海洋型冰川表碛与退缩区土壤微生物群落特征——以阿扎冰川和米堆冰川为例

Characteristics of soil microbial communities in typical temperate glacial debris and Retreat Zones: A case study of the Azha and Midui Glaciers

以藏东南阿扎冰川和米堆冰川为研究区,采用细菌16S rRNA基因扩增子测序和真菌ITS测序技术,研究了冰川表碛与退缩区不同植被演替阶段土壤中微生物群落特征及土壤化学性质影响.结果表明,两条冰川表碛与退缩区土壤中共发现细菌门38个,其中Proteobacteria(40%)、Actinobacteriota(23%)、Bacteroidota(14%)为优势群,共发现真菌门7个,Basidiomycota(47%)和Ascomycota(45%)为优势群.阿扎和米堆冰川表碛中Patescibacteria、RCP2-54、Bacteroidota、Gemmatimonadota和Acidobacteriota的菌群丰度存在显著差异,米堆冰川表碛和退缩区土壤中微生物群落结构和丰度存在显著差异(P<0.05),而退缩区三个演替阶段之间的群落结构差异不显著.适应极端环境的微生物群落在表碛中丰度最高,而随着演替进程参与植物定殖或与植物共生的微生物群落丰度与多样性显著增加,微生物群落的α多样性上升,NMDS模型也逐渐接近重叠,群落结构在植被演替后期逐渐趋于稳定,.除全钾外,养分含量在两条冰川表碛中均较低,随着植被演替土壤pH值逐渐降低而养分逐渐增加,演替后期显著高于前两阶段.表碛中的微生物群落与pH值和全钾显著正相关(P<0.05),而退缩区土壤中则与速效钾、硝酸盐氮、全磷、可溶性有机碳显著正相关(P<0.05),并以磷限制为主.

This study investigates the characteristics of soil microbial communities and the impact of soil chemical properties in the glacier moraine and retreat zones of the Azha and Midui Glaciers in southeastern Tibet, using bacterial 16S rRNA gene amplicon sequencing and fungal ITS sequencing technologies. The results show that a total of 38bacterial phyla were found in the soil of both glacier moraine and retreat zones, with Proteobacteria(40%), Actinobacteriota(23%), and Bacteroidota(14%) being the dominant groups. Seven fungal phyla were identified, with Basidiomycota(47%) and Ascomycota(45%) being the dominant groups.Significant differences were observed in the abundance of Patescibacteria, RCP2-54, Bacteroidota, Gemmatimonadota, and Acidobacteriota between the moraine soils of Azha and Midui Glaciers. Significant differences in microbial community structure and abundance were found between the moraine and retreat zone soils of the Midui Glacier(P<0.05), while no significant differences were observed among the three successional stages within the retreat zone. Microbial communities adapted to extreme environments were most abundant in the moraine, while the abundance and diversity of microbial communities involved in plant colonization or symbiosis with plants significantly increased with succession. The α-diversity of microbial communities increased, and the NMDS model gradually approached overlap, indicating that community structure tended to stabilize in the late stages of vegetation succession. Nutrient content, except for total potassium, was low in both glacier moraine soils. As vegetation succession progressed,soil pH gradually decreased while nutrients gradually increased, with the late succession stage showing significantly higher nutrient levels than the earlier stages. Microbial communities in the moraine soils were significantly positively correlated with pH and total potassium(P<0.05), whereas in the retreat zone soils, they were significantly positively correlated with available potassium, nitrate nitrogen, total phosphorus, and soluble organic carbon(P<0.05), with phosphorus limitation being predominant.