Contemporary Fire Regimes of the Arid Carnarvon Basin Region of Western Australia

Megan Ladbrook,William D Stock,Eddie J B Van Etten

doi:10.3390/fire1030051

Abstract

This study investigates the fire regime for the arid Carnarvon Basin region of Western Australia using remotely sensed imagery. A fire history database was constructed from satellite images to characterise the general fire regime and determine any effect of vegetation types and pre-fire weather and climate. The study area was divided into two sections (northern and southern) due to their inherently different vegetation and climate. A total of 23.8% (15,646 km2) of the study area was burnt during the 39-year study period. Heathland vegetation (54%) burnt the most extensively in the southern study area, and hummock grasslands (68%) in the northern. A single, unusually large fire in 2012 followed exceptional rains in the previous 12 months and accounted for 55% of the total burnt area. This fire burnt mainly through Acacia shrublands and woodlands rather than hummock grasslands, as normally experienced in the northern study area. Antecedent rainfall and fire weather were found to be the main meteorological factors driving fire size. Both study areas showed a moderate to strong correlation between fire size and increased pre-fire rainfall in the year preceding the fire. Predicted future changes in climate may lead to more frequent and higher intensity fires.

Highlights

Vegetation fires in dry regions can be more extensive than in more populated temperate regions [1,2].Bushfires of this magnitude, which are often ignited by lightning, may be left to burn if there are few resources and little willingness or need to extinguish them, since they typically pose little threat to life or property [3]
In a study on fire patterns in a semi-arid region of south-western Australia around Lake Johnston [11], fires ranged from 1.8–1519 km2 ; this study found the driver of large fires differed from those of small- and medium-sized fires
This study found that 13% of the southern part of the arid region that starts just north of Kalbarri burnt in the six-year study period, but only 1% of the drier—more northern region situated in the Carnarvon basin—burnt in this period [2]

Summary

Introduction

Vegetation fires in dry regions can be more extensive than in more populated temperate regions [1,2].Bushfires of this magnitude, which are often ignited by lightning, may be left to burn if there are few resources and little willingness or need to extinguish them, since they typically pose little threat to life or property [3]. For remote regions with few people and resources, such as much of arid Australia, characterising fire regimes through remote sensing techniques is an important first step in understanding fire impacts and clarifying management priorities [4]. Such techniques help elucidate typical fire pathways and intervals, burn extent and the potential causes of the temporal and spatial patterns of fire. Fire size is important since large fires contribute most to the total burn area even though they may be relatively rare occurrences [3,7,8].

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