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.

丛枝菌根真菌（arbuscular mycorrhizal fungi, AMF）是一类对生态系统功能至关重要的土壤微生物，且当前其生物多样性正面临诸多环境威胁，因此阐明驱动AMF多样性与群落组成的因子具有重要意义。此外，在农业生态系统中，此类研究结果可助力评估AMF的应用潜力，推动农业可持续发展。本研究针对比利时中部24个果园的栽培苹果树根系，通过小亚基rRNA基因扩增子（small subunit rRNA gene amplicons）的454焦磷酸测序技术，定量分析AMF的多样性与群落组成，旨在明确影响AMF多样性与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地理区位。本研究共检测到110个AMF操作分类单元（Operational Taxonomic Unit, OTU），其中绝大多数归属于球囊霉科（Glomeraceae，73%）和近明球囊霉科（Claroideoglomeraceae，19%）。研究结果表明，塑造苹果树根系AMF群落的主要因素为土壤特性与耕作制度，而非果园的地理区位。具体而言，土壤有效磷含量与AMF多样性呈负相关关系；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果园。最后，AMF群落的嵌套性程度与土壤有效磷、氮含量显著相关，这表明随着施肥水平提升，AMF类群会逐渐丧失。综合来看，本研究认为：有机果园管理与适度施肥相结合，可维持苹果树根系多样的AMF群落；且在比利时中部的空间尺度下，苹果树根系AMF似乎不存在扩散限制。