Development of fungal community is a potential indicator for evaluating the stability of biological soil crusts in temperate desert revegetation

Development of community compositional and functional gene structure of fungi in biological soil crusts (BSCs) of different successional stages in the Tengger Desert, China, was assessed using Illumina MiSeq sequencing and GeoChip analysis, respectively. Fungal diversity and abundance significantly increased during 60 years of succession, and reached close to the highest level in the late BSC development, corresponding to those in natural habitats. Principal coordinate analysis showed that the BSC fungal communities in 60-year-old revegetation and natural vegetation clustered together, when compared with short-term revegetation. Furthermore, the diversity and relative abundance of fungal functional genes involved in biogeochemical cycling and stress response in dominant phyla reached the highest level after 60 years of BSC development, indicating that this period is an important landmark for fungal community and function. Higher functional and compositional resilience in 60-year-old BSCs implied a higher level of stability of the aggregated BSC ecosystem functions. Thus, the stability of BSC ecosystems could be estimated indirectly based on the development of fungal community, and at least 60 years might be needed for the steady state of BSCs in temperate desert zones without mechanical disturbance.