Assessing fire severity using charcoal reflectance following a recent heathland wildfire on Carn Brea, Cornwall, UK

Abstract

Charcoal has recently been suggested to retain information about the fire that generated it (Belcher and Hudspith, 2016). When looking under a microscope charcoals formed by different aspects of fire behaviour indicate different ability to reflect the amount of light when studied using the appropriate technique. It has been suggested that this method might be able to provide a quantitative fire severity metric that can be used in conjunction with or instead of standard qualitative fire severity scores. We studied charcoals from a recent wildfire in Carn Brea, Cornwall and assessed whether charcoal reflectance (Ro) can be linked to standard qualitative fire severity scores for the burned area. We found that charcoal reflectance was greater at sites along the burned area that have been scored as having a higher fire severity, whilst surrounding sites with a lower severity score have a noticeably lower Ro measurement. We suggest, by measuring the reflectance of charcoals that this may be able to provide quantitative information about the spatial distribution of heat across a burned area post-fire, and that this should provide better linkages between fire behaviour, fire severity and ecosystem effects. Synthesis: Results from the analysis of the Carn Brea charcoal suggests that variation in charcoal reflectance measurements may be due to changes in fire severity across a burn site, enabling researchers to gain information that links fire severity and fire behaviour by analysing the charcoal left behind post-fire. This is particularly useful if quantitative fire severity measurements cannot be obtained via remote sensing.