In South Africa, the loss of wetlands and their associated benefits has been considerable. A need was identified for a system that, using available information, would assist in achieving a balance between local, mainly short-term benefits to individuals and spatially wider and longer term benefits to society. Such a system, termed WETLAND-USE, was developed with the philosophy that:(l) wetlands have been well demonstrated to supply several indirect benefits to society (e.g. water quality enhancement); (2) the impact on these benefits can be described on a qualitative basis using field indicators that characterize the wetland and the disturbance associated with a particular land-use; (3) this information can be communicated to wetland users, which will contribute to achieving a desired balance, provided there is an enabling organizational environment and due consideration is taken of the socio-economic and organizational factors affecting wetland management. The primary conceptual framework underlying WETLAND-USE was the pressure-state-perceptions-policy framework, which depicts: the mode of use (i.e. the pressure); how this affects the state of the system (including its underlying processes and the goods and services it delivers); which in turn shape the perceptions that ultimately determine the policy pertaining to further use. This cycle is repeated at a range of organizational levels from local to national and takes place within a particular socioeconomic context. WETLAND-USE, which was designed for use by fieldworkers, and built using a rule-based, expert system approach, has two main parts, dealing largely with biophysical and social aspects respectively. Part 1, which guides the collection of data relating to the state of the wetland, assists in: (1) predicting the likely impacts of disturbances associated with a proposed land-use (the pressure) on the wetland state, and (2) providing ongoing management guidelines for particular land-uses. Part 2 assists in: (1) describing the social, land tenure and policy contexts of the wetland; and (2) establishing and maintaining organizational arrangements, local policy and management objectives and goals. Several discrete investigations were required for the development and refinement of WETLAND-USE, which was done in an iterative fashion. Initial discrete investigations fed into the development of a prototype system which was refined through evaluation using a questionnaire survey and further discrete investigations. The revised system was re-evaluated using a fieldworkshop approach and, based on the performance of the system in the field, it was revised further to produce the final system. In the two initial discrete studies, protocols were developed for characterizing key physical determinants of wetland functioning, notably: (1) degree of wetness, one of the primary functional determinants, described in the field using readily identifiable soil morphological indicators (e.g. matrix chroma and mottles) and (2) landform setting, which strongly influences local flow patterns and lateral exchange of water and water-borne materials. Graminoid plant species composition and functional groups (defined in terms of photosynthetic pathway) were then described in relation to the above physical determinants, together with rainfall, temperature and soil texture, within wetlands spanning a wide altitudinal range. This revealed that degree of wetness and altitude had the strongest influence over the vegetation parameters examined. An investigation into incorporating cumulative impacts into wetland decision making revealed that consideration should be given to: wetland loss in relation to ecoregions and catchments, and the relation of change in wetland extent, spatial configuration and context respectively to wetland function. Current conservation initiatives in KwaZulu-Natal were shown to account poorly for cumulative impacts on wetlands. Rules of thumb for making such considerations, given severe data limitations, were developed with reference to the high turn-over of species along the altitudinal gradient observed in the vegetation study. The "rules" were than applied to a case-study, the upper Mgeni catchment, as part of an initiative to engage a diversity of stakeholders in wetland information gathering and use. This resulted in the selection of priority wetlands in the catchment and an examination of the extent to which integration had been achieved vertically (across hierarchical levels) and horizontally (across organizations within particular hierarchical levels). In order to broaden the range of land-uses accounted for by the WETLAND-USE prototype, it was applied to a communally used wetland, Mbongolwane, and found to account poorly for the traditional cultivation and vegetation harvesting practices encountered. WETLAND-USE was modified to include a greater diversity of land-use types as well as enhancing its capacity to allow assessments to be conducted using the system's general criteria, thereby making WETLAND-USE more robust. In enhancing the capacity of WETLAND-USE to account for the social and organizational dimension of wetland management, the involvement of local and outside organizations in influencing wetland resource use in five sites was examined in relation to predefined frameworks. The sites, Mandlazini wetland, Mbongolwane wetland, Blood River vlei, Ntabamhlope vlei and Wakkerstroom vlei were chosen to represent a diversity of social contexts and management authorities. This revealed that in communally used areas in particular, a wide range of organizations are involved to varying degrees in influencing the use of different wetland resources. The level to which the local organizational environment contributed to sustainable use varied greatly among wetlands, but in all cases had important deficiencies: (1) self-governing resource-management organizations were largely lacking and in communal areas were weakening under contemporary conditions; and (2) although a formal management system was in place in two of the five wetlands, it was largely absent in the remaining three. There has been little involvement from extension services in facilitating local policy development and in promoting alternative land-uses which have less pressure on the state of the wetland. Local wetland management policy and collaboration among land-owners in wetlands under multiple separate ownership such as Blood River vlei was identified as being particularly poor. The evaluations of WETLAND-USE revealed that, in relation to the underlying philosophy of the thesis, WETLAND-USE had been improved through field application and incorporation of the findings of the discrete investigations. Nevertheless, important limitations of the study were highlighted, including: its high level of reliance on expert opinion in the face of a paucity of empirical data relating to the functioning of local wetlands and their attendant benefits (and how these are affected by anthropogenic disturbances), and a particularly shallow representation of socio-economic factors. The identification of these limitations was useful in highlighting key areas for further research. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1999.

Palmiet peatlands in the agricultural landscape are viewed by farmers as problematic. They obstruct the effective passage of water along watercourses and therefore promote localized flooding of lands and infrastructure, and they trap sediment delivered along watercourses that drowns fields and infrastructure with sedimentary deposits. These events are problematic for farmers trying to make a living off the land. Wetlands are also often viewed as wastelands that should be put to more productive use. The obvious thing to do is to bring in machinery to drain the wetlands and improve the flow of water and sediment through these wetlands.

The Nelson Mandela Bay Municipality (NMBM) is a semi-arid area along the southern coastline of South Africa (SA). Until recently, there was no systematic approach to research on wetland systems in the NMBM. The systematic identification of wetlands was made more difficult by the relatively large number of small, ephemeral systems that can be difficult to delineate. This has meant that fundamental knowledge on wetland distribution, structure and function has been limited and, consequently, management and conservation strategies have been based on knowledge on systems from other regions of the country. Environmental processes occur at different spatial and temporal scales. These processes have an effect on the abiotic factors and biotic structure of wetlands, resulting in inherently complex systems. The location of the NMBM provides a good study area to research some of these environmental and biological attributes at different spatial scales, due to the variability in the underlying geology, geomorphology, vegetation types and the spatial and temporal variability in rainfall, within a relatively small area of 1951 km2. Thus, the aim of this study was to determine the factors influencing wetland distribution, structure and ecosystem functioning within the NMBM. The first Research Objective of work presented here was to identify wetlands using visual interpretation of aerial photographs. A total of 1712 wetlands were identified within the NMBM using aerial photographs, covering an area of 17.88 km2 (Chapter 5). The majority of these wetlands were depressions, seeps and wetland flats. Valley bottom wetlands (channelled and unchannelled) and floodplain wetlands were also identified. A range of wetland sizes was recorded, with 86% of the wetlands being less than 1 ha in size and the largest natural wetland being a floodplain wetland of 57 ha, located south of the Swartkops River. The identified wetlands were used to create a wetland occurrence model using logistic regression (LR) techniques (Chapter 5), in accordance with Objective 2 of the study. An accuracy of 66% was obtained, which was considered acceptable for a semi-arid climate with a relatively high degree of spatial and temporal rainfall variability. The model also highlighted several key environmental variables that are associated with wetland occurrence and distribution at various spatial scales. Some of the important variables included precipitation, evapotranspiration, temperature, flow accumulation and groundwater occurrence. Wetland distribution patterns were described in Chapter 6. Spatial statistics were used to identify whether wetlands are clustered and, therefore, form mosaics within the surrounding landscape (Objective 3). Systems were found to be highly clustered, with 43% of wetlands located within 200 m of another system. Clustering and wetland presence was especially prominent in the southern portion of the Municipality, which is also associated with a higher mean annual precipitation. Smaller wetlands were also significantly more clustered than larger systems (Average Nearest Neighbour statistic, p-value < 0.0001). Average distances also significantly varied according to HGM type, with depressions being the most geographically isolated wetland type compared to the other HGM types. Overall, distances between wetlands indicated good proximal connectivity. Potentially vulnerable areas associated with wetland systems were identified successfully using landscape variables, in accordance with Objective 4. These variables were: land cover, slope gradient, flow accumulation, APAN evaporation, mean annual precipitation (MAP) and annual heat units. The existing Critical Biodiversity Network was also used in connection with these variables to further identify potentially vulnerable areas. The abiotic and biotic characteristics were decribed for three hydrogeomorphic (HGM) types at a total of 46 wetland sites (Chapter 7), as per Objective 5. Depressions, seeps and wetland flats were sampled across the different geological, vegetation and rainfall zones within the NMBM. The wetland sites were delineated up to Level 6 of the Classification System used in SA, and the various abiotic and biotic characteristics of these systems were defined. A total of 307 plant, 144 aquatic macroinvertebrate and 10 tadpole species were identified. Of these species, over 90 species were Eastern Cape and SA endemic species, as well as three threatened species on the IUCN Red List. Multivariate analyses (including Bray-Curtis similarity resemblance analyses, distance-based redundancy analyses, SIMPER analyses and BIOENV analysis in Primer), together with environmental data, were used to define community structure at an HGM level, in accordance with Objective 5. The importance of the spatial scale of the environmental data used to define plant and macroinvertebrate community structure was described in Chapter 7, to address Objective 6. The results showed that both broad-scale and site-level characteristics were important in distinguishing community structure within the HGM types that superseded general location, the sample timing or the stage of inundation. These results also indicated that a combination of both landscape and site-level data are important in defining the community structure in the various HGM types. Some of the important environmental variables that explained some of species assemblages were similar to those in the wetland occurrence model (Chapter 5), with some additional hydrological and soil physico-chemical parameters (e.g. soil electrical conductivity, soil pH, and surface and subsurface water nutrients). These significant variables indicate the complex, multi-scalar role of environmental attributes on wetland distribution, structure and function.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Wetlands are key to providing important ecosystem goods and services yet they are under threat from a number of anthropogenic activities. In particular, in this study area, agriculture in the form of sugarcane farming is a threat to wetlands as sugarcane is reliant on a good water supply. The impacts of sugarcane farming emanates from the fact that sugarcane is a mono crop that requires wetland resources and uses a lot of pesticides and fertilisers. Despite the assumed contribution of sugarcane farming to wetland loss and degradation, few studies have quantitatively assessed the spatio-temporal changes in wetland extent as well as changes in water quality because of this activity. This study assesses the impacts of sugarcane farming on wetland extent and water quality in two coastal wetlands of KwaDukuza, North coast of Zululand, South Africa. Specifically this study sought to (i) assess the impacts of sugarcane farming on the spatial extent of wetlands between 1959 and 2012, (ii) determine if sugarcane farming negatively affect water quality within the wetlands and (iii) evaluate the perceptions of local farmers regarding impacts of sugarcane farming on wetlands. Results of the study indicated an increase in the extent of Zinkwazi sugarcane fields from 62.3% to 67% between 1959 and 1989 and Nonoti sugarcane fields’ extent increased from 50.5 % to 56.4% between 1959 and 2000. The last decade from the year 2000 showed gradual decrease in the area of wetland farmed by sugarcane due to the global sugar price remaining static while the cost of farming inputs increased and due to conversion of some farms to urban developments. Unfortunately, this has not lead to an increase in wetland area as the waterfront type developments, as well as a formal settlement have replace the sugarcane in the wetlands. Water was analysed for nitrogen (N), phosphorus (P) and potassium (K) and results for both Zinkwazi and Nonoti indicated an increasing trend of N and P from upstream to the middle region of the rivers and a decreasing trend of the N and P from the middle region to downstream. Sugarcane farming does not take place below the middle region and so does not provide fresh sources of these nutrients. The downstream area where the N and P decrease also coincides with the area of the river under tidal influence such that the N and P are being diluted by the incoming tidal seawater. K showed an increasing trend from upstream to downstream and its values were higher than N and P. Concentrations of N and P above the South African water quality guidelines for aquatic ecosystem were recorded in the middle region. Furthermore, farmers’ perceived wetlands to have been transformed to agricultural land and related these changes to their sugarcane farming activities. It can thus, be concluded that sugarcane farming has resulted in wetland loss as well as deterioration of water quality within the Zinkwazi and Nonoti wetlands in KwaDukuza. In that regard, there isneed to engage farmers in wetland management programs in order to reduce the negative environmental impacts associated with sugarcane farming in wetlands. / AFRIKAANSE OPSOMMING: Vleilande is die sleutel tot die verskaffing van ‘n belangrike ekosisteem dienste, maar hulle is onder ‘n bedreiging deur 'n aantal menslike aktiwiteite. In besonder in hierdie studie area, is Argriculture in die vorm van suikerriet boerdery is bedraging vir vleilande, en suikerriet is afhanklik van 'n goeie watervoorraad. Ten spyte van die veronderstelde bydraes van suikerriet boerdery, is die vleiland aan die agteruitgang, 'n Paar studies het kwantitatief die tydruimtelike veranderinge in die vleiland, sowel as veranderinge in die gehalte van water as gevolg van hierdie aktiwiteit waargeneem. Spesifiek is hierdie studie gepoog om (i) te bepaal wat die impak van suikerriet boerdery op die ruimtelike omvang van die vleiland tussen 1959 en 2012 is, (ii) bepaal of suikerriet boerdery negatief beïnvloed is deur die gehalte van water in die vleilande en (iii) die persepsies van plaaslike boere rakende die evalueering en impak van suikerriet boerdery op die vleilande. Resultate van die studie het aangedui 'n toename in die omvang van Zinkwazi suikerriet velde van 62,3% tot 67% tussen 1959 en 1989, en die Nonoti suikerriet velde toegeneem het met 50,5% tot 56,4% tussen 1959 en 2000. Die laaste dekade van die jaar 2000 het geleidelike afname in die area van die vleilande getoon, omdat suikerriet as gevolg van die globale suiker prys die koste van boerdery-insette verhoog het, en dit het gelei tot die omskakeling van 'n paar plase na stedelike ontwikkelings. Ongelukkig het dit nie gelei tot 'n toename in die vleiland gebiede nie, met die gevolg die waterfront tipe ontwikkelings, asook 'n formele nedersetting, vervang die suikerriet in die vleilande. Water is ontleed vir N, P en K en resultate vir beide Zinkwazi en Nonoti, het aangedui 'n toenemende tendens van stikstof en Fosfor. Dit gaan stroomop na die middel-streek van die riviere en 'n dalende neiging van die N en P uit die middel streek stroomaf. Suikerriet boerdery vind nie plaas onder die middel streek nie, en so is daar nie vars bronne, wat van hierdie voedingstowwe verskaf nie. Die stroomaf gebied waar die N en P ‘n afname het, val ook saam met die gebied van die rivier onder die gety , en dit beinvloed sodanig dat die N en P se water verdun word deur die inkomende gety se seewater. K het 'n toenemende neiging van stroomop en stroomaf en sy waardes is hoër as van die N en P. Konsentrasies van N en P bo die Suid-Afrikaanse water standaard riglyne is in die middel streek aangeteken. Verder, beskou boere dat die vleilande behoort te verander om die landbougrond en verwante veranderinge aan hul suikerriet boerdery en aktiwiteite. Ons kan dus aflei dat suikerriet boerdery het gelei tot die vleiland se verlies asook die verandering in die watergehalte in die Zinkwazi en die Nonoti vleilande in KwaDukuza. In dié verband is dit nodig dat die boere in die vleiland by programme betrek word ten einde die negatiewe omgewingsimpakte wat met suikerriet boerdery gepaard gaan in vleilande te verminder.

M.Sc. (Environmental Management) / Wetlands play a significant role in our environment as they provide a variety of goods, services and benefits to living species ranging from humans, animals and plants to microorganisms. Despite their importance, wetlands have somewhat been neglected over the past few years which has led to a rapid deterioration of wetland conditions and functions. Wetlands provide unique functions that cannot be provided by any other ecosystem; their value was recognised in the 1960s. Prior to this realisation the value of wetlands had been seriously underestimated to the extent where they were even previously labelled as “wastelands”. The reality is that to date minimal measures have been put in place to assist in the rehabilitation and future conservation of wetlands. The lack of wetland management and monitoring can be attributed to the fact that very little is known about the functioning of some of the wetland systems. Endorheic wetlands have recently been emerging as ecosystems of importance. Very little is known about endorheic wetlands and their ecological functioning. To date a fair amount of studies have been conducted on the pans in Mpumalanga and in the Free State but minimal information exists on the pans in the North West Province. The objectives of this study were therefore to compare the abiotic and biotic composition of pans in Mpumalanga and North West Provinces, in order to contribute to the knowledge which will eventually assist in devising rehabilitation measures and future conservation of pans in the area. Three different water ecosystem components were studied; these included aquatic invertebrate communities, water quality and sediment characteristics. The collected water samples were taken to an accredited laboratory to be analysed. When compared between the two provinces, the water-quality results indicated differences between provinces as well as among individual pans. However, most of the pans in both provinces show characteristics of being dystrophic alkaline systems. The invertebrates were collected using sweep nets and stored in jars containing 5% neutrally buffered formalin and a staining agent (Rose Bengal). The sediment characteristics were determined by using standard techniques and results showed that there were no obvious similarities between the different pans in the different provinces. Water-quality analyses were performed on samples taken during both winter- and summer-sampling surveys and these samples were analysed by a reputable laboratory. Based on the analyses of the invertebrate community samples, 25 taxa were identified; results show similarities in the structure of communities in both provinces with the exception of one or two different species. Sampling was conducted over a period of two seasons at all sampling points and several species were found belonging to different families. Invertebrates sampled in Mpumalanga pans were similar to those reported in previous studies done in the area and most of the invertebrates sampled in Mpumalanga and the North West are known to be commonly found in temporary habitats. Spatial and temporal variations in invertebrate assemblages were determined; this analysis displayed differences in the different variables (biotic, physical and chemical) tested over the two seasons. The pans in Mpumalanga were dominated by coarse sand. Large amounts of coarse sand accompanied by poor water quality were observed in MP Pan A in Mpumalanga Province; this could be an indication of somewhat poor catchment management. The results of the abiotic and biotic comparison show that there are minor similarities and differences among the selected pans studied in each province. The knowledge acquired can now be utilised to enhance the available literature on these pans. Long-term studies have to be done to better understand the ecological functioning of the pans in the North West Province in order to devise mitigation measures as well as appropriate rehabilitation strategies and conservation measures.

M.Sc. (Aquatic Health) / Wetlands play an extremely important role in the hydrological cycle as well as biodiversity. Until recently, however, wetlands in South Africa have been neglected both in terms of research and monitoring. The lack of knowledge is even greater for the inward draining wetlands, which is better known as pans. Pans are isolated aquatic systems, which are quite shallow and do not have an outlet. Pans receive water from precipitation and surface runoff, and lose water mainly through evaporation. Some pans can be ephemeral (dry up often) and other perennial (dry up only during drought). The little ecological knowledge available is mainly focused on these ephemeral pans. In this present study conducted in the Western Free-State province, study was only focused on the perennial pans in this area. Due to the fact that this province are one of the biggest areas for gold mining in the country, the pans suffer under the impacts, and this results in the alteration of community structures in and around the pan, simplifying food chains which can lead to the collapse of an ecosystem. The aim of the study was to assess the water quality, bioaccumulation of toxicants (metals and pesticides) in sediment and aquatic invertebrate community of perennial pans in the Western Free State Province, mainly because of the lack of literature on pans in these areas. Seventeen pans were selected for the study of which eight were classified as saline eutrophic and nine as alkaline dystrophic. Various physico-chemical and sediment characteristics were assessed in addition to the characterization of the aquatic invertebrate communities. It became clear that there is great difference in the physical-chemical characteristics of the selected pans. The difference in the trophic state was the most clear, with differences in water colour, nutrient concentration and vegetation growth, classifying pans as either saline eutrophic or alkaline dystrophic. These trophic states influence the distribution and richness of aquatic invertebrates in certain pans. Mining activity, urbanization, agricultural activities and sewage runoff into the pan, all affects the pans negatively, there is sighs of water quality degradation as well as changes in the community structure of invertebrates when compared to the reference pans.

Lake St Lucia in northern KwaZulu-Natal, South Africa, experiences severe ecological stress during dry periods largely as a result of diminishing freshwater supplies and conditions of hypersalinity. Possible intervention involves diverting the Mfolozi River to the St Lucia Lake system. However, due to high sediment loading, water from the Mfolozi river requires considerable filtration before a link can be established. A suggested option considered in this study is to restore the existing sugarcane farmlands on the Mfolozi Floodplain (~20 800 ha) to previous wetland conditions to reinstate a sediment removal function amongst other benefits. Proposed restoration will have a direct impact on the industries currently supported by the iSimangaliso Wetland Park and the Mfolozi Floodplain (tourism, sugar, conservation). to understand a measure of such impacts, ecosystem services for both Lake St Lucia and the Mfolozi Floodplain were analysed (flood alleviation, water provision, water purification, sediment regulation, tourism, fisheries, vegetation for harvest, existence, cultural and research). Annual economic values for each ecosystem service were determined by means of valuation methods that included benefit transfer and replacement cost. Results showed a current annual minimum value of the Mfolozi Floodplain and Lake St Lucia as greater than R21 million and R1.1 billion respectively. Partial restoration of the floodplain (~6 000 ha) is expected to increase the sum of all ecosystem services values by approximately 26% for the Mfolozi Floodplain and by 23% for the St Lucia System. Full restoration (~20 800 ha) increases the total ecosystem services value by 88% and 50% for the Mfolozi Floodplain and St Lucia System respectively. Results showed that economic values for existence, fisheries, tourism and water provision increase by the greatest percentage for the St Lucia System under both restoration scenarios. Partial and full restoration of the floodplain will result in the greatest increases in economic value for the services existence, tourism, fisheries and the harvesting of vegetation on the Mfolozi Floodplain.

Wetlands provide a number of valuable functions to both the surrounding environment and society. The anaerobic conditions created by flooding in wetlands provide a habitat that supports unique assemblages of plant life. High altitude wetlands are amongst the most species-rich in South Africa. They house a number of rare species and play a vital role in the supply of water to lower lying areas. These are some of the reasons that mountain wetlands are of high conservation value. A phytosociological study was undertaken on the high altitude wetlands of the Great Escarpment with the aim of classifying the plant communities and identifying the environmental drivers of plant community patterns within these ecosystems. Data collection was focused in the Eastern Cape and was supplemented with data from existing studies to gain a more complete understanding of the wetlands of the Great Escarpment of South Africa. Using the Braun-Blanquet approach, Hierarchical Cluster Analysis and Indicator Species Analysis; five broad wetland groups were identified, comprised of 33 individual plant communities and 81 indicator species. Multivariate analysis, including Canonical Correspondence Analysis revealed that the effects of altitude, such as temperature and rainfall, are the most significant large-scale drivers of vegetation patterns. Smaller scale drivers include wetness and soil nutrients including nitrogen, phosphorus, electrical conductivity, sodium, and organic content. The identification of indicator species served to reveal potentially important wetland species across different areas of the Great Escarpment. The effects of altitude on plant community patterns highlights the susceptibility of the high altitude specific communities to upward temperature zone shifts resulting from global warming. Other threats include livestock trampling, water extraction, and land use change for agricultural purposes. The relative absence of alien species in these wetlands gives an indication of their pristine condition and therefore their importance as a reference from which they may be monitored. A large proportion of the wetlands studied here occur outside protected areas, and given the rate of wetland loss in South Africa, it is important that continued effective land management is practiced to ensure that these ecosystems are conserved in the future .

Wetlands in South Africa are increasingly coming under threat from agriculture and urban development and rapidly disappearing, especially small, ephemeral wetlands. In response to the many threats to wetlands, South Africa has seen an increased interest in wetland research, which has introduced many methods to help standardize the approach to research, management and conservation of wetlands. Remote sensing can be a powerful tool to monitor changes in wetland vegetation and degradation leading to losses in wetlands. However, research into wetland ecosystems has focused on large systems (> 8 ha). Small wetlands (< 2 ha), by contrast, are often overlooked and unprotected due to the lack of detailed inventories at a scale that is appropriate for their inclusion. The main aim of this study was to determine if remote sensing (RS) and Geographical Information System (GIS) techniques could detect changes in small, ephemeral wetlands within areas under different management regimes in the Nelson Mandela Bay Metropole (NMBM) at different time intervals. Further, to explore the potential of hyperspectral remote sensing for the discrimination between plant species and to see if differences could be detected in the same species within two areas different management regimes. Four SPOT satellite images taken within a 6-year period (2006-2012) were analysed to detect land cover land changes. Supervised classification to classify land cover classes and post-classification change detection was used. Proportions of dense vegetation were higher in the conservation area and bare surface was higher outside that conservation area in the metropolitan open space area. Statistical tests were performed to compare the spectral responses of the four individual wetland sites using Normalized Difference Vegetation Index (NDVI) and red edge position (REP) .REP results for conserved sites showed significant differences (P < 0.05), as opposed to non-conserved ones. By implication, wetland vegetation that is in less degraded condition can be spectrally discriminated, than the one that is most degraded. Field spectroscopy and multi-temporal imagery can be useful in studying small wetlands.

Thesis (MSc)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Understanding the responses of individual plant communities to variations in near-surface water levels and to water quality is a step towards determining the critical or important factors applicable to a Rapid Wetland Assessment System. This thesis describes and discusses factors associated with wetland plant communities, with an attempt to predict changes in a wetland system. This study was initiated with a primary aim of establishing the relationship between plant communities and the variation in near-surface water levels in areas occupied by various plant communities in the Middelvlei wetland system at Stellenbosch. A second aim was to assess whether water quality had an influence on the plant communities. Seven plant communities are identified and described from this particular wetland system using standard Braun-Blanquet techniques (Typha capensis Reedswamp; Cyperus textilis Sedgeland; Pennisetum macrourum Grassland; Juncus effusus Sedgeland; Cyperus longus Sedgeland; Cliffortia strobilifera Shrubland and Populus canescens Forest). The Typha capensis Reedswamp community is found in the wettest parts of the wetlands, with a fluctuation in water table from 0.10 m above surface during the wet season to 0.43 m below surface during the dry season. The Populus canescens Forest is actively invading the wetland replacing the wetland species by modifying the wetland hydrological condition. Water samples from 35 wells, collected on a monthly basis over 11 months, are used to assess sodium, magnesium, potassium, calcium, nitrate and phosphate, pH, redoxs potencial and dissolved oxygen levels in each community, over four seasons. Both multivariate analysis (ANOVA) and regression tree analysis (CART) are applied to evaluate differences between communities or groups of plant communities on a seasonal basis. Direct gradient analysis (CCA) is used to determine the relationship between plant communities and environmental variable gradients. A wide variation in water quality condition between plant communities is present. The Typha capensis Reedswamp community is associated with low nutrient levels (phosphates and nitrates) in all seasons. The Cyperus textilis Sedgeland is associated with low levels of nitrates and high phosphate levels. The Juncus effusus Sedgeland displays the highest phosphate concentration, occurring in summer, while low nitrate levels occur in this community during all the seasons. Dissolved oxygen in the near-surface water in this wetland is at very low concentrations, and has no significant difference between communities. It plays no major role in determining the occurrence and distribution of the plant communities. Most of the water chemical constituents measured in this study are the result of multiple complex relationships, with constituent variations occurring differently between communities. A remarkable seasonal distinction in the chemical constituents in different communities is present. Despite the complex nature of the relationships between plant communities and environmental factors, the low species diversity levels through the tendency for single species dominance and the strong association of these communities with particular environmental variables, the combination of these factors all add value to the use of wetland vegetation as a good tool to indicate wetland condition. An effort to understand wetland plant communities in relation to determining environmental factors would promote the use of plant communities as user-friendly tools for wetland monitoring and assessment. / AFRIKAANSE OPSOMMING: Om die reaksies van plantgemeenskappe teenoor variasies in naby-oppervlakte watervlakke te verstaan, is die eerste krities-belangrike faktor die ontwikkeling van ‘n sisteem om vleilande vinnig te assesseer. Hierdie studie se basiese mikpunt is om verwantskappe te soek tussen plantgemeenskappe in die Middelvlei Vleilandsisteem en wisseling in naby-oppervlak watervlakke. ‘n Sekondêre doel is om te bepaal of daar enige korrelasie is tussen waterkwaliteit en die plantgemeenskappe teenwoordig in die vleiland. Sewe plantgemeenskappe is in hierdie vleilandsisteem geïdentifiseer en beskryf deur gebruik te maak van standaard Braun-Blanquet tegnieke, naamlik die Typha capensis Rietmoeras; Cyperus textilis Biesieveld; Pennisetum macrourum Grasveld; Juncus effusus Biesieveld; Cyperus longus Biesieveld; Cliffortia strobilifera Struikveld en ‘n Populus canescens Woud. Die Typha capensis Rietmoeras kom in die natste dele van die vleilande voor, met vrywater wisselling vanaf 0.10 m bo grondoppervlakte, tydens die nat-seisoen, tot 0.43 m onder grondoppervlakte tydens die droë seisoen. Die Populus canescens Woud het die grootste wisseling in watervlak vanaf die grondoppervlakte tot ten minste ‘n diepte van 1.0 m gehad. Dit blyk dat die Populus canescens Woud besig is om die vleigemeenskappe aktief binne te dring deur die vleiland uit te droog. Water is maandeliks, oor 11 maande, uit 35 geperforeerde plastiek pype, sogenaamde ‘putte’ onttrek, om natrium, magnesium, kalium, kalsium, nitrate en fosfate, pH, redokspotensiaal en opgeloste suurstof vlakke se seisoenale wisseling te bepaal. Beide veelvuldige analise (ANOVA) en regressie-analises (CART) is bereken om enige betekenisvolle verskille tussen plantgemeenskappe te bepaal. Direkte Gradiëntanalise (CCA) is gebruik om die verwantskap tussen plantgemeenskappe en gradiënte van omgewingsveranderlikes te bepaal. Groot variasies in waterkwaliteit tussen plantgemeenskappe is waargeneem. Die Typha capensis Rietmoeras-gemeenskap is geassosieer met lae voedingstofvlakke (veral van fosfate en nitrate) in alle seisoene. Die Cyperus textilis Biesieveld-gemeenskap is geassosieer met lae nitraat- en hoë fosfaatvlakke. Die Juncus effusus Biesieveldgemeenskap vertoon die hoogste fosfaatvlakke, tydens die die somermaande, terwyl die nitraatvlakke deur al die seisoene ook laag bly. Opgeloste suurstof in die naby-oppervlakte water in die vleilandsisteem het deurgaans ‘n lae konsentrasie vertoon met geen betekenisvolle verskille tussen gemeenskappe nie. Dit speel dus geen belangrike rol in die voorkoms of verspreiding van die plantgemeenskappe nie Die meeste van hierdie faktore, gemeet om die waterkwaliteit te bepaal, het veelvoudige, komplekse verhoudingsverskille, gebaseer veral op konsentrasieverskille, tussen die gemeenskappe. Ten spyte van die komplekse verwantskap tussen die plantgemeenskappe en omgewingsfaktore, is die spesierykheid laag en kom die neiging tot eensoortigedominansie algemeen in die vleiland-plantgemeenskappe voor. Die sterk assosiasie tussen die plantgemeenskappe en bepaalde omgewingsveranderlikes voeg aansienlike waarde daaraan toe om vleilandplantegroei te gebruik as indikator van vleilandtoestand. ‘n Poging om die verwantskappe tussen vleiland-plantgemeenskappe en omgewingsveranderlikes algemeen te bepaal, sal die gebruikersvriendelike nut van vleiland-plantgemeenskappe vir vleilandmonitering en assessering duidelik uitwys.