Two high intensity wildfire events, 70 years apart, burnt large areas of Mountain Ash forests in the Central Highlands, Victoria, Australia. Both resulted in Royal Commissions (the strongest form of judicial inquiry in Australia) as to their cause(s) owing to large losses of life and property. Here we tested the hypothesis that site ‘wetness’—determined using a Topographic Wetness Index—is a major determinant of the extent of fire (% of sample points that burnt) within high intensity wildfire events and across tenures. We show that wetness dominated the extent of fire in these forests in both the 1939 and 2009 wildfire events. Mountain Ash forests are now strongly skewed in their distribution, with wetter and older forests favored by protected tenures (e.g. National Parks) designed to meet needs for water and conservation. In 2009, the extent of fire at the stand scale in water catchments and conservation tenures was twice that in 1939. In land tenures with multiple uses (e.g. State Forests), the extent of fire was one-third less in 2009 than it was in 1939. Topographic controls on water availability, and major droughts, will likely continue to dominate the extent and likelihood of fire in these forests.

两次相隔 70 年的高强度野火事件烧毁了澳大利亚维多利亚州中部高地的大片山灰森林。由于巨大的生命和财产损失，两者都导致皇家委员会（澳大利亚最强大的司法调查形式）对其原因进行了调查。在这里，我们测试了一个假设，即场地“湿度”（使用地形湿度指数确定）是高强度野火事件中和整个任期内火灾程度（燃烧的样本点的百分比）的主要决定因素。我们表明，在 1939 年和 2009 年的野火事件中，湿度主导了这些森林的火灾范围。山灰森林的分布现在严重倾斜，潮湿和古老的森林受到保护权（例如国家公园）的青睐，旨在满足水和保护的需求。在2009年，