AimMicrobial carbon use efficiency (CUE) is one of the key indicators for the formation and release of soil carbon. CUE can be divided into exogenous CUE (CUEex, efficiency in using external carbon sources measured by e.g. 13C or 14C labeling) and endogenous CUE (CUEen, efficiency in using internal carbon sources measured by 18O labeling). Global changes strongly influence CUE, which response depends on the carbon source. However, the effect size and drivers of CUEex and CUEen responses to global changes remain unclear, leading to large uncertainties when forecasting terrestrial carbon cycling. We aimed to quantify the magnitude and direction of microbial CUEex and CUEen responses to global changes.LocationGlobal.Time Period2011–2024.Major Taxa StudiedSoil microorganisms.MethodsDatabase containing 213 paired microbial CUEex and 155 paired microbial CUEen data was integrated and meta‐analysed to assess the impacts of global change factors on microbial CUE. Additional information gathered encompassed latitude, longitude, climate, plant properties, soil properties, microbial properties and experimental conditions.ResultsWe found that CUEex decreased with absolute latitude, while CUEen showed the opposite trend. Warming reduced CUEex and CUEen by 3.6% and 16.5%, respectively. Drought increased CUEex by 7.9%, but decreased CUEen by 14.3%. Nutrient inputs consistently decreased CUEex by 5.0%–17.1%, while nitrogen and nitrogen combined with phosphorus and potassium inputs increased CUEen by 25.5% and 43.1%, respectively. Aridity index, soil pH and cation exchange capacity were the main factors influencing microbial CUEex. In contrast, microbial respiration and growth rates, followed by microbial biomass, were the major predictors of microbial CUEen.Main ConclusionsBiogeochemical models should account for the opposite spatial patterns of microbial CUEex and CUEen, as well as their respective specific drivers under global changes, to accurately predict microbial responses to various carbon sources.

中文翻译：

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全球变化下土壤外源性和内源性土壤微生物碳利用效率的对比


微生物碳利用效率（CUE）是土壤碳形成和释放的关键指标之一。CUE 可分为外源性 CUE（CUEex，通过 13C 或 14C 标记测量的外部碳源使用效率）和内源性 CUE（CUEen，通过 18O 标记测量的内部碳源使用效率）。全球变化强烈影响 CUE，其响应取决于碳源。然而，CUEex 和 CUEen 对全球变化的响应的效应大小和驱动因素仍不清楚，导致预测陆地碳循环时存在很大的不确定性。我们旨在量化微生物 CUEex 和 CUEen 对全球变化的响应的大小和方向。位置Global.Time Period2011–2024.主要分类群研究土壤微生物。方法整合包含 213 个配对微生物 CUEex 和 155 个配对微生物 CUEen 数据的数据库并进行荟萃分析，以评估全局变化因素对微生物 CUE 的影响。收集的其他信息包括纬度、经度、气候、植物特性、土壤特性、微生物特性和实验条件。结果我们发现 CUEex 随绝对纬度的增加而降低，而 CUEen 则表现出相反的趋势。变暖使 CUEex 和 CUEen 分别减少了 3.6% 和 16.5%。干旱使 CUEex 增加了 7.9%，但 CUEen 减少了 14.3%。养分输入持续使 CUEex 降低 5.0%–17.1%，而氮和氮结合磷和钾输入分别使 CUEen 增加 25.5% 和 43.1%。干旱指数、土壤 pH 值和阳离子交换能力是影响微生物 CUEex 的主要因素。相比之下，微生物呼吸和生长速率，其次是微生物生物量，是微生物 CUEen 的主要预测因子。主要结论生物地球化学模型应考虑微生物 CUEex 和 CUEen 的相反空间模式，以及它们在全球变化下各自的特定驱动因素，以准确预测微生物对各种碳源的响应。