The influence of afforestation on soil bacterial community composition in karst rocky desertification areas of Guizhou Province, China

Abstract Purpose Soil microorganisms are important indicators for evaluating the effectiveness of vegetation restoration in karst rocky desertification areas. The mechanism by which afforestation affects the soil microbial community through the soil properties remains unclear, especially in karst areas. This study aimed to explore the effect of afforestation on soil properties and bacterial community diversity and composition, and identify soil environmental factors that drive bacterial variation under different land use types. Materials and methods Here, we investigated the changes in soil properties and assessed soil bacterial community composition and diversity after afforestation in a karst rocky desertification area in Guizhou Province, Southwest China via high-throughput sequencing of the 16S rRNA gene. Soil samples at the 0–10 cm layer from two afforestation types, namely, managed forest (MF) and natural forest (NF), and referenced cropland (CL) were collected. Results and discussion Results show that afforestation shifted the soil bacterial community composition but had a non-significant effect on alpha diversity. The dominant phyla were Acidobacteriota , Actinobacteria , Proteobacteria , and Chloroflexi in all land use sites. The relative abundance of Acidobacteriota and Actinobacteriota increased dramatically, whereas that of Proteobacteria decreased remarkably after afforestation. The enriched bacteria in CL are Proteobacteria , Gemmatimonadota , and Bacteroidota , Chloroflexi was enriched in MF, and Rhizobiales , Latescibacterota , and Methylomirabilota were enriched in NF. Correlation network analysis of bacterial communities identifies Actinobacteriota , Acidobacteriota , Proteobacteria Chloroflexi , and Methylomirabilota are key species in the bacterial network. Redundancy analysis showed that soil pH, Ca 2+ content, total nitrogen content (TN), soil organic carbon (SOC), soil water content (SW), bulk density (BD), soil silt content, and clay content jointly affected the bacterial community structure, and Ca 2+ content had the maximum influence. Conclusions Therefore, afforestation can alter soil bacterial community composition through its effects on soil properties in karst areas. Ca 2+ content had the strongest influence on soil bacterial community structure.