The Distribution Patterns of Biological Soil Crust in Gurbantunggut Desert

The biological soil crust, especially lichen crust, was developed well in Gurbantunggut Desert, the largest fixed and semi-fixed sandy desert in China. Together with vascular plant, biological soil crust becomes an important factors relating to sandy surface fixation. In this study, the reflectance of lichen-dominated biological soil crust was measured and used to develop a new index for detecting and mapping the crust distribution. We examined the feasibility of the index for Landsat ETM sensor by using radiative transfer model (6S) to simulate different coverage of the crust under different atmospheric conditions. Then, we applied the new index to Landsat ETM data of the Gurbantunggut desert to map the spatial distribution patterns of biological soil crust in Gurbantunggut Desert. The results, combined with field investigations, showed that the biological soil crust was mainly distributed in southern part of this desert, but became gradually sparse toward northern, western and eastern parts of this desert. The coverage of biological soil crust was estimated up to 28.7%. The species composition of biological soil crust varies according to different positions of sand dunes and different developmental stages of biological crust.