Although herbivores are well known to incur positive density‐dependent damage and mortality, thereby likely shaping plant community assembly, the response of belowground root feeders to changes in plant density has seldom been addressed. Locally rare plant species (with lower plant biomass per area) are often smaller with shallower roots than common species (with higher plant biomass per area) in competition‐intensive grasslands. Likewise, root feeders are often distributed in the upper soil layers. We hypothesized, therefore, that root feeders would incur negative density (biomass)‐dependent damage across plant species. To test this hypothesis, we investigated the diversity and abundance of plant and root feeder species in an alpine meadow and determined the diet of the root feeders using metabarcoding. Across all species, root feeder load decreased with increasing aboveground plant biomass, root biomass, and total plant biomass per area, indicating a negative density dependence of damage across plant species. Aboveground plant biomass per area increased with increasing individual plant biomass and root depth per area across species, suggesting that rare plant species were smaller in size and had shallower root systems compared to common plant species. Both root biomass per area and root feeder biomass per area decreased with soil depth, but the root feeder biomass decreased disproportionately faster compared to root biomass with increasing root depth. Root feeder load decreased with increasing root depth but was not correlated with the feeding preference of root feeder species. Moreover, the prediction derived from a random process incorporating vertical distributions of root biomass and root feeder biomass significantly accounted for interspecific variation in root feeder load. In conclusion, the data indicate that root feeders incur negative density‐dependent damage across plant species. On this basis, we suggest that manipulative experiments should be conducted to determine the effect of the negative density‐dependent damage on plant community structure and that different types of plant–animal interactions should be concurrently examined to fully understand the effect of plant density on overall herbivore damage across plant species.

中文翻译：

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高寒草甸中昆虫的根部饲养对植物物种造成负密度依赖性损害

尽管众所周知，食草动物会遭受密度依赖性的正损害和死亡率，从而可能影响植物群落的组装，但地下根部饲养者对植物密度变化的反应很少得到解决。在竞争密集的草原上，当地稀有植物物种（单位面积植物生物量较低）通常比常见物种（单位面积植物生物量较高）较小且根部较浅。同样，根部饲养者通常分布在上层土壤中。因此，我们假设根部饲养者会在植物物种中产生负密度（生物量）依赖性损害。为了检验这一假设，我们研究了高山草甸中植物和根部饲养物种的多样性和丰度，并使用元条形码确定了根部饲养者的饮食。在所有物种中，根部饲养负荷随着地上植物生物量、根部生物量和单位面积总植物生物量的增加而减少，这表明植物物种间损害的负密度依赖性。随着物种间单株植物生物量和单位面积根部深度的增加，单位面积地上植物生物量也随之增加，这表明与常见植物物种相比，稀有植物物种尺寸更小，根系更浅。单位面积的根生物量和单位面积的根食生物量均随着土壤深度的增加而减少，但随着根深度的增加，根食生物量的下降速度与根生物量相比不成比例地更快。根部食虫负荷随着根部深度的增加而减少，但与根部食虫物种的取食偏好无关。此外，从结合根生物量和根饲养生物量垂直分布的随机过程得出的预测显着解释了根饲养负载的种间变化。总之，数据表明根食者在不同植物物种中都会遭受负密度依赖性损害。在此基础上，我们建议进行操作性实验来确定负密度依赖性损害对植物群落结构的影响，并同时检查不同类型的动植物相互作用，以充分了解植物密度对整体的影响。食草动物对植物物种造成损害。