The spectral characteristics of typical dune vegetation in Horqin Desert

Field Spec4 portable spectrometer (ASD Company) was used to measure the spectral curves of typical vegetation on the sand dunes of Horqin Desert. The spectrum was extracted and analysed. The results revealed that: 1) spectral morphologies of five typical species (Salix gordejevii, Artemisia frigida, Herbal ephedrae, Artemisia halodendron, Caragana microphylla) were similar. The descending order of seeking “red-edge slope” was A. frigida (0.99%) C. microphylla (0.68%) S. gordejevii (0.59%) H. ephedrae (0.58%) A. halodendron (0.56%). However, the vegetation types can be distinguished according to the spectral differences and the parameters of the multiple spectral features. 2) Spectral reflectance characteristics of A. halodendron in different seasons changed with vegetation growth stages. Although this species showed “twin peaks” and “red shift”, these phenomena were not clearly observed. Because the study area appeared to be persistently exposed to drought in July, water shortage in vegetation was severe, which led to the reduction of ‘red edge position’ of A. halodendron to tiny dots on July 6 that appeared as two ‘red edge platforms’. 3) The analysis of spectral characteristics of A. halodendron at different coverage revealed that the derivative spectra represented ‘twin peaks’. Moreover, when the coverage was more than 40%, the ‘red-edge position’ and the coverage were not directly linked, but the canopy coverage was proportional to the ‘red-edge slope’. Removal of the visible band revealed an increase in absorption depth and decrease in absorption peak area of A. halodendron with increasing coverage. A comparison of coverage-sensitive parameters indicated that the area of the absorption peak was the preferred parameter for studying coverage variation of A. halodendron in this region. Therefore, analysis of vegetation hyperspectral characteristics provide an important reference value for the application of remote sensing-based monitoring of vegetation characteristics, such as growth, vegetation classification, and vegetation cover.