Using Red Edge Position Shift to Monitor Grassland Grazing Intensity in Inner Mongolia

Red edge parameters including wavelength, amplitude and area of the red edge peak are important remote sensing-based descriptors of vegetation which have been widely used for evaluating plant chlorophyll content, biomass and even vegetation stress. This paper investigates the possibility of monitoring grazing intensity based on red edge position (REP) shift. At an experimental site located in the Inner Mongolia Grassland Research Station (E116A degrees 42', N43A degrees 38'), five methods were used to extract REP, which ranged from 703 to 725 nm depending on the extraction method chosen and the degree of grazing intensity (GI). The results showed that grazing can cause REP to shift toward shorter wavelengths, and the amplitude of the shift is related to GI. The likely reason for the REP shift is the "green loss" of grass leaf caused by the grazer. Based on the use of broadband satellite remote sensing data, linear extrapolation is recommended as a relatively optimum method for extracting REP.