长江下游农业生态区CO_2通量的观测试验

MEASUREMENTS OF CO_2 FLUXES OVER TWO DIFFERENT UNDERLYING SURFACES IN AN AGRICULTURAL ECOSYSTEM OVER LOWER BASINS OF THE YANGTZE

利用2001 年6月10日～7月20日在安徽省全椒县稻田和2002年6月10日～7月20日在肥西县农作物混作区观测的近地层 CO2和能量通量资料,对农作物混作区和稻田CO2通量特征进行了比较.结果表明:平均情况下,观测期内稻田白天(夜间)吸收(放出)CO2为55.16 g·m-2(14.19 g·m-2);农作物混作区白天(夜间)吸收(放出)CO2为22.67 g·m-2(12.40 g·m-2);稻田白天吸收的CO2通量随水稻生长而逐渐增加,夜间放出的CO2在拔节期最高;农作物混作区CO2通量在整个观测期并没有显著改变;稻田和农作物混作区均为大气CO2的汇.对CO2通量与光合有效辐射的关系分析表明:白天稻田吸收的CO2通量与到达地面的光合有效辐射存在着显著的负相关关系.文中结果为数值模拟稻田与近地层大气CO2交换提供了重要依据.

In order to better understand the CO2 flux over agricultural ecosystem regional climate change, it is necessary to quantify the C02 fluxes are collected directly by using eddy covariance over a rice paddy in the summer of 2001 and over an inhomogeneous crop surface in the summer of 2002 respectively. On average, daytime absorption and nighttime release of CO2 flux by the rice paddy are 55.16 g·m^-2·d^-1 and 14.19 g·m^- 2·d^-1, and by the inhomogeneous crop surface are 22.67 g·m ^-2·d ^-1 and 12.40 g·m^-2·d^-1. Rice paddy and the inhomogeneous crop surface are sinks of atmospheric CO2. China is a great agricultural country, increasing the area of rice paddy will help CO2 deposition, and will slow down increase of atmospheric CO2 and greenhouse effect. In addition, the relationship between daytime absorption of CO2 flux and Photosynthetically-active radiation is investigated for the rice paddy, and resulting a negative correlation. Hopefully the results obtained in present work will provide an important basis for numerical modeling of CO2 flux between atmosphere and land.