Influence of geographical patterns on bacterial community composition, diversity, and assembly in biocrusts: arid desert to humid tailing mine regions

Biological soil crusts (biocrusts) are widely distributed in terrestrial ecosystems worldwide, they perform an important ecological function in maintaining ecosystem stability. However, the geographic pattern of microbial communities in biocrusts has been studied relatively little and mainly in arid regions. We assessed bacterial communities in biocrusts across four desert regions (Fukang, Shapotou, Dalateqi and Chifeng) and three tailing mine regions (Huangshi, Tongling and Dingnan) using 16S rRNA sequencing. The geographic pattern of biocrust bacterial communities was strongly influenced by both geographic distance and soil substrate conditions. The most abundant bacterial phyla from desert regions and tailing mine regions were Cyanobacteria, Proteobacteria, Chloroflexi and Actinobacteria. Tailing mine biocrusts consisted of more diverse bacterial communities than did desert biocrusts. Deterministic processes governed the spatial variations of bacterial community of biocrusts in all regions. Nutrient content and enzyme activities of tailing mine biocrusts were generally higher than those of desert biocrusts. Our results revealed that the significance changes in diversity, composition and assembly of bacterial community in biocrusts from arid desert to humid tailing mine. The geographic distance and soil substrate conditions determine the distribution of bacterial communities in different ecosystems. As hubs for essential ecosystem services, changes in the dominant species of biocrusts may cause shifts in ecological function. Additionally, deterministic processes control the development and succession of bacterial communities.