Browsing by Author "Midgley, G F"
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- ItemRestrictedA status quo, vulnerability and adaptation assessment of the physical and socio-economic effects of climate change in the Western Cape(2005) Midgley, G F; Chapman, R A; Hewitson, B; Johnston, P; de Wit, M; Ziervogel, G; Mukheibir, P; van Niekerk, L; Tadross, M; van Wilgen, B W; Kgope, B; Morant, P D; Theron, A; Scholes, R J; Forsyth, G GThe South African Country Study on Climate Change, carried out in the late 1990’s, identified the Northern and Western Cape Provinces as being most at risk from projected climate change-induced warming and rainfall change (results of this study are summarized in South Africa’s initial National Communication, prepared in accordance with Article 12 of the United Nations Framework Convention on Climate Change: www.environment.gov.za/Documents/Documents/2005Feb22/NatCom_Nov%202003%20(b). doc ). However, this study was based on a limited set of model projections of climate change that have now been superseded by projections using more advanced techniques. In this study we have carried out a broad reassessment of the vulnerability of the Western Cape to climate change impacts, using a wider range of climate scenarios from more sophisticated climate models, and for a range of sectors (with the exception of agriculture and fisheries, according to our brief). We also identify some key adaptive strategies that might alleviate or avoid the worst impacts of climate change in some sectors. We conclude that further detailed study of some of the implications of these findings will be necessary to explore these and further strategies in order to guide policy development.
- ItemRestrictedWhat controls South African vegetation - climate or fire?(2003) Bond, W J; Midgley, G F; Woodward, F IThe role of fire in determining biome distribution in South Africa has long been debated. Acocks labelled veld types that he thought were ‘fire climax’ as ‘false’. He hypothesised that their current extent was due to extensive forest clearance by Iron Age farmers. We tested the relative importance of fire and climate in determining ecosystem characteristics by simulating potential vegetation of South Africa with and without fire using a Dynamic Global Vegetation Model (DGVM). The simulations suggest that most of the eastern half of the country could support much higher stem biomass without fire and that the vegetation would be dominated by trees instead of grasses. Fynbos regions in mesic winter rainfall areas would also become tree dominated. We collated results of long term fire exclusion studies to further test the relative importance of fire and climate. These show that grassy ecosystems with rainfall > 650mm tend towards fire-sensitive forests with fire excluded. Areas below 650mm showed changes in tree density and size but no trend of changing composition to forest. We discuss recent evidence that C4 grasslands first appeared between 6 and 8M years BP, long before the appearance of modern humans. However these grassy ecosystems are among the most recently developed biomes on the planet. We briefly discuss the importance of fire in promoting their spread in the late Tertiary.