Bibliography: pages 71-83. / A variety of studies have shown the problems of energy supply faced by low-income communities in southern Africa. Most of these communities are dependent upon indigenous fuelwood supplies. In addition, many of these communities use indigenous wood for construction. This largely uncontrolled utilisation imposes severe threats on woody vegetation communities. The Eastern Cape/Ciskei region is an area where energy supply problems are particularly severe and impacts on woody vegetation correspondingly severe. This study aimed to investigate the feasibility of using remote sensing techniques to monitor the the impact caused by collection of wood in the Eastern Cape/Ciskei forest and thicket communities. A variety of remote sensing techniques for landcover analysis were investigated. In all cases, visual interpretation was used because it is considerably cheaper and demands less technical expertise than would computer processing. In addition, many studies have shown visual interpretation to be superior. Maps were drawn from multitemporal aerial photograph sequences and from Landsat and SPOT satellite images. These maps showed that there has been relatively little change in area of woody vegetation in the study area since 1956. However, field studies showed that vegetation community structure had been degraded as a result of intense and sustained human impact. This qualitative decline also reflected a decline in usefulness of the woody vegetation of the area to local communities. This substantial degradation was not visible on any of the remote sensing imageries. This emphasises that field-based checks to monitor human impacts on forest and thicket formations are essential. Strategies for reducing the dependence of low-income communities on indigenous vegetation for energy supplies and constructional timber have been reviewed from the literature and these are descibed in Appendix 1. Most successful strategies in other parts of the world have been the result of a national commitment to tree planting, recognition of a multiplicity of constraints and the voluntary involvement of the communities the strategies are intended to assist.

High structural diversity amongst plant species in the arid winter rainfall region of southern Africa is common to other arid regions of the world. Details of the range and combinations of structural attributes in species, and within plant communities, are not widely known for southern African arid ecosystems. Hence little is known of how plant-form distributions vary within and between arid ecosystems. and of the environmental factors that may be responsible for any variations found. Nor is much information available on how phenological behaviour relates to the structural attributes of plant species. This study examined structural attributes of perennial plant species on the Worcester Veld Reserve, southwestern Cape. in relation to their distribution and phenology. Species were grouped on the basis of above ground structural and anatomical criteria. The distribution of species and plant-forms was assessed through a phytosociological survey along an environmental gradient in the area, and their phenology determined through qualitative and quantitative monitoring of species phenophases over a two year period. The results show that species of the predefined structural groups i) Co-occur throughout the area. but relative abundances vary from site to site and in relation to topography. aspect and the presence of Mirna-like mounds; ii) Phenological patterns for the flora overall are strongly seasonal, but the timing and periods of phenophases differ between, but are relatively uniform within, the defined structural plant groups. Since phenological patterns are indicative of resource-use patterns. these results indicate that the different plant-forms have different functional responses to the conditions of limited water availability and summer drought. This conceivably facilitates the co-existence of species in this water-limited environment. Habitat variability. which can be related to land-form patterns. is also implicated as a factor facilitating the co-existence of a diversity of species and plant-forms. Structural functional relationships known for arid region plants help to explain the relative uniformity of behaviour within plantform groups. and aid in understanding the ecological significance of distribution patterns of plant-forms in the arid landscape. The conclusion is reached that because of the close coupling between photosynthesis and water-use. the water storage potential and photosynthetic organ type are plant attributes which can serve as useful criteria by which arid region species can be grouped into ecologically meaningful categories or functional guilds. The formulation of a practical and meaningful functional classification is necessary to facilitate the understanding of complex vegetation patterns and processes within arid ecosystems. and allow for meaningful inter-ecosystem comparisons.

The growth and recovery of trees from disturbances such as fire and browsing is driven by the intensity of the disturbances and the availability of resources. In savannas, resprouting has become recognized as a key functional trait in plant ecology over the past decade. Although this may indeed be the case, there is still limited information about the physiology and growth strategies of resprouting trees. Available information about the influence of disturbance comes from ecosystems that are in many ways different from tropical and sub-tropical savannas. Therefore it is important to know and understand post-disturbance tree responses and limitations so as to establish sustainable use and management practices. This thesis reports the findings of a study, conducted in the Mpumalanga province of South Africa, aimed at achieving a better understanding of the influences of resource availability (water and nutrients) and disturbances (herbivory and repeated cutting) on the coppicing of a widely distributed savanna tree species that is both ecologically and economically important; Terminalia sericea. To investigate the effects of resource availability, cut trees were exposed to different levels of water and nutrient (nitrogen and phosphorus) supplementation over a period of two years in a factorial experimental design. A number of coppice regrowth variables (e.g. shoot production, resprout shoot diameter and shoot length) were measured monthly, while the phenological responses (e.g. timing of leaf discolouration and fruit presence) were monitored every two weeks. The effects of disturbances were investigated in two separate experiments, in which cut trees were exposed to a five month browsing period and different cutting frequencies, respectively. Coppice regrowth variables were monitored for 12 months in trees exposed to browsing and for five months in trees exposed to different cutting frequencies. The effect of multiple cutting cycles on total non-structural carbohydrates and leaf chemistry (carbon, nitrogen and phosphorus) was measured. There was evidence of self-thinning of coppice shoots within cut trees in all experiments in the second year of growth, with supplemented trees also recording lower shoot numbers. With shoot production higher in trees that received no resource addition, water and nutrients interacted synergistically, doubling shoot diameter and shoot length for supplemented trees after 12-months of addition. The majority of the phenophases monitored peaked in the wet growing season. Supplemented trees changed colour from the typical green to senescent yellow later in the growing season than unsupplemented trees. Fruit presence occurred in the second year after cutting for supplemented trees. Shoot length and shoot diameter for unbrowsed trees were twice those for browsed trees, with leaf nitrogen and phosphorus content significantly higher for browsed trees compared to unbrowsed trees. Trees subjected to multiple cutting cycles recorded half the TNC levels, and half the resprout shoot diameter and shoot length of trees cut only once. Results from this study demonstrate that self-thinning (i.e., negative change in shoot number) is not primarily under resource control. By contrast, the findings suggest that shoot growth characteristics, the timing and duration of phenological stages in coppicing trees are resource-limited in savannas. Browsing induces an initial compensatory response through higher shoot production in browsed trees and should be kept minimal because, in the long run, browsed cut trees would take longer to recover lost biomass compared to unbrowsed cut trees. Repeated cutting significantly depleted non-structural carbohydrate reserves in stems, implying that repeatedly cut trees rely heavily on non-structural carbohydrate reserves for regrowth. The significantly lower shoot diameter and shoot length in repeatedly cut trees imply that the coppicing ability of a tree reduces as the cutting frequencies increase. Such information can be vital in establishing the competitive growth ability of T. sericea in a multiple-species ecosystem affected by changes in resource availability as well as natural disturbances. With reference to multiple cut trees, a form of cutting or harvesting strategy should be in place that allows for sustainable regeneration of the study species. A threshold in terms of number of cutting cycles a tree can tolerate based on either maximum or minimum levels of reserve carbohydrates should also be established, as this has a direct effect on the coppice growth and survival.

Ph.D., Faculty of Science, University of the Witwatersrand, 1987

A thesis submitted to the Faculty of Science University of the Witwatersrand, Johannesburg for the Degree or Doctor or Philosophy October 1987 / A t h r e e - y e a r study was un dertaken in the semi-arid (500mm p a . ) n o rth -eastern lowland area of South Afric a. All the woody plants were removed from one -hectare savanna plots on three d i f f e r e n t soil types , and key hydrological and biological changes were monitored relative to adjacent controls. Runoff increased initially, but decreased once the grass cover increased. Deep drainage and lateral subsurface flow increased on the sandiest site. Evaporation from the soil surface increased on the heavier t e x t u r e d soils. The duration of plant - available water in the soil increased on all cleared p l o t s . & The p re - c l e a r in g woody plant abo veground biomass was in the range of of which 0 . 6 6 to 0 . 8 0 t ha was 5.6 to 11.2 t ha -1 leaf biomass. The annual herbaceous production was stron gly rainfal' dep endent, averaging 1 to 1.5 t ha -1 , and increased by 0 . 4 - 0 6 t .ha -1 except on the most f erti le site ( 0 . 6 - 2 0 t ha ) . Total available forage increased with c l e a ring, but so did its variability The observed changes in herbaceous layer palatability could not be a t trib u t e d to clearing. Woody plants and grasses wore shown to have w a te r- u s e niche separation in both rooting depth and time of water use. Simulation over forty years of wetting patterns indicated 75 to 85 % niche overlap, w t h separation on the depth axis more important in sandy sites, and on the time axis in clayey sites. Competition between woody plants and grasses was strongly asymmetrical in favour of woody plants. w >

The primary aim of this study was to investigate the population dynamics of the fishes associated with a small (17.5 hectares) temporarily open/closed estuary on the south east coast of South Africa. The results are based on the findings of an intensive sampling programme conducted over a period of four years in the East Kleinemonde estuary (33° 32' S : 27° 03' E). By adopting a quantitative approach, this study addresses the need for information on estuarine-associated fish population sizes, standing stock (biomass) estimates and productivity. The ichthyoplankton assemblage in the surf zone adjacent to the mouth of the estuary was dominated by postflexion larvae representing at least 21 taxa in 14 families. Rhabdosargus holubi of sizes ranging between 9 mm and 21 mm BL was the most abundant species with a mean density of 7.3 individuals per 100 m'. This species, which accounted for 77.6% of the catch composition, was recorded throughout the year but revealed a distinct peak in abundance in spring (August - September). The ichthyofaunal community within the East Kleinemonde estuary was dominated by juvenile marine-spawning species and typical of a warm temperate southern African estuary. A total of 30 species in 17 families was recorded, including the endangered estuarine pipefish Syngnathus watermeyeri. Multivariate analyses (classification and ordination) of the catch assemblages revealed a high degree of similarity (> 70%) throughout the estuary, with two distinct groups being identified on the basis of substratum type. The sampling stations near the mouth with a sandy substratum were distinguished from all other sampling sites in the estuary. The dominant estuarine-spawning species were represented by all life-history stages, suggesting that they bred successfully in the estuary. This group was numerically and gravimetrically dominated by the two zooplanktivorous shoaling species Gilchristella aestuaria and Atherina breviceps with density extrapolated population size estimates of 420 973 and 198 275 individuals, and biomass estimates of 1.6 and 0.6 g m⁻² respectively. The total population size of all estuarine-spawning species with a mean biomass 00.4 g m⁻² was estimated at 754 217 individuals. Population size estimates of the marine-spawning species were calculated using data obtained from three independent mark-recapture experiments. The assumptions for the mark-recapture analyses were adequately met and it was concluded that the techniques provided reliable estimates of population size. However, estimates obtained from density extrapolation revealed enormous variability and were considered to be unreliable. The total population size was estimated at 63 342, 18 592 and 13 5 192 during the three mark-recapture experiments respectively. The numerically dominant species during all three experiments was Rhabdosargus holubi. Biomass production of the marine-spawning species was evaluated over a 123 day census period when population sizes and estimates of growth rates were known. Productivity for all fishes with a standing stock of 26.2 g m⁻² was calculated at 4.5 g m⁻² month01 Rhabdosargus holubi accounted for more than 75% of the total marine fish productivity. This study draws attention to the success of Rhabdosargus holubi in the East Kleinemonde estuary, which is ascribed to aspects of its biology. These include an extended breeding season, the ability to recruit into the estuary under adverse open mouth conditions and its omnivorous food habits. The dominance of this migratory species suggests that it plays an important role in the transfer of energy to the coastal marine environment when the mouth of the East Kleinemonde estuary opens. Predation by birds and a dominant piscivorous fish (Lichia amia) was quantitatively assessed over a period of two years. Monthly food consumption by all piscivorous birds revealed large temporal variability, ranging from 32 to 466 kg month-I An unusual invasion of Cape cormorants during the winter of 1994 accounted for large scale mortality (2246 kg of fish) over a relatively short period. The predatory impact of this episodic event was reflected in the findings of the fish mark-recapture experiments, which revealed a 70% reduction in the total population of marine-spawning fishes (above a certain minimum size) in the estuary subsequent to this invasion. Monthly food consumption by the Lichia amia population in the estuary was calculated at 68 and 58 kg month-I for two distinct time periods when the population size was known. These findings suggest that this species is the top piscivorous predator in the East Kleinemonde estuary. Finally, the findings of this study highlight the temporal variability of fish populations within a single estuary. It is suggested that predation and estuary mouth conditions are the main factors influencing the abundance (and its variability) of individual species in the East Kleinemonde estuary.

M.A. (Environmental Management) / Reptiles are internationally one of the least studied taxa compared to all other vertebrates, and even less is known about the large arachnids. This proves problematic as the environmental management of reptile and large arachnid species is generally neglected or only partially considered in environmental impact studies and conservation. Consequently, there is a considerable lack of knowledge on the ecological requirements (dietary and habitat requirements) of reptiles and invertebrates. Furthermore, the environmental management of reptiles and large arachnids in the Leeuspruit Private Nature Reserve is restricted as no data exists on the assemblage of these taxa in the study area. A model based approach was used to examine the ecology of species of reptiles and large arachnids (scorpions and baboon spiders) that were found in the Leeuspruit Private Nature Reserve during this study. The study proposes a baseline analysis between the species found in the study area and the suitability and availability of the ecological requirements necessary to their survival. The ecological requirements of each species were noted and utilised as the variable input categories in a scoring model developed for this study. Each species identified in the study area was allocated points from the scoring model based on favourable ecological requirements for that particular species. Field work was conducted in the Leeuspruit Private Nature Reserve in the northern Free State Province (March 2012 – March 2013) to do a survey on reptile and large arachnid diversity and to record the habitats in which they occur. A list of the reptiles and large arachnids found in the Leeuspruit Private Nature Reserve was compiled. One of the significant results which came to light during this study is that the diversity and abundance of reptiles and large arachnids are dependent on the availability and diversity of habitats with the necessary ecological requirements for those species. For example, the distribution of snake species was largely dependent on the abundance of amphibians and birds for food which coincided with a seasonal wetland in the study area; while rocks and detritus proved imperative to the seasonal functionality of the reptiles.

Macrozoobenthic community structure and composition was investigated along a subtidal-intertidal gradient in the Mngazana Estuary. Six transects were sampled between the spring high water mark (HWST) and the bottom of the river channel in the lower estuary. Fifteen replicate samples were collected along each transect using a Van Veen type grab (211 cm2 bite) during each of three sampling sessions. Samples were sieved through a 500 μm mesh bag and the invertebrates stored in bottles for further analysis in the laboratory. Additional grab samples were collected for sediment particle size analysis and organic matter. Physical variables measured at each transect included: salinity, temperature, dissolved oxygen, depth, pH, percentage mud, organic content and turbidity. Sediment compactness was measured at all intertidal transects and additional sediment samples were collected at mid shore and high shore transects for percentage water content analysis. A total of 104 species were recorded along the intertidal-subtidal gradient in the sampling area. Species richness was higher in the subtidal zone compared to the intertidal zone and polychaetes numerically dominated the macrozoobenthic community at most transects, during all three sessions. At high shore transects the community was characterised by having fewer species, consisting mostly of brachyurans, polychaetes and gastropods. Shannon diversity index (H’) was generally higher for subtidal transects (x¯ = 2.3; range: 2.8 to 1) than for intertidal transects (x¯ = 1.4; range: 2.2 to 0.6) indicating that the distribution of individuals among species in the intertidal zone experienced greater variability. Results for Hill’s numbers followed the same trend as Shannon diversity with subtidal communities mostly consisting of abundant species followed by very abundant species. Intertidal communities generally exhibited lower numbers of abundant and very abundant species. Sedimentary characteristics played a major role in structuring benthic communities in comparison to other physico-chemical variables. Organic content and mud content of the substrate were identified as important factors influencing community patterns observed along the subtidal-intertidal gradient. In addition, sediment compactness and water content of the substrate was found to influence intertidal community structure. Subtidal community structure possibly had a greater dependence on seasonal variations in abiotic and/or biotic factors. Cluster dendrograms used in conjunction with MDS ordination mapping revealed that macrozoobenthic communities were generally distinct between high shore intertidal transects iii and subtidal transects. Most species exhibited a broad spatial distribution along the subtidal-intertidal gradient with mid and high shore transects being the exception. Most species also exhibited marked shifts in abundance and this was especially noticeable at the transition between the subtidal and intertidal zone. Two polychaete species, Prionospio sexoculata and Capitella capitata, were very abundant species and featured amongst the most numerically dominant species collected during each sampling session.

Through out this study ‘relational scenarios’ were seen as the possible outcomes of the expression of human-river relationships in a catchment. Working within Inglis’s (2008, pg. 10) comment that ‘the Human World Relationship is expressed through a person’s views and behaviour towards the natural world, which can be either constructive or destructive’, two relational scenarios were selected to represent these two predicted outcomes of human-environment (or in the case of this thesis human-river) relationships: IWRM, seen as constructive and mutually beneficial to both the social and ecological system, and the Tragedy of the Commons, seen as destructive and parasitic in nature. In respect to this assertion, a conceptual framework or model was developed and used to guide the inductive process of this research. Through a social survey (administered via semi-structured interviews) of stakeholders (water-users) in the Kat River Catchment, Eastern Cape, South Africa, social attitudes towards the Kat River were explored. These attitudes were considered as variables that relate to the expression of ‘Human World Relationships’ namely ‘values and behaviour’ (Inglis, 2008, pg. 10). The findings of this thesis confirm that attitudes are influential components of human-river relationships in the Kat River Catchment. It was observed from the findings that the attitudes individuals have towards the Kat River have the potential to influence the ways people interact with the River and its associated resources, and are in turn influenced by the condition of the River and connections people have or make with the River within their daily lives. Such relationships in turn affect the management of the River and its water resources and influence how individuals approach water-related issues and undertake the associated activities. Given this understanding it was then proposed that attitudes could provide information that enables the prediction of likely ‘relational scenarios’ (IWRM or the Tragedy of the Commons) in a catchment. The findings appear to support this proposal, and three main attitude groups (utilitarian, associative and dissociative) were identified and used to further the discussion into how this knowledge could be used in predicting possible relational scenarios based on human-river relationships. Further exploration of the identified attitude groups suggested that these variables are significantly influenced by environmental ethics and place attachment (present in the community) and a series of guiding frameworks were developed to facilitate the exploration of the attitude groups relative to these concepts. The frameworks were generated from the hypothesis that knowledge of attitude groups in a catchment, in connection with the relative degrees to which moral values and worldviews are expressed, could provide insight into the readiness of a catchment system for the implementation of IWRM and/or the facilitative steps needed to shift the influence of unfavourable attitude groups (i.e. dissociative attitudes). Such steps would most likely involve extensive educational, awareness and capacity building programs. Finally, given the above theoretical frameworks, inductively developed from the findings of the social survey and related literature, the conceptual model was reevaluated and extended to include the thesis findings and hypotheses. It is suggested that in a catchment where there is a balance between the expression of utilitarian and associative attitude groups, then there is a high probability of finding present evidence of mutually beneficial human-river relationships already in play, as well as ‘fertile soil’ for the promotion of IWRM and philosophies and skills that generate such relationships. Alternatively in an area with a strong expression of dissociative attitudes, it is more likely to find evidence of destructive, more parasitic-like relationships being expressed, and a lack of commitment and interest in being involved in changing the status quo. It is likely that where both associative and dissociative attitudes are present there will be an overlap of elements of both scenarios – a situation that is probable in most catchments – depending on the strength of expression of either attitude group the balance will shift (be shifting) between the two relational scenarios.

Increased abstraction of water in the catchment results in a reduced or altered pattern of river flow and this holds serious consequences for the downstream estuarine ecosystem. In South Africa this is a serious concern because freshwater is in limited supply and the demand for freshwater can be expected to increase in the future. A large multi-disciplinary consortium of South African scientists are working on projects to determine the freshwater requirements of estuarine ecosystems. As part of this, this thesis reports on research undertaken to develop mathematical models to determine the freshwater requirements of estuarine macrophytes. Three key macrophytes are selected. The macrophytes are Zostera capensis Setchell, Ruppia cirrhosa Grande, and Phragmites australis. They are common macrophytes in South African estuaries. Zostera and Ruppia are submerged macrophytes and Phragmites is an emergent macrophyte. They have different freshwater environments and therefore respond differently to alterations in freshwater flow. A first order differential equation model is used to determine the effect of different combinations of open and closed mouth conditions of the estuary on Zostera and Ruppia. The scenarios are selected to determine whether achieving a switch in states from a Zostera-dominated estuary to a Ruppia-dominated estuary is possible. To predict encroachment rates and colonisation patterns, a cellular automaton of the vegetative spread of existing Zostera beds is developed. After analysing various scenarios accounting for both an increase and a decrease in freshwater supply, the cellular automaton is extended to include interactions between Ruppia and Phragmites. The multi-species model is applied to the Kromme estuary, South Africa and the Great Brak estuary, South Africa. Various freshwater scenarios are examined from the natural runoff condition to the situation of no freshwater inflow. A sensitivity analysis of the spatial model with Zostera, Ruppia and Phragmites is conducted. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1998.