Reflectance Spectra of High-altitude Lichens Based on In Situ Measurements

Abstract

The unique chemistry together with typical physiology, morphology and anatomy enables lichens to survive in any harsh environment and same forms the basis for their unique spectral signatures. In this study, five lichen species found at Ravanshila, Tungnath in Garhwal Himalaya region were studied for their spectral characteristics. The reflectance measurements were taken using ASD Fieldspec 3 portable spectroradiometer at every 1 nm from 350 to 2,500 nm. The discrimination analysis was performed by band ratios and stepwise discriminant analysis (SDA) . The band ratios of 400/685 and 773/685 nm distinctly provided the spectral characteristics of different colour and growth forms of lichen species. A set of 11 wavelengths were selected using SDA, and most of the variances in the spectra were observed in the NIR and SWIR regions. The maximum variability between lichen species was found at 950 nm (F = 7,572.86; L = 0.00). It was also observed that all lichens showed a more gradual increase through 400–1,300 nm with a maximum inflection point at about 680 nm (red edge). Spectra of all lichens were similar in shape beyond 700 nm, but the magnitude of reflectance varied among them. Between 1,500 and 1,800 nm, all lichens exhibited similar pattern, but with difference in the level of reflectance. Study on spectral properties of high-altitude lichens will be helpful in developing methods for classifying and monitoring lichens using hyperspectral remote sensing .