森林碳汇:后京都时代减排的重要途径

分析指出森林碳汇较其他减排措施具有潜力大、易操作、见效快、成本低、对经济增长影响小、居民福利高的独特优越性,必将受到国家气候变化应对措施选择的青睐。同时指出,森林碳汇不但包括换取排放中的造林和再造林的碳汇项目,而且包括抵消排放中的增加的森林碳库。分析国际气候变化谈判的焦点难点,指出森林碳汇必将成为后京都时代减排的重要途径之一。     

Soil CO2 emission and carbon budget of a wheat/maize annual double-cropped system in response to tillage and residue management in the North China Plain

To investigate the impacts of tillage and crop residue managements on soil CO₂ emission and C budget in a wheat (Triticum aestivum L.)/maize (Zea mays L.) double-cropped system in the North China Plain (NCP), a field experiment was conducted consisting of four treatments: tillage with crop residues retention (CT+), tillage with crop residues removal (CT?), no-till with crop residues retention (NT+), and no-till with crop residues removal (NT?). Daily soil CO₂ fluxes changed with crop growing stage and peaked during the most vigorous growth of period, fluxes in maize season were higher than those in wheat season. Compared to the tilled soils, cumulative CO₂ emissions were significantly lower under no-till treatments. The largest cumulative CO₂ emission occurred under CT+ (65?g CO₂-C m^?2 y^?1) and the smallest was under NT+ (39?g CO₂-C m^?2 y^?1). After 5 years of the experiment, soil organic carbon (SOC) sequestration were greater with crop residues retention (CT+ and NT+) than with crop residues removal (CT? and NT?), the maximum SOC stock was in NT+ (5940?g C m^?2) while the minimum was in CT? (3635?g C m^?2). NT+ could help to mitigate CO₂ emission in the annual wheat/maize double-cropping system of the area.