Abstract:

Aims: Biological soil crusts (BSCs) have important ecological function in arid and semiarid lands. Bacterial community is key to BSCs by playing critical roles in BSCs formation, nutrient cycles and regulatory process. However, bacterial community diversity in BSCs succession and the key environmental factors in Mu Us sandy land remains unclear.
Methods: This study selected bare soil, algal crusts, lichen crusts and moss crusts in Mu Us sandy land as objects. Bacterial abundance and community diversity were investigated by qPCR and Miseq sequencing techniques. The relationship between bacterial community diversity and key environmental factors was explored.
Result: The results indicated that 16S rRNA gene abundance significantly increased with BSCs succession. The index of Chao 1, Shannon diversity and phylogenetic diversity of bacterial community decreased from bare soil to algal crusts and then increased from algal crusts to lichen crusts and moss crusts. There were significant differences in the relative abundance of bacterial phylum, order and genus among different BSCs stages. In bare soil, bacterial communities were dominated by Chitinophagales (Bacteroidota), Tubrobacterales (Actonobacteriota) and Rhizobiales (Proteobacteria). Oscillatoriales (Cyanobacteria) was dominant in algal and lichen crusts, and Chitinophagales (Bacteroidota) and Rhizobiales (Proteobacteria) were dominant members in moss crusts. Total phosphorous, total nitrogen, pH and total organic carbon were key environmental factors in shaping soil bacterial communities.
Conclusion: BSCs succession provides different niches for bacterial communities by changing soil physicochemical characteristics. Soil nutrients (total phosphorous, total nitrogen and soil total organic carbon) and pH play critical roles in screening bacterial species and shaping bacterial community of BSCs in the Mu Us sandy land.

Key words: biological soil crusts, succession, bacterial communities, environmental factors, Mu Us sandy land