Soil organic carbon (SOC) is an indicator of soil fertility. Global warming accelerates SOC decomposition, consequently, resulting in land degradation. Characterization of the response of SOC decomposition to temperature is important for predicting land development. A simulation model based on temperature sensitivity (Q₁₀) of SOC decomposition has been used to predict SOC response to climate warming. However, uncertain Q₁₀ leads to substantial uncertainties in the predictions. A major uncertainty comes from the interference of rainfall. To minimize this interference, we sampled surface (0–5 cm) soils along an isohyet across a temperature gradient in the Qinghai–Tibetan Plateau. The Q₁₀ of bulk soil and the four soil fractions, such as light fraction (LightF), particulate organic matter (POM), hydrolyzable fraction (HydrolysF), and recalcitrant fraction (RecalcitF), were studied by ¹⁴C dating. Turnover time follows the order: LightF < POM < bulk soil < HydrolysF < RecalcitF. The Q₁₀ follows the order: LightF (1.0) = POM (1.0) < HydrolysF (3.63) < bulk soil (5.93) < RecalcitF (7.46). This indicates that stable fractions are much more sensitive to temperature than labile fractions. We also suggest that protection mechanisms rather than molecular composition regulate SOC turnover. A new concept 'protection sensitivity' of SOC decomposition was proposed. Protection sensitivity relates to protection type and primarily controls Q₁₀ variation. A simulation model based on the Q₁₀ of individual fractions predicted SOC change and land development in the Qinghai–Tibetan Plateau in the next 100 years much effectively as compared to simulations based on one‐pool model (Q₁₀ = 2) or bulk soil (Q₁₀ = 5.93).

中文翻译：

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土壤有机物质分解的温度敏感性随其周转时间而增加

土壤有机碳（SOC）是土壤肥力的指标。全球变暖加速了 SOC 分解，从而导致土地退化。表征 SOC 分解对温度的响应对于预测土地开发很重要。基于 SOC 分解的温度敏感性 (Q₁₀) 的模拟模型已被用于预测 SOC 对气候变暖的响应。然而，不确定的 Q₁₀ 会导致预测存在很大的不确定性。一个主要的不确定性来自降雨的干扰。为了最大限度地减少这种干扰，我们沿着青藏高原温度梯度的等温线对地表（0-5 厘米）土壤进行了采样。散装土壤和四种土壤组分的 Q₁₀，如轻质组分 (LightF)、颗粒有机质 (POM)、可水解组分 (HydrolysF)、和顽固分数 (RecalcitF)，通过 ¹⁴C 测年进行了研究。周转时间遵循以下顺序：LightF < POM < 大块土壤 < HydrolysF < RecalcitF。Q₁₀ 遵循以下顺序：LightF (1.0) = POM (1.0) < HydrolysF (3.63) < 大块土壤 (5.93) < RecalcitF (7.46)。这表明稳定馏分比不稳定馏分对温度更敏感。我们还建议保护机制而不是分子组成调节 SOC 周转。提出了SOC分解的新概念“保护灵敏度”。保护灵敏度与保护类型有关，主要控制 Q₁₀ 的变化。