Datasets for fine-root litter decomposition under global change in an alpine ecosystem

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 GCFs-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. 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 global change factors on root traits, soil conditions and microbial functionality would improve our prediction of C and nutrient cycling under interactive global change scenarios.

植物根系约占全球植物生物量的四分之一，同时也是土壤有机碳（C）的主要来源。然而，学界对于根系凋落物分解及其对全球变化因子（GCFs）的响应仍存在诸多不确定性。此类不确定性在很大程度上源于对全球变化因子多因子效应的认知不足，且目前仍不清楚凋落物质量、土壤条件与微生物功能如何介导这些效应。本研究采用互补的野外分解与室内培养手段，评估了在增温、氮（N）沉降以及降水改变情境下，全球变化因子介导的根系凋落物性状、土壤与微生物属性变化对细根分解的相对调控作用。研究结果显示，增温与氮富集可使细根分解速率提升10%以上，二者联合作用呈现加和效应；而降水减少总体上抑制了12%的分解过程，且该抑制效应在单独增温或单独氮富集条件下最为显著。值得注意的是，在增温与氮富集情境下，凋落物质量变化发挥主导调控作用，使细根分解速率提升15%~18%；而在降水减少以及增温与氮富集联合作用的情境中，土壤与微生物属性变化则占据主导地位，使分解速率降低7%~10%。上述研究结果表明，全球变化因子对根系凋落物分解的净效应，取决于全球变化因子调控的根系可分解性与分解环境之间的相互作用，同时也取决于全球变化因子之间的协同或拮抗关系。本研究强调，整合多重全球变化因子对根系性状、土壤条件与微生物功能的遗留效应，将有助于提升我们在交互全球变化情境下对碳与养分循环的预测精度。