中国天然林资源保护工程温室气体排放及净固碳能力

Greenhouse gas emissions and net carbon sequestration of the natural forest protection program in China

基于天然林资源保护工程(简称天保工程)一期(2000—2010年)营造林过程工程边界内碳排放和边界外碳泄漏的计算,分析了天保工程及各区域碳排放和碳泄漏年际变化及影响因素,对比了天保工程及各区域碳排放和碳泄漏的组成特征,研究了天保工程及各区域净固碳量的变化特征。结果表明:天保工程一期西北、中西部地区、南部地区、东北地区和天保工程的碳排放分别为0.89、1.47、0.09、2.45 Tg C;碳泄漏分别为3.17、3.11、6.50、12.78 Tg C。工程措施和碳排放强度的区域性差异导致各区域碳排放组成特征不同。造林及配套森林基础设施建设是西北、中西部地区和南部地区最大的工程措施碳排放;新造林及森林管护是东北地区最大的工程措施碳排放。相应地,各种物资消耗中,建材是西北、中西部地区和南部地区最大的物资碳排放;燃油是东北地区最大的物资碳排放。天保工程在工程边界内外引起的额外温室气体排放量达到15.23 Tg C,抵消了工程固碳效益的9.82%;在西北、中西部地区、南部地区和东北地区的抵消作用分别为10.08%、8.16%和11.24%。天保工程一期净固碳量为139.77 Tg C,年均净固碳量为12.71 Tg C/a。因此,碳排放和碳泄漏对天保工程固碳的抵消较小,工程一期在我国温室气体减排和减缓全球气候变暖上做出了巨大贡献。避免工程基础设施的盲目建设和对工程进行合理规划是减少温室气体排放的可能途径。

Annual variance of carbon emissions and carbon leakage in the Natural Forest Protection Program （NFPP） was analyzed based on the calculation of carbon emissions from afforestation within the project boundary and carbon leakage out of the boundary in the first-stage （2000-2010） of the NFPP. Carbon emissions and carbon leakage were compared among the NFPP and its component regions, and variance of net carbon sequestration was characterized. The results showed that carbon emissions of the NFPP in the combined northwest and mid-west regions, the south region, the northeast region, and the whole NFPP region were 0.89, 1.47, 0.09, 2.45 Tg C, respectively. Meanwhile, carbon leakage from the above regions was 3.17, 3.11, 6.50, 12.78 Tg C, respectively. Spatial differences in program measures and carbon emission intensity were responsible for the differences in carbon emissions between various regions. Program measures showed that afforestation and corresponding forestry infrastructure construction were most prominent for the northwest/mid-west regions and the south region, while protection of young and mature forests was important in the northeast region. Accordingly, production and consumption of building materials were the main sources of carbon emissions for the former two regions, and consumption of fossil fuels was the main source for the latter region. Overall, in the first-stage of the NFPP, additional greenhouse gas emissions resulting from carbon emissions and carbon leakage totaled 15.23 Tg C, which counteracted 9.82% of the sequestered carbon in the program. Greenhouse gas emissions from the northwest/mid-west regions, the south region, and the northeast region could countervail 10.08%, 8.16%, and 11.24% of their carbon sequestration, respectively. Net carbon sequestration in the first-stage of the NFPP was 139.77 Tg C with an annual average of 12.71 Tg C/a. Therefore, carbon emissions and carbon leakage only played a minor role in neutralizing carbon benefits, and the first-stage of the NFPP contributed significantly to greenhouse gas emission reduction in China as well as global climate warming mitigation. Potential routes of greenhouse gas emission reduction include reasonable planning and avoidance of impulsive or reckless construction.