半干旱草原不同生态恢复阶段优势植物的高光谱特征分析

为了将高光谱遥感技术应用到生态恢复监测，采用ASD Fields HH便携式野外光谱仪测量半干旱草原区内蒙古和林格尔县不同生态恢复阶段优势植物物种的高光谱数据，通过ViewSpecPro软件对原始光谱数据进行降维和去噪等处理，进行原始反射率、一阶微分分析，采用排序软件Canoco 4.5进行去趋势典范对应分析。结果表明，生态恢复早期的优势植物物种为狗尾草、小叶锦鸡儿，生态恢复5年的优势植物物种为猪毛菜、小叶锦鸡儿，生态恢复后期的优势植物物种为樟子松、猪毛菜，与实测结果一致。DCCA分析结果表明，生态恢复早期植被的冠层光谱值，特征波段主要为短波光，且各物种光谱值差异较大;生态恢复5年主要受1 000～1 050 nm波段反射率影响，生态恢复后期主要受1 040～1 075 nm波段的近红外反射率影响。采用DCCA方法能够直观反映不同生态恢复阶段优势物种的光谱特征。

Spectral Reflectance Characteristics of Dominant Plant Species at Different Eco-Restoring Stages in the Semi-Arid Grassland

The objective of the research is to apply hyperspectral technique into eco-restoring monitoring. Through the ASD Fields HH portable field spectrometer, the hyperspectral data of dominant plant species in vegetation at different eco-restoring stages in semi-arid grassland in Helin County, Inner Mongolia were collected. The original spectrum reflected data were pretreated by wavelet threshold denoising through ViewSpecPro software before analysis. Using the first derivative spectra between 660 and 800 nm, and the methods of detrended canonical correspondence analysis (DCCA) by Canoco 4.5 software, the canopy hyperspectral datum of 6 dominant plant species was calculated. The results indicated that the dominant plant species at early succession stage were Setaria viridis and Caragana microphylia, at 5 years eco-restoring stage they were Salsola collina and Caragana microphylia and at late succession stage they were Pinus sylvestnis var. mongolica and Salsola collina, same as field survey. The graph of DCCA indicated that the influential bands of dominant species canopy at early eco-succession stage were short bands, with a large variation among species, the influential bands at 5 years eco-restoring stage were near infrared bands between 1 000 and 1 050 nm, and that at late stage were near infrared bands of 1 040～1 075 nm. The DCCA also showed obviously differences in canopy spectrum among 6 dominant species, and obviously differences among 3 eco-restoring stages.