Earthworms (Annelida: Oligochaeta) deposit several tons per hectare of casts enriched in nutrients and/or arbuscular mycorrhizal fungi (AMF) and create a spatial and temporal soil heterogeneity that can play a role in structuring plant communities. However, while we begin to understand the role of surface casts, it is still unclear to what extent plants utilize subsurface casts. We conducted a greenhouse experiment using large mesocosms (volume 45 l) to test whether (1) soil microsites consisting of earthworm casts with or without AMF (four Glomus taxa) affect the biomass production of 11 grassland plant species comprising the three functional groups grasses, forbs, and legumes, (2) different ecological groups of earthworms (soil dwellers—Aporrectodea caliginosa vs. vertical burrowers—Lumbricus terrestris) alter potential influences of soil microsites (i.e., four earthworms × two subsurface microsites × two AMF treatments). Soil microsites were artificially inserted in a 25-cm depth, and afterwards, plant species were sown in a regular pattern; the experiment ran for 6 months. Our results show that minute amounts of subsurface casts (0.89 g kg−1 soil) decreased the shoot and root production of forbs and legumes, but not that of grasses. The presence of earthworms reduced root biomass of grasses only. Our data also suggest that subsurface casts provide microsites from which root AMF colonization can start. Ecological groups of earthworms did not differ in their effects on plant production or AMF distribution. Taken together, these findings suggest that subsurface earthworm casts might play a role in structuring plant communities by specifically affecting the growth of certain functional groups of plants.

中文翻译：

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地下蚯蚓粪可能是重要的土壤微场所，特别影响草原植物的生长

蚯蚓（Annelida：Oligochaeta）每公顷沉积数吨富含营养物质和/或丛枝菌根真菌 (AMF) 的铸件，并产生空间和时间的土壤异质性，可以在构建植物群落中发挥作用。然而，虽然我们开始了解表面铸件的作用，但仍不清楚植物在多大程度上利用地下铸件。我们使用大型中胚层（体积 45 l）进行了一项温室实验，以测试（1）由含有或不含 AMF（四种Glomus 分类群）的蚯蚓粪组成的土壤微场所是否影响由三个功能群草组成的 11 种草原植物物种的生物量生产， forbs 和豆类，(2) 蚯蚓的不同生态群体（土壤栖息者——Aporrectodea caliginosa vs. 垂直挖洞器（Lumbricus terrestris）改变土壤微型站点（即四只蚯蚓×两个地下微型站点×两次AMF处理）的潜在影响。土壤微点人工插入25厘米深，然后按规则播种植物物种；实验进行了 6 个月。我们的结果表明，微量的地下铸件（0.89 g kg−1 土壤）会降低杂草和豆科植物的芽和根产量，但不会降低草的芽和根产量。蚯蚓的存在仅降低了草的根生物量。我们的数据还表明，地下铸型提供了可以开始根系 AMF 定植的微型位点。蚯蚓的生态群体对植物生产或 AMF 分布的影响没有差异。综合起来，