Study on Interaction between Global Warming and Permafrost Thawing

全球变暖与多年冻土融化相互作用的研究

基本信息

批准号：
14102008
负责人：
FUKUDA Masami
金额：
$ 36.61万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (S)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2006
项目状态：
已结题

项目摘要

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.

在西伯利亚针叶林中部，对受干扰和控制地点的碳预算、热量和质量传递进行了长期现场测量。为了进行调查，安装了两座观测塔。干扰前完整的针叶林吸收二氧化碳86mg/m^2.day，但干扰后由于植被损失和土壤呼吸增加，从地面排放二氧化碳140mg/m2.day。地表植被的丧失导致地面通量热量增加20%，并导致上层多年冻土大规模融化。开顶拱法对土壤呼吸的长期现场测量表明，土壤呼吸的程度与土壤温度和土壤湿度成正比。得到了这两个因素的新经验方程。高达 2000 ppm 的高浓度甲烷储存在永久冻土中。扰动后，上部永久冻土层的额外融化导致储存的甲烷排放到大气中。全球变暖背景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。火灾引起的温室气体有三个来源。 1) 燃烧过程中直接排放二氧化碳 2) 燃烧现场土壤呼吸因土壤温度升高而被迫增加 3) 在多年冻土融化过程中，储存的甲烷排放到大气中。它可能对未来全球变暖造成正反馈。