Key Laboratory of State Forestry Administration on Soil and Water Conservation, Beijing Forestry University, Beijing, China; Beijing Engineering Research Center of Soil and Water Conservation, Beijing Forestry University, Beijing, China; School of Soil and Water Conservation, Beijing Forestry University, Beijing, China.
Key Laboratory of State Forestry Administration on Soil and Water Conservation, Beijing Forestry University, Beijing, China; Beijing Engineering Research Center of Soil and Water Conservation, Beijing Forestry University, Beijing, China; School of Soil and Water Conservation, Beijing Forestry University, Beijing, China.
Sci Total Environ. 2020 Jul 15;726:138403. doi: 10.1016/j.scitotenv.2020.138403. Epub 2020 Apr 8.
Vegetation cover has implications for seasonally frozen soil dynamics and greenhouse gas emissions. We examined the frozen soil dynamics and NO and CO efflux in a forest plantation (Populus ssp.) and farmland. The experiments were carried out at a forest reclamation site in Zhangbei county, Hebei province, China, from November 2017 to May 2018. Compared to the farmland, the forest plantation prolonged the retention of frozen soil because the shallower snow and the longer duration of snow cover in the forest contributed to a deeper frost depth and delayed soil thawing. The canopy also sheltered the frozen soil from the extreme fluctuations in freeze-thaw cycles (FTCs) during the snow-free period. Contrasting snow regimes and FTC dynamics contributed to variations in CO and NO between the forest plantation and the farmland. Path analysis showed that the soil water content and soil temperature were the main regulators of NO and CO emissions, respectively, in both land-use types. By contrast, soil substrate and microorganism biomass minimally influenced NO and CO efflux. In conclusion, forest cover influences frozen soil dynamics and greenhouse gas emissions by buffering temperature fluctuations in both snow-covered and snow-free periods. This study further highlights the potential importance of anthropogenic land-use changes in influencing the cold season energy balance and gas efflux in future milder winter climates.
植被覆盖对季节性冻土动态和温室气体排放有影响。我们研究了森林种植园（杨树属）和农田的冻土动态和 NO 和 CO 排放。实验于 2017 年 11 月至 2018 年 5 月在中国河北省张北县的一个造林地进行。与农田相比，森林种植园延长了冻土的保留时间，因为较浅的积雪和较长的积雪覆盖时间导致了更深的冻结深度，并延迟了土壤解冻。树冠还保护了冻土免受无雪期冻融循环（FTC）极端波动的影响。对比不同的积雪状况和 FTC 动态导致了森林种植园和农田之间 CO 和 NO 的差异。路径分析表明，土壤水分含量和土壤温度分别是两种土地利用类型中 NO 和 CO 排放的主要调节因素。相比之下，土壤基质和微生物生物量对 NO 和 CO 通量的影响最小。总之，森林覆盖通过缓冲雪覆盖和无雪期的温度波动来影响冻土动态和温室气体排放。本研究进一步强调了人为土地利用变化在未来更温暖的冬季气候中影响寒冷季节能量平衡和气体排放的潜在重要性。
