输电线路下行林区优势树种的冠层光谱特征分析

Analysis of canopy spectral characteristics of dominant tree species in the downstream forest area of transmission line

通过对安徽省池州市青阳县输电线下行通道的优势树种进行光谱测量与分析,以建立优势树种光谱库,为输电线通道下行林区的树种精细分类提供理论和技术支持。利用便携式光谱仪对研究区6个优势树种的冠层光谱数据进行采集,并生成平均冠层反射光谱曲线,经过导数变换、植被特征参数(蓝边、黄边和红边)分析及冠层光谱的可分性研究,进而分析出不同树种的不同波段光谱特征差异。结果表明,在原始光谱可见光波段毛竹冠层反射率高于其他树种;而在近红外波段,栎树的冠层反射率高于其他树种。6个树种的蓝边位置、黄边位置及红边位置存在差异较小,毛竹的蓝边斜率最大;杉木的黄边斜率最大;栎树的红边斜率和红边面积均为最大。通过可分性研究可知,原始光谱在550 nm、900 nm及一阶导数光谱在718 nm处,有助于精细区分不同树种类型。

The dominant trees of the transmission line in Chizhou,Anhui Province were measured and analyzed to establish a spectral library of dominant tree species and provide theoretical and technical support for the fine classification of tree species in the downlink of transmission lines.The spectral data of the six dominant tree species in the study area were collected using the portable spectrometer and the average canopy reflection spectra were generated.The separability of the spectrum of the canopy was studied by the derivative transform and the vegetation characteristic parameters(blue edge,yellow edge,red edge).Then the spectral characteristics of different bands of different trees were analyzed.Through derivative transforming,vegetation characteristic parameters(blue edge,yellow edge and red edge)and separable researching were analyzed to distinguish the difference in different tree species of different bands.The results showed that the reflectivity of the Phyllostachys pubescens canopy was higher than that of other tree species in the original spectral visible band.In the near infrared band,the canopy reflectance of the Quercus Linn was higher than that of other species.The blue edge position,yellow edge position and red edge position of six tree species were small different.But the blue edge slope of Phyllostachys pubescens was the highest.The yellow edge slope of Cunninghamia lanceolata was the highest.The red side slope and red side area of the Quercus Linn were the largest.According to the separable studies,the original spectra at 550 nm,900 nm and first derivative spectra at 718 nm improve to distinguish different tree species.