Mechanical sand fixing is more beneficial than chemical sand fixing for artificial cyanobacteria crust colonization and development in a sand desert

The incubation of biological soil crusts (BSCs) can potentially determine a decrease in abiotic stress levels, which can then shift the state of the ecosystem and combat desertification due to their key ecological roles in drylands. Stabilized sand soil surface is the primary factor for natural and induced BSCs successful establishment in harsh dryland environments. Mechanical sand fixing, such as straw checkerboard barriers and chemical sand fixing are two effective ways to stabilized sandy soil surface. The impacts of these two sand fixing methods on artificial cyanobacteria colonization have not been frequently been compared in the field. In this study, five cyanobacteria, Anabaena sp., Nostoc sp., Phormidium sp., Scytonema sp. and Tolypothrix sp. were isolated and cultured. The straw checkerboard method was represented mechanical sand fixing and W-OH (modified water-borne polyurethane) method was used to test chemical sand fixing. Coverage, thickness and biomass of artificial cyanobacterial crust as well as wind erosion intensity and dust deposition were measured after 16 months of inoculation. Results show that the highest coverage, thickness and biomass of artificial cyanobacterial crust was in the straw checkerboard mechanical method, with cyanobacteria measuring higher than other treatments (p < 0.05) at 28.3%, 3.01 mm and 0.24 mg cm(-2), respectively, and showed both positive relationships with dust deposition and herb coverage, but negatively with wind erosion intensity (p < 0.05). Thus, mechanical sand fixing was more beneficial to artificial cyanobacterial crust incubation in field conditions rather than chemical sand fixing, due to sustaining increase in dust deposition to sand surface stability. In addition, mechanical sand fixing uses lessees water than chemical sand fixing. Our results also indicated that annual herb coverage should be closely managed during the artificial cyanobacterial crust incubation in field conditions.