黄土高原水蚀风蚀交错区不同类型生物土壤结皮光谱特征

Spectral Characteristics of Biological Soil Crusts under the Different Types in the Water-Wind Erosion Crisscross Region on the Loess Plateau

黄土高原水蚀风蚀交错区生物土壤结皮光谱特征的研究,为基于遥感的区域尺度生物土壤结皮的识别提供了重要的科学价值,为进一步估算生物土壤结皮在区域水土流失防治中所起的作用提供了重要的技术支持。采用地物光谱测定技术,在黄土高原水蚀风蚀交错区六道沟小流域对不同覆盖度藻类和不同类型藓类生物土壤结皮以及不同高等植被进行了光谱测定,并进行定量分析。研究表明,黄土高原水蚀风蚀交错区藻类生物土壤结皮与土壤具有相似的光谱特征,光谱曲线没有明显的"峰-谷"。藻类生物土壤结皮光谱特征主要表现为光谱反射率随生物土壤结皮覆盖度增加而降低的变化规律;其中可见光区,覆盖度10%~20%,30%~40%及50%~60%藻类生物土壤结皮相比于裸地,反射率归一化均值分别下降了8.64%,15.80%和23.09%。随藻类结皮覆盖度增加,680nm处吸收特征(叶绿素)越来越明显,2 200nm处吸收谷(次生矿物)越来越小。藓类生物土壤结皮光谱曲线表现出与高等植物相似的特征,形成绿波段的反射峰和红光波段的吸收谷以及近红外波段的高反射。但在760~930nm区间,藓类生物土壤结皮的斜率明显大于高等植物,藓类生物土壤结皮的光谱斜率Slope(930/760)是高等植物的2.5~4.5倍。黄土高原生物土壤结皮光谱特征的研究可为生物土壤结皮的遥感识别提供一定的理论依据和技术支持。

The study on spectral characteristics of biological soil crust in the water-wind erosion crisscross region in the Loess Plateau has important scientific value for the identification of biological soil crust based on remote sensing technology at regional scale,also provides important technical support for estimating the effect of biological soil crust on regional soil erosion control.The spectra of higher vegetation as well as the biological soil crust of algae with different coverage and different types of mosses were measured and quantified by Surface Species Spectrometry.The results are as follows,the algal bio-soil crust has similar spectral characteristics with soil in the water-wind erosion crisscross region in the Loess Plateau,and there is no obvious＂peakvalley＂characteristic in the spectral curve.The reflectivity was reduced by the increasing coverage of the biological soil crust.Compared with the bare area,the spectral reflectance normalized mean of algae biological soil crust deceased 8.64%,15.80%and 23.09% respectively in the coverage of 10% to 20%,30% to 40% and 50% to 60% in the visible area.The absorption characteristic at 680 nm（Chlorophyll）became increasingly obvious and the absorption valley at 2 200 nm（secondary mineral）became smaller as the coverage of algae biological soil crust increased.The spectral curve of moss biological soil crust showed the reflection peak of the green band,the absorption valley of the red light band and the high reflection of the near infrared band,which is similar with the vegetation.In the range of 760～930 nm,the slope of moss biological soil crust was 2.5 to 4.5 timed higher than that of vegetation.The study can provide some theoretical basis and technical support for the identification of biological soil crust.