Abstract: Soil moisture and heat conditions are the main factors affecting steppe degeneration and steppe ecosystem. The seasonal dynamic changes of soil temperature and soil moisture content in a degenerated steppe in the Qinghai-Tibet Plateau can be predicted, which is of the guiding significance for regenerating and improving the degenerated ecology and environment. In this study, the 1-year data observed in a typical degenerated steppe in Maduo County in the Qinghai-Tibet Plateau were used to analyze the relationships between soil temperature, moisture content and heat flux and their seasonal and annual variation. The results show that the values of soil temperature and moisture content were the highest in summer, there was a consistent trend in seasonal change of soil temperature, the change range of soil heat flux was higher than that of soil temperature and moisture content, and its daily fluctuation was 102 W•m^-2. The maximum and minimum values of soil moisture content occurred in June and December separately, and the annual range of the extreme value was 12.6%. Soil heat flux was higher than 0 W•m^-2 in spring and summer but lower than this value in winter. There were the significant seasonal and annual changes of soil temperature, moisture content and heat flux, and the soil moisture content was high in summer but low in sparing and autumn. Soil in the Qinghai-Tibet Plateau froze in November and thawed in April. The value of soil heat flux in spring and summer was positive, which reveals that heat transferred from air to soil in these two seasons, and contrarily, heat transferred from soil to air in winter. Holistically, there were the significant positive correlations between soil temperature, moisture content and heat flux.

Key words: degenerated steppe, soil temperature, soil moisture content, soil heat flux, Maduo County, Yellow River