The genetics of flammability in the eucalypt landscape

Fire is a part of the Australian landscape and eucalypts have a great propensity to promote fire. If fire promoting traits are to directly or indirectly evolve, there needs to be genetic variation in the expression of these traits within species. However, to our knowledge, no studies have addressed intraspecific genetic variation in flammability traits in eucalypts. Here, we use a common environment field trial to examine genetic variability in leaf flammability traits between different genetically distinct populations across the geographic range of Eucalyptus globulus. Results show clear genetic-based variation in ignitibility of leaves, sustainability of the flame and rate of leaf area consumed. In addition, three leaf traits related to flammability; oil yield, leaf size and leaf moisture content. Population variation in foliar flammability appear to follow an adaptive environmental gradient from the drought prone north-east Tasmania to the less drought prone regions in the south. Fire appears easier to propagate but burns at a lower intensity in the north-east than the southern localities which are harder to ignite but burn at a higher intensity. This study places flammability in an evolutionary context, whereby, there is significant genetic variation in fire promoting traits within a eucalypt species for selection to directly or indirectly influence.