Microbial-Mediated Soil Nutrient Enhancement in Moso Bamboo–Liquidambar formosana vs. Phoebe chekiangensis Mixed Plantings

This study investigated how Moso bamboo (Phyllostachys edulis)–broadleaf mixed forests influence soil properties and microbial communities to support ecological function and sustainable bamboo forest management. Three forest types were examined: pure Moso bamboo stands (MB) and mixed stands with Liquidambar formosana (LB) or Phoebe chekiangensis (PB). Soil chemical properties, microbial diversity, and community composition were assessed using high-throughput sequencing, and functional taxa were correlated with soil nutrients. The results showed that mixed forests significantly influenced soil chemical properties. PB showed the lowest pH and highest total nitrogen (TN), while MB exhibited the highest soil organic matter (SOM) and total potassium (TK). LB maintained moderate TN, high SOM and TK, and stable pH, indicating a balanced nutrient profile. Although α-diversity did not differ significantly, β-diversity analysis revealed distinct microbial community structure (p < 0.01). LB was enriched with carbon-decomposing taxa (Terriglobales and Sphingomonas), PB with acid-tolerant, nitrogen-cycling groups (Candidatus Binatus), and MB with nitrogen-fixing taxa (Nitrobacteraceae and Bradyrhizobium). Co-occurrence network and functional pathway analyses indicated group-specific microbial associations and greater metabolic diversity in LB and PB. In conclusion, mixed Moso bamboo with broadleaf species significantly modified soil chemical properties and microbial community structure, with the Moso bamboo—L. formosana combination showing potential for improving soil nutrient status and microbial function.