Warming as a climate change phenomenon affects soil organic matter dynamics, especially in high elevation ecosystems. However, our understanding of the controls of soil organic matter mineralization and dynamics remains limited, particularly in alpine (above treeline) and subalpine (below treeline) grassland ecosystems. Here, we investigated how downslope (warming) and upslope (cooling) translocations, in a 5-years reciprocal transplanting experiment, affects soil respiration and its temperature sensitivity (Q10), soil aggregation, and soil organic matter carbon (C) and nitrogen (N) composition (C/N ratio). Downslope translocation of the alpine (2440 m a.s.l.) and subalpine (1850 m a.s.l.) to the lowland site (350 m a.s.l.) resulted in a temperature change during the growing seasons of + 4.4K and + 3.3K, respectively. Warming of alpine soils (+ 4.4K) reduced soil organic carbon (SOC) content by 32%, which was accompanied by a significant decrease of soil macroaggregates. Macroaggregate breakdown induced an increased respiration quotient (qCO₂) by 27% following warming of alpine soils. The increase in qCO₂ respiration was associated with a significant decrease (from 2.84 ± 0.05 to 2.46 ± 0.05) in Q10, and a change in soil organic matter composition (lower C/N ratios). Cooling did not show the opposite patterns to warming, implying that other mechanisms, such as plant and microbial community shifts and adaptation, were involved. This study highlights the important role of SOC degradability in regulating the temperature response of soil organic matter mineralization. To predict the adverse effect of warming on soil CO₂ release and, consequently, its negative feedback on climate change, a comprehensive understanding of the mechanisms of C storage and turnover is needed, especially at high elevations in the Alps that are particularly affected by rising temperatures.

变暖作为一种气候变化现象会影响土壤有机质动态，尤其是在高海拔生态系统中。然而，我们对土壤有机质矿化和动力学控制的理解仍然有限，特别是在高山（林线以上）和亚高山（林线以下）草原生态系统中。在这里，我们研究了在 5 年的互惠移栽实验中，下坡（变暖）和上坡（冷却）易位如何影响土壤呼吸及其温度敏感性 （Q10）、土壤聚集体以及土壤有机质碳 （C） 和氮 （N） 组成 （C/N 比）。高山（海拔 2440 米）和亚高山（海拔 1850 米）向低地（海拔 350 米）的下坡迁移导致生长季节的温度变化分别为 + 4.4K 和 + 3.3K。高山土壤变暖 （+ 4.4K） 使土壤有机碳 （SOC） 含量降低了 32%，同时土壤大团聚体也显著减少。高寒土壤变暖后，大团聚体分解导致呼吸商 （qCO₂） 增加 27%。qCO₂ 呼吸的增加与 Q10 的显著减少 （从 2.84 ± 0.05 到 2.46 ± 0.05） 和土壤有机质组成的变化 （较低的 C/N 比） 有关。冷却没有显示出与变暖相反的模式，这意味着涉及其他机制，例如植物和微生物群落的转变和适应。本研究强调了 SOC 可降解性在调节土壤有机质矿化温度响应中的重要作用。 为了预测变暖对土壤 CO₂ 释放的不利影响，以及由此产生的对气候变化的负反馈，需要全面了解碳的储存和周转机制，尤其是在阿尔卑斯山的高海拔地区，这些地区尤其受气温上升的影响。