Plant productivity, decomposition and nutrient cycling are controlled by plant-soil-biota interactions. However, it remains poorly understood how plant species diversity impacts belowground communities that modulate these processes in intensively-managed grassland systems. In managed grassland communities comprising species selected for agronomic performance, we investigated how plant species diversity affected the soil nematode community and associated ecological indices with a focus on assessing aboveground-belowground interactions. A total of 27 nematode taxa were identified from 61 experimental field plots in which plant species diversity was systematically manipulated from a pool of six plant species within three functional groups (FGs; grasses, legumes, herbs). In general, there were strong effects of plant species identity on the nematode community; interspecific interaction effects did not consistently occur, but where they did were best related to plant community evenness. The equi-proportional six-species plant community had a significantly higher nematode diversity, maturity index (MI), structure index (SI) and proportion of sensitive taxa (omnivore and predators) but a lower enrichment index (EI) than the individual monocultures. The two legumes (Trifolium pratense and Trifolium repens) had the highest EI but lowest abundance of fungivores and channel index, indicating a bacterial-dominated decomposition pathway. Moreover, the community structure of nematodes in the equi-proportional six-species community was significantly different from that in the monocultures. This change in community structure was associated with factors highly correlated with plant diversity, including higher aboveground biomass yield and total nitrogen in harvested biomass as well as lower biomass of weed species. Overall, our results show that multi-species forage sward mixtures that include grasses, legumes, and herbs can have a positive effect on the soil nematode community and nematode-based soil quality indices. This is of practical relevance for farmers and for EU agricultural policy targeted at sustainability, soil health and farming for biodiversity benefits.

植物生产力、分解和养分循环受植物-土壤-生物群相互作用的控制。然而，人们对植物物种多样性如何影响集约管理的草地系统中调节这些过程的地下群落仍然知之甚少。在由农艺性能选择的物种组成的管理草原群落中，我们研究了植物物种多样性如何影响土壤线虫群落和相关生态指数，重点是评估地上地下相互作用。从 61 个实验田地中鉴定出总共 27 个线虫类群，其中植物物种多样性是从三个功能组（FG；禾本科植物、豆科植物、草本植物）内的六种植物物种库中系统地操纵的。一般来说，植物物种特性对线虫群落有强烈影响；种间相互作用效应并不总是发生，但发生的情况与植物群落均匀度最相关。等比例的六种植物群落的线虫多样性、成熟度指数（MI）、结构指数（SI）和敏感类群（杂食动物和捕食者）的比例显着高于单个单一栽培，但富集指数（EI）较低。两种豆类（结构指数（SI）和敏感类群（杂食动物和捕食者）的比例，但富集指数（EI）低于单个单一栽培。两种豆类（结构指数（SI）和敏感类群（杂食动物和捕食者）的比例，但富集指数（EI）低于单个单一栽培。两种豆类（红三叶草和白三叶草）具有最高的 EI，但食真菌丰度和通道指数最低，表明细菌主导的分解途径。此外，等比例六种群落中线虫的群落结构与单一栽培中存在显着差异。群落结构的这种变化与与植物多样性高度相关的因素有关，包括较高的地上生物量产量和收获生物量中的总氮以及较低的杂草物种生物量。总体而言，我们的结果表明，包括禾本科、豆类和草本植物在内的多品种饲草混合物可以对土壤线虫群落和基于线虫的土壤质量指数产生积极影响。这对于农民和以可持续发展为目标的欧盟农业政策具有实际意义，