Rapid warming increases winter soil carbon dioxide (CO2) efflux in Arctic tundra ecosystems, which can significantly offset carbon (C) uptake during growing seasons and affect the overall annual C balance. In winter, the Arctic landscape is predominantly covered with snow, which is vital for regulating ecological processes. Nevertheless, the impact of snow redistribution on the spatial distribution of winter soil CO2 efflux remains uncertain. In this study, we fitted an empirical model to quantify changes in total winter soil CO2 efflux based on accumulated snow depths, using in situ measurements from a snow manipulation experiment in a dry heath tundra ecosystem of Western Greenland. By employing a distributed snow model, we upscaled the spatial-temporal variations in winter soil CO2 efflux for a dry heath region of approx. 6 km2 during 2010–2020. We found that the total winter soil CO2 efflux increases linearly with the increasing total snow depth. In our study plots, the annual mean winter CO2 efflux ranged from 55 to 58 g C m−2 year−1 in ambient plots and 62 to 71 g C m−2 year−1 in snow addition plots (due to the snow fence) during 2013–2020. Spatially, wind-induced snow redistribution caused the annual mean winter CO2 efflux to vary from 51 to 76 g C m−2 year−1. Winter soil CO2 loss increased by 6 % if snow redistribution was not taken into account, primarily due to snow mass losses from the process of snow redistribution (such as blowing snow sublimation). Our results highlight the importance of snow redistribution on winter soil CO2 emissions, particularly when using regional land models in predictions of annual C balance in the Arctic ecosystems under a changing climate.

中文翻译：

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雪的重新分配减少了北极干燥石南苔原冬季土壤碳的流失


快速变暖增加了北极苔原生态系统中冬季土壤二氧化碳（CO2）的流出，这可以显着抵消生长季节的碳（C）吸收并影响总体年度碳平衡。冬季，北极景观主要被雪覆盖，这对于调节生态过程至关重要。然而，积雪重新分布对冬季土壤二氧化碳流出空间分布的影响仍不确定。在这项研究中，我们利用格陵兰岛西部干燥石南苔原生态系统的雪操纵实验的现场测量数据，建立了一个经验模型，根据积雪深度来量化冬季土壤二氧化碳总流出量的变化。通过采用分布式雪模型，我们扩大了干燥石南地区冬季土壤二氧化碳排放的时空变化。 2010-2020 年期间为 6 平方公里。我们发现冬季土壤二氧化碳总流出量随着总雪深的增加而线性增加。在我们的研究地块中，环境地块中冬季二氧化碳年平均流出量为 55 至 58 g C m−2year−1，加雪地块中年平均冬季 CO2 流出量为 62 至 71 g C m−2year−1（由于雪栅栏） 2013 年至 2020 年期间。在空间上，风引起的雪重新分布导致冬季二氧化碳年平均流出量从 51 到 76 g C m−2year−1 不等。如果不考虑雪的重新分布，冬季土壤二氧化碳损失会增加 6%，这主要是由于雪重新分布过程（例如吹雪升华）造成的雪量损失。我们的结果强调了雪的重新分配对冬季土壤二氧化碳排放的重要性，特别是在使用区域土地模型预测气候变化下北极生态系统的年度碳平衡时。