1965-2010年大兴安岭森林火灾碳排放的估算研究

Estimation of carbon emissions due to forest fire in Daxing'an Mountains from 1965 to 2010

火干扰是森林生态系统的重要干扰因子, 是导致植被和土壤碳储量发生变化的重要原因。火干扰所排放的含碳气体对气候变化具有重要的影响。科学有效地对森林火灾所排放的碳进行计量, 对了解区域和全球的碳平衡及碳循环具有重要的意义。根据大兴安岭森林资源调查数据和1965–2010年森林火灾统计资料, 利用地理信息系统GIS (geographic information system)技术, 通过野外火烧迹地调查与室内控制环境实验相结合的方法确定各种计量参数, 从林分水平上, 采用排放因子法, 估算了大兴安岭1965–2010年46年间森林火灾所排放的碳和含碳气体量。结果表明: 大兴安岭46年间森林火灾排放的碳为2.93 × 107t, 年平均排放量为6.38 × 105t, 约占全国年均森林火灾碳排放量的5.64%; 含碳气体CO_2、CO、CH_4和非甲烷烃(NMHC)的排放量分别为1.02 × 108、9.41 × 106、5.41 × 105和2.11 × 105t, 含碳气体CO_2、CO、CH_4和NMHC的年均排放量分别为2.22 × 106、2.05 × 105、1.18 × 104和4.59 × 103t, 分别占全国年均森林火灾各含碳气体排放量的5.46%、7.56%、10.54%和4.06%; 针阔混交林燃烧效率较低, 虽然火烧面积占总过火面积的21.23%, 但排放的碳只占总排放量的7.81%, 为此提出了相应的林火管理策略。

Aims Forest fire is a major disturbance factor for forest ecosystems and an important pathway of decreasing vegetation and soil-carbon storage. Scientifically and effectively measuring carbonaceous gases emission from forest fire is important in understanding the significance of forest fire in carbon balance and climate change. However, carbon emissions from forest fire remain unclear. Our objective was to estimate carbon emissions from forest fires from 1965 to 2010 in Daxing＇an Mountains of Heilongjiang Province, China. Methods We used a geographic information system （GIS） based modeling approach to generate emission estimates using a two-step procedure. First, we calculated total carbon released from forest fires in Daxing＇an Mountains for selected years between 1965 and 2010 by merging and analyzing several measurement parameters. Second, we calculated amounts of four carbonaceous gases released during the burns, carbon dioxide （COs）, carbon monoxide （CO）, methane （CH4）, and nonmethane hydrocarbon （NMHC）, using several different experimentally derived emission factors. The origin of each of the inputs used in our models is based on a combination of analysis of forest fire statistics, forest resources inventory, field research and laboratory experiments. Important findings Direct total carbon emissions from forest fires in Daxing＇an Mountains during 1965-2010 are about 2.93 x 10^7 t, and mean annual carbon emissions are about 6.38 x 10^5t per year, accounting for 5.64% of the direct total carbon emissions from forest fires in China. Carbon atmospheric emissions of COs, CO, CH4 and NMHC from forest fires were 1.02 x 10^8t, 9.41 x 10^6t, 5.41 x 10^5t and 2.11 x 10^5t, respectively, and mean annual emissions of CO2, CO, CH4, and NMHC from forest fires were 2.22 x 10^6t, 2.05 x 10^5t, 1.18 x 10^4t and 4.59 x 10^3 t, respectively, accounting for 5.46%, 7.56%, 10.54% and 4.06% of the amounts of four carbonaceous gases released from forest fires in China, respectively. Our results indicate that combustion efficiency of coniferous broad-leaved mixed forests is lower than other forest types, and burned area of coniferous broad-leaved mixed forests accounts for 21.23% of total burned area, but carbon emissions accounts for 7.81% of total carbon emissions.