Soil organic carbon primarily shaped soil bacterial community composition during grassland restoration

Soil microbial community plays a key role in land restoration through direct involvement in various soil biochemical processes. However, our knowledge about how different land restoration practices shape bacterial communities is limited.

Soil samples were collected at 0-10 cm and 10-20 cm depths from a seven-year-old naturally restored grassland, an artificially restored grassland (restored either with grass, legume, or a mixture of two), and continuously cultivated cropland. Changes in soil biochemistry and bacterial community structure using targeted high-throughput amplicon sequencing were to identify characteristics of bacterial taxa associated with soil biochemistry altered by the grassland restoration process. The soil bacterial community composition was highly similar under the three artificial grassland management models, but significantly different from arable and naturally restored grasslands. Different grassland restoration approaches indirectly determined the composition and function of soil bacterial communities by regulating vegetation and environmental factors, which further drives the dynamic regulation of enzyme function. The structural equation modeling results indicated that soil organic carbon (SOC) may exert a direct effect on enzyme activity. Additionally, SOC may also indirectly influence enzyme activity through shifts in bacterial community composition mediated by plant biomass.

We found that SOC shaped the bacterial community function through multiple pathways during grassland restoration, providing an important driver for the recovery of grassland ecosystem function.