Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
Mol Ecol. 2013 May;22(10):2827-38. doi: 10.1111/mec.12259. Epub 2013 Apr 22.
Microbial communities play a major role in terrestrial ecosystem functioning, but the determinates of their diversity and functional interactions are not well known. In this study, we explored leaf litter fungal diversity in a diverse Panama lowland tropical forest in which a replicated factorial N, P, K and micronutrient fertilization experiment of 40 × 40 m plots had been ongoing for nine years. We extracted DNA from leaf litter samples and used fungal-specific amplification and a 454 pyrosequencing approach to sequence two loci, the nuclear ribosomal internal transcribed spacer (ITS) region and the nuclear ribosomal large subunit (LSU) D1 region. Using a 95% sequence similarity threshold for ITS1 spacer recovered a total of 2523 OTUs, and the number of unique ITS1 OTUs per 0.5-1.0 g leaf litter sample ranged from 55 to 177. Ascomycota were the dominant phylum among the leaf litter fungi (71% of the OTUs), followed by Basidiomycota (26% of the OTUs). In contrast to our expectations based on temperate ecosystems, long-term addition of nutrients increased, rather than decreased, species richness relative to controls. Effect of individual nutrients was more subtle and seen primarily as changes in community compositions especially at lower taxonomic levels, rather than as significant changes in species richness. For example, plots receiving P tended to show a greater similarity in community composition compared to the other nutrient treatments, the +PK, +NK and +NPK plots appeared to be more dominated by the Nectriaceae than other treatments, and indicator species for particular nutrient combinations were identified.
微生物群落在陆地生态系统功能中起着重要作用，但它们多样性和功能相互作用的决定因素还不是很清楚。在这项研究中，我们探索了巴拿马低地热带雨林中落叶真菌的多样性，在这片森林中，一个 40×40 米的样地重复进行了九年的 N、P、K 和微量元素施肥实验。我们从落叶样本中提取 DNA，使用真菌特异性扩增和 454 焦磷酸测序方法对两个基因座进行测序，核核糖体内转录间隔区（ITS）和核核糖体大亚基（LSU）D1 区。使用 95%的 ITS1 间隔区序列相似性阈值共恢复了 2523 个 OTUs，每个 0.5-1.0 g 落叶样本的独特 ITS1 OTUs 数量从 55 到 177 不等。在落叶真菌中，子囊菌门是优势门（占 OTUs 的 71%），其次是担子菌门（占 OTUs 的 26%）。与我们基于温带生态系统的预期相反，长期添加养分增加了物种丰富度，而不是像对照那样减少。个别养分的影响较为微妙，主要表现为群落组成的变化，特别是在较低的分类学水平上，而不是物种丰富度的显著变化。例如，与其他养分处理相比，接受 P 的样地表现出更高的群落组成相似性，与其他处理相比，+PK、+NK 和+NPK 样地似乎更受 Nectriaceae 的支配，并且确定了特定养分组合的指示物种。
