Masters Degrees (Forestry)

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The above-ground biomass composition and nutrient content of commercial Eucalypts and their use in managing sustainable intensive forestry in South Africa.
(2003) Herbert, Martin Antony.; Zwolinski, Janusz.
A study was undertaken of the biomass composition of ten eucalypt species growing on five sites in the timber growing regions of southeastern Mpumalanga. The species comprised E. deanei, E. dunnii, E. elata, E. fastigata. E. grandis, E. macarthurii, E. nitens, E. saligna, E. smithii and E. viminalis. The average tree height was 19.3 m and dbh 15.9, with stocking at 1494 stems/ha and merchantable yield at 153 t/ha. The sites had been established under commercial conditions seven years earlier as a series of identical site-species trials, and differed widely with respect to air temperature and effective precipitation. The soils were derived from granite, and either shallow and rocky (Glenrosa form) or deep and friable (Inanda forms). Sample trees were felled at the height of summer, separated into the biomass components of leaves, branches, on-tree dead matter, bole bark and bole wood, and weighed for fresh mass. Sub-samples were taken of each component for laboratory determinations of moisture and nutrient content, as well as bole wood density. Statistical analysis of the results show significant differences between species and sites as well as site species interactions for the tree mass of biomass components, and nutrient composition and water content. While overall E. smithii and E. dunnii produces the largest biomass, there are strong site interactions due to the varying degrees of site specificity required by different species. The proportions of the different biomass components differ between species and across sites, with the bole mass fraction increasing as growth rate improves. Biomass moisture is highest in bark and leaves, especially for the Viminales species group of the genus Symphyomyrtus. This group also has the highest wood density, while density within the stem is remarkably uniform for most species. Density generally increases with tree vigour. Nutrient concentrations are greatest in leaf and bark and least in bole wood, and are strongly influenced by soil nutrient status. There are considerable differences between species, with the subgenus Monocalyptus showing generally the lowest values. Models are developed to estimate biomass components from tree mensurational parameters and their nutrient content from soil variables. Nutrient budgets are developed on an equivalent tree mass basis to estimate the quantity of nutrients required to grow biomass. Nutrient quotients of the biomass produced per unit of nutrient are calculated to compare the efficacy with which biomass is produced per species, and comparisons made for average growing conditions across the study region. While the most economical subgenus is Monocalyptus, the most efficient of current commercial species is E. smithii, followed by E. nitens, E. macarthurii, E. grandis and E. dunnii. Nutrient export during harvesting exceeds natural inputs, is exacerbated by 60% on average when retaining bark on logs, and more than doubled if slash is burnt. Further research is required into estimating soil reserves and extending the study to other site types.
Comparative evaluation of Celtis Africana in Lesotho with that in KwaZulu-Natal, South Africa.
(2005) Ts'ehlana, Moses Ts'eliso.; Underwood, Timothy Michael.
Research was conducted in three study sites in Lesotho, and the fourth, which was used on comparative basis, was in KwaZulu-Natal, South Africa. The study was suitable for Lesotho as it is a small country with very limited natural resources. Lesotho's weak economy, exacerbated by the increasing population, needs concerted efforts to redress its socio-economic problems. This study is one of such efforts to explore the potentials of the indigenous forests with the aim of addressing wood demands. Celtis africana is one of the species with a proven record in Lesotho to have been a well adapted, resourceful timber tree in the past. Over-exploitation has degenerated it to its brink of extinction. It is against this background that this research was conducted with the aim of restoring Celtis africana to its original status in Lesotho. The results revealed that due to climatic conditions, seeds from Kwazulu-Natal are heavier than those from localities in Lesotho. However, wood densities from study sites in Lesotho are higher than those of KwaZulu-Natal. Pre-treatment method of manual scarification showed the best outcomes in terms of germination percent and vigour while the control was the last. The diverse nature of Celtis africana allows it to survive and prosper in a wide and varying range of habitats. Its pliable and adaptive characters are manifested by its ability to adapt in novel environments. Under ideal warm and moist conditions Celtis africana keeps its foliage all the year round, but in dry or abnormally cold years it becomes a deciduous tree. Though it is distributed in a variety of habitats, Celtis africana prefers moist habitats. It also demonstrates greater "affinities" for the carbonates in the soils, in particular, calcium carbonate (CaC03) and dolomite (CaMgC03). More research and determined reforestation programmes are required in order to improve the status of Celtis africana in Lesotho. Its natural existence in Lesotho can curtail expense of provenance identification. Both extension strategies and silvicultural operations, which can assist in tree improvement, should be adopted. Social benefits which, are rendered by Celtis africana in South Africa, can be emulated and adopted in Lesotho. Other than being an admired and valuable recreational tree (planted in parks and in the homesteads), it is a protected tree in South Africa.
Developing a non-destructive screening tool for pulp yield in Acacia mearnsii (Black wattle)
(2009) Dunlop, Robert William.; Njuho, Peter Mungai.; Dyer, Colin.
Acacia mearnsii (black wattle) is an important South African commercial forestry species, providing a source of high quality raw material (fibre) for both the domestic and international pulp and paper industries. Compared with many Pinus and Eucalyptus species, there has been very little research into the wood and pulping properties of black wattle. The ability to assess pulp yield in a non-destructive manner, using near infrared (NIR) spectroscopy, is vital from a tree improvement perspective. Destructive sampling and analysis, results in the loss of the genotype, while also being very expensive and time consuming. In order to assess some of the important characteristics that make the species desirable from a fibre perspective, this study investigates growth characteristics, wood density and pulp yield of ten trees grown on each of three different sites namely, Bloemendal, Glen Echo and Phoenix, and from each of three different age classes being 7- , 9- and 11-years-old. In total, 90 trees were sampled for this stage of the study. In general, physical characteristics such as utilisable height and diameter at breast height of the trees differed between sites and increased with age, this age effect trend was not reflected in the pulp yield or wood density results. Pulp yield measurements ranged from 52.61 to 59.91% across all sites and age classes, which, when compared to the pulp yield from many other forestry species, is relatively high. Laboratory pulp yield data was used in conjunction with NIR spectra obtained from the same wood samples to calibrate a NIR spectrophotometer to predict pulp yield. Thirty 11- year-old trees were then chosen from the Bloemendal site and sampled extensively to investigate the within-tree variation in pulp yield. The NIR model developed was used to measure the pulp yield from the numerous samples taken from within the trees. In general, pulp yield decreased from pith to bark and from the base of the tree to about 20% of the tree height and then decreased towards the top of the tree. The within-tree variation data for pulp yield was analysed to identify the best position for non-destructive sampling, and a model was then developed to predict whole tree pulp yield based on this sample, which was taken at 1.4 m up the tree. The analyses of small samples of wood meal, using near infrared spectroscopy, enabled the prediction of whole tree pulp yield.
The development of a wall-less plug for planting stock of forest trees.
(2011) Schuermans, Jean.; Van Niekerk, Renate.; Da Costa, Dean.
High output commercial nurseries that cater for the forestry industry are continuously challenged to efficiently and cost effectively produce good quality planting stock to establish large plantations. Currently, South African commercial nurseries produce planting stock in solid compartmentalized trays. One of the major drawbacks of these containers is the susceptibility of trees to root deformation following outplanting, combined with the need for the return of empty containers to the nursery. A potential solution to these challenges is the introduction of wall-less plugs for the production of planting stock. Wall-less plugs are volumes of growing medium, usually cylindrical in shape, devoid of an impenetrable wall in which a plant can grow and establish itself. Such plugs may enable the production of planting stock with improved root systems, without the need for the return of empty containers after outplanting. In this research four prototypes of wall-less plugs were developed, produced on a small scale and tested. These were: 1) Paper-maché plugs made using the original WRIBLOK protocol whereby composted pine bark was bound together with repulped newspaper, 2) Sponge blocks, 3) Hessian bags and 4) Covetan bags. The performance of these prototype wall-less plugs was compared with the performance of four tray types used commercially by the forestry industry: 1) Poly 128 shallow, 2) Poly 98 deep, 3) Unigro 128 and 4) Sappi 49. These are polystyrene and polypropylene-based containers. Of these containers the Unigro 128 and Sappi 49 containers were of similar performance. Performance in terms of height and root collar diameter increase over ten weeks from the time of sowing of the paper-maché plugs was similar to that of the Unigro and Sappi 49 containers. The sponge block, Hessian bags and Covetan bags produced inferior quality planting stock compared to the other treatments tested. Although little progress was made in the ability to describe how one root system differs from another in terms of their branching patterns, a technique was developed to determine root surface area by image analysis software that is freely available. This method may prove useful for further research and for determining seedling quality in commercial nurseries.
The effect of genetic improvement, fertilisation, weed control and regeneration method on the establishment and performance of Eucalyptus macarthurii and Eucalyptus nitens.
(2005) Van den Berg, Gerhardus Johannes.; Zwolinski, Janusz.; Little, Keith MacMillan.
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.
Evaluation of tree performance, site conditions and silvicultural procedures in forest plantations at high altitude sites in Lesotho.
(2005) Pama, Mokete M.; Zwolinski, Janusz.
The permanent sample plots (PSP) and silvicultural trial plots established by the Forestry Research Section of the Forestry Department of the Ministry of Forestry and Land Reclamation in Lesotho were used as a source of information for this study. The study area is located in the forest plantations on high altitude sites in Lesotho which have the aim to determine important aspects of timber production for commercial use and to address the problem of fuel wood scarcity and energy crisis. The major objective of the study was to describe performance (survival, growth and timber volume) of exotic tree species introduced in Lesotho. The height and diameter relationships for trees in the 33 plots of Eucalyptus rubida and 44 plots of Pinus radiata were determined by a simple linear regression. There are four plots of Eucalyptus macarthurii, three plots of Pinus halepensis, one plot of Eucalyptus nitens and one plot of Pinus pinaster. The permanent sample plots data were analysed with the use of a statistical package Genstat (7th edition). Categorical analysis were used to detect the number of live and dead trees. The correlation analysis was used to study association between site and performance variables, while multiple regression analysis was utilised to analyse relationships between site index and site variables. The growth curves developed for E. rubida and P. radiata tended to indicate a sigmoidal shape. Analysis of variance was utilised to analyse the performance of species in terms of survival and growth (HT and DBH) for the four species and provenance trials. The early mortality rate was 2% for E. macarthurii, 14% for E. rubida, 0% for E. nitens. Later, it was found that the percentage of dead trees is as follows: 7% for E. macarthurii, 15% for E. rubida, 29% for E. nitens. It was detected that the mortality rate for eucalypts was 14% at last assessments. Similarly, it was detected that the final mortality rate for P. halepensis, P. pinaster and P. radiata was 2%, 19% and 20% respectively. The mean diameter for P. radiata ranged between 1,87 cm at age 3,75 years and 24,49 cm at age 18 years. The mean height ranged from 1,51 m at age 0,75 yrs and 13,51 m at 16 years. It was discovered that the mean diameter is found between 8,0 cm at age 4,83 yrs and 14,41 cm at age 8,83 yrs for P. halepensis. The mean height was 2,1 m at age 4,83 years and 16,48 m at age 13,50 years. The mean diameter ranged from 7,41 cm at age 6,42 years and 15,92 cm at age 10,42 years for P. pinaster. Similarly, the mean height was detected to be between 5 m at age 6,42 years and 7,75 m at age 12,42 years for P. pinaster. It was noted that the mean diameter for E. rubida ranged from 2,04 cm at age 2,25 years to15,87 cm at age 11,75 years. On the same line the mean height started at 4,55 m at age 2,42 years and ended at 16,15 m at age 11,75 years. The mean diameter for E. macarthurii was noted to be 13,64 cm at age 10 years. It was noticed that mean height is found between 3,8 m at age 2,17 years and 16,03 m at age 10 years. It was also detected that the mean diameter started from 4,45 cm at age 2,50 years and 10,78 cm at age 6,50 years for E. nitens. The mean diameter ranged from 5,98 cm at age 2,50 years and from 12,05 m at age 6,50 years for E. nitens. The mean annual increment (MAI) for P. radiata is found between 0,15 m3/ha/yr at age 2,25 years and 21,91 m3/ha/yr at age 6,50 years. The MAI ranged from 0,58 m3/ha/yr at age 3,42 years and 10,81 m3/ha/yr at age 10,42 years for E. rubida. It was determined that the MAI started from 0,25 m3/ha/yr at age 2,17 years to 9,99 m3/ha/yr at age 4,17 years for E. macarthurii. The MAI started from 1,59 m3/ha/yr at age 2,50 years and to 7,54 m3/ha/yr at age 6,50 years for E. nitens. It was noted that the MAI for P. halepensis began from 0,01 m3/ha/yr at age 4,83 years and 3,52 m3/ha/yr at age 13,50 years. Similarly, the MAI began from 0,73 m3/ha/yr at age 6,42 years and 2,70 m3/ha/yr at age 10,42 years for P. pinaster. The Site indices for E. rubida and P. radiata were calculated. They ranged from 6,72 to 14,40 m and from 12,05 to 18,43 m for E. rubida and P. radiata at age 6 years and 15 years respectively. The MAI and SI of different species justify that a viable commercial forestry can be implemented in Lesotho, if advanced selection of genetic material, improved silviculture and appropriate site species matching can be followed. It was noticed that various silvicultural practices like proper land preparation methods, weed management and deep planting have a large impact on tree performance. Based on these results, larger afforestation projects for commercial timber production and bioenergy are recommended.
Factors affecting the successful deployment of Pinus patula as rooted cuttings.
(2005) Mitchell, Richard Glen.; Zwolinski, Janusz.; Jones, Nicky B.; Coutinho, Teresa Ann.
Summary: The future mass propagation of elite families of Pinus patula by cuttings is a realistic method of deployment if the short-term performance of cuttings and seedlings are confirmed at harvesting. This will impact significantly on the future outlook of forestry in South Africa as softwood yields are improved substantially through the introduction of material of high genetic value in commercial plantings. This, however, will require significant changes in future silviculture and other management practices as foresters and plantation staff learn to regenerate, maintain, and schedule the harvesting of cutting stands according to a different set of demands as a result of the change in plant type. Contrary to operational experience, cutting survival was similar to seedling survival in all field studies. This indicates that factors other than those that were studied and reported on, such as planting techniques, may be contributing to mortality. Also, due to the different root structure of cuttings they may be more fragile. The similar survival observed in these trials, therefore, may have been due to the close supervision given to the planting operations by the research staff. Although survival was similar, both plant types survived unacceptably poorly in the majority of studies with an average stocking of approximately 50% at one year. It is therefore anticipated that commercial stands will require several blanking operations in order to achieve an acceptable stocking in excess of 85% by the following planting season. The reduction in expected profitability as a result of blanking costs, delayed establishment, and the loss of improved genetic plant material, indicates that this is an area that still requires further research irrespective of what plant type is being planted. The pathogen, Fusarium circinatum, was commonly isolated from the planting stock before and after planting in two studies. Due to its virulent nature, it was assumed that mortality on the trees on which F. circinatum was isolated was principally due to this pathogen. At planting all plants were observed to be healthy and free of disease indicating that this pathogen maybe carried from the nursery to the field in a cryptic form, either inside or outside the plant tissue , which results in the death of the newly planted tree. In two field studies, where F. circinatum was commonly isolated, the application of Benomyl fungicide and to some extent the biological control agent Trichoderma harzianum at planting appeared to improve survival although this improvement was not significant. Laboratory studies, designed to determine alternatives to Benomyl fungicide, indicated that three fungicides (Octave, Folicur and Tilt), three sterilants (Sporekill®, Prasin®and Citex®) , as well as a biological control agent (T.harzianum), were all highly successful in controlling F. circinatum colony growth in vitro. It is recommended that these products undergo nursery testing , where the plant material is inoculated with F. circinatum spores, in order to test their efficacy and possible phytotoxicity in vivo before commercial application. Post-planting survival was also affected by site climate . Greater temperature extremes, as well as lower humidity and less rainfall resulted in poor survival. Plant dimension at planting was found to interact with site quality where it was a significant factor on a poor quality site. Optimal cutting dimensions at planting was a root collar diameter of 2.8 - 3.2 mm, and a stem height greater than 7 cm at planting for cuttings produced in cavities 90 ml in volume. Optimal seedling dimensions at planting were a root collar diameter of 1.8 - 2 mm, and a stem height of 10 - 15 cm for seedlings produced in cavities 80 ml in volume. In a separate study, plant morphological criteria influenced medium-term growth, where greater root mass and thicker cutting root collar diameters at planting improved field growth performance for seven years after planting. A greater root mass at planting was achieved by raising cuttings in containers that could support greater medium volume. From the study it was concluded that cuttings should be raised for an approximate period of 9 months in container cavities no smaller than 80 ml in volume and possess an oven-dry root mass of 0.3 - 0.5 g at planting. In addition to similar survival, the cuttings in this study grew either similarly to, or in some cases out-performed, the seedlings that were used as a control. Several other published studies indicate that hedge maturation poses the greatest threat to the success of softwood cutting deployment. This is especially true in clonal forestry and methods to maintain juvenility, such as cold storage of shoots and cryopreservation, require further research before clonal plantations of P. patula can be realised. In the studies carried out on family hedges in this report, the effect of donor hedge maturation was found to influence nursery management practice and the characteristics of rooted cuttings. The nursery data indicates that rooting efficiency, root system quality, and stem size and form, all decline with increasing hedge age particularly from two years after the date of sowing. A decline in root system quality was particularly apparent and was observed prior to a decline in rooting efficiency. If field trials indicate poorer performance from older hedges , it may be necessary to determine whether the causes are purely ontogenetic, morphological, or both before drawing final conclusions about hedge longevity. Until such results are known, it is recommended that P. patula cuttings should be propagated from seedling donors maintained as hedges , approximately 15 cm high, for a period not more than three years from the date of sowing.
Growth of four pine species at high altitude sites in the Eastern Cape Province.
(2002) Theart, George Frederik.; Zwolinski, Janusz.
The growth of four pine species Pinus patula, P. greggii, P. elliottii and P. taeda was investigated on first rotation high altitude sites in the north-eastern region of the Eastern Cape Province. The study area encompass a broad range of sites in terms of soils (texture, drainage, depth) and climate (temperature and precipitation). Afforestation across the study area proved challenging and there is a need to better understand survival, tree growth and site variables that contribute to the unique forestry environment. Enumeration data of 539 compartments totalling 11 380 ha with an age-class distribution from 4 to 13 years were analysed using statistical analyses techniques, interpretation based on other research results and personal field experience. The dataset represents the first commercial scale growth information for the four species in the study area. The research was designed to study the survival of the four pine species and to analyse if there were any seasonal impacts on the latter. Furthermore, the tree growth, expressed as a site index at age 10 years (Sl (10)) and basal area at age 10 years (BA (10), was analysed to investigate the performance of the four pine species. Lastly, the relationship between tree growth expressed in site index (Sl (10) and basal area (BA (10) and site characteristics was investigated. On average the best survival species were P. elliottii and P. greggii yielding 69% and 68% respectively, with P. patula yielding a 56% survival. There was no statistically significant difference in the survival between the planting months for all species combined, however, P. patula showed significant differences between planting months. In addition there are statistically significant differences between the species in terms of Site Index and Basal Area and there is a relationship between growth and site variables. Evidence leading to the following conclusions is provided: i) P. patula is the worst species planted in North East Cape Forests (NECF) in terms of survival; ii) August is the best and November the worst planting month for P. patula; iii) the importance of species selection and site matching; iv) the successful introduction of P. greggii; v) tree performance can be explained with site variables, especially those derived from climatic information.
The impact of urban expansion and population growth on productivity of forestlands : study area: Rustenburg Local Municipality.
(2007) Seokwang, Modise.; Underwood, Timothy Michael.
The survey has been carried out in North West Province within Rustenburg Local Municipality. This is an Urban Forestry research in which six sites including peri-urban, urban, suburban and semi-rural areas were selected for the study. The aim of the study was to determine the relationship between households and their local trees and forests. Forest in this context included community gardens, vegetation cover, open spaces, soil, water, productive sites and animals that form part of forest. Data collection was mainly based on questionnaires and covered sample of 272 households. Statistical Package of Social Sciences (SPSS) 15.0 using 5% sampling intensity (confidence level) was used in which the data has been represented by numbers. Analysis was based on determining households’ relationship with their trees and local forest, and how they influence forest productivity or development. With SPSS two techniques, regression model and descriptive statistics were applied to analyze quantitative and qualitative data. Regression model was significant in prediction of the dependent variable (Y) using independent variables (X), and proved to be a good model to analyze data for fuelwood, timber and forest food production. Descriptive statistics was important in counting number of times each category or variable is used. Participants had varying perceptions regarding the use of forest due to factors such as availability of forest resource, type of residence, and their living standard. Generally, households in suburban and urban areas value the forests for economic and environmental benefit, while the peri-urban and semi-rural households utilized their trees and forest to meet their energy demand. A large number of households consume forest food as compared to timber and fuelwood due to the availability of the resources. The Municipality as a whole is undergoing rapid development expected to continue throughout years. These developments are stimulated by mining activities and influx of people in the area. All these factors threaten the existing natural resources especially forest areas and water. Areas of these resources are declining due to the current demand for housing, new mining sites and continuous establishment of informal settlements. Trees and forest within peri-urban and semi-rural areas are in poor conditions as compared to urban and suburban areas. Poor waste management and poverty are issues aggravating the situation especially in poor developing sites that have been studied. Most agricultural sites have been transformed into residential areas, and thus exacerbating problems of food insecurity in the whole country. Household size has major influence in fuelwood, timber and forest food production as an increase or decrease in the size will determine the amount of consumption, production or development. Value for forest, access to forest, level of interaction and restrictions regarding the use of forest are also significant aspects contributing to forest productivity and development as they show the relationship that exists between forest and households.
Parameterisation of the 3-PG process-based model in predicting the growth and water use of Pinus elliottii in South Africa.
(2011) Sithole, Zola.; Dye, Peter.; Zwolinski, Janusz.
A simplified process-based model simulating growth and water use in forest plantations was utilised to predict the growth of Pinus elliottii in South African forest plantations. The model is called 3-PG (Physiological Principles in Predicting Growth) and predicted the growth of trees by simulating physiological processes that determine growth and water use, and the way trees are affected by the physical conditions to which they are subjected, and with which they react. Pinus elliottii growth data recorded in 301 sample stands around South Africa were sourced from forestry companies. A selection procedure reduced the number of stands to 44, where 32 were used to parameterise 3-PG and 12 were reserved for testing the final model parameters. This was accomplished by matching model output to observed data. All stand simulations were initialised at age four years and continued to the maximum age of recorded growth. A provisional set of parameter values provided a good fit to most stands and minor adjustments of the specific leaf area (σ), which was assigned a value of 5 m2.kg-1, were made, bringing about an improved fit. The predictions of mean DBH, Height, and TPH were relatively good, achieving R2 of 0.8036, 0.8975, and 0.661 respectively, while predictions of stem volumes were worse (R2 =0.5922, n=32). The 3-PG model over-predicted DBH in 20 stands, while modelled volume predictions improved substantially in thinned stands (R2 =0.8582, n=14) compared to unthinned stands (R2 =0.3456, n=18). The height predictions were generally good producing an R2 =0.8975. The final set of 3-PG parameter values was then validated against growth data from the 12 independent stands. The predictions of mean DBH, Height, and TPH were relatively good, achieving R2 of 0.8467, 0.7649, and 0.9916 respectively, while predictions of stem volumes were worse (R2 =0.5766, n=12). The results of this study demonstrated the potential for 3-PG to respond to many growth factors and to predict growth and water use by trees with encouraging realism. Patterns of changing leaf area index (L) over time, responses to drought, and annual evaporation patterns all look realistic. Consequently, 3-PG is judged to have potential as a strategic forestry tool.
A quality management system for the Namibia Water Corporation Limited.
(2004) Van Eeden, G. A.; Raubenheimer, W. H.
A company cannot survive without giving attention to quality. Ensuring quality in products is so important that many companies give major attention to actively managing processes to make sure that quality permeates everything the company does. Quality management is a company's unique approach for addressing all aspects of quality. It requires vision, a quality policy, a quality standard, a quality system and the control of the system. The water industry is a natural monopoly in which no competition exists to provide customers the opportunity to choose between different suppliers. Due to the monopolistic nature of a water utility, the tendency was previously to neglect the customer and his needs. For water utilities, the quality of the product water has always been the important factor mainly because of their responsibility towards the protection of public health. The quality emphasis was mainly towards meeting the demands of the primary and secondary sector of the water industry that is to provide water of an acceptable standard to the customers. It was only during the 1980's that water utilities became concerned about service quality in pursuance of the example set by the broader industry. Since then the emphasis on quality shifted gradually towards the tertiary sector of the water industry, the provision of quality services to the customer. The Namibia Water Corporations Act, 1997 requires that a performance contract should be concluded between the owners of the company (the State) and the Corporation. It further requires that the Namibia Water Corporation (NamWater) should formulate and maintain service standards in respect of the provision of water, services or facilities. As both these requirements are primarily based on efficiency, performance,achievements, cost-effectiveness and the optimum use of resources, there is a need to develop a system that will address all these aspects. This document describes the outcome of a study to develop a quality management system for NamWater that will address all these aspects, to identify shortcomings within NamWater and to monitor progress regarding meeting the quality standards on a continuous basis. Together with the development of a proposed quality policy document, this study also resulted in the compilation of a proposed set of service standards as prescribed by the Namibia Water Corporation Act of 1997. Performance gaps where existing practices in NamWater do not meet industry's best practice were identified by making use of performance indicators developed by the International Water Association (IWA) and the benchmarking exercise of the Water Utility Partnership (WUP). A set of performance indicators was developed to monitor the progress of NamWater in meeting standards on a continuous basis. The study concludes with a proposal for a quality management system for NamWater to ensure that the work is carried out in accordance with the quality policy and the quality standards. To identify possible performance gaps in NamWater, the information from the Water Utility Partnership programme on performance indicators and benchmarking was used to evaluate the performance of the NamWater against other water utilities in Africa. In general terms, the performance of NamWater is better than in many other African countries. However, by evaluating the results of the benchmarking exercise performance gaps were identified within NamWater that needs urgent attention. This study identifies the Sales Process as being the area to concentrate on as a first priority, with the focus on the improvement of revenue collection, the improvement of customer relations and the decrease in total cost. The Support Process should be the second priority with the improvement of the asset management organisation high on the list. There are two fields in the Production Process that needs special attention. They are unaccounted-for-water, and supply interruptions. The identification of industry's best performers in the various fields where performance gaps exist is beyond the scope of this study. It will form part of the implementation phase of a quality management system for NamWater. To monitor NamWater's performance on a continuous basis over time in meeting the requirements of the quality policy, various performance indicators have been identified. These indicators will also identify future performance gaps, determine various performance trends in the company, and measure and monitor the benefits of the implementation of best practice. Performance indicators were identified (from the IWA and WUP programmes) due to the fact that it will serve the abovementioned purpose and it is compatible with the present situation within NamWater. As can be seen from the performance gap analysis all three processes in the NamWater organisation have shortcomings that will have to be addressed through a quality management system. The situation is ideal for the implementation of TQM for NamWater. Such a project should be high on the priority list of the management of the company.
A site analysis and classification system for Eucalyptus grandis on the Zululand coastal plain.
(2001) Du Plessis, Marius.; Zwolinski, Janusz.
A site analysis for Eucalyptus grandis planted on the Zululand coastal plain was carried out. Data from the permanent sample plot program from Mondi Forests was used to derive meaningful site quality relationships. Although water availability to trees is clearly identified as the single most important factor in forest land use management in South Africa, the matrix of other site factors such as soil, climate, genetic advancement and environmental constraints make timber plantations operationally complex and fascinating for research. The correlation between environmental parameters influencing tree growth and the yield obtained from a stand of trees is researched in this study. Growth models in the form of mathematical relationships are developed to enable the forest manager to predict tree growth from easily attainable input variables such as age, diameter or clay content of soils. The Chapman-Richards model was used to define the basic sigmoidal height growth curve over age for a given site. A site index model developed through a non-linear modelling process was constructed from permanent sample plot data. This model proved to be different from the site index model developed for a larger data set of the same physiographic zone. A site quality prediction model estimating site index at reference age five, from soil attributes was constructed. Soil morphology and grid referenced climatic data were found to be of limited value for the prediction of site index, but organic content in the top-soil and clay content in the sub-soil proved to be valuable predictors of site growth potential. For further site analysis studies, soil and climate variables will have to be measured on-site as opposed to using computer simulated figures. A site classification exercise was carried out by using the statistical technique known as clustering. Clusters were derived for the study area making use of clay content and mean annual precipitation (MAP) as input variables to separate the study area geographically, into meaningful structures on the basis of similarity. Significant clusters were derived using Ward's technique, which proposed three distinct site classification units for the study area. Site index for each of the site classification units was modelled and it was proved that the models predicted significantly different height - age relationships for each unit. From this site classification exercise it is shown that the variance in height growth within each site classification unit (SCU) is sufficiently small for each unit to be regarded as an independent site, uniform in its attributes of soil, climate, topography, water and nutrients status. A methodology for site classification is proposed from this study.

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