Aridity and decreasing soil heterogeneity reduce microbial network complexity and stability in the semi-arid grasslands

Soil microbes play vital roles in mediating the functions and services of terrestrial ecosystems in the context of ongoing climate change and human disturbance. There are complex interactions between soil microbial taxa. However, research on the drivers of soil microbial network complexity and stability based on microbial taxa interactions is still in its infancy. We examined network structure and the complexity and stability of soil microbial communities across a large-scale environmental gradient in semi-arid grasslands of northern China by combining network theory and high-throughput sequencing. We found that aridity was the strongest driver of soil microbial network structure. Increasing aridity directly reduced the complexity and stability of soil microbial networks by decreasing the ratio of microbial taxa that participated in network construction and the ratio of potential positive and negative interactions of networks. Soil heterogeneity enhanced microbial network complexity and stability by potentially promoting diverse host plants and mediating uneven distribution of soil resources. These findings suggest that aridity and decreasing soil heterogeneity may have detrimental influences on soil microbial functions and the associated plant performance. This study provides new insights into the controls of climatic and/or edaphic variables in regulating soil microbial networks and highlights the importance of environmental heterogeneity in community assembly mechanisms of soil microbes.

Automated summary

Soil microbes play important roles in regulating the functions and services of terrestrial ecosystems under climate change and human disturbance. Soil microbial networks are influenced by complex interactions and environmental factors such as aridity and soil heterogeneity. This study found that aridity was the main driver of soil microbial network structure and decreased complexity and stability. Soil heterogeneity, on the other hand, increased microbial network complexity and stability by promoting diverse host plants and mediating soil resource distribution. Overall, this research highlights the importance of climate and soil variables, as well as environmental heterogeneity, in regulating soil microbial networks.