Data from: Vertical distribution of the soil microbiota along a successional gradient in a glacier forefield

Spatial patterns of microbial communities have been extensively surveyed in well-developed soils, but few studies investigated the vertical distribution of microorganisms in newly developed soils after glacier retreat. We used 454-pyrosequencing to assess whether bacterial and fungal community structures differed between stages of soil development (SSD) characterized by an increasing vegetation cover from barren (vegetation cover: 0%/ age: 10 years), sparsely-vegetated (13%/ 60 years), transient (60%/ 80 years) to vegetated (95%/ 110 years) and depths (surface, 5 and 20 cm) along the Damma glacier forefield (Switzerland). Stage of soil development significantly influenced the bacterial and fungal communities. Based on indicator species analyses, metabolically versatile bacteria (e.g. Geobacter) and psychrophilic yeasts (e.g. Mrakia) characterized the barren soils. Vegetated soils with higher C, N and root biomass consisted of bacteria able to degrade complex organic compounds (e.g. Candidatus Solibacter), ligno-cellulolytic Ascomycota (e.g. Geoglossum) and ectomycorrhizal Basidiomycota (e.g. Laccaria). Soil depth only influenced bacterial and fungal communities in barren and sparsely-vegetated soils. These changes were partly due to more silt and higher soil moisture in the surface. In both soil ages, the surface was characterized by OTUs affiliated to Phormidium and Sphingobacteriales. In lower depths, however, bacterial and fungal communities differed between both SSDs. Lower depths of sparsely-vegetated soils consisted of OTUs affiliated to Acidobacteria and Geoglossum whereas depths of barren soils were characterized by OTUs related to Gemmatimonadetes. Overall, plant establishment drives the soil microbiota along the successional gradient but does not influence the vertical distribution of microbiota in recently deglaciated soils.

成熟土壤中的微生物群落空间分布模式已得到广泛调研，但针对冰川退缩后新生土壤内微生物垂直分布的研究仍较为匮乏。本研究依托瑞士达马冰川前缘样带，采用454焦磷酸测序技术，探究不同土壤发育阶段（Stages of Soil Development, SSD）及土层深度下细菌与真菌群落结构的差异。其中土壤发育阶段随植被覆盖度提升依次划分为：裸地（植被覆盖0%，形成时长10年）、稀疏植被覆盖地（13%，60年）、过渡阶段（60%，80年）以及茂密植被覆盖地（95%，110年）；土层深度则设置为表层、5 cm及20 cm三层。土壤发育阶段对细菌与真菌群落结构均存在显著影响。通过指示物种分析可知，裸地土壤的特征类群为代谢多功能细菌（如地杆菌属（Geobacter））与嗜冷酵母菌（如梅奇酵母属（Mrakia））。有机碳、总氮含量及根系生物量均较高的植被覆盖土壤，其群落组成包含可降解复杂有机物的细菌（如候选索杆菌属（Candidatus Solibacter））、木质纤维素降解型子囊菌（如地舌菌属（Geoglossum））以及外生菌根型担子菌（如蜡蘑属（Laccaria））。土层深度仅对裸地与稀疏植被覆盖土壤的细菌及真菌群落存在影响，该差异部分源于表层土壤粉粒占比更高、土壤含水量更大。在两类不同形成时长的土壤中，表层土壤的特征操作分类单元（Operational Taxonomic Unit, OTU）均隶属于席藻属（Phormidium）与鞘脂杆菌目（Sphingobacteriales）。但在较深土层中，不同土壤发育阶段的细菌与真菌群落结构存在显著差异：稀疏植被覆盖土壤的较深土层中，特征OTU隶属于酸杆菌门（Acidobacteria）与地舌菌属；而裸地土壤的较深土层则以芽单胞菌门（Gemmatimonadetes）相关OTU为特征类群。总体而言，植物定殖沿演替梯度塑造了土壤微生物群落，但并未影响新近冰川退缩土壤中微生物的垂直分布格局。