Abstract:Biological soil crusts (BSCs) are the association of soil organisms including algea, cyanobacteria, bacteria, fungi, lichen and moss and soil particles, which cover as much as 70% of the interspaces between vegetation and are the key component of arid and semiarid ecosystems. They play a significant role in the process of soil formation and biogeochemical cycling of carbon and nitrogen. Although the functions of BSCs in soil carbon cycling in drylands have been extensively described in the literature, previous research has primarily focused on the effects of BSCs on soil carbon sequestration and respiration. Knowledge is rather poor regarding their effects on soil organic carbon mineralization which is the major part of global carbon cycling and an important process of carbon loss from soils in terrestrial ecosystem. Consequently, understanding the effects of BSCs on soil organic mineralization and their regulating factors is crucial to thoroughly addressing their contribution to the soil carbon budget and balance in drylands.In this study, both intact soil (IS) and BSC-being-removed soil (BRS) samples were collected from algae-, lichen-, and moss-covered soil plots in the southeastern fringe of the Tengger Desert. Carbon mineralization rates of different types of soils and their responses to soil moisture and temperature were investigated by dark incubation. The relationships between soil mineralization rates and soil physicochemical factors were also analyzed. The results showed that (1) SOC mineralization rates and cumulative CO2-C release from IS were significantly higher than those from BRS. These two parameters for both IS and BRS were in the order moss crust > lichen crust > algae crust. (2) The average and maximum soil carbon mineralization rates increased with increasing magnitude of incubation temperature and soil water content, and the dynamic patterns of their response both were similar. (3) Temperature sensitivity (Q10) of the three intact soils and their respective subsoils were closely linked to BSC types, with the highest value for moss-covered soil and the lowest for algae-covered soil. Our understanding of the effects of on soil carbon mineralization suggests that the evolution of BSCs from algae-dominated to moss-dominated soil promoted carbon mineralization, and their regulation of soil carbon cycling was strongly controlled by environmental factors, such as temperature and soil moisture.