Thesis (Ph. D.)--Rhodes University, 2004. / Title from PDF t.p. (viewed on May 2, 2006). Includes bibliographical references (p. 263-293).

Burkea africana Hook. (wild syringa) is an average sized leguminous tree, 10-12 m in height occasionally reaching over 20m. This monotypic genus is dominant and codominant in Zambia, and is present throughout Africa as far north as Ethopia and west to Nigeria, and south to South Africa especially Limpopo, North West, Gauteng and Mpumalanga. It inhabits dry, non–calcareous sandy soils in savanna and woodlands up to 1500 m altitude or gentle slope of 1080 m elevation. Burkea africana produces a relatively large number of seeds, which is unusual for a resprouting species. Several studies conducted on B. africana trees paid more attention to the medicinal attributes, however little or nothing is known regarding the factors and dynamics that contribute to the growth and existence of these trees, particularly because these trees grow naturally in nutrient-poor savanna soils. Although B. africana trees have been in existence for a very long period of time, propagating it through thinning and transplanting of seedlings for regeneration and/ or re-establishment of seedlings to survive until sexual maturity still remains a mystery. It is hypothesized that factors controlling establishment and development of B. africana trees are related to microbial activities in the soil, very complex and species specific but poorly understood. This study aimed to identify, if there is a symbiotic relationship between the soil and mycorhizal fungi, and rhizobium bacteria or other growth stimulating activities, in the Burkea soils, which will accelerate and assist effective growth of B. africana trees to reach reproductive stage and produce pods without dying. The chemical composition of Burkea soil and non-Burkea soils was analysed using HCl extraction method.). The results indicated the similar values (p>0.05) were observed for all micro and macro minerals as well as total nitrogen, pH and organic matter. However, total ions nitrate and ammonium concentration levels of Burkea soils were higher (p<0.05) than those found in non-Burkea soils. The use of advanced metabolomics tool using1H-NMR was used to determine and identify soil metabolites which may be responsible for successful growth and establishment of the Burkea africana trees. The findings of this study indicated that metabolomic analysis showed different metabolites in the respective soils. Growth-promoting metabolites (GPM) such as trehalose and betaine were found to be in higher concentrations in the Burkea soils. Conversely, acetate, lactate and formate, were found in higher concentrations in the non-Burkea soils. Furthermore, LC-MS was used to determine the soil components present in Burkea soil as compared to non-Burkea soil using. The results indicated that a total of 22 compounds consisted of essential amino acids such as phenylalamine, threonine, tryptophan, leucine, isoleucine and lysine; conditional essential amino acids such as arginine, cysteine, glycine, glutamine, proline and tyrosine; non-essential amino acids such as citruline, alinine, aspartic acids, asparagine, glutamic acid and serine; nucleobased amino acids such as guanosine, adenine, adenosine, cytindine; dicarboxylic acid such as fumaric acid as well as common non-proteinogenic amino acids such as 4-hydroxyproline compounds were found in both Burkea and nonBurkea soils. The study investigated the microbial communities in the soil where Burkea africana trees grows successfully (Burkea soils) and how it varies from the soils where they do not grow (non-Burkea soils). DNA was extracted from the soil and a high throughput sequence bask local assignment search tool (BLAST) was used to analyze the microbial diversity (bacterial and fungal) and composition found in both soils, for a comprehensive understanding of the soil microflora. The results revealed that Penicillum sp is prevalent in Burkea soils and was the main discriminant between the two soils. On the contrary, non-cultured fungi, which could not be identified, dominated the non-Burkea soils. The variances in soil composition suggests that species supremacy play a role in the growth of B. africana trees. Lastly, the current study investigated and also identified what attracts caterpillars known as Cirina forda to invade and feed on B. africana trees. In addition, to determining if there is a symbiotic relationship between the plant-growth metabolites; growth-promoting fungi (Penicilium sp) and the caterpillars. The results of the study, revealed that the fungus Pleurostomophora richardsiae was predominant in the leaves of B. africana trees as well as in the caterpillars. It is proposed that Pl. richardsiae is a volatile compound which attracts caterpillars and makes B. africana trees susceptible to caterpillars’ outbreaks. The second largest percentage of fungi found in the caterpillars was Aspergillus nomius. / School of Agriculture and Life Sciences / Ph. D. (Agriculture)

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science 17th August 2015 in Johannesburg, South Africa / Ecosystem services provide a vital lifeline to millions of people living in rural areas. The poorest people in these areas depend upon the natural resource base in their surroundings to provide these services. With growing populations in rural areas of South Africa, the natural resource base is under considerable pressure; however, uncovering the dynamics of vegetation in these systems has proven difficult. While much attention has been given to savanna ecology, long term studies on the patterns and drivers of woody biomass are few. We used 65 years of aerial imagery (from 1944 to 2009) over 31 953 ha of rural savanna in a communal rangeland in South Africa to determine the abundance of woody canopy cover. This data were captured at hectare resolution, giving a fine enough level of detail for local level analysis. We also captured data for five potential drivers for change at this resolution, in order to analyse these drivers for their relative importance in determining woody canopy cover throughout the study period. Surprisingly, while individual sites showed varied trends in the amounts of woody canopy cover through time, when pooled across all sites the total woody canopy cover increased over the 65 year period. Disturbance gradients were found around some of the villages, but only in 2009, suggesting that the drivers of disturbance gradients in these systems may have only operated sufficiently to produce disturbance gradients in recent years. A hot spot analysis (hot spots indicate cells that have similarly high values beyond what would be expected in a random distribution, with cold spots indicating the inverse) revealed an increase in both hot and cold spots through time, but with a low persistence of both through time. High canopy cover cells are presumed to be the result of bush encroachment, while low canopy cover cells are presumed to be the result of harvesting of trees for fuelwood or clearing for fields. The low persistence of hot and cold spots points to a system in continual change, with patches of hot and cold spots appearing and disappearing, and therefore drivers of change operating in short periods of time. MAP (Mean Annual Precipitation), and not an anthropogenic driver, was found to be the most important driver for woody canopy cover throughout the study period, with MAP up to 670 mm having a predictable pattern of hot and cold spots through time. Higher MAP was shown to have a non-linear and unpredictable pattern of hot and cold spots through time, indicating that low precipitation may produce a system where woody canopy cover is less influenced by other drivers and is more stable when acted upon by other drivers. This research demonstrates the value of a long term dataset, and the applicability of our methods for monitoring woody canopy cover. As such, it may well serve as a baseline for woody canopy cover in communal savanna rangeland systems, with the methodology employed here suitable for an early warning detection system for sudden changes in the woody canopy cover.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Science, Johannesburg, South Africa 2017. / Fuelwood is still heavily relied upon by rural communities as a source of energy. The current levels of wood harvesting have been deemed unsustainable, with models predicting the local exhaustion of wood resources in most cases. However, wood depletion has generally not happened to the level of severity predicted by the models. This may partially due to under-accounting for coppice regeneration. Many savanna species that are harvested for fuelwood demonstrate strong coppicing ability, which allows for regrowth after a disturbance. This ability to regrow or coppice is a key functional trait which allows species to persist and survive in frequently disturbed environments. There is surprisingly limited knowledge about coppice dynamics in savanna trees and how managerial actions might influence the coppice response and production of savanna species. To address this problem, this study investigated the influence of four post-harvest treatments on various aspects of the coppice response of Terminalia sericea and Dichrostachys cinerea – two important savanna fuelwood species – in a field experiment. A total of 108 felled trees per species were exposed to one of four treatments, which were applied monthly for 12 months. The treatments were (1) Control – no coppice shoots were removed for 12 months, (2) Harvest – all coppice shots were removed monthly, (3) Single prune – the coppice shoot with the widest diameter was left on the stump, and (4) Usable – coppice shoots that reached a diameter of 2 cm were removed. The effect that these treatments had on the average diameter, length and cumulative number of coppice shoots produced per stump was compared. The measurements of diameter and length were used in developing allometric equations for the prediction of coppice shoot biomass. The predicted biomass produced through the study was compared across treatments to gain an understanding of how productivity could be influenced by management of coppice shoots. The mean shoot diameter, length, as well as cumulative number of coppice shoots produced per stump was higher in the single prune treatment for both species while the harvest treatment resulted in high numbers of coppice shoots but with low average diameter and length. Applying the growth rates of coppice shoots found in this study it can be assumed that unmanaged coppice shoots will take approximately 5.5 years to reach a preferred harvestable diameter of 4 cm, while single prune coppice shoots would take 3.3 years to reach the preferred harvestable diameter. Diameter had more of an influence on the predicted coppice biomass production of T. sericea while D. cinerea biomass prediction was more influenced by shoot length. However, only diameter was used to compare the prediction of coppice biomass with previously developed equations as these equations did not consider length for predicting biomass of different components of trees. From the derived models, the calculated biomass at the end of the study period as well as the calculated biomass produced through the year was greatest for the control treatment. The predicted dry shoot stem biomass at the harvestable diameter of 4 cm was 114.60 g for T. sericea and 95.88 g for D. cinerea. From the findings of this study it is clear that post-harvest management can be utilised to manipulate coppice response and biomass production. Keywords: Fuelwood; Coppice shoot; Post-harvest treatment; Diameter; Length; Biomass / LG2018

I describe the spider biodiversity for a savanna ecosystem, assess sampling techniques, investigate surrogate measures of species richness and measure the biotic and abiotic processes affecting spider diversity. Spiders were sampled at Makalali Game Reserve, Northern Province, South Africa from February to December 1999 using pitfall traps, sweep netting, beating and active searching. A total of 4832 individuals from 268 species (14 potentially new), 147 genera (8 endemic and 2 new records for South Africa) and 37 families (1 new record for South Africa) were recorded. There was no overall significant difference in spider diversity among different physiognomic habitat types. However, analysing the results at a functional group level revealed that the web builders were significantly affected by the habitat type. Mopane woodland habitat type had the greatest number of web builders and general bushveld the least. Sweeping and active searching sampled the greatest number of individuals and species respectively. I recommend a combination of at least beating and active searching, which together sampled the highest number of unique species, for efficient and cost effective surveys. There was a significant relationship between the spider species richness and other invertebrate richness. However, the relationship is not significant when functional groups are considered separately. There was also a significant relationship between the number of species and families and species and genera. However, species level identifications remain ideal for conservation purposes. Inexperienced participants significantly overestimate the number of species. The use of surrogates is not supported by the work conducted in this study. It is still unclear what biotic and abiotic processes or combination of processes influence spider diversity patterns at the local scale. Different spider functional groups are significantly influenced by different factors. However, habitat diversity (branches and vegetation density) was the most common factor influencing spider diversity . Predicted diversity (modelled using GIS and beta-coefficients from multiple regression analyses) was higher than measured diversity values. While further research into the role of other environmental variables is clearly required, current reserve management should aim to maximise microhabitat structural diversity. / Thesis (M.Sc.)-University of Natal, Durban, 2000.

No abstract available. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1996.

Note: / ln May 1962 the McGill University Savanna Research Project wasestablished and has been conducted since that date in the Department ofGeography p McGill University and in the savannas of the Rupununi Di strict pBritish Guiana and the Territorio do Rio Brancop Brazi!.It is generally recognised that although a very wide range of theoryhas been propounded to explain the nature and origin of savannas p no onehas yet brought forward a single convincing viewpoint which has met withuniversal acceptance. One reason for this is that the majority of theoriesextant are based upon inadequate fie ld data with almost a total lack ofexperimental evidence. The McGill Univers ity Sa vanna Research Projectwas set up for the purpose of initiating an experimental and observati onalfield programme which it was hoped would shed light upon the ecologicalrelations of the savanna p and would ultimately enable an explanation to bemade of the nature and distribution of the savanna vegetation of the region .

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 74-85). Also available on the Internet.

Univ., Diss.--Göttingen, 2003.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 74-85). Also available on the Internet.