A comprehensive understanding of the formation of mineral‐associated organic matter (MAOM) is a prerequisite for the sustainable management of soil carbon (C) and the development of effective long‐term strategies for C sequestration in soils. Nevertheless, the precise manner by which microbial and mineral properties drive MAOM formation efficiency and its subsequent response to elevated temperature at the regional scale remains unclear. Here, we employed isotopically labelled laboratory incubations (at 15°C and 25°C) with soil samples from a ~3000 km transect across the Tibetan Plateau to elucidate the mechanisms underlying MAOM formation and its temperature response. The results indicated that both mineral protection and microbial properties were critical predictors of MAOM formation across the geographic gradient. The efficiency of MAOM formation was found to increase with the content of iron (Fe) oxides and their reactivity [i.e., the ratio of poorly crystalline Fe oxides to total Fe oxides (Feo:Fed)] but to decrease with the relative abundance of Gammaproteobacteria and Actinobacteria across the plateau. Moreover, a notable decline in MAOM formation efficiency was observed under elevated temperatures, which was concomitant with a reduction in the content and reactivity of Fe oxides, as well as the microbial assimilation of the labelled substrate. The attenuation of mineral–organic associations was identified as the primary factor contributing to the warming‐induced reduction in MAOM formation. These findings highlight the necessity of incorporating organo–mineral associations and microbial properties into Earth System Models to accurately project soil C dynamics under changing climate.

中文翻译：

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矿物和微生物特性驱动矿物相关有机物的形成及其对温度升高的反应


全面了解矿物伴生有机物 （MAOM） 的形成是可持续管理土壤碳 （C） 和制定有效的土壤碳封存长期策略的先决条件。然而，微生物和矿物特性驱动 MAOM 形成效率及其随后在区域范围内对高温的响应的确切方式仍不清楚。在这里，我们采用同位素标记的实验室孵育（在 15°C 和 25°C）与来自青藏高原 ~3000 公里样带的土壤样本来阐明 MAOM 形成的潜在机制及其温度响应。结果表明，矿物保护和微生物特性是整个地理梯度上 MAOM 形成的关键预测因子。发现 MAOM 形成的效率随着铁 （Fe） 氧化物的含量及其反应性 [即，结晶度差的 Fe 氧化物与总 Fe 氧化物的比率 （Feo：Fed）] 而增加，但随着整个高原上 γ 变形菌门和放线菌门的相对丰度而降低。此外，在高温下观察到 MAOM 形成效率显着下降，这与 Fe 氧化物的含量和反应性以及标记底物的微生物同化一起发生。矿物-有机结合的减弱被确定为导致变暖诱导的 MAOM 形成减少的主要因素。这些发现强调了将有机矿物关联和微生物特性纳入地球系统模型的必要性，以准确预测气候变化下的土壤 C 动态。