土地利用变化对碳排放的影响

Effects of Land Use Change on Carbon Emissions

大气中温室气体浓度增加是人类面临的严峻挑战。土地利用变化已成为仅次于化石能源燃烧的第二大温室气体排放源。本文在界定土地利用变化碳排放作用机制及内涵的基础上,从农用地向非农用地转换、农用地内部土地利用以及非农用地内部土地利用三个方面综述了土地利用变化对碳排放的影响。农用地向非农用地的转换会增加碳排放量。农用地内部土地利用变化方面,农田转换为森林或草地能够使土壤和植被碳储量增加,但是土壤碳汇集速率存在一定的差异;农田、森林和草地管理措施对生态系统碳循环的影响目前还存在争议,但基本观点是合理的管理措施能够减少碳排放量。非农用地内部土地利用变化方面,从能源消耗角度考虑,二产用地向三产用地转换会减少碳排放量。因此合理组织土地利用对帮助我国实现碳减排承诺,发展低碳经济有重要意义。

The increase of greenhouse gas in the atmosphere is now one of the greatest challenge to human beings. Following the burning of fossil fuels, land use change has become the second largest source of greenhouse gas emissions. This paper explored the mechanisms of carbon emissions caused by land use change and reviewed the effects of land use change, including the conversion of farmland to construction land, internal changes of land use in farmland and internal changes of land use in construction land on carbon emissions. The conversion of farmland to construction land increases carbon emissions. Regarding internal changes of land use in farmland, the conversion of cultivated land to forestland or grassland increases the carbon storage in vegetation and soil, while the rate of carbon accumulation in soil varies ; the effects of cultivated land, forestland and grassland management practices on ecosystem carbon cycle are still under debate. However, it is generally recognized that appropriate management practices could reduce carbon emissions. Regarding internal changes of land use in construction land, from the perspective of energy consumption, the conversion of construction land used for the secondary industry to the tertiary industry reduces carbon emissions. Therefore appropriate land use is extremely necessary for achieving carbon emission reduction commitments and for developing low carbon economy in China.