Abstract:Bacteria, as a key component of biocrusts, which constitute up to or more than 70% of the living cover in arid and semiarid lands worldwide, play the primary role in carbon and nitrogen inputs in deserts. Thus, changes in bacterial community structure and diversity can significantly alter their ecological processes and the functions of biocrusts. Sand burial is a common environmental stress of the biocrusts in arid and semiarid areas, yet little information is available regarding the effects of sand burial on bacterial community structure and diversity within biocrusts. Therefore, we adopted the high-throughput sequencing techniques to investigate the effects of sand burial on bacterial community structure and diversity of biocrusts dominated by Bryum argenteum following sand burial of 0 (control), 0.5, 2 and 10 mm in Shapotou, southeastern edge of the Tengger Desert. Bacterial community species composition, abundance variation, and diversity indices including the Shannon-Wiener diversity and the richness indices Chao and abundance-based coverage estimator were compared among biocrusts that suffered sand burial at various depths. The results showed the following:(1) In total, 38 phyla, 106 classes, and 181 genera were identified within biocrusts dominated by B. argenteum, of which the dominant bacterial phyla included Actinobacteria, Proteobacteria, Cyanobacteria, Planctomycetes, Bacteroidetes, and Acidobacteria, which comprised 78.4%-83.0% of the whole community. (2) Principal component analysis showed that, compared to the control, the bacterial community structure was the most variable in soils at 2 and 10 mm depths. Sand burial induced significant changes in bacterial community composition; with the highest abundance were Cyanobacteria, Proteobacteria, Planctomycetes and Actinobacteria following 0, 0.5, 2 and 10 mm burial depths, respectively. With the increase in burial depth, the relative abundance of Actinobacteria, Proteobacteria, Planctomycetes, Bacteroidetes, Verrucomicrobia, Gemmatimonadetes, and FBP increased, while that of the phyla Cyanobacteria, Acidobacteria, and Chloroflexi decreased. In addition, the abundance of photosynthetic bacteria, nitrogen fixing bacteria, and mycelial genera of Actinobacteria all increased largely at 0.5 mm burial depth and decreased sharply at 2 and 10 mm burial depths. (3) The total count of bacteria, species richness, and microbial diversity of biocrusts dominated by B. argenteum increased following sand burial, among which the biocrusts subjected to 0.5 mm burial depth had the highest richness indices and biocrusts subjected to 2 mm burial depth had the highest diversity indices. The study demonstrated that various depths of sand burial had significant effects on bacterial community and diverse features within biocrusts dominated by B. argenteum in Shapotou and thus offered the theoretical foundation for further understanding of the influence mechanism of sand burial on the structure and ecological functions of biocrusts in arid desert areas.