Temporal shifts in cyanobacterial diversity and their relationships to different types of biological soil crust in the southeastern Tengger Desert

Abstract

Diverse cyanobacteria play an important role in improving local environments in desert ecosystems by forming biocrusts. Seasonal changes can directly or indirectly affect the structure of microbial communities through changes in temperature and precipitation; however, the impact of seasonal changes on the cyanobacterial communities in biocrusts is poorly understood. We characterized the cyanobacterial diversity of biocrusts and their sublayers in the southeastern Tengger Desert along a seasonal gradient using Illumina MiSeq sequencing and bioinformatics analyses and explored the combined effects of seasonal dynamics, biocrust types, and chemical properties on cyanobacterial communities. The results showed that the cyanobacterial diversity of both types of biocrust and of the moss biocrust sublayer was significantly higher in summer than in the other three seasons. The cyanobacterial diversity in the cyanobacterial biocrust sublayer did not change significantly with the seasons. Seasonal dynamics influenced the composition, dominant group and core group of the cyanobacterial communities in both biocrust types and in their sublayers. The biocrusts types (R2 = 0.437, P = 0.001) was the variable that affected cyanobacterial community diversity the most, followed by total nitrogen (R2 = 0.128, P = 0.001), seasonal dynamics (R2 = 0.120, P = 0.001), total organic carbon (R2 = 0.076, P = 0.002), nitrate (R2 = 0.048, P = 0.003) and ammonium (R2 = 0.019, P = 0.156). The potential for photosynthesis, carbon fixation, and nitrogen-sulfur cycle participation in the biocrusts and in the cyanobacterial biocrust sublayer was lowest in the summer. There were no significant changes in the moss biocrust sublayer throughout the year. Generally, seasonal dynamics are an important environmental factor affecting the cyanobacterial community and should be considered seriously in future experiments. These results suggested that seasonal dynamics should be taken into consideration in future experiments that involve biological soil sample collection.