Data from: Topology of tree-mycorrhizal fungus interaction networks in xeric and mesic Douglas-fir forests

Abstract1. From the phytocentric perspective, a mycorrhizal network (MN) is formed when the roots of two or more plants are colonized by the same fungal genet. MNs can be modelled as interaction networks with plants as nodes and fungal genets as links. The potential effects of MNs on facilitation or competition between plants are increasingly recognized, but their network topologies remain largely unknown. This information is needed to understand the ecological significance of MN functional traits. 2. The objectives of this study were to describe the interaction network topologies of MNs formed between two ectomycorrhizal fungal species, Rhizopogon vesiculosus and R. vinicolor, and interior Douglas-fir trees at the forest stand scale, identify factors leading to this structure and to contrast MN structures between forest plots with xeric versus mesic soil moisture regimes. 3. Tuberculate mycorrhizas were sampled in six 10 × 10 m plots with either xeric or mesic soil moisture regimes. Microsatellite DNA markers were used to identify tree and fungal genotypes isolated from mycorrhizas and for comparison with reference tree boles above-ground. 4. In all six plots, trees and fungal genets were highly interconnected. Size asymmetries between different tree cohorts led to non-random MN topologies, while differences in size and connectivity between Rhizopogon species-specific subnetwork components contributed towards MN nestedness. Large mature trees acted as network hubs with a significantly higher node degree compared to smaller trees. MNs representing trees linked by R. vinicolor genets were mostly nested within larger, more highly connected R. vesiculosus-linked MNs. 5. Attributes of network nodes showed that hub trees were more important to MN topology on xeric than mesic sites, but the emergent structures of MNs were similar in the two soil moisture regimes. 6. Synthesis. This study suggests MNs formed between interior Douglas-fir trees and R. vesiculosus and R. vinicolor genets are resilient to the random loss of participants, and to soil water stress, but may be susceptible to the loss of large trees or fungal genets. Our results regarding the topology of MNs contribute to the understanding of forest stand dynamics and the resilience of forests to stress or disturbance., Usage notesBeiler,etal_Datapack_JEcol-2014-0405.R2Sample location and genetic data from: Topology of tree-mycorrhizal fungus interaction networks in xeric and mesic Douglas-fir forests1. 从植物中心视角来看，当两株及以上植物的根系被同一真菌克隆系（fungal genet）定殖时，便会形成菌根网络（mycorrhizal network, MN）。菌根网络可被建模为以植物为节点、真菌克隆系为连接边的交互网络。学界日益认识到菌根网络对植物间促进或竞争作用的潜在影响，但其网络拓扑结构仍鲜为人知。阐明菌根网络功能性状的生态意义，亟需相关数据支撑。 2. 本研究的目标为：在林分尺度上，描述两种外生菌根真菌（ectomycorrhizal fungal）——泡囊根须霉（Rhizopogon vesiculosus）和酒色根须霉（R. vinicolor）与内陆花旗松（interior Douglas-fir）之间形成的菌根网络的交互拓扑结构；解析塑造该结构的影响因子；对比干旱与湿润土壤水分状况下林分中菌根网络结构的差异。 3. 研究人员在6块10×10 m的样地中采集结节状菌根（tuberculate mycorrhizas）样本，这些样地分别对应干旱或湿润的土壤水分状况。研究使用微卫星DNA标记（microsatellite DNA markers）对从菌根中分离得到的植物与真菌基因型进行鉴定，并与地上参考树干的基因型进行比对。 4. 在全部6块样地中，植物与真菌克隆系均呈现高度互联的状态。不同树木年龄组间的大小不对称性导致菌根网络拓扑结构呈现非随机特征；而两种根须霉物种特异性子网组件在大小与连接性上的差异，促成了菌根网络的嵌套性（nestedness）。大型成熟树木充当网络枢纽（network hubs），其节点度（node degree）显著高于小型树木。由酒色根须霉克隆系连接形成的菌根网络，大多嵌套在由泡囊根须霉克隆系连接形成的规模更大、连通性更强的菌根网络之中。 5. 网络节点属性分析显示，相较于湿润生境样地，枢纽树木对干旱生境样地的菌根网络拓扑结构更为关键，但两种土壤水分状况下菌根网络的涌现结构并无显著差异。 6. 综合结论：本研究表明，内陆花旗松与泡囊根须霉、酒色根须霉克隆系形成的菌根网络，对网络成员的随机丢失以及土壤水分胁迫均具有较强韧性，但可能易受大型树木或真菌克隆系消失的影响。本研究关于菌根网络拓扑结构的结果，有助于深化对林分动态以及森林应对胁迫或干扰的韧性的理解。 使用说明：Beiler等人数据集包JEcol-2014-0405.R2。样本位置与遗传数据来自论文：《干旱与湿润生境花旗松林树木-菌根真菌交互网络拓扑结构》（Topology of tree-mycorrhizal fungus interaction networks in xeric and mesic Douglas-fir forests）