基于机载高光谱的思茅松林光谱特征及其影响因子分析

Spectral Characteristics and Influencing Factors of Pinus kesiya var. langbianensis Based on Airborne Hyperspectral Technique

[目的]以云南普洱菜阳河为例,基于机载遥感影像,探讨思茅松林冠层高光谱特征及坡向对其光谱反射率的影响。[方法]以2014年4月机载Li CHy系统获取的高光谱和激光雷达DEM提取的坡向数据,结合该地区二类调查数据,对不同坡向的思茅松林冠层光谱曲线特征值进行统计比较。[结果](1)思茅松冠层光谱反射特征与绿色植物光谱曲线总体相似,在0.74~1.0μm近红外波段冠层反射率较高,0.89μm最高;(2)阴坡思茅松冠层光谱反射率普遍高于阳坡,北坡、东北坡与南坡、东南坡的峰值波段反射率在0.05水平上差异显著;(3)根据太阳高度角,迎光面的东坡、东北坡、东南坡比背光面西坡、西北坡、西南坡光谱反射率在0.89μm波段增加了14%~23%。[结论](1)思茅松冠层光谱反射率表现出"两谷一峰"、"红边"等典型的植被光谱特征,反射率较高的0.74~1.0μm波段为思茅松的特征光谱段;(2)太阳高度角是影响不同坡向光谱反射率的主要因素,而坡向也是造成反射率差异的另一个重要原因。

[ Objective] Hyperspectral characteristics and effect of aspect on spectral reflectance of Pinus kesiya var. langbianensis canopy based on airborne remote sensing imagery were investigated in Caiyanghe National Park, south- east Purr, Yunnan province. [ Method] Hyperspectral and Lidar data were obtained using airborne LiCHy system in April, 2014. The Lidar data were used to get DEM and slope data. In addition, the characteristic values of spec- tral curves of P. kesiya var. langbianensis stands in different aspects were statistically analyzed using hyperspectral and forest resources inventory data. [ Result] （ 1 ） The spectral reflectance of P. kesiya var. langbianensis canopy was similar to that of green plant. The canopy reflectivity was high in the near infrared band （0.74 -1.0 μm）, of which, the highest reflectivity located in 0.89μm. （2） The spectral reflectance of P. kesiya var. langbianensis can- opy in shady slope was higher than that in sunny slope. There was a significant difference at the peak reflectance of band in north, northeast, south and southeast slopes. （3） According to the solar elevation angle, east, northeast and southeast slopes where face the light has more light radiation than west, northwest and southwest slope and the spectral reflectance was also high. In 0.89 μm band, the reflection of the backlight was 14% ~ 23% lower than that of the face light. [ Conclusion ] （ 1 ） The spectral reflectance of P. kesiya var. langbianensis canopy shows typi- cal vegetation spectrum characteristics such as ＂two valleys and one peak＂ and ＂red edge＂. The reflectivity is high- er in 0.74 ~ 1.0μm band which usually used as special spectrum for P. kesiya var. langbianensis. （2） The solar elevation angle is the main factor affecting the spectral reflectance of different aspect. Besides, the aspect is another important reason causing the difference of reflectance. This study will provide references for complex terrain hyper- spectral quantitative remote sensing and tree species identification.