Donovan C. Kotze

The role of geomorphology in evaluating remediation options for floodplain wetlands: the case of Ramsar-listed Seekoeivlei, eastern South Africa

The range of benefits bestowed by wetlands is today increasingly recognized, and remediation of degraded wetlands is being carried out around the world. Many degraded wetlands are associated with river floodplains, and an essential requirement for their remediation planning is a comprehensive knowledge of the geomorphological functioning of the river channel and floodplain. Here, we review previous geomorphological investigations of the Ramsar-listed Seekoeivlei floodplain wetlands, Free State Province, South Africa, and demonstrate how the knowledge gained is playing a key role in evaluating remediation options that are needed following more than a century of direct and indirect human impacts. Faunal and floral changes, coupled with channel modifications, have altered the flow and sediment regime and initiated major changes to erosional and depositional patterns, including promoting rapid headward growth of a new channel and abandonment of a former channel. These changes have led to further management interventions, including installation of weirs and erosion control structures. In an ideal world, remediation would strive to return a wetland to its natural, pre-impact state but, in reality, other management goals have to be taken into consideration. In the case of Seekoeivlei, these include maintaining current habitat and biodiversity (this has the added advantage of promoting local tourism, especially bird watching), and using the wetlands for water quality enhancement. Attempts to return the wetlands to their pre-impact state (e.g. by removing exotic trees and erosion control structures) would in fact further reduce habitat and biodiversity, permanently in the case of some avian species, and for centuries in the case of some aquatic species, because of the very slow natural rates of channel and floodplain change. Alternative options will all require ongoing intervention, albeit of variable intensity, but in effect will mean that the wetland will never return to its pre-impact state. Remediation will thus create an essentially ‘artificial’ wetland complex that restores some of the ecological and hydrological functions but that is likely to remain very far from its natural geomorphic condition.

Testing the applicability of the SASS5 scoring procedure for assessing wetland health: a case study in the KwaZulu-Natal midlands, South Africa

A study was undertaken between 29th January and 17th February 2004 to test the applicability of the South African Scoring System Version 5 (SASS5) scoring and calculation procedure in nutrient-enriched palustrine wetlands in the midlands of KwaZulu-Natal, South Africa. Four reference wetlands and three dairy-effluent impacted wetlands were sampled. Six macroinvertebrate samples were collected with a SASS net from each wetland. For each sample, the macroinvertebrates were identified and assigned a predetermined SASS5 tolerance score. Data for selected physico-chemical variables, macrohabitat condition, biotope suitability and organism detectability were collected to assist in interpretation of results. Thirty-eight taxa, identified to family level, were collected during sampling. Total SASS5 scores ranged from 15 to 82. Five of the wetlands had mean SASS5 scores of between 46 and 59. Five of the wetlands had an intra-wetland SASS5 score range of greater than 30. Average score per taxa (ASPT) values ranged from 3.3 to 5.5, and few high scoring (≥ 8) taxa were collected. There was no significant difference in SASS5 scores between samples collected above, at, and downstream of, an effluent discharge point within the same impacted wetland. SASS5 scores for reference wetlands were also not significantly higher than those recorded for impacted wetlands. Comparison of ranked SASS5 scores and environmental data did suggest a relationship between the variables, but this was not significant. Based on the SASS5 score water quality guidelines, all sampled wetlands were considered to have impacted water quality. However, this was not supported by the macrohabitat and physico-chemical results. There are a number of possible reasons for the low SASS5 scores: the lack of biotopes present in wetlands compared to rivers (most notably the absence of the stones-in-current biotope), lower levels of dissolved oxygen present compared to rivers, limited habitat availability due to low rainfall during the sampling season, and the limited detectability of organisms due to large amounts of substrate in the samples. Without modification, SASS5 appears unsuitable for assessing wetlands. However, variation in taxon composition — within impacted wetlands and between reference and impacted wetlands, revealed through multivariate analysis — suggests that macroinvertebrates are responsive to changes in wetland condition, and thus show potential as indicators of wetland water quality. It is recommended that a habitat or biotope index be further developed and used in conjunction with any future wetland macroinvertebrate bioassessment protocols.

The effects of fire on wetland structure and functioning

Fire is an extensively used wetland management tool in both tropical and temperate areas, but its effects on wetlands are not well understood. The purpose of this paper is to review the effects of fire on wetland hydrology, biogeochemical cycling and vegetation composition, including primary effects that take place during the fire such as combustion of plant material, loss of volatile substances to the atmosphere and deposition of ash on the soil surface, and secondary effects such as alteration of soil pH as a result of ash deposition, exposure of the soil surface to solar radiation, and increased availability of nutrients. Several of the secondary effects are most dramatic immediately after a fire, but become progressively modulated by newly stimulated vegetation growth. The findings suggest that the effects of fire depend upon a wetlands characteristics, including its climatic and hydrological context, as well as upon interactions with other disturbances such as grazing. Thus, similar fire regimes may have dramatically different outcomes. Where knowledge gaps were identified, some general predictions are offered, drawing from comparable ecosystems such as mesic grasslands. These predictions provide potential hypotheses for further research.

The application of a framework for assessing ecological condition and sustainability of use to three wetlands in Malawi

In Africa, the direct use of wetlands has long contributed to livelihoods, but use may lead to the degradation of wetlands. In order to better understand how the biophysical features of a wetland influence the sustainability of its use, an investigation was undertaken of the ecological condition and use of three wetlands in the Kasungu District, Malawi, where human pressures on wetlands are high. The first wetland, at the head of the catchment, had sandy soils and a gentle longitudinal slope, the second wetland, lower in the catchment, had clay soils and a steeper longitudinal slope, and the third wetland was intermediate. A framework was applied to score five functional components of ecological condition: hydrology, geomorphology, soil organic matter (SOM) accumulation, nutrient cycling and vegetation composition in terms of human impact, based on pre-defined field indicators. The framework highlighted particular vulnerabilities of individual wetlands in the face of human pressure. Vulnerability varied greatly across the wetlands in terms of: recovery of native vegetation composition following cultivation, geomorphic change through gully erosion and depletion of SOM. The framework is recommended for wider application in Africa as a means of highlighting the specific vulnerabilities of individual wetlands and for the improved focus of organizations which promote the ecologically sustainable use of wetlands.

Wetland Plant Species Used for Craft Production in Kwazulu–Natal, South Africa: Ethnobotanical Knowledge and Environmental Sustainability

Wetland Plant Species Used for Craft Production in Kwazulu–Natal, South Africa: Ethnobotanical Knowledge and Environmental Sustainability. In KwaZulu–Natal Province, there is a rich tradition of wetland plant utilization for craft production. A survey of the province, based on interviews and participatory field walks, revealed which wetland plant species are harvested and how the different species are used. The principal plant species utilized varied greatly among regions: In the coastal region it was Cyperus latifolius Poir. (iKhwane) and Juncus kraussii Hochst. (iNcema), whereas in the uplands it was Cyperus marginatus Thunb. (iNcema). The initial hypothesis that the diversity of plant morphologies added to the diversity of different weave types and products was confirmed by the data. Plant morphological characteristics influenced the weaving techniques suitable for craft production. For example, the fine culms of J. kraussii and C. marginatus have particular value for twilling, twining, and straight sewing and the robust C. latifolius leaves are well suited for the plait. Pressures on the supply of the natural resource were greatest from competing land uses, such as wetland cultivation and, to a lesser extent, from competition among plant harvesters. There was a high demand for J. kraussii, which is traded beyond the limits of its geographical distribution to a much greater extent than the other species. The paper concludes by recommending the wider application of the approach and methods used in the study in order to inform initiatives promoting small business development based upon sustainably harvested natural resources.

Toward an analytical framework for understanding complex social- ecological systems when conducting environmental impact assessments in South Africa

Consideration of biophysical impacts has historically dominated environmental impact assessment (EIA) practice. Despite the emergence of social impact assessment, the consideration of socioeconomic impacts in EIA is variable, as is the extent of their integration in EIA findings. There is growing recognition for the need to move EIA practice toward sustainability assessment, characterized by comprehensiveness, i.e., scope of impacts, integration, i.e., of biophysical and socioeconomic impacts, and a greater strategic focus. This is particularly the case in developing regions and in countries like South Africa, which have statutory requirements for the full consideration of socioeconomic impacts in EIA. We suggest that EIA practice could benefit from incorporating evolving theory around social-ecological systems (SES) as an effective way of moving toward sustainability assessment. As far as we are aware, our study constitutes the first attempt to apply and formalize SES constructs to EIA practice within a regulated procedure. Our framework goes beyond conventional scoping approaches reliant on checklists and matrices by requiring the EIA practitioner to cocreate a conceptual model of the current and future social-ecological system with the implicated communities. This means social and biophysical impacts are assessed integratively, and that communities participate meaningfully in the EIA process, thereby helping address two of the most common shortfalls of EIA practice. The framework was applied in two case studies, establishment of community- based accommodation linked to existing tourism infrastructure (Eastern Cape, South Africa), and a proposed wine estate (KwaZulu- Natal, South Africa). The framework revealed impacts, which would not be considered in a biophysically-oriented EIA, and helped identify development synergies and institutional and governance needs that are equally likely to have been overlooked. We suggest the framework has value as a counterpoint to established approaches and could contribute to improving the quality of EIAs with respect to the complex SESs that characterize the developing world.

Assessment of the long-term response to rehabilitation of two wetlands in KwaZulu-Natal, South Africa

Assessing the ecological outcomes of wetland rehabilitation activities is an important need recognised by the ‘Working for Wetlands’ programme in South Africa. An assessment of ecological response was conducted in the Killarney and Kruisfontein wetlands, KwaZulu-Natal, in 2005 prior to rehabilitation in 2006, and again in 2011 and 2012, respectively, following rehabilitation. The assessment criteria included an evaluation of changes in ecological integrity, the supply of ecosystem services, and vegetation composition. Improvements in hydrological and geomorphic integrity were recorded in both wetlands, resulting in improved ecosystem delivery. However, investigation of vegetation composition using the wetland index value and floristic quality assessment index indices showed that, seven years after rehabilitation, Killarneys vegetation composition had improved, but Kruisfonteins vegetation was still largely dominated by pioneer species and appeared to be stable, but in a severely transformed state. The response of these wetlands has shown that sites for rehabilitation should be screened before work begins, and wetlands requiring intensive management of vegetation recovery should be assessed in terms of the objectives and the anticipated benefits of the project.

Hierarchical spatial organization and prioritization of wetlands: a conceptual model for wetland rehabilitation in South Africa

Wetland rehabilitation planning needs to take into account many different aspects of the wetland and its context. In South Africa, much emphasis is placed on the delivery of ecosystem services, poverty relief and skills development for those involved in labour-intensive rehabilitation measures. A framework is presented that facilitates decision-making with regards to wetland rehabilitation planning. This starts with prioritizing which wetlands need attention within a catchment. This is followed by decisions regarding which rehabilitation measures would be effective in improving certain ecosystem services based upon the aims of rehabilitation and the social context of the surrounding catchment. The functional unit that is most suitable to work with for rehabilitation is the Hydrogeomorphic (HGM) Unit, defined as a section of a wetland with more or less uniform hydrological and geomorphological characteristics. An individual wetland may comprise several HGM units, and a HGM Unit itself can be sub-divided into several smaller habitat or vegetation units. Different rehabilitation measures have been identified which are appropriate for the different scales in this spatial framework. Two case studies are presented as examples of how this spatial framework impacts upon the decisions made by the rehabilitation practitioner.

Towards the development of a macroinvertebrate sampling technique for palustrine wetlands in South Africa: a pilot investigation in the KwaZulu-Natal midlands

A study was undertaken in November 2003 to derive a suitable sampling technique for collecting a representative sample of aquatic macroinvertebrates from a selected emergent vegetation biotope in a palustrine wetland, Melmoth Vlei, KwaZulu-Natal, South Africa. The aim was to undertake a preliminary investigation on the development and testing of a macroinvertebrate sampling technique for use in emergent sedge-dominated palustrine wetlands (sensu Cowardin et al. 1979), which could contribute to the development of a South African wetland health biomonitoring programme. Sweep nets and activity traps were evaluated for their effectiveness in terms of macroinvertebrate collection. Sweep net sampling was tested over a range of sweep intensities to determine the minimum number of sweeps required to collect a representative sample. Sampling efficiency of activity traps placed at four depths was tested, and taxon diversity and composition of sweep net and activity trap samples were compared to determine whether activity traps are required to supplement sweep net data. A total of 32 taxa (identified mainly to family level) were identified in the samples collected. Taxon diversity and composition did not differ in the activity traps placed at the four depth locations. Taxon diversity did not differ significantly between different sweep intensities. This may be a result of high variability of macroinvertebrate distribution within a wetland. There is evidence, however, to suggest that this result is due to an inadequate sample size. There was a significant difference in taxon composition between the different sweep intensities (P < 0.05) and between activity trap and sweep net samples (P < 0.05). Sixty-eight percent of taxa appeared more frequently in sweep net sampling than in activity trap sampling. Two taxa were found exclusively in activity traps, although the numbers of these taxa collected were not significant, and they do not represent any unique trophic group. Based on these findings, it was concluded that activity traps are not required to supplement sweep net data, and a technique using a sweep net with a sweep intensity of five would be suitable for collecting a representative sample of macroinvertebrates from a palustrine wetland.

Long-term landscape changes in vegetation structure: fire management in the wetlands of KwaMbonambi, South Africa

In wetlands the effects of fire on vegetation dynamics are somewhat uncertain. A change detection analysis in the herbaceous wetlands of KwaMbonambi, South Africa, which were subject to frequent fires, revealed that in 1937 the study area comprised grassland (69%), herbaceous wetland (25%), indigenous swamp forest (4%) and tree plantations (1%). However, by 1970, tree plantations occupied 78% of the landscape and grasslands and herbaceous wetlands had declined to 9% and 6%, respectively, whereas indigenous swamp forest had increased to 6%. By 2009 tree plantations had been removed from the wetland areas. Despite this opportunity for herbaceous wetlands to recover their historical extent, they decreased to only 2%, mostly changing to indigenous swamp forest or to an herbaceous/fern (Stenochlaena tenuifolia)/woodland mosaic. Fire records showed suppression of fire to be an important contributing factor, particularly in wetlands that had been disturbed by tree plantations, although subsequently removed. A pilot burning experiment revealed that S. tenuifolia did not inhibit fire. It is therefore practicable to increase fire frequency to prevent the mosaic developing into forest. A conceptual model of the influence of fire regime on wetland vegetation type is presented and priorities for further research on wetlands and fire are recommended.