1981～2000年中国陆地生态系统碳通量的年际变化(英文)

Interannual Variation in Terrestrial Ecosystem Carbon Fluxes in China from 1981 to 1998

应用一个生物地球化学模型 (CEVSA)估算了中国陆地净初级生产力 (NPP)、土壤异养呼吸 (HR)和净生态系统生产力 (NEP)在 1981～ 1998年期间对气候和大气CO2 浓度变化的动态响应。结果显示 ,全国NPP总量波动于 2 .89～ 3.37GtC/a之间 ,平均值为 3.0 9GtC/a ,年平均增长趋势约为 0 .32 %。HR总量变化范围为 2 .89～ 3.2 1GtC/a ,平均值为 3.0 2GtC/a ,年均增长 0 .4 0 %。NEP总量变动于 - 0 .32和 0 .2 5GtC/a之间 ,在统计上没有明显的年际变化趋势。在研究时段内 ,年平均NEP约为 0 .0 7GtC/a ,表明中国陆地生态系统在气候与大气CO2 浓度变化的条件下吸收了碳 ,为碳汇 ,总的吸收量为 1.2 2GtC ,约占全球碳吸收总量的 10 % ,与同期内美国由大气CO2 和气候变化所产生的碳吸收量大致相当。尽管由于较高的年际变率 ,NEP在统计上没有明显的变化趋势 ,但NPP的增长率低于HR的增长率 ,说明在研究时段内 ,中国陆地生态系统的吸碳能力由于气候变化降低了。全国大多数地区年平均NEP接近零 ,明显的NEP正值区 (即碳汇 )出现在东北平原、西藏东南部和黄淮平原等地区 ,而大小兴安岭、黄土高原和云贵高原等地区NEP为负值 (即碳源 )。研究认为 ,1981～ 1998年期间中国气候温暖、干旱 ,因此估算的NEP可能低于其他时段。

A dynamic biogeochemical model was used to estimate the responses of China's terrestrial net primary productivity (NPP), soil heterotrophic respiration (HR) and net ecosystem productivity (NEP) to changes in climate and atmospheric CO2 from 1981 to 1998. Results show that China's total NPP varied between 2.89 and 3.37 Gt C/a and had an increasing trend by 0.32% per year, HR varied between 2.89 and 3.21 Gt C/a and grew by 0.40% per year, Annual NEP varied between -0.32 and 0.25 Gt C but had no statistically significant interannual trend. The positive mean NEP indicates that China's terrestrial ecosystems were taking up carbon with a total carbon sequestration of 1.22 Gt C during the analysis period. The terrestrial NEP in China related to climate and atmospheric CO2 increases accounted for about 10% of the world's total and was similar to the level of the United States in the same period. The mean annual NEP for the analysis period was near to zero for most of the regions in China, but significantly positive NEP occurred in Northeast China Plain, the southeastern Xizang (Tibet) and Huang-Huai-Hai Plain, and negative NEP occurred in the Da Hinggan Mountains, Xiao Hinggan Mountains, Loess Plateau and Yunnan-Guizhou Plateau. China's climate at the time was warm and dry relative to other periods, so the estimated NEP is probably lower than the average level. China's terrestrial NEP may increase if climate becomes wetter but is likely to continue to decrease if the present warming and drying trend sustains.