Abstract: Frozen soil is sensitive to climatic change. Fungi in the frozen soil are critical to predicting the potential feedback mechanism between frozen soil and climate. The characteristic profile of fungal community structures in surface soils of different frozen soil types in Heilongjiang Province was examined by employing high-throughput sequencing technology to amplify and sequencethe V5-V7 region of 18S rDNA of soil fungi. A total of 454833 sequences wereobtained, which could be classified into 6 phyla, 40 classes, 86 orders and 122 families. The fungal community in surface frozen soil mainly included phyla Ascomycota, Basidiomycota, Mucoromycota, Blastocladiomycota, Zoopagomycota, Chytridiomycota, as well as some strains with undetermined or unclear phylum, with each phylum exhibiting distinct proportions in permafrost and seasonal frozen soil. Among these, Ascomycota was the dominant phylum, with proportions of 81.23% and 76.56%, respectively. Considering the relative abundance, only Cladosporium, Mrakia, Fusarium,Mortierella and Solicoccozyma were classified among the top 20 bacteria genera. LEfSe analysis detected 20 species in permafrost, but none in seasonal frozen soil. The average richness and evenness of fungi in permafrost were not different from those of seasonal frozen soil. The ratios of observed OTU index and Faith’s phylogenetic diversity index of fungi in permafrost soil were significantly higher than those in seasonal frozen soil (P＜0.05). Our results provide insights into the evaluation of fungal communities in soil permafrost regions.

Key words: surface frozen soil, fungi, community structure, high-throughput sequencing, Heilongjiang Province.