The effect of wildfires on vegetation cover and dune activity in Australia's desert dunes: a multisensor analysis

Most of Australia's desert dune fields are stable; however, wildfires may reduce vegetation and biological soil crust cover so that sand movement may take place until vegetation recovers. In this study, we aimed to study the recovery rate of vegetation cover in spinifex (Triodia)-dominated desert dunes following wildfires using satellite imagery-derived spectral indices to: (1) determine for how long after fire these dunes may be active until critical levels of vegetation cover are attained; (2) determine which spectral index is the most suitable for monitoring vegetation recovery in this area. We have used a combination of MODIS, Landsat, Aster and QuickBird images to analyse vegetation cover following fire at various spatial and temporal scales, in the Great Victoria Desert, WA. The following spectral indices were compared: Brightness Index, Biological Soil Crust Index (BSCI), Crust Index, Enhanced Vegetation Index, Normalised Burn Ratio, Normalised Difference Vegetation Index, Soil Adjusted Vegetation Index and the Stress related Vegetation Index. The BSCI was found to outperform the other spectral indices in monitoring vegetation cover in this area. Whereas full recovery of vegetation following wildfires in the study area was attained only after 25-30 years, critical thresholds of vegetation cover limiting sand movement were attained after just 1-5 years. The frequency and intensity of wildfires is therefore an important factor controlling dune activity in Australia's deserts.