Browsing by Author "Underwood, Timothy Michael."

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Black wattle (Acacia mearnsii) and the fever tree (Acacia xanthophloea) in alleycropping systems.
(2006) Nhamucho, Luis Jeremias.; Rijkenberg, Fredericus Hermanus Johannes.; Everson, Theresa Mary.; Underwood, Timothy Michael.; Matakala, Patrick.
Alleycropping is an agroforestry technology of planting crops between rows of trees, preferable legumes to promote an interaction among them with positive benefits in terms of improving soil fertility and hence good crop yields. The technology has been tested with a variety of trees/shrubs species in association with crops (alleycropping) or with grasses (alleygrazing), sometimes with encouraging results and sometimes not, in a wide range of environmental conditions around the world. Research in alleycropping started in late 1970s and sinc~ then many publications have been released. However, little or nothing has been reported about this technology using black wattle and the fever tree, two nitrogen-fixing trees common in South Africa and reported as fast-growing species which produce a considerable amount of biomass within a short period of time. Due to that fact, a two-year trial was established in 2003 at the Ukulinga research farm, Pietermaritzburg, South Africa to evaluate the potential of the two tree species under alleycropping with maize and cowpeas as joint intercrops, under alleycropping with pumpkin, and under alleygrazing with Eragrostis curvula and with Panicum maximum. The trial assessed the crop yields and the biomass production from all the components, and their fodder digestibility using Neutral Detergent Fibre (NDF) and Acid Detergent Fibre (ADF) determinations. Additionally the changes in tree grovlth vaa."'i.ables (difu~eter, total height, total \lollhl1e and biomass) were mortitored to produce regression equations to predict those variables, one from another, using regression analysis. The diameter was taken at ground level (dgl) and at the height of 1.3 m, normally called diameter at breast height (dbh). The results showed that tree growth and biomass production were better in black wattle alleycropping than in association with the fever tree. The average dgl of black wattle after 12 months was 48mm and the average dbh was 36mlll. Over the same period the total tree height was about 406cm. A tree pruning was done to one-year old black wattle in the whole trial and the prunings produced about 5.6t/ha of fresh foliage biomass in the association with maize and cowpea and 4.5t/ha in the association with pumpkin. In alleygrazing the growth variables were similar to those obtained in alleycropping but the biomass production was considerably different. The prunings produced about 7.66t/ha of fresh foliage biomass. The dry matter biomass from the prunings was 1.96t/ha, 1.58t/ha and 2.68t/ha in the association with maize and cowpeas, pumpkin and E. curvula respectively. The dry matter was obtained from 4days- oven-dried samples and it was 35% of the fresh foliage biomass and 60% of the fresh woody biomass. The fever tree did not grow significantly during the study period and due to that fact, the species was discarded from the study. Similarly, because after several endeavours using different seed lots, P. maximum had germinated very unevenly, and this grass was excluded from the experimentation. Values ofNDF and ADF less than 35% are considered good, between 35% and 60% fair and poor if greater than 50%. Using is classification the NDF and ADF values from this study were good in pumpkin (30.5% and 29.9%) and cowpeas (36.5% and 46.9%) biomass, fair in E. curvula (41.9% and 39.9%) and maize stover (53.6% and 42.1%) and poor in black wattle (76.58% and 68.1%) foliage. If black wattle is to be used as fodder, it must be mixed with highly digestible fodder like P. maximum, Digitaria sp., and other legume plants, to increase animal intake and to avoid any risk of it becoming an animal hazard due to tannin effects. The regression equations produced linear relationships between dgl and age, and biomass and dbh. The other interactions were not linear. The best equations were obtained in the interaction between dgl and age (dgl= 4.8*Age -7.03; R2 =0.86; SE= 6.6), dgl and height (h= -0.03dg12 + 10.5dgl - 21.25; R2= 0.96, SE= 42.9, h= height), biomass and dbh (lny = 2.409*lndbh; R2=0.99, SE=O.O, Y= tree foliage biomass). During the study, monkeys, cattle, birds and bushbucks posed a threat to the success of the study due to damage they caused to the crops. It was possible to keep the damage below the critical levels, although at high cost.
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.
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.
An instrumental evaluation of selected metal functionalised semiconductors in the facilitation of photo-organic transformations.
(2019) Underwood, Timothy Michael.; Robinson, Ross Stuart.
Throughout this research study, various strategies to design, synthesise and test the photo-reactivity of attenuated wide band gap semiconductors in alcohol oxidation studies have been explored. An alizarin red-sensitised zinc oxide photocatalyst which was stabilised in a silver-sodium electrolyte effectively facilitated a broad aromatic and aliphatic alcohol oxidation table with reported conversions ranging from 10 to ≥ 99 %. A systematic characterisation of the alizarin red-sensitised zinc oxide investigated the photoelectronic migrations across the alizarin red–zinc oxide interface and detected the transfer of electrons from the highest occupied molecular orbital of alizarin to the defect site of zinc oxide at 507 nm. Further studies were directed towards the development of a novel titanium dioxide semiconductor that was activated by visible light. Three attempted strategies (pseudo perovskites [Cu3TiO5, Ni3TiO5, and Mn3TiO5], silver functionalised cadmium sulfide and a heterojunction between cadmium sulfide and titanium dioxide) explored the possibility of lowering the band gap potential of wide band gap semiconductors through metal ion functionalisation (Cu, Ni, Mn, and Ag) and heterojunction principles for the purpose of finding applications in mediating alcohol oxidations. Whilst the three strategies were unable to demonstrate viable photocatalytic properties, the instrumental insight obtained during the process identified a suitable three-component semiconductor system (Cu/Pd-N-TiO2). Cu/Pd-N-TiO2 was extensively characterised with an array of instrumental techniques, thus developing an in-depth understanding of the photophysical properties that governed the photo-oxidative transformation of a range of cyclic alcohols and in the remediation of two dyestuffs typically associated with environmental contamination.
Small-scale timber growers' participation in the development of national principles, criteria, indicators and standards for sustainable forest management in South Africa.
(2005) Ngubane, Steven Zama.; Underwood, Timothy Michael.
The aim of this study was to engage small-scale timber growers in the development of national principles, criteria, indicators and standards (PCI&S) for sustainable forest management (SFM) in South Africa (SA). To ensure effective participation of small-scale timber growers in the development PCI&S, an overview of sustainable and small-scale forestry was explored. Furthermore, because of the importance of globalisation on the SFM concept, its conceptual framework and small-scale forestry development in relation to SFM were investigated. Participatory rural appraisal (PRA) methods, and PCI&S evaluation and development processes were used to engage small-scale timber growers by identifying and integrating their perceptions into the process of SFM standards development. These small-scale timber growers' perceptions focused on social, economic, environment and policy issues. The stUdy indicates that the views of small-scale timber growers regarding SFM do not vary significantly from those held globally. However, they demonstrate that local conditions determined issues of relevance and importance to this specific group. The results further support the view that there is value in combining both top-down and bottom-up approaches in developing an appropriate set of PCI&S. This is critical because the perceptions of small-scale timber growers for SFM are scale sensitive. Finally, the results supported the view that there is a need to give attention to and strengthen socio-economic issues versus those of the physical environment to improve inequalities of the past, and influence future decisions.
A study towards the use of semiconductors as mediators in organic oxidation transformations.
Underwood, Timothy Michael.; Robinson, Ross Stuart.
Abstract available in PDF file.