农田生态系统CO_2通量的转换计算

Transitional calculation on carbon dioxide flux over agro-ec osystem

通过冬小麦单叶CO2 通量与冠层CO2 通量的同步测定 ,发现不同日期净光合速率 (Pn)和冠层CO2 通量 (FCO2 )变化趋势相同 ,但峰值出现的时间不一致 .CO2 浓度差与FCO2 日变化趋势相反 ,CO2 浓度差最小时FCO2达到最大值 ;空气动力学法计算的FCO2 与采用积分法计算的冠层CO2 通量 (Ac)呈明显的倒“U”字型日变化趋势 ,而Ac日变化过程波动性小 ;采用积分法模拟的日同化量与空气动力学法计算日同化量有时相差很小 ,但有时误差大 ,由于模拟冠层通量Ac值只考虑了光强的变化 ,而实际上 ,温度、风速、土壤湿度等变化均对冠层CO2通量产生影响 .

Through simultaneous measuring on photosynthesis rate of a single leaf and CO 2 flux above winter wheat canopy, the results showed that diurnal change of net p hotosynthesis rate was the same as that of canopy CO 2 flux (F CO 2 abstract Diu rnal change of CO 2 difference was contrary to that of F CO 2 , and while the CO 2 difference was the least, F CO 2 was the highest. The diurnal c hange of F CO 2 calculated by aerodynamics and Ac calculated by net photos ynthesis rate were both in the shape of inverted 'U', but the diurnal change o f Ac fluctuated more smoothly than that of F CO 2 . The daily assimilation quantity calculated by integral method was almost the same as that calculated by aerodynamics in some days, but not in other days because the simulating Ac was only considered light intensity. Actually, other environmental factors such as t emperature, wind speed, and soil moisture would affect canopy CO 2 flux.