1. In many terrestrial ecosystems, earthworms operate at the interface between plants and soil. As ecosystem engineers, they affect key ecosystem functions such as decomposition, nutrient cycling and bioturbation. Their incidence and abundance depends on several soil properties, yet simultaneously they also impact soil properties themselves. The existence of a positive feedback loop in which earthworm activity maintains their own niche—by promoting turnover rate in the forest floor, thereby increasing topsoil pH and creating suitable living conditions for themselves—has been suggested before, yet lacks supporting evidence.
2. Here we assessed how tree species litter traits relate to such below‐ground interactions in forests across Europe. Specifically, we hypothesized a below‐ground feedback loop between burrowing earthworm biomass, humus form and pH, affected by litter quality. We tested this hypothesis by means of structural equation modelling.
3. Our results demonstrate that litter nutrient concentrations affect both burrowing and litter dwelling earthworm biomass, which in turn directly impacts humus form and indirectly soil pH. At a continental scale, that is, including all edaphic conditions, soil pH did not feed into earthworm biomass nor could we link leaf structural recalcitrance (e.g. lignin) or functional diversity to below‐ground interactions.
4. However, in forests where moisture is not limiting, soil acidity proved an important factor determining the context of below‐ground interactions. Therefore, we were able to confirm the hypothesized feedback loop for forest ecosystems with soil pH ≤ 5. In calcareous and/or periodically dry forests, other factors than soil chemistry and litter quality became determinant for earthworm biomass.
5. The activity of burrowing earthworms is pivotal in below‐ground ecosystem functioning of mesic forest soils, impacting litter accumulation and forest floor conditions above‐ground, the pH and nutrient status below‐ground and ultimately their own living conditions. This highlights earthworm bioturbation as a key mechanism for understanding plant–soil interactions in forests.

中文翻译：

---

worm，腐殖质和土壤pH之间的正反馈回路增强了欧洲森林中forest的丰度

1. 在许多陆地生态系统中，earth在植物和土壤之间的界面处运行。作为生态系统工程师，他们影响关键的生态系统功能，例如分解，养分循环和生物扰动。它们的发生率和丰度取决于几种土壤特性，但同时它们本身也会影响土壤特性。以前有人提出过存在一个正反馈回路，在该回路中，activity的活动通过提高森林地表的周转率，从而增加表土的pH值并为其自身创造了适宜的生活条件而保持了自身的生态位，但尚缺乏支持证据。
2. 在这里，我们评估了树种凋落物性状与整个欧洲森林中这种地下互动的关系。具体来说，我们假设在地下earth生物量，腐殖质形式和pH值之间的地下反馈回路受垫料质量的影响。我们通过结构方程模型验证了这一假设。
3. 我们的结果表明，凋落物养分浓度会影响穴居和栖息地lit的生物量，进而直接影响腐殖质的形态和间接影响土壤的pH值。在整个大陆范围内，即包括所有土壤条件，土壤pH值都不会进入feed生物量，我们也无法将叶片的结构抗拒性（例如木质素）或功能多样性与地下相互作用联系起来。
4. 但是，在水分不受限制的森林中，土壤酸度被证明是决定地下相互作用环境的重要因素。因此，我们能够确定土壤pH≤5的森林生态系统的假想反馈回路。在钙质和/或定期干旱的森林中，除土壤化学和凋落物质量以外的其他因素成为worm生物量的决定因素。
5. 穴居earth的活动对中性森林土壤的地下生态系统功能，影响垃圾堆积和地上森林地面状况，pH值和地下营养状况以及最终影响其自身生存状况至关重要。这突显了bio的生物扰动是理解森林中植物与土壤相互作用的关键机制。