Responses of Microalgal-Microbial Biomass and Enzyme Activities of Biological Soil Crusts to Moisture and InoculatedMicrocoleus vaginatusGradients

Microcoleus vaginatus Gom., the dominant cyanobacterial species in biological soil crusts (BSCs), plays a critical role in forming BSCs. Four inoculum dosages of M. vaginatus (0.5, 1, 3, and 7 g · m−2) were inoculated across a sand surface and subjected to five moisture treatments (0, 1, 2, 3, and 4 L · m−2). Microalgal biomass, microbial biomass, and enzyme activities (invertase, alkaline phosphatase, and urease) were subsequently determined. In general, microalgal biomass, microbial biomass composed of carbon and nitrogen, as well as alkaline phosphatase and urease activity were increased by increasing inoculum dosages and moisture, whereas invertase activity decreased with higher moisture content. Combination of 7 g m−2 inoculum and 2 or 3 L m−2 moisture was recommended for M. vaginatus to recover BSCs. Significant positive correlations were observed between microalgal biomass, microbial biomass, C:N ratios, and enzyme activities. Increasing microalgal biomass can act as an energy source for microbial ...