新疆天山北坡常见盐生植物端元尺度光谱特征及识别

Response Characteristics of the Field-Measured Spectrum for the Four Gerneral Types of Halophyte and Species Recognition in the Northern Slope Area of Tianshan Mountain in Xinjiang

通过野外定点光谱采样,从端元尺度对天山北坡四种常见的盐生植物芨芨草、苦豆子、樟味藜、骆驼刺进行了光谱特征分析和种类识别。结果表明:从CARI和SIPI两个常用的叶绿素高光谱指数来看,骆驼刺的叶绿素含量和类胡萝卜素含量均较高,苦豆子虽然生长旺盛,由于受到光谱中花的因素影响,这两个指数值较低。苦豆子株冠郁闭度较高,其NDVI值高于其他三种植物。苦豆子和樟味藜的光谱位置参数较稳定,而芨芨草和骆驼刺则既存在BEP"红移",也存在REP"蓝移",红边和蓝边变化幅度较大。生长旺季中不同植物端元光谱曲线之间差异较小,存在明显的混合光谱现象,利用遥感常用的红/近红外特征空间难以准确区分樟味藜和骆驼刺。采用逐步多元判别分析,筛选出Rn,REP,Rg,MSAVI和CARI作为判别指标构建判别方程,芨芨草和樟味藜可以100%被识别,四种植物的判别总精度达92%以上。

Based on the field-measured Vis-NIR reflectance of four common types of halophyte（Achnatherum splendens（Trin.）Nevski,Sophora alopecuroides L.,Camphorosma monspeliaca L.subsp.lessingii（L.）Aellen,Alhagi sparsifolia shap）withingiven spots in the Northern Slope Area of Tianshan Mountain in Xinjiang,the spectral response characteristics and species recog-nition of these types of halophyte were analyzed.The results showed that（Alhagi sparsifolia shap）had higher chlorophyll andcarotenoid by CARI and SIPI index.（Sophora alopecuroides L.was at a vigorously growing state and had a higher NDVI com-pared with the other three types of halophyte because of its greater canopy density.But its CARI and SIPI values were lower dueto the influence of its flowers.（Sophora alopecuroides L.）and（Camphorosma monspeliaca L.subsp.lessingii（L.））had stableREPs and BEPs,but REPs and BEPs of（Achnatherum splendens（Trin.）Nevski,Aellen,Alhagi sparsifolia shap）whose spec-tra red shift and spectra blue shift occurred concurrently obviously changed.There was little difference in spectral curves amongthe four types of halophyte,so the spectrum mixing phenomenon was severe.（Camphorosma monspeliaca L.subsp.lessingii（L.）Aellen）and（Alhagi sparsifolia shap）could not be separated exactly in a usual R/NIR feature space in remote sensing.U-sing the stepwise discriminant analysis,five indices were selected to establish the discriminant model,and the model accuracywas discussed using the validated sample group.The total accuracy of the discriminant model was above 92%and（Achnatherum splendens（Trin.）Nevski）and（Camphorosma monspeliaca L.subsp.lessingii（L.）Aellen）could be respectively recognized 100%correctly.