Study on Interaction between Global Warming and Permafrost Thawing

在西伯利亚泰加中部，对干扰点和控制点的碳收支、热量和质量传输进行了长期的现场测量。在调查方面，安装了两座瞭望塔。干扰前原始林吸收二氧化碳86 mg/m2·d，干扰后由于植被丧失和土壤呼吸增加，地面排放二氧化碳140 mg/m2·d。地表植被的丧失导致地表热通量增加20%，导致上冻土大规模融化。通过开顶法对土壤呼吸的长期田间观测表明，土壤呼吸强度与土壤温度和土壤水分成正比。得到了这两个因素的新的经验公式。高达2000ppm的高浓度甲烷储存在永久冻土中。在扰动之后，上层冻土的额外融化导致储存的甲烷排放到大气中。全球变暖下多年冻土扰动的影响可能是西伯利亚多年冻土区二氧化碳和甲烷的来源。由火灾扰动引起的温室气体有三个来源。1)燃烧过程中二氧化碳的直接排放2)土壤呼吸作用随土壤温度的升高而增加。3)在冻土融化过程中，储存的甲烷被排放到大气中。这可能会导致对未来全球变暖的正反馈。

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.