Litter crusts promote herb species formation by improving surface microhabitats in a desert ecosystem

The degradation of soil and vegetation substantially damages ecosystem functions. Litter crusts play an active role in the vegetation restoration and management in desert ecosystems. In this study, the effects of litter crusts on surface microhabitats and species formation on sandy land were studied in the wind-water erosion crisscross region in the Mu Us Desert, northwest China. Soil microhabitat features including moisture, temperature, and organic matter content were measured in different positions of litter crusts and bare sand, seedling species richness, and total seedling number of all species were recorded in litter crusts on the sand's surface. The results showed that there were significant differences between litter crusts and bare sand in terms of soil moisture, temperature, organic matter content, and light intensity. Compared with that of bare sand, soil moisture below litter crusts was increased by an average of 17.0% overall, soil organic matter content was increased by 77.5% at the 0-5 cm depth and by 80.8% at the 5-10 cm depth. Litter crusts decreased soil temperature and light intensity by an average of 16.6% and 31.6%, respectively. Seedling species richness and total seedling number of all species were significantly higher in litter crusts than those in bare sand. Our findings revealed that litter crusts modify the surface microhabitats of sand by maintaining soil moisture, regulating soil temperature, increasing soil nutrients, and reducing light intensity, thus promoting species establishment in the wind-water erosion crisscross region.