Drivers of wildfire behaviour, severity and magnitude in the Limietbergconservation area : understanding the complexity of wildfire risk

[摘要] ENGLISH ABSTRACT: The Western Cape Province in South Africa is home to one of the most diverse plantcommunities in the world, and has one of the highest concentrations of plants species in anytemperate ecosystem in the world. The dominant vegetation is both fire-prone and fire-dependant(Van Wilgen & Scott 2001, Forsyth et al. 2010). The Western Cape in particular is emerging as aprovince that is increasingly prone to disaster events, particularly the threat of veld fires. Theconsequences of large wildfire disaster events are often devastating and far reaching (VanWilgen & Scott 2001, Forsyth et al. 2010). This study was conducted in an attempt to investigatethe drivers of wildfire behaviour, severity and magnitude in the Limietberg Conservation Area inorder to gain a greater insight and understanding of the complexity of wildfire risk. Recognisingthe disaster prone character of the Western Cape and the increasing probabilities of futurewildfire events in the province, this study aimed to strengthen the understanding of the drivers ofwildland fire behaviour (i.e. wildland fire risk) in the Limietberg Conservation Area by analysinga number of fires to identify a range of drivers and patterns; examining the factors driving bothfire danger and fire behaviour, including climate, topography, slope and fuel; examining thefactors driving fire frequency and regime; and finally, determining possible ecological damagecaused by the last 10 – 20 years of wildfire events in the Limietberg Conservation Area asmeasured by post-fire seedling ratios. This was achieved through the use of statistical techniquesincluding multiple regression (McDonald 2009), ordination in the form of principal componentanalysis and non-metric multi-dimensional scaling (Clarke & Warwick 1994), and fieldwork inthe form of post-fire regeneration (Proteaceae parent:seedling ratio) monitoring techniques(Bond et al. 1984; Vlok & Yeaton 2000; De Klerk et al. 2007). The results indicated that theinteractions between factors driving fire danger and fire behaviour were indeed complex, beinginfluenced mainly by meteorological variables (temperature, relative humidity, wind speed) butalso quite strongly influenced by physical environmental factors (slope, topography). The use ofordination techniques in this sort of complex analysis was seen as extremely effective and its usein further fire research was strongly recommended.

[发布机构] Stellenbosch University