极端降雪对北亚热带-暖温带气候过渡带人工林土壤呼吸的影响

目的]本研究的主要目的是研究极端降雪对北亚热带-暖温带气候过渡带人工林土壤呼吸的影响机制。方法]以信阳市人工林为研究对象,以2018年1月信阳市的暴雪为契机,设置增加雪被、自然降雪、去除雪被的控制试验,利用LI-8100测定了不同厚度雪被处理下土壤呼吸的变化,并结合土壤温度、土壤湿度、土壤微生物量碳氮含量、土壤可利用性氮含量等变化,研究土壤呼吸与环境因子之间的关系。结果]在试验前期,增加雪被显著提高了土壤温度,但增加雪被处理下,试验中后期土壤温度值及整个试验阶段的土壤温度平均值均显著低于对照处理。增加雪被厚度可使土壤呼吸速率提高21.57%,而去除雪被对土壤呼吸速率无显著影响。雪被变化对于微生物量碳氮、土壤可利用性氮含量均无显著影响。增雪处理引起的土壤呼吸速率增加主要由试验前期土壤温度的升高导致的。结论]极端暴雪可能提高气候过渡带人工林的土壤呼吸速率,但这种提高受到降雪量的影响,30 cm左右的降雪并未显著影响土壤呼吸速率,如果积雪深度继续增加,土壤碳排放速率会有所增强。此外,积雪深度在不同的融雪阶段对土壤呼吸的影响幅度不一致,降雪对土壤呼吸的影响主要发生在积雪完全消融之前这一阶段。本结果可为建立气候变化下的生态系统碳循环模型提供部分数据支持。

Effect of Extreme Snowfall on Soil Respiration of Plantations in North Subtropics-Warm Temperature Transition Zone

Objective] To study the effect of extreme snowfall on soil respiration of plantations in north subtropicswarm temperate transition zone. Method] A controlled experiment including snow addition, natural snowfall and snow remove was conducted in a plantation after a heavy snowfall in January 2018 in Xinyang, He’nan Province. The soil respiration variations under different treatments were measured with LI-8100 in different snow cover depths. The soil temperature, soil moisture, microbial biomass carbon, microbial biomass nitrogen, and soil available nitrogen contents were detected to determine the relationships between soil respiration and environmental factors. Result]The results showed that the snow addition significantly elevated soil temperature in the earlier stage of the experiment. However, the soil temperature under snow addition treatment was significantly lower than that in the control during the middle and later stage, and across the whole experiment, respectively. Snow addition elevated the soil respiration rate by 21.57%, but snow remove did not affect the soil respiration. The change of snowfall did not affect the contents of microbial biomass carbon, microbial biomass nitrogen and soil available nitrogen. The elevated soil respiration was mainly ascribed to the elevation of soil temperature in the early stage of the experiment. Conclusion]Extreme snowfall may increase soil respiration rate in plantations in the climate transitional zone, but it is affected by snowfall. The snowfall with the depth of about 30 cm will not significantly affect soil respiration rate. If snow depth continues to increase, the soil carbon emission rate will increase. In addition, the impact of snow depth on soil respiration at different stages of snowmelt is not consistent, and the impact of snow on soil respiration mainly occurs before the snow melts completely. This study can provide partial data supporting the establishment of ecosystem carbon cycle model under climate change scenario.