Soil characteristics and bacterial community characteristics of shelterbelts of different tree species in black soil region of China.

To understand how surface soil characteristics and bacterial communities are affected by the establishment of farmland shelterbelts. Five types of shelterbelts in the mid-west of Heilongjiang Province China were selected for the study. The physicochemical characteristics and bacterial diversity of Populus×xiaohei monoculture (X), Larix gmelinii monoculture (L), Pinus sylvestris monoculture (Z), Pinus sylvestris and Larix gmelinii mixed forest (ZL), and Fraxinus mandshurica and Larix gmelinii mixed forest (SL), as well as in fallow land (CK), were measured and analyzed, respectively. Soil physicochemical characteristics and bacterial diversity (via high-throughput sequencing) were analyzed across 0-20 cm depths. Results showed that shelterbelts significantly altered soil characteristics: X increased moisture, ammonium nitrogen, and microbial biomass nitrogen but reduced aeration. ZL exhibited the highest bacterial richness and enhanced water-holding capacity, aeration, and nutrient retention (total organic carbon, nitrogen, phosphorus). ZL outperformed monocultures in promoting soil health, with available potassium (0-10 cm) and pH (10-20 cm) identified as key drivers of bacterial community variation. Unique genera like Krasilnikovia and Rubrobacter dominated shelterbelt soils, reflecting species-specific effects. Shelterbelts induced surface accumulation of nitrate-nitrogen, potassium, and microbial biomass carbon. Overall, Pinus sylvestris and Larix gmelinii mixed forests optimized soil structure, microbial diversity, and nutrient cycling, underscoring their ecological benefits for sustainable agroforestry. This study highlights the critical role of mixed forest shelterbelts in enhancing soil health and microbial biodiversity, which are essential for sustainable land management practices in the black soil region of China.