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Measurements were made of density, size and shape of colonies of the soil lichen Psora crenata at sites with varying disturbance histories at Maralinga in arid South Australia. Lichens were measured along transects at 10 sites with recovery intervals ranging from 3 to 42 years, and on four undisturbed control sites. As the time since disturbance increased, the number of lichen colonies increased markedly, colony size declined, but colony shape remained unchanged. We tentatively suggest that at least 60 years is required for disturbed sites to approach the condition of undisturbed sites. These results reinforce the notion that lichen recovery is very slow, and suggest that colony density of Psora could be a useful indicator of recovery after disturbance in rangelands where crusts are a common component of the soil surface. Keywords: Psora crenata, rangelands, soil crusts, cryptogams, rangeland health