Changes in precipitation regimes have significant effects on soil carbon (C) cycles; however, these effects may vary in arid versus humid areas. Additionally, the corresponding details of soil C cycles in response to altered precipitation regimes have not been well documented. Here, a meta-analysis was performed using 845 pairwise observations (control vs. increased or decreased precipitation) from 214 published articles to quantify the responses of the input process of exogenous C, the contents of various forms of C in soil, and the soil-atmosphere C fluxes relative to increased or decreased precipitation. The results showed that the effects of altered precipitation regimes did not differ between rainfall and snowfall. Increased precipitation significantly enhanced the soil C inputs, pools and outputs by 18.17%, 18.50%, and 21.04%, respectively, while decreased precipitation led to a significant decline in these soil C parameters by 10.18%, 9.96%, and 17.98%, respectively. The effects of increased precipitation on soil C cycles were more significant in arid areas (where mean annual precipitation, MAP <500 mm), but the effects of decreased precipitation were more significant in humid areas (where MAP ≥500 mm), indicating that the original MAP partially determined the responses of the soil C cycles to altered precipitation regimes. This study implies that for the same of precipitation variation, soil C cycles respond at different magnitudes: not only should the direction (decrease vs. increase) be counted but also the region (arid vs. humid) should be considered. These results deepened our understanding on regional differentiation in soil C cycles under climate change scenarios.

中文翻译：

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干旱与潮湿陆地生态系统中降水方式改变对土壤碳循环的不同影响

降水状况的变化对土壤碳（C）循环有显着影响；然而，这些影响在干旱和潮湿地区可能会有所不同。此外，土壤碳循环响应改变的降水情况的相应细节尚未得到很好的记录。在这里，使用来自 214 篇已发表文章的 845 对成对观察（控制与增加或减少的降水）进行了荟萃分析，以量化外源 C 输入过程的响应、土壤中各种形式 C 的含量以及土壤- 大气 C 通量与降水的增加或减少有关。结果表明，降雨和降雪对改变降水制度的影响没有差异。降水增加显着提高了土壤碳的输入、库和输出，分别提高了 18.17%、18.50% 和 21.04%，而降水减少导致这些土壤碳参数分别显着下降 10.18%、9.96% 和 17.98%。降水增加对土壤碳循环的影响在干旱地区（平均年降水量，MAP <500 mm）更显着，但降水减少对湿润地区（MAP≥500 mm）的影响更显着，表明原始 MAP 部分确定了土壤碳循环对改变的降水状况的响应。本研究表明，对于相同的降水变化，土壤碳循环响应的幅度不同：不仅应计算方向（减少与增加），还应考虑区域（干旱与潮湿）。这些结果加深了我们对气候变化情景下土壤碳循环区域差异的理解。