Abstract: Wetland ecosystem is considered as one of the important ecosystems for life and human society sustainability, and also one of the most important terrestrial C stocks on the Earth. Therefore, conservation of wetland soil C stock may play a significant role in mitigation of increasing greenhouse gas in the atmosphere. China has widely-distributed wetlands with diverse types of wetland ecosystems. However, severe challenges such as intense shift to cultivation, low C density and C stock reduction due to cultivation have emerged since the 1950's. It is estimated that China's wetlands have a total C stock in the range of 8-10 Pg, in a proportion of one tenth to one eighth to the state total terrestrial C stock. A reduction of about 1.5 Pg in total C stock was also estimated for the last 50 years. Cultivation and over-grazing have been considered as the dominant forcing factors for this C reduction. Practical measures should be implemented in the near future for conserving wetland soil C stock and further for enhancing the total terrestrial C sink as China is facing a great pressure to mitigate the increasing greenhouse gas emissions.

Key words: wetland, soil carbon, terrestrial C stock, climate change mitigation