Abstract
Fire severity is an important characteristic of fire regimes; however, global assessments of fire regimes typically focus more on fire frequency and burnt area. Our objective in this case study is to use multiple lines of evidence to understand fire severity and intensity patterns and their environmental correlates in the extreme 2013 Forcett-Dunalley fire in southeast Tasmania, Australia. We use maximum likelihood classification of aerial photography, and fire behavior equations, to report on fire severity and intensity patterns, and compare the performance of multiple thresholds of the normalised burn ratio (dNBR) and normalized difference vegetation index (dNDVI) (from pre- and post-fire Landsat 7 images) against classified aerial photography. We investigate how vegetation, topography, and fire weather, and therefore intensity, influenced fire severity patterns. According to the aerial photographic classification, the fire burnt 25,950 ha of which 5% burnt at low severities, 17% at medium severity, 32% at high severity, 23% at very high severities, while 22% contained unburnt patches. Generalized linear modelling revealed that fire severity was strongly influenced by slope angle, aspect, and interactions between vegetation type and fire weather (FFDI) ranging from moderate (12) to catastrophic (>100). Extreme fire weather, which occurred in 2% of the total fire duration of the fire (16 days), caused the fire to burn nearly half (46%) of the total area of the fireground and resulted in modelled extreme fireline intensities among all vegetation types, including an inferred peak of 68,000 kW·m−1 in dry forest. The best satellite-based severity map was the site-specific dNBR (45% congruence with aerial photography) showing dNBR potential in Eucalyptus forests, but the reliability of this approach must be assessed using aerial photography, and/or ground assessment.
Highlights
Fire regimes are a multidimensional concept that capture the spatiotemporal variation in landscape fire in terms of physio-chemical processes and biological effects [1,2]
Our analysis shows that the Forcett-Dunalley fire burnt 20,200 ha over 16 days from January 3 to January 18 under variable fire weather conditions, with severe to extreme forest fire danger index (FFDI 50–90) in the first two days, and achieving catastrophic levels (FFDI c. > 100) at 15:38 on January 4, 2013 (Figure 3a)
We found strong evidence that fire severity differed between different vegetation types under varying fire weather conditions and between slope angles
Summary
Fire regimes are a multidimensional concept that capture the spatiotemporal variation in landscape fire in terms of physio-chemical processes and biological effects [1,2]. A key facet of the fire regime concept is fire severity, which is defined as the degree of post-fire ecological change associated with loss of organic matter aboveground and belowground [3,4]. Fire severity is different from fire intensity, which refers to the energy output of a fire during burning, both concepts are loosely connected [4,10]. A fast, high-intensity flaming fire in grassland ecosystems can produce less severe impacts than. The most commonly used fire intensity metric is fireline intensity, defined as the rate of energy release per unit length of firefront [12]. Fire behavior modelling provides a practical alternative means of estimating fire intensity
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
