Response of soil carbon emission of biological crust to hydrothermal factors in mining subsidence area in aeolian

Soil carbon emission of the lands covered by biocrusts is an important component in the carbon cycle.To clarify the carbon emission pattern of typical biocrusts in the coal mining subsidence area of Mawwusu sand and its response to changes in soil hydrothermal factors,the soil carbon emission rate,soil temperature and humidity were measured by the Automated Soil CO2 Exchange Station (ACE),and the relationship between them was explored.The results show that:① on the whole,the diurnal variation characteristic curves of soil carbon emission rates of three typical biologically-crusted soils generally show the characteristics of asymmetrical bell single peak’curve,with the peak value between 12:00-13:00.The daily average soil carbon emission rate order is algae overlying crust (0.47 μmol/(m2·s)) > moss overlying crust (0.45 μmol/(m2·s)) > lichen crust (0.44 μmol/(m2·s)).② The soil respiration rate of three typical biologically-crusted soils shows a quadratic function relationship with the surface soil temperature,and their determination coefficients are 0.59,0.46 and 0.64,respectively,all of which reach extremely significant positive correlation levels (P＜0.01).③ The relationship between soil carbon emission rate and surface soil water content is quadratic function,and the best fitting relationship between the soil water content of moss overlying soil is quadratic function,and its coefficient R2 reaches a very significant level of 0.45 (P