Gorzelak Monika A, Pickles Brian J, Hart Miranda M
Department of Forest and Conservation Science, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
School of Biological Sciences, University of Reading, Harborne Building, Whiteknights, Reading, RG6 8AS, UK.
Mol Ecol. 2017 Mar;26(6):1586-1597. doi: 10.1111/mec.14023. Epub 2017 Feb 8.
Arbuscular mycorrhizal fungi (AMF) are globally distributed, monophyletic root symbionts with ancient origins. Their contribution to carbon cycling and nutrient dynamics is ecologically important, given their obligate association with over 70% of vascular plant species. Current understanding of AMF species richness and community structure is based primarily on studies of grasses, herbs and agricultural crops, typically in disturbed environments. Few studies have considered AMF interactions with long-lived woody perennial species in undisturbed ecosystems. Here we examined AMF communities associated with roots and soils of young, mature and old western redcedar (Thuja plicata) at two sites in the old-growth temperate rainforests of British Columbia. Due to the unique biology of AMF, community richness and structure were assessed using a conservative, clade-based approach. We found 91 AMF OTUs across all samples, with significantly greater AMF richness in the southern site, but no differences in richness along the host chronosequence at either site. All host age classes harboured AMF communities that were overdispersed (more different to each other than expected by chance), with young tree communities most resembling old tree communities. A comparison with similar clade richness data obtained from the literature indicates that western redcedar AMF communities are as rich as those of grasses, tropical trees and palms. Our examination of undisturbed temperate old-growth rainforests suggests that priority effects, rather than succession, are an important aspect of AMF community assembly in this ecosystem.
丛枝菌根真菌（AMF）广泛分布于全球，是具有古老起源的单系根共生体。鉴于它们与超过70%的维管植物物种存在专性共生关系，其对碳循环和养分动态的贡献在生态上具有重要意义。目前对AMF物种丰富度和群落结构的认识主要基于对禾本科植物、草本植物和农作物的研究，这些研究通常在受干扰的环境中进行。很少有研究考虑过AMF在未受干扰的生态系统中与长寿木本多年生植物物种的相互作用。在这里，我们研究了不列颠哥伦比亚省原始温带雨林中两个地点的年轻、成熟和老龄西部红雪松（Thuja plicata）的根和土壤相关的AMF群落。由于AMF独特的生物学特性，我们采用了一种保守的、基于进化枝的方法来评估群落丰富度和结构。我们在所有样本中发现了91个AMF操作分类单元（OTU），南部地点的AMF丰富度显著更高，但在两个地点的宿主年龄序列上丰富度没有差异。所有宿主年龄组都拥有过度分散的AMF群落（彼此之间的差异比随机预期的更大），幼树群落与老树群落最为相似。与从文献中获得的类似进化枝丰富度数据进行比较表明，西部红雪松的AMF群落与禾本科植物、热带树木和棕榈的群落一样丰富。我们对未受干扰的温带原始雨林的研究表明，优先效应而非演替是该生态系统中AMF群落组装的一个重要方面。
