Abstract:

Aims: Soil microorganisms play an irreplaceable role in the energy flow and material cycle of forest ecosystems. Larix gmelinii is the dominant tree species in the Greater Khingan Mountains of China, and the Aershan area is the southernmost point of its distribution in China, which is significantly affected by climate warming. Exploring the soil microbial community structure under L. gmelinii forest is of great significance to understand and maintain the stability of forest ecosystem in Northeast China.

Method: In this study, we collected soil samples from Bailang Town and Tianchi Town in the Aershan area and used high-throughput sequencing technique to analyze the soil bacterial and fungal communities in two forest stands.

Results: The results showed that (1) 5,163 bacterial operational taxonomic units (OTUs) and 2,439 fungal OTUs were obtained according to a 97% sequence similarity level. The diversity of bacteria was higher in the Tianchi area than in the Bailang area, but no significant difference in fungal diversity between the two sites. (2) The dominant phyla of bacteria were Actinobacteriota, Proteobacteria, Verrucomicrobiota, Chloroflexi, and Acidobacteriota, and the dominant phyla of fungi were Basidiomycota and Ascomycota. The dominant bacterial genus was Candidatus_Udaeobacter, and the dominant genera of fungi were Inocybe, Sebacina, Piloderma and Tomentella. (3) The correlation analysis indicated that soil pH and cation exchange capacity were the main factors driving soil bacterial species diversity, and soil total nitrogen and organic carbon were the main factors driving fungal species diversity. (4) Soil total nitrogen, organic carbon, available phosphorus and cation exchange capacity were important factors affecting soil bacterial community composition, while fungal community composition was not significantly affected by the physical and chemical properties of the soil. (5) The relative abundance of Chloroflexi was significantly correlated with pH; the relative abundance of Basidiomycota was significantly correlated with soil total nitrogen and organic carbon, while that of Ascomycota was significantly correlated with soil total nitrogen, organic carbon and cation exchange capacity.

Conclusion: The results of this study indicate that soil physicochemical properties have a significant impact on the soil microbial community structure in L. gmelinii forest within the Aershan area, and the diversity of bacterial and fungal communities also plays an integral role in maintaining the soil ecology and functional environment in this area.

Key words: Larix gmelinii, soil microorganism, high-throughput sequencing, community structure, diversity