Post-cultivation recovery of biological soil crusts in semi-arid native grasslands, southern Australia

Abstract

Biological soil crusts take a long time to recover after soil disturbance but data on the rate and trajectory of crust recovery are lacking. Using a space-for-time chronosequence of time-since-cultivation, we assessed the recovery of crust diversity and cover in semi-arid grasslands in southern Australia. Using sites that spanned from recently-cultivated to never-cultivated, we show that the recovery of soil crust cover is highly variable with time-since-cultivation; recently-cultivated sites generally had the lowest total cover of biological soil crusts and morphological type diversity relative to sites allowed to recover for ≥60 yrs. Moss, liverworts, squamulose and crustose lichens return to grasslands quickly after cultivation, but cover returned at highly variable rates; this might reflect that other factors (stock grazing, microtopography, soils) also affect crust cover recovery. Our results suggest that soil crusts are initially slow to recover after soil disturbance. However, post-cultivation recovery does occur but this is in the context of historical and spatial contingencies. The patterns of cover and diversity that we observed provide a useful way to interpret effects of disturbance on semi-arid grasslands in Australia and may be useful indicators of grassland condition where cultivation history is not known.