黑龙江省温带森林火灾碳排放的计量估算研究

Abstract

As global climate change continues to accelerate,the frequency and intensity of forest fires continue to grow.Forest fires,which play an important ecological role in forest ecosystems,have a very significant effect on carbon emissions and carbon sinks,and also play an important role in the carbon cycle. Although the impact of forest fires on carbon emissions has been analyzed in detail,studies that scientifically and accurately measure carbon and carbonaceous gas emissions from forest fires are lacking. Carbon dioxide( CO2) emissions from temperate forest fires are usually calculated based on Intergovernmental Panel on Climate Change guidelines( IPCC 1997) and only include direct effects of burning.Forest fires have been shown to release significant amounts of carbon into the atmosphere and play a significant role in theglobal carbon cycle and carbon balance. In this study,we estimated the level of emissions from forest fires for carbon and carbonaceous gases including CO2,carbon monoxide( CO),methane( CH4),and non-methane hydrocarbons( NMHC)from 1953 to 2012 in Heilongjiang Province,China. We used a geographic information system based modeling approach to simulate emissions using a two-step procedure. First,we calculated total carbon released from forest fires in Heilongjiang for selected years between 1953 and 2012 by merging and analyzing measurements of several parameters. Second,we calculated the amounts of four carbonaceous gases released during the burn,CO2,CO,CH4,and NMHC,using several different experimentally derived emission factors. The origin of each of the inputs used in our models was based on a combination of analysis of forest fire inventory,forest resources inventory,field research,and laboratory experiments.Direct total carbon emissions from forest fires in Heilongjiang during 1953—2012 were about 5. 88×107t,and mean annual carbon emissions were about 9. 80 ×105t per year,accounting for 8. 66% of the direct total carbon emissions from forest fires in China. Carbon emissions of four trace gases,CO2,CO,CH4and NMHC,from forest fires were 1. 89×108,1.06×107,6.33×105and 4. 43×105t,respectively; mean annual emissions of CO2,CO,CH4and NMHC were 3. 15×106,1.77×105,1.05×104and 7. 38×103t,respectively,accounting for 7. 74%,6. 52%,9. 42% and 6. 53% of the amounts of CO2,CO,CH4and NMHC released from forest fires in China,respectively,during that period. Our results indicate that combustion efficiency of coniferous broad-leaved mixed forest is lower than other forest types. The mean annual burned area for this type of forest accounts for 57. 54% of China's total burn area,while this area's fires account for only 38. 57% of carbon total emissions from forest fires. We propose the following forest fire management strategy. First,our studies show that the area's mean annual forest fire carbon emissions have an important impact on the regional carbon balance. So,we suggest strengthening the management of forest fuels( fine fuels,heavy fuels,etc.) as part of the regional forest fire management strategy. Fuels on the ground do not decompose easily in Heilongjiang's cold and dry temperate forests. Land managers should implement a reasonable prescribed burning plan designed to reduce the accumulation of combustible fuels.A policy for conducting periodic prescribed burning will reduce the incidence of forest fires. Prescribed burning should help land managers to control and limit the incidence and intensity of wildfires while allowing them to improve the condition of the ecosystem. Finally,we should give full consideration to the role of forest fires in maintaining the ecological balance of forest ecosystems.