Abstract:Net photosynthetic rate, annual carbon fixation, and total carbon fixation of cyanobacterial crusts in relation to history of artificial revegetation (16, 21, 27, 44 and 52 years) were investigated at Shapotou, the southeast edge of the Tengger desert, and their relationships with biological parameters (coverage and biomass) of the cyanobacterial crusts, and organic carbon content in the surface soil (0~3cm) were also analyzed. Results show 1) the maximum net photosynthetic rate of the crusts profoundly increased with the history of revegetation, from 1.63 μmol m-2 s-1 in the area revegetated for 16 years to 2.81 μmol m-2 s-1 in the area revegetated for 52 years, showing significant positive relationship with coverage and biomass of the crusts; 2) annual carbon fixation increased exponentially with the history of revegetation, from 0.2 g m-2 a-1 C in the area revegetated for 16 years to 2.78 g m-2 a-1 in the area revegetated for 52 years; and 3) the total carbon fixation of the crusts experienced two phases of variation after the revegetation; in the first phase (from 16a to 27a) low in total carbon fixation, in the range from 2.2~6.2 g m-2 C, and in the second phase (after 44 a) high in total carbon fixation reaching 23.9 g m-2 C; showing a linear positive relationship with organic carbon content in the surface soil. The findings indicate that the maturity of cyanobacterial crusts improved along with the succession of the artificial revegetation, cyanobacterial crusts are getting more and more mature and increasing significantly in photosynthetic carbon fixation capacity, which is conducive to accumulation of soil organic carbon in arid soils.