青海祁连瑞香狼毒的光谱差异特征提取

瑞香狼毒是分布在青海省高寒草甸的主要毒害草之一，近年来其迅速蔓延对当地畜牧业危害严重并使草地生态系统日趋退化.在海北州祁连县选取狼毒分布的典型退化草甸，采用2012—2014年狼毒盛花期获取的实测光谱数据，分析狼毒与牧草的光谱差异性.结果表明： 在350~900 nm的可见光 近红外波段，狼毒顶花的光谱反射特征明显异于狼毒叶片和同期牧草等绿色背景，顶花与绿色背景的光谱反射率差异主要体现在红谷和蓝谷.随着盖度的增加，狼毒群落光谱反射率整体升高，在近红外反射峰处狼毒群落与牧草群落光谱反射率具有最大差值，且不同盖度狼毒群落之间的差异性最明显.顶花与绿色背景以及狼毒群落与牧草群落的一阶导数光谱差异均体现在黄边幅值和蓝边幅值.狼毒群落盖度与光谱特征参量的线性回归分析表明，红谷与狼毒群落盖度的相关性最好(R²=0.94)，反演狼毒群落盖度的精度最高.盛花期区分狼毒与牧草的主要光谱特征参量为红谷、蓝谷与近红外反射峰，其对应的红、蓝及近红外波段的组合可用于构建狼毒提取的敏感指数.

Extraction of spectral difference characteristics of Stellera chamaejasme in Qilian County of Qinghai Province,Northwest China.

Stellera chamaejasme is one of the main poisonous weeds distributed in alpine meadow of Qinghai Province. Rapid spreading of S. chamaejasme has done serious harm to local animal husbandry and caused continuous grassland ecosystem degradation. This paper focused on the spectral differences between S. chamaejasme and herbage, taking the typical degraded alpine meadow dominated by S. chamaejasme in Qilian County of Haibei Region as the test site and using the spectral measurements acquired in the full blossom period of S. chamaejasme from 2012 to 2014. The results showed that the spectral behavior of flowers of S. chamaejasme differed significantly from green background that included leaves of S. chamaejasme and herbage within 350-900 nm of VIS NIR wavebands. The biggest reflectance difference between flowers of S. chamaejasme and green background was located in the red valley, followed by the blue valley. The reflectance of S. chamaejasme community increased with the rising of coverage, the biggest reflectance difference between S. chamaejasme and herbage communities lied in the near infrared peak, and the best separability between S. chamaejasme communities with different coverage was also at the point. The difference of first derivative spectra between flowers of S. chamaejasme and green background located in amplitude of yellow edge was remarkable, followed by amplitude of blue edge, the same as differences between S. chamaejasme and herbage communities. Linear regression analysis between coverage of S. chamaejasme and spectral feature parameters showed best result for red valley (R²=0.94). Finally, the red valley, the blue valley and the near infrared peak were proposed for discriminating S. chamaejasme from herbage in the full blossom period of S. chamaejasme, and the combination of corresponding red, blue and near infrared bands could be used to build sensitive indices for S. chamaejasme recognition. 