Biocrust-forming cyanobacteria inoculation assisted by a vegetal fiber mesh, in a semi-arid degraded area: characterization of the polysaccharidic matrix

Land degradation in drylands is one of the most worrisome drawbacks of the combined action of climate change and human activities. New techniques have been developed to induce the formation of artificial biocrust as a restoration tool: one is inoculating soils with cyanobacteria adapted to extreme environments. Our aim was to evaluate on field the effect of the inoculation of biocrust-forming cyanobacteria in a semiarid degraded area (El Cautivo, Tabernas desert, Spain), assisted by the presence of an organic mesh. Three heterocystous strains, isolated from the target site, were inoculated in mixture 1:1:1: Nostoc commune, Scytonema hyalinum, and Tolypothrix distorta. Soil plots of 1mx1m were subjected to the following treatments: 1) control 2) inoculated with cyanobacteria 3) inoculated with cyanobacteria, assisted by a vegetal fiber mesh 4) control vegetal fiber mesh. After 6 months, for each treatment, the polysaccharidic matrix was characterized in terms of total carbohydrates and monosaccharidic composition. Preliminary results showed a positive effect of the mesh combined with cyanobacteria in terms of total carbohydrates, compared to the other treatments. The monosaccharidic composition showed that the mesh increased glucose, mannose and xylose in soil, while the presence of cyanobacteria (alone or with the mesh) gave a higher sugar complexity (8 different sugars).