关键词: 塔里木盆地, 荒漠, 降水, 土壤细菌群落, 共现网络

Abstract

Aims: Precipitation is one of the pivotal parameters for the desert ecosystems. Analyzing the diversity and stability of soil microbial communities across precipitation gradients would provide crucial insights into the environmental adaptability of the desert bacteria. 

Methods: Seventy-five soil samples (0–10 cm depth) were collected from deserts at the southern margin of the Tarim Basin, spanning a mean annual precipitation (MAP) gradient from 26.26 to 91.43 mm, which corresponds to the MAP of Qiemo County (QM, 26.26 mm), Minfeng County (MF, 53.10 mm), Hetian County (HT, 59.77 mm), Pishan County (PS, 69.26 mm), and Bachu County (BC, 91.43 mm). Through high-throughput sequencing and co-occurrence network modeling, we compared soil bacterial community diversity and stability. 

Results: The results indicated that: (1) different precipitation conditions significantly affected the composition, diversity and community structure of desert soil bacteria at the southern margin of the Tarim Basin. Pseudomonadota, Actinomycetota, Bacteroidota, Bacillota and Gemmatimonadota were the dominant phyla of bacterial communities. Despite the higher relative abundance of specific bacteria, the composition and diversity of the whole soil bacterial communities were more similar to those of common bacterial communities and significantly different from those of specific bacterial communities. (2) The desert soil bacteria at the southern margin of the Tarim Basin were mainly cooperative. The key bacteria belong to S0134_terrestrial_group, Motococcus and Bacillus, etc. The stability of co-occurrence network was influenced by precipitation. Sufficient precipitation can improve the stability of soil bacterial co-occurrence network, while precipitation frequency had a stronger correlation. 

Conclusion: Bacterial composition and diversity in desert soils at the southern margin of the Tarim Basin are governed by soil moisture and saline-alkaline constraints, with cooperative interactions dominating microbial networks, while the precipitation frequency is significantly correlated with the stability of soil bacterial community. These results help to understand how desert ecosystems respond to their environment.

Key words: Tarim Basin, desert, precipitation, soil bacterial communtiy, co-occurrence network