Abstract:

Aims：To investigate the elevational patterns and driving factors of soil microbial diversity and community composition in Abies fargesii var. faxoniana forests in Shennongjia National Park, and to analyze the relationships between soil microbial communities and plant communities along the elevational gradient. 

Methods：This study was conducted in A. fargesii forests in Shennongjia National Park. Soil samples were collected along an elevational gradient. High-throughput sequencing was used to analyze the diversity and community composition of soil bacterial and fungal communities. In addition, inter-kingdom ecological networks (IDENs) were constructed to examine the characteristics of soil microbial communities and their relationships with plant communities across different elevations. 

Results：With increasing elevation, total nitrogen, soil organic carbon, and mean annual precipitation (MAP) significantly increased, whereas total phosphorus (TP), available potassium (TK), and plant alpha diversity significantly decreased (P < 0.05). Bacterial Shannon index and richness significantly declined with elevation (P < 0.05), while fungal diversity indices showed no significant change. Among dominant bacterial phyla, the relative abundance of Acidobacteriota, particularly subgroups Gp2, Gp1, and Gp3, increased significantly with elevation (P < 0.05). Dominant fungal phyla showed no significant elevational trends, but Russula increased and Inocybe decreased at the genus level (P < 0.05). Partial Mantel tests indicated that mean annual temperature (MAT) and MAP were the main drivers of microbial community variation, and canonical correspondence analysis (CCA) further showed that MAP and plant diversity significantly shaped bacterial and fungal community structures. Network modularity, connectance, and nestedness increased significantly along the elevational gradient (P < 0.05). Rhododendron przewalskii and Acer mono were the main plant components of module hubs in the plant–microbe IDEN, whereas A. fargesii occupied a central position as a network hub in the plant–fungus IDEN. 

Conclusion：Soil microbial communities in A. fargesii forests exhibit clear elevational patterns. With increasing elevation, bacterial diversity decreases significantly, whereas fungal diversity remains relatively stable. MAT, MAP, and plant diversity are important drivers shaping microbial community structure. In addition, the connectance and modularity of plant–microbe inter-kingdom ecological networks increase significantly with elevation. Plants act as network hub species and, together with key microbial taxa involved in decomposition and nutrient cycling, jointly maintain the structural and functional stability of plant–microbe interaction networks.

Key words: Abies fargesii, Soil microbial community structure, elevational gradient, inter–kingdom ecological network, Shennongjia National Park