Study on Interaction between Global Warming and Permafrost Thawing

在西伯利亚针叶林中部，在扰动和控制点进行了长期的碳收支、热量和质量转移的野外测量。为了调查，安装了两个观察塔。干扰前完整的针叶林吸收CO2为86 mg/m^2·d，干扰后由于植被损失和土壤呼吸增加，CO2从地面释放140 mg/m^2·m2.day。地表植被的丧失导致了地表热量通量增加20%，并导致了冻土上部大规模的融化。采用开顶拱法对土壤呼吸进行了长期的野外测定，结果表明，土壤呼吸强度与土壤温度和土壤湿度成正比。得到了这两个因素的新的经验方程。高达2000 ppm的高浓度甲烷储存在永久冻土中。扰动后，上部永久冻土的额外融化导致储存的甲烷排放到大气中。全球气候变暖对冻土扰动的影响可能是西伯利亚冻土区CO2和CH 4的来源。火灾扰动引起的绿色房屋气体有三个来源。1)燃烧过程中CO2的直接排放2）火烧迹地土壤温度的升高迫使土壤呼吸增加3）在冻土融化过程中，储存的甲烷被排放到大气中。它可能会对未来全球变暖产生正反馈作用。

In the Mid of Siberian Taiga, long term field measurements at disturbed and control sites on Carbon budget, heat and mass transfers were conducted. As to investigation, two observation towers were installed. Before disturbance intact Taiga forest absorbed carbon dioxide by 86mg/m^2.day, but after disturbance carbon dioxide was emitted from the ground by 140 mg/m2.day due to the loss of vegetation and increase of soil respiration. Loss of surface vegetation resulted in the increase of flux heat to the ground by 20% and it caused the large scale thawing of upper permafrost. The long term filed measurements of soil respiration by the method of open top camber indicated that the degree of soil respiration is proportional to soil temperature as well as soil moisture. The new empirical equations of these two factors were obtained. The highly concentrated methane as much as 2000 ppm was stored in the permafrost. After disturbance an additional thawing of upper permafrost resulted in the emission of stored methane to the atmosphere. Impact of permafrost disturbance under the global warming may the source of carbon dioxide and methane in Siberian permafrost area. There are three sources of green house gases induced by fire disturbance. 1) direct emission of carbon dioxide during combustion 2) at the burned site soil respiration was forced to increase by the increased soil temperature 3) in the process of permafrost thawing, stored methane was emitted to atmosphere. It may cause to the positive feedback of future global warming.