石漠化强度对喀斯特植被演替过程土壤真菌组成及多样性的影响

喀斯特是我国南方广泛分布的地貌类型,土壤真菌对喀斯特植被演替恢复具有重要调节功能,不同石漠化程度的喀斯特区植被演替受到土壤微生物影响,因此研究不同石漠化区域植被演替阶段的土壤真菌组成及多样性,探索土壤真菌在喀斯特植被演替过程中的作用机制具有重要意义。本文采用时空替代法采集了不同石漠化程度（潜在、中度和强度）的喀斯特区植被演替乔木、灌木和草本演替阶段土壤样品,通过Illumina HiSeq第二代高通量测序分析了土壤真菌组成及多样性。结果表明,试验共获得3 871个OTUs,分属4门17纲116科174属;潜在和中度石漠化区各演替阶段土壤真菌优势门均为担子菌门,强度石漠化区各演替阶段土壤真菌无相同优势门;土壤真菌组成及多样性在潜在石漠化区表现为乔木>草本>灌木,中度石漠化区为灌木>乔木>草本,强度石漠化区为灌木>草本>乔木,且石漠化程度对真菌组成及多样性的影响大于植被演替的影响;土壤理化性质随石漠化程度及演替阶段发生变化,且显著影响真菌多样性指数,以碱解氮为主导因子显著影响土壤真菌群落。

Effects of rocky desertification intensity on soil fungal composition and diversity during karst vegetation succession

Karst is a widely distributed landform type in southern China. Soil fungi, have important regulatory functions to karst vegetation succession restoration. The vegetation succession is affected by soil microbes under different rocky desertification grade in karst areas. Studying the composition and diversity of soil fungi in karst vegetation with different rocky desertification grade and the functional mechanism of fungi during vegetation succession are of great significance. In this study, soil samples in karst areas with different vegetation succession stages (trees, bushes and herbs) and different rocky desertification grades (potential, moderate and strong) were collected by using spatiotemporal substitution method. Soil fungal composition and diversity were analyzed by Illumina HiSeq second-generation high-throughput sequencing. As a result, a total of 3 871 OTUs species were obtained, belonging to four phylum, 17 classes, 116 families and 174 genera. The dominant phylum was basidiomycetes in all stages of succession in potential and moderate rocky desertification areas. There are no similar dominant phylum in strong rocky desertification area. The community composition and diversity of soil fungi were progressively manifested in order of trees > herbs > bushes in the potential rocky desertification area, bushes > trees > herbs in the moderate rocky desertification area, and bushes > herbs > trees in the intense rocky desertification area. The effect of rocky desertification level on fungal composition and diversity is greater than the influence of vegetation succession. Soil physical and chemical properties changed with the degree of rocky desertification and vegetation succession, and significantly influenced the diversity index of fungi. As the dominant factor, the soil fungal community was significantly affected by alkali-hydrolyzed nitrogen.