季节性雪被是高寒森林冬季土壤呼吸的重要调控因子, 气候变化导致的季节性雪被减少可能对高寒森林冬季土壤呼吸产生显著影响。该研究采用人工去除雪被的方法, 研究雪被去除对川西亚高山云杉(Picea asperata)人工林冬季土壤呼吸的影响。结果表明: 与对照相比, 雪被去除加大了土壤温度波动, 使冬季土壤表层和5 cm平均温度分别降低了1.12和0.34 ℃, 冻融循环次数分别增加了39和12次; 冬季平均土壤呼吸速率和土壤碳排放通量分别为0.52 μmol·m^-2·s^-1和88.44 g·m^-2, 雪被去除使冬季平均土壤呼吸速率和碳排放通量分别降低了21.02%和25.99%, 雪被效应主要发生在雪被初期; 冬季土壤呼吸与土壤温度存在显著的指数关系, 雪被去除显著降低了冬季土壤呼吸温度敏感性。未来气候变化所引发的季节性雪被减少可能会降低川西亚高山森林冬季土壤碳排放, 从而对亚高山森林土壤碳动态产生深远影响。

Aims Seasonal snow cover is one of the most important factors that control winter soil respiration in the cold biomes. The warming-induced decreases in snowpack could affect winter soil respiration of subalpine forests. The aim of this study was to explore the effects of snow removal on winter soil respiration in a Picea asperata forest.Methods A snow removal experiment was conducted in a P. asperata forest stand in western Sichuan during the winter of 2015/2016. The snow removal treatment was implemented using wooden roof method. Soil temperatures, snow depth and soil respiration rate were simultaneously measured in plots of snow removal and controls during the experimental period.Important findings Compared to the control, snow removal increased the fluctuations of soil temperatures. The average daily temperature of the soil surface and that at 5 cm depth were 1.12 °C and 0.34 °C lower, respectively, and the numbers of freeze-thaw cycles of the soil surface and that at 5 cm depth were increased by 39 and 12, respectively, in plots of snow removal than in the controls. The average rate of winter soil respiration and CO₂ efflux were 0.52 μmol·m^-2·s^-1 and 88.44 g·m^-2, respectively. On average, snow removal reduced soil respiration rate by 21.02% and CO₂ efflux by 25.99%, respectively. More importantly, the snow effect mainly occurred in the early winter. The winter soil respiration rate had a significant exponential relationship with soil temperature. However, snow removal significantly reduced temperature sensitivity of the winter soil respiration. Our results suggest that seasonal snow reduction associated with climate change could inhibit winter soil respiration in the subalpine forests of western Sichuan, with significant implications for the carbon dynamics of the subalpine forests.