Data from: Decrease in diversity and changes in community composition of arbuscular mycorrhizal fungi in roots of apple trees with increasing orchard management intensity across a regional scale

Understanding which factors drive the diversity and community composition of arbuscular mycorrhizal fungi (AMF) is important due to the role of these soil microorganisms in ecosystem functioning and current environmental threats to AMF biodiversity. Additionally, in agro-ecosystems, this knowledge may help to evaluate their use in making agriculture more sustainable. Here, we used 454-pyrosequencing of small subunit rRNA gene amplicons to quantify AMF diversity and community composition in the roots of cultivated apple trees across 24 orchards in central Belgium. We aimed at identifying the factors (soil chemical variables, organic versus conventional farming, and geographical location) that affect AMF diversity and community composition. In total, 110 AMF OTUs were detected, of which the majority belonged to the Glomeraceae (73%) and the Claroideoglomeraceae (19%). We show that soil characteristics and farming system, rather than the geographical location of the orchards, shape AMF communities on apple trees. Particularly, plant-available P content of the soil was associated with lower AMF diversity. In orchards with a lower plant-available P content of the soil (P < 100 mg/kg soil), we also found a significantly higher AMF diversity in organically managed orchards as compared to conventionally managed orchards. Finally, the degree of nestedness of the AMF communities was related to plant-available P and N content of the soil, pointing at a progressive loss of AMF taxa with increasing fertilization. Overall, we conclude that a combination of organic orchard management and moderate fertilization may preserve diverse AMF communities on apple trees, and that AMF in the roots of apple trees appear not to be dispersal limited at the scale of central Belgium.阐明丛枝菌根真菌（arbuscular mycorrhizal fungi, AMF）的多样性与群落组成的驱动因子具有重要意义，这类土壤微生物在生态系统功能中发挥关键作用，且当前AMF生物多样性正面临诸多环境威胁。此外，在农业生态系统中，相关研究成果可助力评估其在推动农业可持续发展中的应用潜力。 本研究通过对小亚基rRNA基因扩增子开展454焦磷酸测序，对比利时中部24个果园中栽培苹果树根系内的AMF多样性与群落组成进行了定量分析，旨在明确影响AMF多样性及群落组成的相关因子，包括土壤化学变量、有机与常规耕作模式以及果园地理位置。 总计检测到110个AMF操作分类单元（Operational Taxonomic Units, OTUs），其中绝大多数隶属于球囊霉科（Glomeraceae，占比73%）与近明球囊霉科（Claroideoglomeraceae，占比19%）。研究结果表明，相较于果园的地理位置，土壤特性与耕作系统对苹果树根系AMF群落结构的塑造作用更为显著。具体而言，土壤有效磷含量与AMF多样性呈负相关：在土壤有效磷含量低于100 mg/kg的果园中，有机管理模式下的AMF多样性显著高于常规管理模式的果园。 进一步分析发现，AMF群落的嵌套性与土壤有效磷、有效氮含量密切相关，这意味着随着施肥水平提升，AMF类群会逐渐丧失。 综上，本研究认为，有机果园管理与适度施肥的结合可有效维持苹果树根系内多样的AMF群落，且在比利时中部的空间尺度下，苹果树根系中的AMF并未呈现扩散限制现象。