中文摘要：

SunScan冠层分析仪是一种利用间接测量法观测叶面积指数（LAI）的仪器，通过给定反映植被几何特征的椭球体叶倾角分布参数（ELADP），测量透射率获得LAI。于2005、2006年在黑龙江省嫩江县鹤山农场布设大豆试验地，通过比较LI-3100叶面积仪直接测量的LAI和SunScan冠层分析仪间接测量的LAI，得出ELADP率定结果，并验证了SunScan冠层分析仪测量LAI的精度。结果表明：用SunScan测量大豆冠层LAI时，ELADP取值为4．0；设定该参数后，SunScan测量的LAI与LI-3100测量结果一致，二者拟合的线性回归方程显著；随生长季叶面积的变化，SunScan测量误差略有变化；播种后50～85d，Sun—Scan观测值偏低7．2％，播种96d以后观测值偏高12．5％，播种后85～96d与LI-3100观测值十分接近，误差只有2．0％；经过参数率定后的SunScan测量LAI效果较好。

英文摘要：

SunScan canopy analysis system is an instrument for indirectly measuring leaf area index （LAI）. The instrument can give LAI values by measuring the ratio of transmitted radiation through canopy to incident radiation, based on the canopy geometry features described by ellipsoidal leaf angle distribution parameter （ELADP）. In 2005 and 2006, the LAI values of soybean plants at the Heshan Farm of Nenjiang County, Heilongjiang Province were measured with LI- 3100 LAI apparatus and SunScan canopy analysis system, the ELADP value was calibrated for accurate LAI, and the precision of the LAI values measured by SunScan canopy analysis system was validated. The results showed that the ELADP value for soybean canopy was 4.0, and the LAI values measured by SunScan canopy analysis system were consistent with those measured by LI-3100. The regression correlation of the LAI values measured by the two instruments was significant. During the growth season of soybean, the measurement error of SunScan canopy analysis system had a slight change, i. e. , the LAI was underestimated by 7.2% from 50 to 85 days after sowing and overestimated by 12.5% from 96 days after sowing, but close to that measured by LI- 3100, with an error of 2. 0%. In conclasion, SunScan canopy analysis system could be used to measure the LAI accurately if the ELADP was calibrated for different canopies.