[The changes of the soil hydrothermal condition and the dynamics of C, N after the mire tillage].

The wetlands gain increasing attention to its crucial ecological and environmental function. The tillage of the mires in the Sanjiang Plain has played the important role in regulation of the region ecological balance and climate. Prior to tillage, the mean soil temperature of the topsoil (10 cm) in mire from June to September was 12.72 degrees C +/- 4.12 degrees C, distinctly lower than that of the tilled soil, which was 16.71 degrees C +/- 3.81 degrees C. However, the daily mean evaporation of 4.87 mm +/- 3.78 mm in the mire was larger than that of the tilled soil with mean soil temperature of 2.66 mm +/- 3.78 mm from May to September. The alteration of the oxidization-reduction condition and the augment of the soil temperature led to the increases of soil organic matter (SOM) decomposition ratio and the soil respiration flux, the mean soil respiration (CO2) flux [(946.36 +/- 195.78) mg x (m2 x h)(-1)] was 6 times larger than that of the mire [(153.75 +/- 82.59) mg x (m2 x h)(-1)] from August to September. At the initial stage (5-7a) of the mire tillage, the SOM and the nutrients levels change significantly, but after the 15-20a of continuous cultivation, the SOM loss curve came to a relative stable value. The lessen of the input and strength of the decomposition rate of SOM resulted in the accretion of soil bulk capacity and specific gravity, its changing trend was similar to the changing of the soil organic carbon (SOC) loss.