Microbiotic crusts and their interrelations with environmental factors in the Gurbantonggut desert, western China

Located in the Junggar Basin in Xinjiang, the Gurbantonggut Desert is the second largest desert in China. Microbiotic crusts consisting of animalcule, lichen, moss, and algae species develop extensively in the region. Their formation, species composition and distribution pattern are closely related to the environmental conditions along the different parts of sand dune. Analysis of microbiotic crust distribution and relationship to environmental factors shows that average microbiotic crust thickness is 0.05-0.1 cm at the tops dunes, 0.2-1.5 cm in the upper part, 1.5-2.5 cm in middle and lower parts of dunes, and 1.5-5.0 cm in interdune areas, while areal coverage is 30.5, 48.5, 55.5, and 75.5%, respectively. Microbiotic crust differentiation along dune slopes is a result of the development stage and converse-succession resistance of the different microbiotic crusts. The numbers of species, thickness and degree of development of microbiotic crusts increase from the upper part to the middle and lower parts of dune slopes. The development and differentiation of microbiotic crusts at various dune slope positions are a reflection of the ecological expression of the comprehensive adaptability and natural selection of different microbiotic crust species to the local environmental conditions, and are closely related to such ecological conditions as the physiochemical properties of soils and topsoil textural stability.