Systematic fire mapping is critical for fire ecology, planning and management: A case study in the semi-arid Murray Mallee, south-eastern Australia

• We mapped fire scars and unburnt patches across a 104,000 km2 region.
• A small number of large fires (>10,000 ha) dominate the fire history.
• Although fire-prone, <3% of mallee vegetation burned more than once from 1972 to 2007.
• Fire regimes differed markedly between conservation reserves and between states.
• Cross-jurisdictional planning and management for fire is essential.

Fire is a natural disturbance process that shapes ecosystems worldwide and influences the distribution of many species of plants and animals. In fire-prone regions, planning for both fire management and biodiversity conservation requires a sound understanding of fire history and spatial patterns. However, in many fire-prone areas, accurate fire records and systematic fire maps are lacking. We used Landsat imagery to map the fire history of the Murray Mallee region of southeastern Australia from 1972 to 2007. Our study in this semi-arid, fire-prone ecosystem encompassed an area of 104,000 km2. An area equivalent to 40% of the tree-mallee vegetation (vegetation characterised by small, multi-stemmed eucalypts) was burnt during the 35-year period, but less than 3% of tree-mallee experienced more than one fire in this time. Large fires (>10,000 ha) accounted for 89% of the area burnt, and were the main influence on the distribution of fire age-classes in conservation reserves. Different vegetation types burned disproportionately, illustrating the value of combining region-wide vegetation mapping with fire history mapping. Although the perception is that large fires occur on an approximately decadal cycle following years of above-average rainfall, our analyses revealed that above-average rainfall is not the only influence on large fires. The distribution of fire age-classes differed between reserves and across states, highlighting the need to manage fire-prone landscapes at ecologically meaningful regional-scales that cross jurisdictional boundaries. Systematic and consistent mapping of fires in fire-prone regions is an essential foundation for improved fire management and more effective landscape planning for conservation.