By the end of 2008, and following a prolonged drought period, a mass death of shrubs was observed in a semi-arid region of the Northern Negev Desert. This study followed the development of biological soil crusts (BSCs) on the soil mounds in the sites of the dead shrubs, spanning over a three year period, from the disappearance of the shrub skeletons until the mounds were flattened. In addition to on-site physical measurements, BSC samples were collected and analyzed for their physical and biochemical properties (15-17 parameters) and their microbial community structure and compared to those of mature crusts. Statistical analyses showed significant differences in the biochemical properties and the microbial community structure between the developing BSCs and the mature ones during five sampling campaigns. Interestingly, significant differences were observed also between the north-facing and the south-facing slopes of the mounds. The extent of these observed differences was linked to the sampling dates, implying an effect of the soil moisture. Significant differences persisted even after the mounds were totally flattened. This slow development of BSCs on the bare soil mounds after shrub death and decomposition in semi-arid ecosystems, may allow the establishment of new shrubs in these sites and the recovery of the affected ecosystem.
