Salt pan landscape and halophyte re-establishment

International research on disturbed landscapes has shown that active erosion of soil-free bare ground can maintain distinctive local geological features and biodiversity by preventing incursion of a robust vegetation cover. In this study, we have tested this approach by removing exotic vegetation and associated proto-soil that had encroached over evaporative salt pans in inland southern South Island. The ten study sites were all on clay-altered Otago Schist basement and talus. All the sites rapidly (months) re-developed high salinity (EC >1 mS/cm) and alkaline pH 8-10. Sloping sites (10-30°) rapidly developed surficial erosion regimes that involved scouring and runnel formation (cm scale), with regular sediment reworking downslope on the cm-dm scale during rain events. The combination of active surface remobilisation, high salinity and alkaline pH was effective at limiting recolonisation of exotic vegetation. In contrast, rare New Zealand endemic salt-tolerant plants (halophytes) colonised parts of the dynamic bare surfaces from relict nearby patches, initially within months, and some sites had almost complete halophyte cover after four years. The results show that with suitable intervention it is possible to prevent disappearance of these unique geological, geochemical, and biodiverse landscape features.