The response of the carbon (C) cycle to global warming in terrestrial ecosystems is a major issue that must be considered when predicting future climate change. Due to warming simultaneously affects both vegetation and soil, therefore the response of soil organic carbon (SOC) has shown contradictory results in different warming experiments. A 7-year soil warming experiment using plastic film mulching (PM) was conducted with and without plants in a dryland agriculture system to determine the responses of SOC and its fractions to warming. Under different treatments, the δ¹³C signature and a C model were applied to analyze changes in SOC and its sub-pools: soil heavy-fraction organic C (HFOC) and light-fraction organic C (LFOC). The results showed that PM-induced soil warming controlled the LFOC change and the crop-produced C inputs controlled the HFOC change. The LFOC significantly decreased (p < 0.05) and HFOC did not significantly change under treatments with and without warming and planting; however, total SOC was significantly decreased in warming treatments at the end of the experiment. The crop C input and warming significantly increased (p < 0.05) the turnover rates of C₃-sourced C (C₃-C) in LFOC and had no significant (p > 0.05) impact in HFOC. The C₄-sourced C (C₄-C) had longer mean residence time (MRT) than C₃-C in both LFOC and HFOC, and soil warming reduced MRT of C₄-C in LFOC. Soil warming significantly reduced the new C accumulation in LFOC (17.77% lower) and had no effect on new C accumulation in HFOC (1.71% lower); therefore, the crop residue C return ratio is crucial to recover decomposed LFOC and for SOC sustainability in a PM system. Different residue return ratios can alter the SOC change trend, and SOC changes under PM for different residue management should be compared with caution.

碳（C）循环对陆地生态系统全球变暖的响应是预测未来气候变化时必须考虑的主要问题。由于变暖同时影响植被和土壤，因此土壤有机碳（SOC）的响应在不同的变暖实验中表现出相互矛盾的结果。在旱地农业系统中有和没有植物的情况下，使用塑料薄膜覆盖 (PM) 进行了为期 7 年的土壤变暖实验，以确定 SOC 及其分数对变暖的响应。不同处理下，δ ¹³应用 C 特征和 C 模型来分析 SOC 及其子库的变化：土壤重部分有机 C (HFOC) 和轻部分有机 C (LFOC)。结果表明，PM 诱导的土壤变暖控制了 LFOC 的变化，作物生产的 C 输入控制了 HFOC 的变化。 LFOC显着降低（p < 0.05），HFOC在加温和不加温种植处理下没有显着变化；然而，在实验结束时，在加温处理中总 SOC 显着降低。作物碳输入和变暖显着增加了 ( p  < 0.05) LFOC中 C _{3 源}碳 (C ₃ -C)的周转率，并且 对 HFOC没有显着影响 ( p > 0.05)。C ₄LFOC 和HFOC 中-源C (C ₄ -C) 的平均停留时间(MRT) 比C ₃ -C 长，土壤变暖降低了LFOC 中C ₄ -C 的MRT 。土壤变暖显着降低了 LFOC 中新 C 的积累（降低了 17.77%），对 HFOC 中新 C 的积累没有影响（降低 1.71%）；因此，作物残渣 C 回收率对于恢复分解的 LFOC 和 PM 系统中 SOC 的可持续性至关重要。不同的残留物回收率可以改变 SOC 变化趋势，应谨慎比较 PM 下不同残留物管理的 SOC 变化。