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Drylands cover ~41% of the earth's surface and suffer from degradation, soil erosion, and biodiversity and biomass reductions of vascular plant and biological soil crusts (BSC). Biological soil crusts are communities of cyanobacteria, lichens, algae and bryophytes associated with soil particles. This study aims to identify the optimal growth conditions of biological soil crusts, through culture and propagation tests in greenhouse under different light, moisture, and salinity levels. Different types of biocrusts, dominated by cyanobacteria, cyanolichens, and mosses, were cultivated in greenhouses. The biocrusts were grown in pots under three radiation (high, medium and low) and irrigation (distilled water every three and two weeks and weekly watering). The salt dissolved in the irrigation water was added to another group of pots (S1: -0.05 M NaCl; S2: -0.1 M NaCl). Total biological soil crust cover and each functional type of cover was determined by photographs of each pot using the SamplePoint free software. Results indicated that total biocrust cover increased after 24 months of being cultivated. Higher total biocrust cover were obtained under the weekly irrigation treatments for medium and low radiation levels. Among these treatments, pots sown with mosses reached higher biocrust cover than the other functional types, more than 70%, followed by pots sown with cyanobacteria and cyanolichens. Pots without sowing also registered biological soil crust growth, favored by low and medium irradiances with maximum irrigation. Furthermore, at the end of the experiment, cyanobacteria grew in pots sown with all functional types. Saline solution irrigation impaired biological soil crust cover compared to pots without saline solution. In conclusion, functional type sown as cyanobacteria and mosses, low radiation and high irrigation frequency benefited biocrusts growth. [ABSTRACT FROM AUTHOR]

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