 %, respectively. Two forms of competition (interspecific and intraspecific competition) were evident in the weedy control at different stages of tree development in contrast to the one (intraspecific competition) in the manually weeded treatment. Interspecific competition resulted in greater variability between the trees in the weedy control by the time canopy closure had occurred. This differentiation in tree size was further enhanced by asymmetric intraspecific competition once the trees had become established. The onset of intraspecific competition was first detected 995 days after planting for the manually weeded treatment and 1641 days after planting for the weedy control. Of the various competition indices that were tested in order to try and explain this differential growth in terms of individual tree performance, none was able to do so to complete satisfaction. The growth rates of different tree size classes were therefore compared for the weedy control and manually weeded treatment. The diverging slopes of the different stem area classes indicated that the larger trees were growing at the expense of the smaller trees. This type of competition is known as asymmetric intraspecific competition. In addition, a comparison was made between the slopes for the weedy and weedfree treatments for similar stem area classes. No significant difference was detected, indicating that similar size classes in these two treatments grew at similar rates. Trees from three treatments were selected (manually weeded treatment, 1.2 m row weeding treatment and the weedy control) and tested for the wood and pulping properties of density, active alkali consumption, extractable content, screened pulp yield, pulp yield per hectare and fibre length and coarseness. The use of Canonical Variate Analysis to determine if there were differences between the three treatments for the variates measured, indicated that they were significantly different. There was a significantly positive trend of an increase in density, extractable content and active alkali consumption with increased weed control. A possible explanation for this could be that the larger trees of the manually weeded treatment were under more stress (from increased intraspecific competition) during the latter phase of their growth. This was demonstrated by comparing the growth rates for these three treatments. The smaller trees of the 1.2 m row weeding treatment and the weedy control exhibited a lower rate of decline. As no significant difference was detected for screened pulp yield between the treatments, any differences in the pulp yield per hectare values could be attributed to differences in the merchantable volume. There was a 22.6 % and 40.8 % increase in the pulp yield per hectare for the manually weeded treatment in comparison to the 1.2 m row weeding treatment and the weedy control. The planting of cover-crops, although beneficial in terms of weed suppression, caused significant tree suppression. This occurred despite the fact that their initial biomass accumulation was slower than that of the natural weed population. Of the two cover-crops, the use of the velvet bean was not considered suitable due to its vigorous vining habit which affected the growth form of the trees. Subsequent work suggests that if the beneficial qualities of cowpeas are to be realised (that of weed suppression, erosion control and nitrogen fixation), a delay in their planting by three months after establishment of the trees should alleviate any negative impacts on tree growth. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1999.

Made available in DSpace on 2014-06-11T19:24:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2004-08-25Bitstream added on 2014-06-13T19:52:19Z : No. of bitstreams: 1 calonego_fw_me_botfca.pdf: 1047073 bytes, checksum: 21280f1c5afee5c936363dd679a08263 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Universidade Estadual Paulista (UNESP) / The present study to have to do as aim to determine the log steaming time its involvement on the sawing process and on the drying of Eucalyptus grandis wood. In order to do it so, were used logs with diameter of 20 at <25, 25 at <30 and 30 at <35 cm, from the Horto Florestal, Manduri, São Paulo. The logs were heated during 20 hours at 90ºC of temperature and 100% of relative humidity. For the adaptation of the logs heating general model developed by Steinhagen to make use of thermocouples fixed it logs center and a datalogger recorded the time and real temperature at each minute. Later the logs were sawing for width tangential system and measuring of the defects resulted from the growth stress were performed with intention to evaluate the effect of steaming treatment and the growth stress behavior with logs diameters. The sawn wood was dry in the dry-kiln and were available the dry defects of the sawn wood deriving as much the control logs as the steamed logs. The results indicate that: the log steaming time determination general model developed by Steinhagen don't is applied for eucalypts and that are necessary the use of the adjustment factors that provided the used them model for studied kind; the logs steaming provided the release of a great part of the growth stress, without, however, eliminate them completely, showing, nevertheless, that this treatment to be feasible and advisable for the growth stress relief; there are among the boards a difference on the growth stress magnitude with the logs diameters showing that the bigger logs to produce boards to be inclined cracks and that logs with diameter smaller to develop biggest boards opening during the sawing process; across of the drying schedules used so much boards provided of the control logs as the heated logs don't to presented collapse e that the warping and end checks were smaller in the heated material; the boards provided... (Complete abstract click electronic access below)

Orientador: Elias Taylor Durgante Severo / Banca: Claudio Angeli Sansígolo / Banca: Geraldo Bortoletto Junior / Abstract: The present study to have to do as aim to determine the log steaming time its involvement on the sawing process and on the drying of Eucalyptus grandis wood. In order to do it so, were used logs with diameter of 20 at <25, 25 at <30 and 30 at <35 cm, from the Horto Florestal, Manduri, São Paulo. The logs were heated during 20 hours at 90ºC of temperature and 100% of relative humidity. For the adaptation of the logs heating general model developed by Steinhagen to make use of thermocouples fixed it logs center and a datalogger recorded the time and real temperature at each minute. Later the logs were sawing for width tangential system and measuring of the defects resulted from the growth stress were performed with intention to evaluate the effect of steaming treatment and the growth stress behavior with logs diameters. The sawn wood was dry in the dry-kiln and were available the dry defects of the sawn wood deriving as much the control logs as the steamed logs. The results indicate that: the log steaming time determination general model developed by Steinhagen don't is applied for eucalypts and that are necessary the use of the adjustment factors that provided the used them model for studied kind; the logs steaming provided the release of a great part of the growth stress, without, however, eliminate them completely, showing, nevertheless, that this treatment to be feasible and advisable for the growth stress relief; there are among the boards a difference on the growth stress magnitude with the logs diameters showing that the bigger logs to produce boards to be inclined cracks and that logs with diameter smaller to develop biggest boards opening during the sawing process; across of the drying schedules used so much boards provided of the control logs as the heated logs don't to presented collapse e that the warping and end checks were smaller in the heated material; the boards provided... (Complete abstract click electronic access below) / Mestre

The first objective of this study was to evaluate Eucalyptus urophylla S.T. Blake provenances in terms of their growth, basic wood density and pulp yield properties. The second objective was to determine the genetic and phenotypic associations that may exist between growth, basic wood density and pulp yield. Data of 9022 open-pollinated progenies representing 306 families, collected from 17 provenances, were used to evaluate growth. To evaluate basic wood density and pulp yield, as well as the genetic and phenotypic associations between the three traits, data of 300 open-pollinated progenies representing 30 selected families from 11 provenances were used. Narrow-sense heritabilities for all three traits were estimated from data collected in a single E. urophylla provenance/progeny trial planted in northern KwaZulu-Natal. The results showed that significant provenance effects for growth, basic wood density and pulp yield were observed. Heritability was found to be strong for basic wood density (h2 = 0.51) and moderate to weak for volume growth and pulp yield (h2 = 0.17 and h2 = 0.11, respectively). This suggests that big genetic gains can be achieved for basic wood density. Although the heritability estimates for volume growth and pulp yield were weaker, this still allows for tree breeders to make significant genetic gains through accurate selection from this E. urophylla breeding population. Genetic and phenotypic associations between the three traits were estimated from data collected in the same trial. The genetic correlation between volume growth and pulp yield was positive and moderately strong (rA = 0.66). The genetic correlation estimate between volume growth and basic wood density was found to be negative but weak (rA = -0.08). The genetic association between pulp yield and basic wood density was found to be positive but weak (rA = 0.17). Correlation estimates between volume growth and basic wood density, as well as between pulp yield and basic wood density produced standard errors greater than the correlation itself (s.e. = ± 0.32 and ± 0.22, respectively). These high standard errors, coupled with weak genetic correlations, suggest that these correlation estimates are non-significant, but are probably a result of utilizing a small sample size. However, these correlations have a value in making breeding choices, if treated with caution. Key words: Eucalyptus urophylla, provenance, growth, basic wood density, pulp yield, heritability, genetic correlation / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

Made available in DSpace on 2015-03-26T13:50:18Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1916552 bytes, checksum: c18d32a0eda19b2b7b6680811092f773 (MD5) Previous issue date: 2006-08-11 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The planted eucalyptus forests are the bigger and the most productive in Brazil. The high growth rate and the short cycle are intrinsic to this wood production system, making essential the development of management and operational practices that guarantee the economic feed-back and the sustainability of these crops. Attempt to estimate the productive potential of an area, by using growth models based on physiologic methods, permits the risk evaluation of climate changes and identification of new areas capable to grow forests. Climate changes scenarios associated to growth models based on processes can be useful to identify the risks of negative consequences on the future yield of planted forests, and consequently, reduce the impacts of climate changes and evaluate adaptation ways. Thereby, this study had the goal to evaluate climate changes on the forest production of eucalyptus through the growth model 3-PG in two productive areas: Area I - north Espirito Santo and south Bahia; and Area II &#150; mid-east Minas Gerais. Two climate change scenarios (A2 and B2) from the global climatic model CCSR/NIES, for three future periods (2011-2040, 2041-2070 e 2071- 2100) were used to feed the model 3-PG with climate data. To evaluate the simulated results of the future yield, was used as a base period the data bank climatology of the CRU, obtaining by that, the current yield. According to the anomalies generated, by the difference between the future scenarios values and the climatology, was observed the rising on the maximum and minimum temperature values on the two studied areas and the decrease of rainfall values in both areas. Has been proved in this study also that, the future variations on temperature and rainfall have caused a reduction on the eucalyptus yield in both analyzed areas, being the reduction on north Espirito Santo and south Bahia of 39,1% in 2071 &#150; 2100 on A2 scenario, and on mid-east Minas Gerais 36,9% in 2071-2100 also on A2 scenario. Through the results was concluded that the eucalyptus crops can suffer impacts on their yields due to climate changes, mainly referring to temperature and rainfall variations. / As florestas plantadas de eucalipto são as maiores e mais produtivas do Brasil, a alta taxa de crescimento e o ciclo curto são típicos destes sistemas de produção de madeira, portanto torna-se essencial que práticas operacionais e de manejo sejam desenvolvidas para garantir retorno econômico e assegurar a longo-prazo a sustentabilidade destas plantações. A tentativa de estimar o potencial produtivo de uma região, por meio de modelos de crescimento baseados em processos fisiológicos, permite a avaliação dos riscos da variação climática e a identificação de novas áreas aptas ao plantio florestal. Cenários de mudanças climáticas associados a modelos de crescimento baseados em processos, podem ser úteis para identificar os riscos de conseqüências negativas na produtividade futura de florestas plantadas, podendo assim, mitigar os impactos das mudanças climáticas e avaliar meios de adaptação. Desta forma, este trabalho teve como objetivo avaliar os impactos das mudanças climáticas na produção florestal de eucalipto, por meio do modelo de crescimento 3-PG, em duas regiões produtoras: Região I - norte do Espírito Santo e sul da Bahia; e Região II - centro-leste de Minas Gerais. Foram utilizados como dados de entrada de clima no modelo 3-PG, dois cenários de mudanças climáticas (A2 e B2) do modelo climático global CCSR/NIES, para três períodos futuros: 2011-2040, 2041-2070 e 2071-2100. Para avaliar os resultados simulados da produtividade futura, utilizou-se como período base a climatologia do banco de dados do CRU, obtendo assim, a produtividade &#147;atual&#148;. Conforme as anomalias geradas, pela diferença entre os valores dos cenários futuros e da climatologia, observou-se aumento nos valores de temperatura máxima e mínima nas duas regiões estudadas e decréscimo nos valores de precipitação em ambas as regiões. Comprovou-se neste estudo, que as variações futuras na temperatura e precipitação provocaram redução na produtividade de eucalipto nas duas regiões analisadas, sendo que na região do norte do Espírito Santo e sul da Bahia essa redução chegou a 39,7% em 2071-2100 no cenário A2, e no centro-leste de Minas Gerais a redução chegou a 41,7% em 2071-2100 também no cenário A2. Diante dos resultados, concluiu-se que as plantações de eucalipto podem sofrer impactos em sua produtividade, devido às mudanças climáticas, principalmente no que diz respeito às variações na temperatura e na precipitação.

Concerns have been raised over the long-term site productivity (LTSP) of short rotation plantation forests, such as those of Eucalyptus, in South Africa. This is because diminished productivity of long rotation plantations overseas has been found to be generally due to decreases in soil porosity and organic matter. Since soil porosity and organic matter in plantations are mainly affected by soil compaction by harvesting machinery and residue management, the more frequent harvesting of short rotation plantations are of particular concern. Therefore the effects of soil compaction and residue management on soil properties at two sites, one a low organic carbon, sandy soil (Rattray), the other a high organic carbon, clay soil (Shafton) were investigated. The potential of early E. grandis productivity as an indicator of changes in soil properties at these sites was also evaluated. Three different levels of compaction (low, moderate and high) were applied to the sites by three methods of timber extraction, i.e. manual, logger and forwarder loaded by a logger, respectively. Three types of residue management, i.e. broadcast, windrow and residue removal were also applied. A factorial treatment design was used to ensure a resource-efficient study that allowed separation of main and interaction effects. Various soil physical and chemical properties were measured at intervals from before treatment implementation, until approximately 44, and 38 months after treatment implementation at Rattray and Shafton, respectively. Trees were planted at a commercial espacement at both trials, and their growth monitored over the same time period. In addition, to accelerate early growth, negate silvicultural variation, and determine changes in stand productivity with treatments, a portion of the treatment plots were planted at a very high density and harvested when these trees reached canopy closure at about six months of age. Moderate and high compaction treatments at both sites resulted in significant increases in penetrometer soil strength, and often in bulk density. Increasing residue retention decreased the compaction effects of machinery and, generally, increased the total quantity of nutrients contained in residues and soil. Changes in soil bulk density and organic matter as a result of the treatments in turn affected soil water characteristics, generally decreasing plant available water capacity with increasing compaction intensity and residue removal. Tree growth measurements showed that at both sites, tree productivity was negatively affected at some point by increasing compaction. In contrast, residue management only significantly affected tree growth at Shafton, initially increasing and later decreasing growth with residue removal. These variations in tree growth over time in response to treatments are most likely a result of changes in tree characteristics that occurred with age. In addition, trees did not always reflect changes in soil properties that may affect LTSP, most likely because these soil properties had not yet reached levels that would affect tree growth. It was therefore concluded that early tree growth is not always a good indicator of changes in LTSP, and that soil properties are a more reliable indicator. Plantation management practices that lead to soil compaction and residue removals will negatively impact LTSP in South Africa. However, variable responses of the two soils indicate that soils vary in their sensitivity to compaction and residue management. This therefore needs to be quantified across a range of major soil types in the South African forestry industry. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

Made available in DSpace on 2014-08-20T14:36:56Z (GMT). No. of bitstreams: 1 Tese_Carlos_Roberto_Soares_ Severo.pdf: 7267743 bytes, checksum: 6e2b8a9babdbf6bf9ff708708ea6d3ee (MD5) Previous issue date: 2009-05-28 / The knowledge of the distribution of the soils allows the planning of agricultural activities in a way to maximize the productivity of cultures and reduce the environmental degradation. That way, the water and nutrient availability to the plants become of great importance and may be evaluated by means of physical, chemical and mineralogical analysis and its interpretation of local conditions. This study had the objective of surveying and mapping the soils of a hydrographic microbasin used in the culture of eucalyptus, relating its physico-hydrical and chemical characteristics with the culture development. The study area has 63,53 hectares and belongs to VPC Florestal, located in the Alamos Farm in the city of Pinheiro Machado, where the culture of eucalyptus saligna is being cultivated. To represent the mapping units were characterized in field and collected 9 soil profiles, representing the classes of Argisoils, Cambisoils, Chernosoils, Luvisoils and Neosoils. In relation to total nutrients, the class of soil that presented the greater quantity of available nutrients in t.ha-1 in the microbasin was the Cambisoil, followed by Luvisoil, Chernosoil, Neosoil and Argisoil. Relating to total nutrients, the class of soil that showed a greater quantity in t in the microbasin was the Argisoil, followed by the Neosoil, Luvisoil, Chernosoil and Cambisoil. The soils present in the hydrographic microbasin of the Alamos Farm have a total of 1300 basic available cations and a total of 15770 basic cations. As for the water availability, the Alamos Farm has a storing capacity in its soil of 121245m³ of water, of those 20778m³ available to the plants. Relating to the development of eucalyptus, the results show there was a differentiated growth in different soil mapping units, and the greater growth was showed in the class of Argisoil. / O conhecimento da distribuição dos solos permite o planejamento das atividades agrícolas de forma a maximizar a produtividade das culturas e a reduzir a degradação ambiental. Dessa forma, a reserva e a disponibilidade de água e de nutrientes para as plantas se tornam de grande importância, podendo ser avaliadas por meio de análises físicas, químicas e mineralógicas dos solos e da sua interpretação para as condições locais. Este estudo teve por objetivo, fazer um levantamento e mapeamento dos solos em uma microbacia hidrográfica utilizada com a cultura do eucalipto, relacionando suas características físico-hídricas e químicas com o desenvolvimento da cultura. A área de estudo, com 63,53 hectares, está localizada na Fazenda Álamos, pertencente a VCP Florestal, no município de Pinheiro Machado, onde está sendo cultivada a cultura do eucalipto saligna. Para representação das unidades de mapeamento foram caracterizados a campo e coletados 9 perfis de solo, representando as classes dos Argissolos, Cambissolos, Chernossolos, Luvissolos e Neossolos. Em relação aos nutrientes, a classe de solo que apresentou uma maior quantidade de nutrientes disponíveis em t.ha-1, na microbacia, foi o Cambissolo, seguido do Luvissolo, do Chernossolo, do Neossolo e dos Argissolos. Em relação aos nutrientes totais, a classe de solo que apresentou uma maior quantidade em t.ha-1, na microbacia, foi o Argissolo, seguido do Neossolo, do Luvissolo, do Chernossolo e do Cambissolo. Os solos presentes na microbacia hidrográfica da Fazenda Álamos, possuem um total de 1300t.ha-1 de cátions básicos disponíveis e um total de 15770t.ha-1 de cátions básicos totais. Quanto à disponibilidade de água, a microbacia da Fazenda Álamos, possui uma capacidade de armazenamento de água em seus solos de 121245m3 de água, destes 20778m3 disponíveis as plantas. Em relação ao desenvolvimento do eucalipto, os resultados mostram que houve um crescimento diferenciado, conforme a unidade de mapeamento de solos, sendo observado o maior crescimento na classe dos Argissolos.

A study was undertaken to compare growth potential of three Eucalyptus species of natural origin in South Eastern Australia, with commercially grown species on mid and high altitude temperate sites in the summer rainfall growing zones in South Africa. The three species were Eucalyptus globulus subsp. bicostata (E. bicostata), Eucalyptus cypellocarpa and Eucalyptus nobilis. Nine sites were selected to represent the growing areas of South Africa experiencing cold winter drought with occasional snow falls. Improved, commercially grown pure Eucalyptus species and interspecific hybrid clones were included as controls in the trials to give comparative growth performances on specific sites. Both balanced and unbalanced lattice designs were used to evaluate the growth potential of the unimproved Australian species and the improved commercial controls incorporated into the trials. Volume production and basal area growth were assessed for the three species at all sites. However, only three sub species E.globulus (E. bicostata, E. maidenii and E. globulus) showed varying levels of disease (Mychosphaerella nobilosa) infestation and this was therefore assessed in trials at 12 and 30 months respectively, and correlation analysis was used to study the relationship between the impact of disease infestation and growth performance. It was found that negative phenotypic correlations existed between the levels of infection and tree growth. ie greater infection slower growth. Evaluation of genotype x environment interaction (GXE) revealed that this did not exist in the E. bicostata nor E. nobilis populations, and therefore one population of each species can be developed for all the sites tested. E. cypellocarpa was the only species that showed some GXE interaction implying that separate populations to be developed for different sites. Contrary to what was expected, unimproved Eucalyptus species being investigated performed equally as well as the improved commercial species included as controls, thus providing potential for commercial deployment with selection and breeding. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.