Patterns of landscape fire and predicted vegetation response in the North Kimberley region of Western Australia

Abstract

The paper reports on the development of a decadal fire history, 1990–1999, derived from Landsat imagery, and associated assessment of landscape-scale patterns, in a remote, sparsely human-populated region of the high rainfall zone of monsoonal north-western Australia. The assembled fire history confirms observations, derived from coarser-scale imagery, that substantial areas of the North Kimberley are burnt each year. The annual mean extent of burning was 31% (albeit involving marked inter-annual variability), with most burning occurring in the latter part of the dry season under relatively severe fire weather conditions. Extent of burning was found to be associated with intensity of landuse; most burning occurred on pastoral lands, particularly in association with more fertile basalt soils. Based on previous modelling studies, predicted effects of contemporary fire regimes include increased development of woody regeneration size-classes, especially on non-basalt substrates. In contrast, on sandstone-derived substrata, fire interval data indicate that longer-lived obligate-seeder shrub species are likely to be suppressed and ultimately displaced by contemporary fire regimes. Such observations are supported by recent evidence of regional collapse of the long-lived obligate seeder tree species, Callitris intratropica. Collectively, assembled data point to the need to undertake a thorough appraisal of the status of regional biota in this remote, ostensibly ecologically intact region.