Browsing by Author "Foden, Wendy"
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- ItemOpen AccessAn assessment of critical carbon services and water resources in South Africa’s terrestrial protected area network(2022) Plaistowe, Jonathan; Foden, Wendy; O'Farrell, Patrick; Hoffman, MichaelConservation planning can more greatly emphasise the importance of considering ecosystem services alongside biodiversity features to improve the planet's climate change resilience. Protected Areas (PAs) are a form of area-based conservation that successfully protects biodiversity and may conserve ecosystem services important for societal climate change resilience. This study assesses the performance of South Africa's protected area network in protecting strategic carbon and water services, which are important for climate change resilience. My first question investigated how well the country's PAs perform regarding the area coverage of carbon stocks and Strategic Water Source Areas (SWSA). My second question investigated whether the country's PAs have effectively protected the carbon stocks inside their borders. I hypothesised that the carbon stock values would be higher in PAs, given that PAs have successfully prevented the loss of natural land cover inside their borders. I also compared the effectiveness of PAs in protecting carbon stocks in terms of their management authority, province and land cover classes. I used existing datasets of PAs, environmental variables, SWSAs and carbon stocks for this study. Using the total organic carbon (TOC) and South Africa's Natural Land Cover, I calculated natural Strategic Total Organic Carbon Areas (STOCA). Then I used the STOCAs and SWSAs to assess the PA coverage of these two strategic ecosystem service areas and their overlapping areas. For the second question, I investigated the carbon stock values inside and outside PAs while controlling for environmental variables. I also investigated the effect of natural land cover, provincial designations and management authorities. Results indicate that South Africa's PAs cover 9.8% of the country's mainland but protect 14.8% of SWSAs, 21.7% of STOCAs and 28.5% of the SWSA & STOCA areas. The PAs have greater TOC, Total Soil Organic Carbon (TSOC) and Total Biomass Organic Carbon (TBOC) values inside their borders than outside. Natural areas inside PAs are higher in TOC, TSOC and TBOC values than outside natural or transformed areas. These results provide evidence that South Africa's PAs are effectively protecting their carbon stocks. Therefore, there is evidence that PAs are important for climate change mitigation and may be important for Nature-based Solutions (NbS) in increasing climate change resilience. Eastern Cape, KwaZulu-Natal, Limpopo, and Western Cape PAs should be studied to improve other PAs' management. Although the PA network is strategically placed to protect the country's ecosystem service areas, the extent of this protection is short of international PA targets. There are many more strategic ecosystem service areas available for protection. Considering the effectiveness of Eastern Cape and KwaZulu-Natal PAs and the availability of strategic ecosystem service areas for protection, policy-makers and conservation managers should consider these provinces for PA expansion. Limpopo should also be considered for PA expansion, given the high carbon stock values outside PAs. This study shows the importance of South Africa's protected area network for climate change resilience and provides information on where its necessary expansion can best be planned for. It also offers a potential set of metrics and targets for monitoring in the future.
- ItemOpen AccessAre local range expansions in southerly populations of Aloidendron dichotomum early indicators of a future range shift?(2019) Grey, Kerry-Anne; Cunningham, Susan; Midgley, Guy; Foden, WendyAloidendron dichotomum is predicted to undergo a south and south-eastern range shift in response to anthropogenic climate warming. Despite this, its range is suggested to be limited by low temperature extremes at the cool range edge and no such range shift has yet been confirmed. However, eco-physiological knowledge necessary to predict and detect this range shift is lacking. This study aimed to determine whether physiological performance of A. dichotomum differs at a regional and local scale, and if so, whether regional and local temperatures explain physiological differences. Performance metrics and temperature data were collected during summer at 14 microsites in two sites at the cool range edge of A. dichotomum. Microsites were stratified by aspect and elevation. This study confirmed that A. dichotomum is performing CAM photosynthesis at its cool range edge. Further, the results provide evidence for the temperature dependence of A. dichotomum’s physiological performance. Higher performance was associated with warmer nights and the warmer north facing slopes. This is in keeping with our hypothesis that A. dichotomum individuals at the cool range edge would take advantage of higher temperatures more typical of their core range areas. Opposing this, higher carbon gain was found at Gannabos - the cooler of the two study sites. This may be due to the less variable rainfall pattern at Gannabos. Furthermore, performance was higher on the flats where temperatures were also cooler. This may be due to lower water runoff on the flats compared to the slopes. As a result, I suggest that the cool range edge of A. dichotomum is limited both by low temperatures and rainfall variability and that, with warming, constraints on these populations are being removed. This is substantiated by the observed high levels of juvenile recruitment in these populations relative to others, and in time, is likely to lead to range expansion in the region.
- ItemOpen AccessAssessing the climate change vulnerability of reptile and amphibian species found in Table Mountain National Park(University of Cape Town, 2020) Harper, Jack; Cunningham, Susan; Foden, Wendy; Van Wilgen, NicolaIt is increasingly apparent that climate change and its associated impacts are a major threat to the rich biodiversity of the Cape floristic region. As the knowledge of the associations between biological traits and climate change impacts strengthens it has become clear that the assessment of climate change vulnerability is a key consideration in the management of biodiversity. This study is the first attempt to use a trait-based approach at the scale of a single national park, focusing on the climate change vulnerability of reptile and amphibian species found in Table Mountain National Park (including historically present species). The park and its immediate surrounding areas are home to a rich diversity of herpetofauna including the Critically Endangered Table Mountain ghost frog (Heleophryne rosei), Rose's mountain toadlet (Capensibufo rosei) and micro frog (Microbatrachella capensis), and the Endangered western leopard toad (Sclerophrys pantherina). Amphibian and reptile-specific assessment frameworks of biological and ecological traits were designed to identify the species most sensitive and least able to adapt to climate change pressures. Using a combination of a literature review and expert consultation, 18 species of amphibian and 41 species of reptile were assessed. The assessment highlighted that, in the worst-case scenario, 85% of the park's reptile species and 67% of the park's amphibian species are predicted to be highly vulnerable to climate change. The southern adder (Bitis armata), Cape long-tailed seps (Tetradactylus tetradactylus), Table Mountain ghost frog (Heleophryne rosei) and the Lightfoot's moss frog (Arthroleptella lightfooti) were identified as being the species most vulnerable to climate change within their respective taxa. All three of the Critically Endangered amphibian species were identified as having both high sensitivity and low adaptive capacity to climate change. Among the focal reptile species, climate change vulnerability was independent of current IUCN Red List status, highlighting that species currently not identified to be under threat by other anthropogenic pressures could imminently become threatened by climate change. Spatiallyexplicit presentation of the assessment output will help prioritise the management of areas within Table Mountain National Park that contain a high diversity of climate-vulnerable species. By reducing the threats from other human-associated impacts to these species, and by identifying when direct intervention is appropriate, the park's management can give these species the best opportunity of persistence in an uncertain climate future.
- ItemOpen AccessAssessing the vulnerability of South Africa's national protected areas to climate change(2018) Coldrey, Kevin; Turpie, Jane; Foden, WendyProtected areas should be reviewed under expected future climate conditions so that conservation and expansion strategies can be developed appropriately. An assessment of the vulnerability of protected areas to climate change is a necessary step in developing such strategies. Indeed, a vulnerability assessment is an important step in developing adaptation strategies for conservation. This is important as substantial climate change has already been experienced at a park level in South Africa. The aim of this study was to develop a method for assessing the relative vulnerability of protected areas to climate change and to apply this to South Africa’s 19 national parks. The method includes identifying and quantifying potential impacts of climate change on each focal protected area, carried out by developing and/or using projections for species, ecosystems, infrastructure, tourism and neighbouring communities. Potential impacts were combined with measures of each park’s adaptive capacity to develop an overall park vulnerability score. This study has taken vulnerability assessment at a protected area level further than has been attempted before by assessing not only the biophysical but also the socioeconomic impacts of climate change on a protected area, quantifying the potential changes (potential impacts) and developing a relative index. The results indicate that climate change has the potential to contribute significantly to the threats faced by South Africa’s national parks. Apart from a potentially devastating impact on species and ecosystems, the effects on tourism demand, community relations and infrastructure are of concern. Not surprisingly, the most vulnerable parks are largely coastal, where tourist infrastructure is at risk of both flooding and sea-level rise, and there are higher population densities. Furthermore, coastal ecosystems are expected to transform significantly which will have consequences for range-restricted species. Management strategies need to take heed of the magnitude of potential impacts identified in this study and work towards developing adaptation pathways.
- ItemOpen AccessHandling the heat: keeping water available for birds of the Tankwa Karoo Desert(2023) Morar, Sean; Cunningham, Susan J; Lee, Alan; van Wilgen, Nicola; Foden, WendyClimate change poses one of the biggest risks to biodiversity globally. Africa is warming at twice the global average rate and African bird species are therefore at risk, particularly in desert environments where they are already operating near physiological limits. Desert air temperatures in the subtropical latitudes will rise by 3°-5°C by the end of the century. When air temperatures are higher than body temperature, birds must use evaporative cooling to avoid hyperthermia. However, evaporative cooling requires water and a tradeoff exists between hyperthermia and dehydration. For drinking species which need open water sources in order to rehydrate, this tradeoff is exacerbated by high operative temperatures on the ground near the water's edge during periods of extreme heat. This study assessed whether providing artificial shade at waterholes can buffer impacts of high temperature by increasing accessibility of water to birds, potentially facilitating persistence of desert bird communities under climate change. I used a before-after control-impact experimental design to test the impact of shade provision on visitation rates, species richness and the timing of visits by desert birds to waterholes in the Tankwa Karoo National Park of South Africa. Providing shade reduced afternoon waterside operative temperatures below lethal limits for many small passerine species and successfully buffered birds' visitation rates to the water's edge during hot periods, although species richness did not change. Overall bird visitation rates to waterholes increased in the afternoon relative to control sites in response to the addition of shade but decreased in the morning, likely due to a perceived/actual predation risk while operative temperatures were low and shade structures provided no thermal benefit. Responses to shade were species-specific, with the overall positive response driven in part by two common species: Grey-backed Sparrow-larks Eremopterix verticalis and Tractrac Chats Emarginata tractrac. Two species (Cape Sparrows Passer melanurus and White-throated Canaries Crithagra albogularis) responded negatively to the provision of shade. There was an observed shift in bird visitation rates from the morning to the afternoon at shaded structures, suggesting temperature as a primary driver in the use of shade. As temperatures increase under climate change, birds may be forced to drink more in the afternoon due to rising water demands for thermoregulation. Shade structures such as those trialed in this study may have the potential to facilitate this shift and keep water accessible to desert birds in the face of temperature increases.
- ItemOpen AccessImpacts of alien clearing on post-fire biodiversity and erosion.(2017-11-14) Foden, Wendy