Plant roots represent about a quarter of global plant biomass and constitute a primary source of soil organic carbon (C). Yet, considerable uncertainty persists regarding root litter decomposition and their responses to global change factors (GCFs). Much of this uncertainty stems from a limited understanding of the multifactorial effects of GCFs and it remains unclear how these effects are mediated by litter quality, soil conditions and microbial functionality. Using complementary field decomposition and laboratory incubation approaches, we assessed the relative controls of GCF‐mediated changes in root litter traits and soil and microbial properties on fine‐root decomposition under warming, nitrogen (N) enrichment, and precipitation alteration. We found that warming and N enrichment accelerated fine‐root decomposition by over 10%, and their combination showed an additive effect, while precipitation reduction suppressed decomposition overall by 12%, with the suppressive effect being most significant under warming‐alone and N enrichment‐alone conditions. Significantly, changes in litter quality played a dominant role and accelerated fine‐root decomposition by 15% ~ 18% under warming and N enrichment, while changes in soil and microbial properties were predominant and reduced decomposition by 7% ~ 10% under precipitation reduction and the combined warming and N enrichment. Examining only the decomposition environment or litter properties in isolation can distort global change effects on root decomposition, underestimating precipitation reduction impacts by 38% and overstating warming and N effects by up to 73%. These findings highlight that the net impact of GCFs on root litter decomposition hinges on the interplay between GCF‐modulated root decomposability and decomposition environment, as well as on the synergistic or antagonistic relationships among GCFs themselves. Our study emphasizes that integrating the legacy effects of multiple GCFs on root traits, soil conditions and microbial functionality would improve our prediction of C and nutrient cycling under interactive global change scenarios.

中文翻译：

---

解决多个全局变化驱动因素对凋落物根系分解的复杂影响


植物根系约占全球植物生物量的四分之一，是土壤有机碳 （C） 的主要来源。然而，关于凋落物根系分解及其对全球变化因子 （GCF） 的响应仍然存在相当大的不确定性。这种不确定性在很大程度上源于对 GCF 多因素影响的有限理解，目前尚不清楚这些影响是如何由凋落物质量、土壤条件和微生物功能介导的。使用互补田间分解和实验室培养方法，我们评估了在变暖、氮 （N） 富集和降水改变下 GCF 介导的根凋落物性状和土壤以及微生物特性对细根分解的相对控制。研究发现，增温和氮肥富集加速了细根分解 10% 以上，它们的组合显示出加性效应，而降水减少总体抑制了 12%，其中抑制效应在单独增温和单独氮肥集条件下最为显著。显著显著的是，在增温和氮肥集中下，凋落物质量的变化起主导作用，加速了细根分解15%~18%，而土壤和微生物性质的变化占主导地位，在降水减少和增温氮素混合下分解减少了7%~10%。单独检查分解环境或凋落物特性可能会扭曲全球变化对根系分解的影响，低估了 38% 的降水减少影响，并夸大了高达 73% 的变暖和氮效应。 这些发现强调，GCFs 对凋落物根系分解的净影响取决于 GCF 调制的根系分解性和分解环境之间的相互作用，以及 GCF 本身之间的协同或拮抗关系。我们的研究强调，整合多个 GCF 对根系性状、土壤条件和微生物功能的传统影响将改进我们在交互式全球变化情景下对 C 和养分循环的预测。