【作者】 侯振宏；

【导师】 肖文发；

【作者基本信息】 中国林业科学研究院 ， 生态学， 2010， 博士

【摘要】 随着近年来温室效应和气候变暖的加剧,森林碳汇问题越来越受到全世界的重视。如何能在付出较少经济代价的同时,取得同等减排效果是目前国际社会普遍关心的议题。在减缓全球变化的各种努力中,林业活动具有十分重要和不可替代的地位和作用。1997年签订的“京都议定书”第3.3款和3.4款中规定,造林、再造林、毁林、森林管理、农地管理、牧地管理和植被恢复等人为活动引起的温室气体源排放或汇清除,可通过适当的方式用于抵消附件I国家承诺的温室气体减限排指标。这就要求对这些活动引起的排放减少或汇清除进行科学评价和监测。林业活动产生的森林碳汇是降低大气温室气体增长的一个较好的选择,为此国际社会、各国政府和科学家都十分重视林业活动的碳计量。本论文在IPCC指南框架下,从全国尺度计量和预测了中国目前主要林业活动(造林再造林、毁林、森林管理等)的碳汇及其潜力,以确认中国林业活动碳汇潜力热点区域,为未来帮助我国抵消部分由于经济快速发展造成的温室气体排放提供数据支撑,为开展林业碳汇项目选址提供技术支持。利用目前国际碳贸易契机,引进国外资金和先进技术,帮助我国林业取得更大发展。研究结果表明:1)2020年前我国造林再造林年碳储量变化呈迅速增加趋势,2020年以后稳定在约100 MtC.a-1的水平。基年越早,造林再造林碳汇潜力越大,2020年以后差距缩小,说明2020年后基年选择对造林再造林碳汇影响不大。1990~2009年造林再造林累计吸收10.89亿吨碳,其中生物量固定8.18亿吨碳,土壤2.71亿吨碳。2)造林再造林碳吸收主要以人工造林为主,约占总碳吸收量的90%,飞播造林占10%。基年为1990年时,人工造林碳吸收在2010年前主要来自经济林造林和用材林造林。2010年后防护林造林碳吸收迅速增加,成为人工造林碳吸收的主要来源,其次为用材林、经济林和竹林造林,薪炭林造林碳吸收潜力较小。基年为2000年时,防护林造林为主要碳吸收汇,是其它林种造林总碳吸收汇的近两倍,其次为用材林、经济林、竹林和薪炭林造林。3)西南地区造林再造林生物量碳吸收潜力明显大于其它地区,其次为华东华南、西北和华北,其潜力相近,再次为东北,西藏的潜力非常小。为我国今后发展碳汇项目选址提供支持。4)基年为1990年时,森林转化排放在2002年以前呈迅速上升趋势,以后逐渐降低。当基年为2000年时,森林转化碳排放在2003年以前迅速增加,之后逐渐降低。基年越晚,森林转化碳排放越大。森林转化引起的土壤碳排放量大于生物量碳排放。1990~2009年,森林转化累计碳排放6.19亿吨碳,其中生物量2.94亿吨碳,土壤排放3.25亿吨碳。在森林转化碳排放及减排额中,生物量约占44%,土壤碳排放占55%左右。5)同一基年,总-净核算方式和净-净核算方式下的森林管理碳吸收汇变化趋势相同,总-净核算方式下的森林管理碳吸收汇大于净-净核算方式下的森林管理碳吸收汇;总-净核算方式下,基年越早,森林管理活动的面积越小,碳汇潜力越小;净-净核算方式下,基年越早,森林管理活动的碳汇潜力越高。基准年选择的不同,对森林管理的碳汇计量影响较大。6)综合我国造林再造林、森林转化、封山育林及森林管理碳汇计量结果发现,我国林业活动总碳汇潜力从基年到2020年左右,呈快速增加趋势,2020年后增长速度明显减缓。总-净核算方式下,我国林业活动从基年开始就一直表现为碳吸收汇,且在2020年前基年为1990年时的碳汇量大于基年为2000年的碳汇量,2020年后两种基年情况下的碳汇量基本相同。但是,在净-净核算方式下,基年后的第2~3年表现为碳排放源,以后才表现为净碳吸收汇,且基年为1990时的碳汇量始终明显大于基年为2000年的碳汇量。7)林业活动碳吸收汇主要来自林木生长碳吸收。一旦发生森林转化,对土壤碳的影响是巨大的。研究发现,我国造林再造林、森林管理带来的林业碳汇是巨大的,可以支持我国相关气候变化谈判,同时和我国对2020年的林业承诺是一致的,可以完成我国的“413”目标下的林业碳汇任务。但还需认识到由于研究方法中涉及的某些参数来自文献收集和中国森林资源清查数据,这对研究结果的精度带来影响。下一步还需针对方法中的参数进行细致研究,以降低估算结果的不确定性,为我国制定可持续发展的林业碳汇政策提供技术支持。更多还原

【Abstract】 With the increased greenhouse effective and climate warming recent years, forest carbon sink is payed more and more attention by the world. The most popularly concerned topic by the international society is how to get biggest mitigation effect under the smallest economy cost. In the every endeavor to mitigate the global change, forest activities have very important and irreplaceable position and role. The article 3.3 and 3.4 of Kyoto Protocol signed in 1997 regulate that greenhouse gas emission or removal caused by the human activities such as afforestation, reafforestation, deforestation, forest management, farmland management and vegetation restoration and so on can be used to offset the greenhouse gas emission goal that annex I countries promised through the appropriate way. But the emission reduced or sink cleared caused by these activities must be transparent, measured and verified. It requests to scientificly evaluate and monitor the emission reduced and sink cleared caused by these activities. Forest carbon sink produced by the forestry activities is a better choice to slow down the greenhouse gas increasement in the atmosphere. So international society, governments and scientists all pay attention to the study on the carbon accounting of forestry activities.Under the framework of IPCC Guidance, the paper evaluates and predicts the carbon sink and its potential of the main forestry activities (afforestation, reafforestation, deforestation, forest management) in china at the country scale, and confirm the hot spot of the china forestry activities carbon sequestration. It can provide data support for china to offset part of greenhouse gas emission because of the quick economy development in the future, and technical support for the site choice to develop forest carbon sink projects. Using the chance of the international carbon trade at present, forestry department also can induce the foreign fund and technology to gain the further development. The results show that,1) Annual carbon stock change of afforestation and reafforestation in China shows rapid increasement trend before 2020, and remain about 100 MtC.a-1 after 2020. The earlier is the baseline, the bigger is carbon sink potential of afforestation and reafforestation. The gap becomes smaller after 2020. It means that the choice of baseline year has a small effect on the carbon sink of affforestation and reafforestation after 2020. Afforestation and reafforestation together absorb 10.89×10~9tC between 1990 and 2009, of which biomass absorb 8.18×10~9tC and soil aborb 2.71×10~9tC.2) Carbon absorbsion in afforestation and reafforestation is mainly man-made afforestation, which is about 90% of total carbon absorbsion. And afforestation from air-boern is about 10%. When 1990 is baseline year, before 2010 carbon absorbsion of man-made afforestation is mainly from cash forest and forest for timber. Carbon absorbsion of forest for protection rapidly increase after 2010, become the main source of man-made afforestation, followed by the forest for timber, cash forest and bamboo. The carbon absorbsion potentional of forest for fire is smaller. When baseline is 2000, forest for protection is the main carbon sink and is about twice of other forest, followed bu the forest for timber, cash forest, bamboo and forest for fire.3) The carbon sink potential of afforestation and reafforestation in Southwest region of China is parently bigger than that of the other regions, followed by the East and South of China, Northwest, North of China and Northeast region. The potential in Xizang is very small. It can provide support for our site choice of forest carbon sink project development.4) When baseline year is 1990, carbon emission from deforestation shows quick increasement trend before 2002, then declines afterward. When the baseline year is 2000, carbon emission from deforestation increase rapidly before 2003, then decline slowly. The later is the baseline year, the bigger is the carbon emission from deforestation. Soil carbon emission caused by the deforestation is bigger than the biomass carbon emission during deforestation. Carbon emission from deforestation is totally 6.19×109tC, of which biomass emit 2.94×109tC and is about 44% of deforestation total emission. And soil emit 3.25×109tC, is about 55%.5) Carbon sink change trend from forest management are the same under the gross-net and net-net at the same baseline year. But the carbon sink amount is bigger under the gross-net than that under the net-net. The earlier is the baseline year, and the smaller is the area of forest management, the smaller of the carbon sink potential under the gross-net. Under net-net, the earlier is the baseline, the higher is the carbon sink potential of the forest management. The difference of the baseline year choice has a bigger affect on the carbon accounting of forest management.6)Combined with the afforestation and reafforestation, deforestation, closing hillsides to facilitate afforestation and forest management, the accounting results show that total carbon sink potential trend of forest activities in China increase rapidly from baseline year to 2020 and then slow down. Under gross-net, forest activities always are carbon sink from beginning, and carbon sink is bigger in 2020 when baseline is 1990 than that when baseline is 2000. The carbon sink almost are the same after 2020 under two baselines. Under net-net, the total carbon accounting of Chinese forest activities shows carbon source at the first 2-3 years after baseline, then changes to net carbon sink. And the carbon sink amount is bigger when baseline is 1990 than the amount when baseline is 2000.7)Carbon sink of forest activities come mainly from tree growth. But if deforestation happens, it will have a huge affect on the soil carbon.We find that the carbon sink from afforestation and reafforestation, forest management is huge and can satisfy the need of climate change negotiations of our country to the certain. And this is the same as the forest promise of china for 2020 at the same time. It can finish our forest carbon sink task under“413”goal. But we also need to realise that some facors needed by the study meathod come mainly from liberations collection and Chinese inventory of forest resource. It has an impact on the precision of the study result. We need to further carefully study the factors in the accounting method in the next step, reduce the uncertainty of accounting results, and provide technical support for drawing up the forest carbon sink sustainable development policy of China.更多还原