西北荒漠草甸植被光谱反射特征研究

Research on Spectral Reflectance Characteristics for Desert Meadow of Northwest China

选取位于西北干旱内陆地区的安西荒漠草场为观测试验区,分别对盐生低地草甸、极旱荒漠草甸和荒漠灌丛三类草地进行了地面反射光谱测定,并分析了主要荒漠草甸植被光谱反射的一般特征和红边参数特征,进而探讨了形成草地光谱特征差异的主要内在原因和影响因素。结果表明:在近红外波段,由于荒漠植被类别间叶片内部结构变化大,因此冠层光谱反射率差异较大;同一植被冠层光谱反射率的大小主要受植被长势的影响;受沙地背景的影响,在近红外波段,植被冠层的光谱反射率要明显小于叶片的光谱反射率;荒漠植被冠层光谱的红边也具有“双峰”现象,红边特征的参数表现为:沙地植被>绿洲植被>沙漠植被。对安西荒漠植被光谱特征的分析研究,对于研究干旱区荒漠植被的理化性能、遥感反演、植被分类、植被调查等都具有重要的意义。

Taking Anxi desert grassland that locates in northwestern arid zone as experimental area of the observation, ground spectral reflectance of the saline lowland meadow, extremely arid desert meadow and desert shrubs were determined. The paper analyzes the spectral reflectance common characteristics and red edge parameter characteristics of main desert meadow vegetations. At the same time, the major interior reasons and influencing factors that lead to the difference of grassland spectral characteristics are discussed. The results show that canopy spectral reflectance has a marked difference for different desert meadow types in the near infrared waves because the internal structures of leaf laminae change greatly. The canopy spectral reflectance of the same vegetation has relation to their growing status. Influenced by sandy land backgrounds, in the near infrared waves, the canopy spectral reflectance of desert meadow is clearly smaller than the leaf spectral reflectance. There are ＂double peak＂ phenomena for the red edge of canopy spectra in desert meadow, and the maximum value of red edge parameters of different vegetative types is the biggest for sandy land vegetation and the smallest for desert vegetation. Research on spectral reflectance characteristics for desert meadow of Anxi plays an important role in the research of physical chemistry performances, remote sensing retrieval, classification and investigation on the vegetation in an arid area.