Abstract: Mycorrhizal fungi are one of the most important functional groups in soils, which significantly affect plant community composition and ecosystem function. Betula platyphylla, a typical ectomycorrhizal fungi-dominated tree species, is a pioneer species in natural secondary succession of forests. To better understand the composition of ectomycorrhizal fungi, Illumina MiSeq high-throughput sequencing was used to examine the diversity and community structure of ectomycorrhizal fungi in the rhizosphere soil of B. platyphylla in three sites of Jingerliang (JEL), Hadamen Forest Park (HDM), and Xiaojinggou (XJG) in Daqing Mountain, Hohhot. The results showed that the ectomycorrhizal fungi belonged to 2 phyla, 3 classes, 7 orders, 17 families, and 25 genera. At the phylum level, Basidiomycota accounted for 98.79% of all ectomycorrhizal fungi, with the rest being Ascomycota (1.21%). At the genus level, Russula,Cortinarius, Clavulina, Hysterangium,Hebeloma, Hygrophorus,Amanita and Tuber were the dominant ectomycorrhizal fungi. The diversity and richness of ectomycorrhizal fungi communities significantly differed among the three sites, with XJG being the highest, followed by HDM, and JEL being the lowest. The PCA clustering results of ectomycorrhizal fungi communities showed that the ectomycorrhizal fungal community structure in HDM and XJG was similar, which was quite different from that in JEL. The RDA was employed to analyze the ecological causes of the differences in the community composition of ectomycorrhizal fungi in the three sites. All soil factors explained 98.3% of the differences in the community composition of ectomycorrhizal fungi, with AP, TN, OM and AK being the main factors driving the differences of community composition of ectomycorrhizal fungi among the three sites.

Key words: ectomycorrhizal fungi, high-throughput sequencing, soil physical and chemical properties, community structure.