Abstract:

Biological soil crust plays an important ecological function in desert ecosystems， but different types of biological soil crust have great differences in ecological functions due to their different compositions and proportions of organisms. This article is intended for the development of stable moss and algae crust in Mu Us Sandy Land， through field survey monitoring and indoor index determination， in-depth analysis of the influence scale of two types of biological crust on soil water content， wind erosion， nutrient content， and establishing a comprehensive evaluation model quantitatively contrasts the ecological function differences between the two. The results show that： （1） the soil water content of the two types of the biological soil crust increases first and then decreases fluctuating with the increase of soil depth. There is a significant（P<0.05） difference in soil water content between the two biological soil crusts， which indicates that the soil water content of moss crust is greater than that of algae crust in the depth range of 0-80 cm， and the opposite is true in the depth range between 90-100 cm； （2）compared with bare land， the soil wind erosion under the influence of moss crust and algae crust decreased by 156.0% and 136.6%， respectively， but there is no significant difference between them； （3） the soil nutrient content under the influence of the two types of crust is significantly different （P<0.05）， showing that the total nitrogen， total phosphorus， and organic matter content of the soil under the moss crust are 3.3 times， 3.5 times， and 2 times of the algal crust， respectively； （4）the comprehensive scoring order of ecological functions of different types of biological crust is： moss crust>algal crust>bare land （1.60>-0.64>-9.78）. This study confirmed the differences in the ecological functions of different types of biological soil crust in desert ecosystems， and their contribution to maintaining the circulation of soil， water and nutrients， highlighting the accurate classification of their types or compositions in exploring the importance of biological soil crust.

Key words: biological soil crusts, soil water content, soil wind erosion, soil nutrients, comprehensive evaluation model