尖峰岭热带森林土壤真菌群落的海拔变化格局及驱动因素

Altitudinal pattern and driving factors of soil fungal community in the tropical forest of Jianfengling, Hai-nan, China

真菌是土壤微生物的重要类群,探究其组成和多样性的海拔变化格局与驱动因素是生物多样性与生态系统研究领域的重要议题。本文运用Illumina高通量测序技术,以尖峰岭自然保护区热带森林400~1500 m海拔梯度范围内表层(0~20 cm)和下层(20~40 cm)土壤为对象,研究了真菌群落α和β多样性沿海拔的变化及其环境控制。结果表明:子囊菌门和担子菌门是尖峰岭土壤真菌的优势菌门,其相对丰度达到90%以上;表层土壤真菌群落α多样性无明显的海拔分异,下层土壤真菌α多样性随海拔增加而下降,在整个海拔梯度上,表层土壤真菌α多样性高于下层土壤;土壤真菌β多样性受到海拔变化的显著影响,温度是驱动表层和下层土壤真菌β多样性海拔变异的主要环境因素;土壤真菌群落相似性随着地理距离的增加而显著下降,而不随环境距离的增加发生明显变化,并且整个海拔梯度上,稀有门(被孢菌门、毛霉门和罗兹菌门)的相似性显著低于丰富门(子囊菌门和担子菌门),说明扩散限制决定着真菌群落结构在海拔梯度上的分异。以上结果说明,尖峰岭热带森林土壤真菌多样性受到海拔的影响,稀有门而非丰富门随海拔梯度的变化是真菌β多样性海拔变异的重要来源。

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.