苜蓿草地FPAR时间变化规律研究

Temporal variation of FPAR in the alfalfa pasture

使用AccuPAR植物冠层分析仪对海拉尔地区紫花苜蓿(Medicago sativa)栽培草地光合有效辐射(PAR)各分量进行观测,研究苜蓿栽培草地入射PAR、冠层反射PAR、透过冠层到达地面的PAR及地面反射的PAR的时间变化规律,通过试验测定的PAR数据,分析苜蓿栽培草地吸收性光合有效辐射(FPAR)的时间变化规律。结果表明,苜蓿栽培草地入射PAR与透射PAR日变化规律基本一致,呈"正弦曲线";FPAR的日变化规律呈"多峰"型,FPAR在11:30左右达到全天最低值,下午2:30左右数值最大,日平均FPAR值可以用7:30或太阳天顶角80°时的瞬时FPAR值表示。

The AccuPAR Plant Canopy Analyzer was used to measure the alfalfa pasture canopy PAR during the flowering period in the Hulunbeier regions,including the incident PAR,the reflective PAR of the canopy,the transmittance of PAR through the canopy,the reflectance of land surface.Based on the PAR data,this study analyzed the temporal Variation of FPAR in the Alfalfa pasture,and showed that the incident PAR and the transmittance PAR diurnal variation was a curve of sine,and the diurnal FPAR variation was a double peak curve in clear day.FPAR was found to be highest in 2：30 am,and the lowest near to 11：30 pm.The daily average of FPAR may be approximated the incident FPAR values when the solar zenith angle was 80° at 7：30.