As the third largest country in the world, China has highly variable environmental condition and eco- logical pattern in both space and time. Quantification of the spatial-temporal pattern and dynamic of terrestrial ecosystem carbon cycle in China is of great significance to regional and global carbon budget. In this study, we used a high-resolution climate database and an improved ecosystem process-based model to quantify spatio-temporal pattern and dynamic of net ecosystem productivity (NEP) in China and its responses to climate change during 1981 to 2000. The results showed that NEP increased from north to south and from northeast to southwest. Positive NEP (carbon sinks) occurred in the west of Southwest China, southeastern Tibet, Sanjiang Plain, Da Hinggan Mountains and the mid-west of North China. Negative NEP (carbon sources) were mainly found in Central China, the south of Southwest China, the north of Xinjiang, west and north of Inner Mongolia, and parts of North China. From the 1980s to 1990s, the increasing trend of NEP occurred in the middle of Northeast China Plain and the Loess Plateau and decreasing trends mainly occurred in a greater part of Central China. In the study period, natural forests had minimal carbon uptake, while grassland and shrublands accounted for nearly three fourths of the total carbon terrestrial uptakes in China during 1981―2000.
TAO Bo1, CAO MingKui1, LI KeRang1, GU FengXue1, JI JinJun1,2, HUANG Mei1 & ZHANG LeiMing1 1 Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
采用FACE(Free Air Carbon-dioxide Enrichment)技术研究2种N水平下CO2浓度升高对水稻生物量及C、N吸收分配的影响结果表明，与对照相比，高CO2显著降低水稻生物量和C在叶的分配比例，增加其茎、穗和根的分配。高CO2使N在叶的分配降低，穗的分配增加；低N和常规N处理水稻抽穗期根的分配分别降低9．67％和13．1％，其他生育期则增加3．5％～26．6％；拔节期茎的分配分别增加7．03％和5．71％，成熟期分别降低10．5％和7．43％。N水平对水稻生物量和养分分配的影响不显著。
