Classification of relevé data aims to present the best possible explanation of the vegetation within a specific study area. The variety of multivariate techniques available to classify vegetation into ecological communities has developed in recent years, which contributes to uncertainty among vegetation scientists as to which methods and computer software to select for optimum classification results. The wide application of the classical TWINSPAN algorithm along with the Braun-Blanquet approach of plant community descriptions and diagnostic species identification in southern Africa prompted a comparison of classification results between these classical approaches and a modern approach. The modern approach, as being referred to in this study, entails the recent improvement on the classical TWINSPAN algorithm, namely the Modified TWINSPAN algorithm in combination with statistical measures of species fidelity. Comparisons between classification end-results were undertaken at various spatial scales to test whether discrepancies between results obtained from the different approaches are similar when applied to a broad-scale synthesis, an intermediate synthesis and a local-scale classification within a similar vegetation type, the Mopaneveld. Such a comparative study is envisaged to present insight on the credibility of the use of classical approaches in phytosociology at various spatial scales. A modern approach was tested upon three previous vegetation classification studies which followed the classical approach. These vegetation classification studies were all undertaken at different spatial scales and are being referred to as the reference classifications. The data that were subjected to the modern approach were analogous to those used in the reference classifications. The computer package JUICE 7.0 was used in which the Modified TWINSPAN algorithm was applied in combination with statistical measures of species fidelity, which was obtained as a function directly in the JUICE program. Classification hierarchies were constructed for both the classical and modern approach results to compare and describe similarities and discrepancies between the different hierarchical dendrograms. Fidelity syntables were constructed to assist in the grouping of diagnostic species according to highest fidelity values. Such diagnostic species groups were compared with the lists of diagnostic species in the reference classifications. At the broadest spatial scale, comparisons revealed discrepancies between classification results from the classical and the modern approach. The modern approach presented a more robust synthesis of the Mopaneveld in southern Africa since the vegetation units and their associated diagnostic species are ecologically better expressed. The intermediate scale synthesis comparison revealed similar discrepancies, which again question the credibility of the classical approach at broader spatial scales. The application of the modern approach to the local scale classification, however, revealed little difference with the results obtained through the classical approach. Although more alternative classification techniques need to be applied to report on the most robust technique for vegetation classifications across spatial scales, it could be reported that the classical TWINSPAN algorithm is not favorable for vegetation classifications and syntheses beyond the local scale. The ecological reliability of the modern approach at the intermediate scale prompted its application in a synthesis of the riparian vegetation within the Mopane Bioregion of South Africa, which was not achieved in any previous study. Riparian vegetation plays an important role in maintaining good water quality and also provides habitat for many species. Riparian vegetation therefore needs to be classified and described. The synthesis of the riparian vegetation in the Mopane Bioregion of South Africa revealed six distinct plant communities which are described and discussed in terms of diagnostic, constant and dominant species along with variance in plant species diversity. / Thesis (Ph.D. (Botany))--North-West University, Potchefstroom Campus, 2012

Classification of relevé data aims to present the best possible explanation of the vegetation within a specific study area. The variety of multivariate techniques available to classify vegetation into ecological communities has developed in recent years, which contributes to uncertainty among vegetation scientists as to which methods and computer software to select for optimum classification results. The wide application of the classical TWINSPAN algorithm along with the Braun-Blanquet approach of plant community descriptions and diagnostic species identification in southern Africa prompted a comparison of classification results between these classical approaches and a modern approach. The modern approach, as being referred to in this study, entails the recent improvement on the classical TWINSPAN algorithm, namely the Modified TWINSPAN algorithm in combination with statistical measures of species fidelity. Comparisons between classification end-results were undertaken at various spatial scales to test whether discrepancies between results obtained from the different approaches are similar when applied to a broad-scale synthesis, an intermediate synthesis and a local-scale classification within a similar vegetation type, the Mopaneveld. Such a comparative study is envisaged to present insight on the credibility of the use of classical approaches in phytosociology at various spatial scales. A modern approach was tested upon three previous vegetation classification studies which followed the classical approach. These vegetation classification studies were all undertaken at different spatial scales and are being referred to as the reference classifications. The data that were subjected to the modern approach were analogous to those used in the reference classifications. The computer package JUICE 7.0 was used in which the Modified TWINSPAN algorithm was applied in combination with statistical measures of species fidelity, which was obtained as a function directly in the JUICE program. Classification hierarchies were constructed for both the classical and modern approach results to compare and describe similarities and discrepancies between the different hierarchical dendrograms. Fidelity syntables were constructed to assist in the grouping of diagnostic species according to highest fidelity values. Such diagnostic species groups were compared with the lists of diagnostic species in the reference classifications. At the broadest spatial scale, comparisons revealed discrepancies between classification results from the classical and the modern approach. The modern approach presented a more robust synthesis of the Mopaneveld in southern Africa since the vegetation units and their associated diagnostic species are ecologically better expressed. The intermediate scale synthesis comparison revealed similar discrepancies, which again question the credibility of the classical approach at broader spatial scales. The application of the modern approach to the local scale classification, however, revealed little difference with the results obtained through the classical approach. Although more alternative classification techniques need to be applied to report on the most robust technique for vegetation classifications across spatial scales, it could be reported that the classical TWINSPAN algorithm is not favorable for vegetation classifications and syntheses beyond the local scale. The ecological reliability of the modern approach at the intermediate scale prompted its application in a synthesis of the riparian vegetation within the Mopane Bioregion of South Africa, which was not achieved in any previous study. Riparian vegetation plays an important role in maintaining good water quality and also provides habitat for many species. Riparian vegetation therefore needs to be classified and described. The synthesis of the riparian vegetation in the Mopane Bioregion of South Africa revealed six distinct plant communities which are described and discussed in terms of diagnostic, constant and dominant species along with variance in plant species diversity. / Thesis (Ph.D. (Botany))--North-West University, Potchefstroom Campus, 2012

Understanding relationships between large herbivores and plant species diversity in dynamic riparian zones, and more specifically sodic zones, is critical to biodiversity conservation. Sodic patches form an integral part of savanna ecosystems because of the ecosystem services and functions they provide, i.e. accumulation of nutrients, provision of open spaces for predator vigilance and formation of wet season wallowing points. Furthermore, these key resource areas sustain body condition for dry season survival and support reproduction through nutritional benefits, making them „nutrient hotspots.‟ The Nkuhlu research exclosures in the Kruger National Park (KNP) provide a unique opportunity to investigate spatial and temporal heterogeneity patterns within riparian zones, and how these patterns are affected by fire and herbivory. A monitoring project was initiated to answer questions pertaining to the dynamics of the herbaceous layer and was aimed at determining (a) whether there exists meaningful variance in herbaceous plant species richness and diversity across different treatments of fire and herbivory in the ecologically sensitive sodic zone, (b) if temporal shifts in plant species composition and diversity occurs, (c) whether an increase in herbaceous biomass, an artifact of herbivory and fire exclusion, suppresses herbaceous plant species diversity and richness, and (d) whether there exists a significant relationship between herbaceous biomass and species richness/diversity. The Nkuhlu exclosures consist of three herbivory treatments, each divided into a fire and no-fire treatment, hence six treatment combinations overall. Herbivory treatments consisted of, (1) a partially fenced area designed to specifically exclude elephants (giraffes are also excluded due to body size), (2) an open, unfenced area and (3) a fully fenced area, designed to exclude all herbivores larger than a hare. Herbaceous vegetation was sampled in two 1 m2 circular sub-plots in the eastern and western corners of each of the 82 fixed plots. Biomass of each plot was estimated with a Disc Pasture Meter (DPM) by sampling ten points diagonally within each plot. DPM-readings were converted to kg/ha according to latest conversions for the Lowveld Savanna. Species richness and biomass showed significant variance across treatments for the 2010 dataset, whereas no significant variation in herbaceous species diversity was perceived. Combined treatment of fire absence and herbivore presence contributed to higher forb species richness in the sodic zone. Biomass was significantly higher in fully fenced areas where herbivores were excluded, opposed to the open and partially fenced areas. Although no significant variation was recorded for diversity across treatments, lowest diversity was recorded in the absence of all herbivores, especially in combination with fire treatment. After nine years of herbivory exclusion, diversity of herbaceous species varied significantly. Herbaceous species composition changed over time in areas exposed to herbivory, while composition of fully fenced treatments did not reveal change. A hump-shaped relationship exists between herbaceous species richness/diversity and field biomass, at least for areas with biomass levels not exceeding 2500 kg/ha. Herbivores are therefore considered essential in sustaining herbaceous plant species richness and system heterogeneity in the sodic zone, since herbaceous species richness/diversity was higher in herbivore presence and herbaceous species composition changed over time in areas exposed to herbivory. Although statistically non-significant, fire seems to suppress species richness. Conservation implications: This study could be used as framework to advance and develop sciencebased management strategies for, at least, the sodic zones of the KNP. Research in these exclosures contributes to our understanding of these landscapes and benefit ecosystem conservation planning. It also provides valuable long-term data for key ecological processes. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014

Understanding relationships between large herbivores and plant species diversity in dynamic riparian zones, and more specifically sodic zones, is critical to biodiversity conservation. Sodic patches form an integral part of savanna ecosystems because of the ecosystem services and functions they provide, i.e. accumulation of nutrients, provision of open spaces for predator vigilance and formation of wet season wallowing points. Furthermore, these key resource areas sustain body condition for dry season survival and support reproduction through nutritional benefits, making them „nutrient hotspots.‟ The Nkuhlu research exclosures in the Kruger National Park (KNP) provide a unique opportunity to investigate spatial and temporal heterogeneity patterns within riparian zones, and how these patterns are affected by fire and herbivory. A monitoring project was initiated to answer questions pertaining to the dynamics of the herbaceous layer and was aimed at determining (a) whether there exists meaningful variance in herbaceous plant species richness and diversity across different treatments of fire and herbivory in the ecologically sensitive sodic zone, (b) if temporal shifts in plant species composition and diversity occurs, (c) whether an increase in herbaceous biomass, an artifact of herbivory and fire exclusion, suppresses herbaceous plant species diversity and richness, and (d) whether there exists a significant relationship between herbaceous biomass and species richness/diversity. The Nkuhlu exclosures consist of three herbivory treatments, each divided into a fire and no-fire treatment, hence six treatment combinations overall. Herbivory treatments consisted of, (1) a partially fenced area designed to specifically exclude elephants (giraffes are also excluded due to body size), (2) an open, unfenced area and (3) a fully fenced area, designed to exclude all herbivores larger than a hare. Herbaceous vegetation was sampled in two 1 m2 circular sub-plots in the eastern and western corners of each of the 82 fixed plots. Biomass of each plot was estimated with a Disc Pasture Meter (DPM) by sampling ten points diagonally within each plot. DPM-readings were converted to kg/ha according to latest conversions for the Lowveld Savanna. Species richness and biomass showed significant variance across treatments for the 2010 dataset, whereas no significant variation in herbaceous species diversity was perceived. Combined treatment of fire absence and herbivore presence contributed to higher forb species richness in the sodic zone. Biomass was significantly higher in fully fenced areas where herbivores were excluded, opposed to the open and partially fenced areas. Although no significant variation was recorded for diversity across treatments, lowest diversity was recorded in the absence of all herbivores, especially in combination with fire treatment. After nine years of herbivory exclusion, diversity of herbaceous species varied significantly. Herbaceous species composition changed over time in areas exposed to herbivory, while composition of fully fenced treatments did not reveal change. A hump-shaped relationship exists between herbaceous species richness/diversity and field biomass, at least for areas with biomass levels not exceeding 2500 kg/ha. Herbivores are therefore considered essential in sustaining herbaceous plant species richness and system heterogeneity in the sodic zone, since herbaceous species richness/diversity was higher in herbivore presence and herbaceous species composition changed over time in areas exposed to herbivory. Although statistically non-significant, fire seems to suppress species richness. Conservation implications: This study could be used as framework to advance and develop sciencebased management strategies for, at least, the sodic zones of the KNP. Research in these exclosures contributes to our understanding of these landscapes and benefit ecosystem conservation planning. It also provides valuable long-term data for key ecological processes. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014