Soil bacterial community succession during desertification in a desert steppe ecosystem

Desertification often occurs in fragile steppe ecosystems, which may lead to severe soil degradation. Understanding how soil microbial communities respond to desertification is critical for ecological restoration of degraded desert steppes. We used an Ion S5™ XL sequencing platform to explore the soil bacterial community succession across four desertification stages in a desert steppe in Ningxia, China. The results showed that soils from potential to light desertification stage had similar physicochemical properties, whereas significantly lower macronutrients, silt, and clay contents and higher pH, moisture, and sand contents were observed in the severe and very severe stages . Due to change in soil conditions, bacterial communities shifted drastically across the four stages. Variation in bacterial community composition was driven mainly by the deterministic processes (i.e., habitat filtering based on resource availability and space limitations), but their effects decreased toward the very severe desertification stage. More potential indicator species including members of the genera Nitrosomonas , Pirellula , and Methylobacterium were selected to predict very severe desertification relative to the other three stages. These potential indicators could survive in a wide range of habitats with low availability of carbon and nitrogen sources. Co‐occurrence network analysis revealed that most of soil microorganisms might form symbiotic relationships in response to the habitat heterogeneity caused by desertification. In conclusion, as desertification intensified, distinct shifts in soil bacterial communities were driven primarily by the deterministic processes, which provide new insights for the restoration of degraded habitats and sustainable development of land resources.