Microbial Evolution Research Group, Department of Biosciences, University of Oslo, P.O. Box 1066, 0316, Oslo, Norway.
Mol Ecol. 2013 Oct;22(19):5040-52. doi: 10.1111/mec.12437. Epub 2013 Aug 21.
The main gradient in vascular plant, bryophyte and lichen species composition in alpine areas, structured by the topographic gradient from wind-exposed ridges to snowbeds, has been extensively studied. Tolerance to environmental stress, resulting from wind abrasion and desiccation towards windswept ridges or reduced growing season due to prolonged snow cover towards snowbeds, is an important ecological mechanism in this gradient. The extent to which belowground fungal communities are structured by the same topographic gradient and the eventual mechanisms involved are less well known. In this study, we analysed variation in fungal diversity and community composition associated with roots of the ectomycorrhizal plant Bistorta vivipara along the ridge-to-snowbed gradient. We collected root samples from fifty B. vivipara plants in ten plots in an alpine area in central Norway. The fungal communities were analysed using 454 pyrosequencing analyses of tag-encoded ITS1 amplicons. A distinct gradient in the fungal community composition was found that coincided with variation from ridge to snowbeds. This gradient was paralleled by change in soil content of carbon, nitrogen and phosphorus. A large proportion (66%) of the detected 801 nonsingleton operational taxonomic units (OTUs) were ascomycetes, while basidiomycetes dominated quantitatively (i.e. with respect to number of reads). Numerous fungal OTUs, many with taxonomic affinity to Sebacinales, Cortinarius and Meliniomyces, showed distinct affinities either to ridge or to snowbed plots, indicating habitat specialization. The compositional turnover of fungal communities along the gradient was not paralleled by a gradient in species richness.
高山地区的维管植物、苔藓植物和地衣物种组成的主要梯度是由从风蚀山脊到雪床的地形梯度构建的，这已经得到了广泛的研究。对环境胁迫的耐受性，由于风吹的山脊上的风磨损和干燥，或由于雪床延长的生长季节减少，是这种梯度中的一个重要生态机制。地下真菌群落受同一地形梯度结构的程度及其最终涉及的机制知之甚少。在这项研究中，我们分析了与挪威中部高山地区一个地区的外生菌根植物 Bistorta vivipara 根系相关的真菌多样性和群落组成的变化，沿山脊到雪床梯度。我们从挪威中部高山地区的十个样地的五十株 Bistorta vivipara 植物中采集了根样本。使用 454 焦磷酸测序技术对标记编码的 ITS1 扩增子进行了真菌群落分析。发现真菌群落组成存在明显的梯度，与从山脊到雪床的变化相吻合。该梯度与土壤中碳、氮和磷的含量变化相吻合。所检测到的 801 个非单倍型操作分类单元（OTU）中，有很大一部分（66%）是子囊菌，而担子菌在数量上占主导地位（即相对于读取数）。许多真菌 OTU 与 Sebacinales、Cortinarius 和 Meliniomyces 具有分类亲缘关系，它们要么与山脊，要么与雪床样地具有明显的亲缘关系，表明其具有生境专化性。真菌群落沿梯度的组成周转率与物种丰富度的梯度并不平行。
