冬季升温对高山生态系统碳氮循环过程的影响

全球温度升高是目前面临的重要环境问题,但存在明显的季节差异性,即冬季升温幅度显著高于夏季的季节非对称性趋势,这在高纬度和高海拔地区更加显著。冬季升温会直接影响积雪覆盖与冰冻层厚度,并引起冻融交替循环的增加,而冬季植物处于休眠状态,这会直接影响土壤中有效氮的吸收与损失,引起土壤有效氮可利用性的变化。然而,关于冬季增温对后续生长季节植物活动、土壤碳氮循环过程的影响等方面的研究仍存在诸多不确定。综述了冬季升温对积雪覆盖与冻融交替循环改变对高山生态系统物质循环的影响,以及冬季升温对土壤碳氮循环、微生物与酶活性的影响,并由此引起的植物物候期、群落结构、生产与养分循环与凋落物分解等生理、生态过程方面的研究进展。在未来的研究中,应针对不同生态系统特点选择合适的冬季增温方式,加强非极地苔原地区关于冬季升温的研究,注重关注冬季升温对植物-土壤微生物之间反馈作用的影响,重点关注冬季升温对生态系统的延滞效应。

Effects of winter warming on carbon and nitrogen cycling in alpine ecosystems: a review

Global warming is an important environmental issue. There is a significant seasonal difference in global temperature rise, with a significant warming trend in winter than in summer. In the future climate change scenario, winter warming has an important impact on the ecosystem carbon and nitrogen cycle, which is more pronounced at high latitude and high altitudes regions. Warming in winter will directly affect the thickness of snow cover and frozen layer, and cause the increase of the freezing and thawing events. At this time, plant roots largely inactive, coupled with an increased frequency of soil freeze-thaw cycles, may increase soil nitrogen leaching losses and decrease soil available nitrogen content. These changes may have pronounced impacts on plant activities and soil carbon and nitrogen cycling processes in the subsequent growing season. However, there are still many uncertainties about the effects of winter warming on plant activities in the subsequent growing season and the effects on soil carbon and nitrogen cycles. This paper reviewed the effects of winter warming on snow cover changes and freeze-thaw cycles on the material cycling of alpine ecosystems, and the effects of winter warming on soil carbon and nitrogen cycles, microbes and enzyme activities, as well as on plant phenology and communities. In addition, we also summarized the subsequent effects of winter warming on the physiological and ecological processes such as community structure, production and nutrient cycling, and litter decomposition. Finally, we proposed some prospects for conducting winter warming experiment research in future climate change conditions. In future, appropriate warming methods should be selected for different ecosystem characteristics, and research on winter warming in non-polar tundra areas should be strengthened. In addition, the effects of winter warming on plant-soil microbial feedback should be focused on, especially the lag effect on the alpine ecosystems.