石羊河流域下游民勤县典型荒漠土壤光谱特征分析

为了找出荒漠区土壤地物光谱特征变异的规律及其与植被覆盖度变化之间的对应关系，以石羊河流域下游荒漠化典型地区民勤县为研究区，用SVC HR768光谱仪对流沙地、砾质戈壁和土质戈壁进行了野外光谱测量。对土壤光谱反射率特征曲线和光谱一阶导数分析结果表明，研究区土壤具独特的波浪型光谱曲线，光谱曲线形状相似，土质戈壁的光谱反射率明显高于流沙地和砾质戈壁，其差异在700~1000 nm最为明显；在红边范围内(680~760 nm)，导数光谱可以抑制土壤背景信息，突出植被的“红边效应”，这可以作为荒漠植被信息的定量反演的波段范围；在所测波长范围内，流沙地和砾质戈壁的土壤反射率都随植被覆盖度的增加而降低，土壤反射率对植被变化较为敏感。因此，荒漠土壤光谱反射曲线变化可反映出沙化程度的变化，可以作为荒漠化定量研究的可靠依据。

Spectral Characteristics of Typical Desert Soil in Minqin County

In order to find the variation law of soil spectral characteristics and their relationship with vegetation cover change, the author took the Minqin County in the lower reaches of Shiyang River as objective, SVC HR768 type ground object spectrometer was used to measure the soil spectrum of sandy land, gravel gobi and soil gobi. Based on characteristic curve of soil spectral reflectance and first derivative analysis, the result showed that the soils in study area had the unique wave-shaped spectral curves; the spectra were similar in shape. Spectral reflectance of clay gobi was significantly higher than the sandy land and gravel gobi, and it was most obvious in 700-1000 nm. In the red edge range (680-760 nm), derivative spectra could inhibit soil background information, highlight the ‘red edge’ effect of vegetation, this wavelength could be used in quantitative inversion of desert vegetation. In the measured wavelength range, with the increasing of vegetation cover, the soil spectral reflectance of sandy land and gravel gobi was reducing. Soil reflectance was sensitive to vegetation changes. So, desert soil spectral reflectance curve could reflect the change of desertification degree, it could be used as a reliable basis for quantitative studies of desertification.