Carbon balance along the Northeast China Transect(NECT-IGBP)  

作　　者：周广胜 王玉辉 蒋延玲 许振柱 

机构地区：[1]Laboratory of Quantitative Vegetation Ecology, Institute of Botany, Chinese Academy of Sciences

出　　处：《Science China(Life Sciences)》2002年第z1期18-29,共12页中国科学（生命科学英文版）

基　　金：This work was jointly supported by NKBRSF(Grant No.G1999043407);National Natural Science Foundation of China(Grant Nos.30070642,49905005,30028001);the Chinese Academy of Sciences(Grant No.KSCX2-1-07,KZCX1-SW-01-12).

摘　　要：The Northeast China Transect (NECT) along a precipitation gradient wasused to calculate the carbon balance of different vegetation types, land-use practices and temporal scales. NECT consists of mixed coniferous-broadleaved forest ecosystems, meadow steppe ecosystems and typical steppe ecosystems. Analyses of the C budget were carried out with field measurement based on dark enclosed chamber techniques and alkali absorption methods, and the application of the CENTURY model. Results indicated that: (1) soil CO2 flux had a strong diurnal and seasonal variation influenced by grassland type and land-use practices. However, the seasonal variation on soil CO2 fluxes did not show obvious changes between non-grazing and grazing Leymus chinensis dominated grasslands. (2) Hourly soil CO2 fluxes mainly depended on temperature, while daily CO2 fluxes were affected bothby temperature and moisture. (3) NPP of the three typical ecosystems showed linear relationships with inter-annual precipitation, but total soil carbon of those ecosystems did not. NPP and total soil carbon values decreased westward with decreasing precipitation. (4) Model simulation of NPP and total soil carbon showed that mean annual precipitation was the major limiting factor for ecosystem productivity along NECT. (5) Mean annual carbon budget is the largest for the mixedconiferous- broadleaved forest ecosystem (503.2 gC m-2 a-1), followed by the meadow steppe ecosystem (227.1 gC m-2 a-1), and the lowest being the typical steppe ecosystem (175.8 gC m-2 a-1). This study shows that concurrent field measurements of terrestrial ecosystems including the soil and plant systems with surface layer measurements along the water-driven IGBP-NECT are valuable in understanding the mechanisms driving the carbon cycle in different vegetation types under different land-use practices. Future transect research should be emphasized.The Northeast China Transect (NECT) along a precipitation gradient was used to cal- culate the carbon balance of different vegetation types, land-use practices and temporal scales. NECT consists of mixed coniferous-broadleaved forest ecosystems, meadow steppe ecosystems and typical steppe ecosystems. Analyses of the C budget were carried out with field measurement based on dark enclosed chamber techniques and alkali absorption methods, and the application of the CENTURY model. Results indicated that: (1) soil CO_2 flux had a strong diurnal and seasonal variation influenced by grassland type and land-use practices. However, the seasonal variation on soil CO_2 fluxes did not show obvious changes between non-grazing and grazing Leymus chinensis dominated grasslands. (2) Hourly soil CO_2 fluxes mainly depended on temperature, while daily CO_2 fluxes were affected both by temperature and moisture. (3) NPP of the three typical ecosys- tems showed linear relationships with inter-annual precipitation, but total soil carbon of those eco- systems did not. NPP and total soil carbon values decreased westward with decreasing precipita- tion. (4) Model simulation of NPP and total soil carbon showed that mean annual precipitation was the major limiting factor for ecosystem productivity along NECT. (5) Mean annual carbon budget is the largest for the mixed coniferous- broadleaved forest ecosystem (503.2 gC m^(-2)a^(-1)), followed by the meadow steppe ecosystem (227.1 gC m^(-2)a^(-1)), and the lowest being the typical steppe eco- system (175.8 gC m^(-2)a^(-1)). This study shows that concurrent field measurements of terrestrial ecosystems including the soil and plant systems with surface layer measurements along the wa- ter-driven IGBP-NECT are valuable in understanding the mechanisms driving the carbon cycle in different vegetation types under different land-use practices. Future transect research should be emphasized.

关 键 词：TEMPERATE grassland  terrestrial NPP  CENTURY model. 

分 类 号：S154[农业科学—土壤学]