Biological soil crust community structures associated with shrub desiccation

A mass death of shrubs was observed in the Northern Negev Desert that was associated with a prolonged drought period. This study followed the development of biological soil crust (biocrust) on the soil mounds in the sites ofthe dead shrubs. The study expanded over a three years period, starting after the disappearance of the shrub skeletons, until the mounds were flattened. In addition to on—site physical measurements, biocrust samples were collected and analyzed for their biochemical properties (15-17 parameters) in addition to 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 biocrust and the mature ones during five sampling field campaigns. Interestingly, significant differences were observed between the north—facing and the south—facing slopes of the mounds. The magnitude of the measured differences was associated with the sampling date implying a soil moisture effect. Differences were measured even after the mounds were flattened. The results indicate the slow development of biocrust on mounds of dead shrub mounds in arid ecosystems allowing the recovery of the ecosystem and the establishment of shrubs in these sites.