Abstract.
Fire regimes in many north Australian savanna regions are today characterised by frequent wildfires occurring
in the latter part of the 7-month dry season. A fire management program instigated from 2005 over 24 000 km2 of
biodiversity-rich Western Arnhem Land aims to reduce the area and severity of late dry-season fires, and associated
greenhouse gas emissions, through targeted early dry-season prescribed burning. This study used fire history mapping
derived mostly from Landsat imagery over the period 1990–2009 and statistical modelling to quantify the mitigation of
late dry-season wildfire through prescribed burning. From 2005, there has been a reduction in mean annual total proportion
burnt (from 38 to 30%), and particularly of late dry-season fires (from 29 to 12.5%). The slope of the relationship between
the proportion of early-season prescribed fire and subsequent late dry-season wildfire was,–1. This means that imposing
prescribed early dry-season burning can substantially reduce late dry-season fire area, by direct one-to-one replacement.
There is some evidence that the spatially strategic program has achieved even better mitigation than this. The observed
reduction in late dry-season fire without concomitant increase in overall area burnt has important ecological and
greenhouse gas emissions implications. This efficient mitigation of wildfire contrasts markedly with observations reported
from temperate fire-prone forested systems.
Additional keywords: fire management, greenhouse gas emissions, Leverage, planned fire, unplanned fire.
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