Indices to monitor biological soil crust growth rate—lab and field experiments

The aim of this work was to identify test meth-ods for accelerating growth of biological soil crust (BSC). The BSC in the Yamin Plateau in the north-east of the Negev Desert is composed of cyanobacteria such as microcoleus spp. nostoc spp. and others. Cyanobacteria are well adapted to dry environments, owing to their ability to survive desiccation, high temperatures and solar radiation. Since the BSC is a live component in the ecosystem, it can repair itself in the event of failures such as environmental disturbances by living things. In the lab, we used five different treatments and mediums: natural BSC, pure sand as reference, pure sand with spores and propagules, pure sand with whey, and pure sand with spores and propa-gules and whey. The spores were collected from specified collecting areas in the field. Each Petri dish was irrigated daily with 10 mL of double- distilled water. The testing period ran for 4.5 months with 10 samples taken from each treatment at 1.5 month intervals. The analyses criteria were: NDVI for chlorophyll content by remote sensing techniques, polysaccharide content, infiltration rate through the crust, pro-tein and organic content. The results showed that NDVI, polysaccharides and infiltration rates are good indicators for showing growth accel-eration of the crust; while protein and organic content were found to be less indicative. The treatments using whey for preliminary crust failed in the lab since cracks were observed, but succeeded in the field experiments. In the field, we measured only the chlorophyll content with a time interval of 20 months. The methodology of how to accelerate the growth of BSC was found to be effective.