Source of the research subject: The research subject was entrusted and supported by the National Natural Science Foundation of China (Grant No. 90202019), “Light of the West Regions” of Chinese Academy of Sciences, local fund (Grant No. 200421128 ) and National “863” Program of China (Grant No. 2004AA227110-3).

　　Study period: From January 2002 to September 2006.

　　Award: The research subject won a Third Award of Scientific and Technological Progress of Xinjiang Uygur Autonomous Region in 2006.

　　Main accomplishing scientists: 1 Zhang Yuanming, 2 Wang Xueqin

　　Brief introduction of the research subject

　　In this research subject, desert microbiotic crusts were researched from the aspects of species composition, macro-distribution and environmental features of microbiotic crusts, formation mechanism of desert microbiotic crusts, effects of microbiotic crusts on surface stability, diversity of spermatophytes and rainfall permeation, photosynthesis and physiological features of microbiotic crusts, growth characteristics of the micro-structure of microbiotic crusts, cultivation of the relative species of microbiotic crusts, laboratory and field experiments of microbiotic crusts, etc. In this research subject, the microbiotic crust index (BSCI) suitable for cold desert was developed, and the spatial distribution features of desert microbiotic crusts were revealed; a viewpoint that it is advantageous for the diversity of desert spermatophytes to moderately disturb desert microbiotic crusts was put forward; the nitrogen fixation amounts of desert microbiotic crusts were estimated, the micro-structure and its succession laws of microbiotic crusts were revealed, and the suitable cultivation conditions of the low-nutrient bacteria, desert algae and desert mosses were put forward. The research subject was comprehensively carried out in an interdiscipline way of spore botany, microbiology, geomorphology, agrology, remote sensing, etc., the different microbiotic crusts were regarded as an organic whole to lucubrate, and the inorganic environment and the biological factors were comprehensively considered so as to reveal the formation and sand-fixation mechanisms of desert microbiotic crusts.