Abstract: Fungi are an important group of soil microorganisms. Exploring the altitudinal pattern and driving factors of fungal composition and diversity is an important topic in the field of biodiversity and ecosystem function. We employed the Illumina high-throughput sequencing technology to investigate the variation and environmental control of fungal α-diversity and β-diversity at the topsoil (0-20 cm) and subsoil (20-40 cm) across an altitudinal gra-dient of 400-1500 m in a tropical forest of Jianfengling Nature Reserve. The results showed that Ascomycota and Basidiomycota dominated soil fungal community, reaching a relative abundance of more than 90%. Fungal α-diversity at the topsoil exhibited no obvious altitudinal pattern, and that of the subsoil decreased with the increases in altitude. Higher fungal α-diversity was observed in the topsoil. Soil fungi β-diversity was significantly affected by altitude. Morover, temperature was the driving force of the altitude pattern of fungi β-diversity. The similarity of fungal community decreased significantly with the increases in geographical distance, but did not change with the increases in environmental distance. The similarity of rare phyla (Mortierellomycota, Mucoromycota and Rozellomycota) was significantly lower than that of rich phyla (Ascomycota and Basidiomycota), indicating that diffusion restriction determined the differentiation of fungal community structure along the altitude gradient. Our study demonstrated that the diversity of soil fungal community was affected by altitude. The rare phyla, rather than rich phyla, determined the altitudinal variation of fungi β-diversity in Jianfengling tropical forest.

Key words: tropical forest, altitudinal differentiation, soil depth, geographical attenuation