Abstract:

The effect of wetland carbon element change on the global climate change has been a focus in the world for a long time. Some works have been done in studying carbon cycles of marsh wetland at Sanjiang Plain in China, but little was reported on the same work in Ruoergai Plateau situated in north-east part of Qinghai-Tibetan Plateau, which is one of the most sensitive areas with respect to global climate change in the world. The cold climate and abundant water in this area, vast marsh area and rich reserves of the peat are all very specific in China and in the world. To evaluate the effect of wetland carbon cycles on global climate change, the author studied organic carbon distribution and flow from three kinds of plant (Carex muliensis, Carex meyeriana and Kobresia tibetica) communities to three kinds of soil (peat soil, peat bog soil and meadow bog soil) using a field decomposition approach. The purposes are as follows: 1) to investigate the amount and distribution of soil organic carbon and 2) to verify the amount of C lost and C retained in the wetlands in Ruoergai Plateau. The results showed that the content of soil organic carbon was high and decreased with the increase of the depth of the soil layer. The disappearing rate of the organic carbon was different in different chemical constituents at different stages of living plants, standing dead and litter. Among several chemical constituents, the disappearing rate of the easy-decomposing C was the highest and reached 61.37%, 69.59% and 66.34% respectively in the three marsh plant communities, while the disappearing rate of the lignin C (44.53%-52.98%) was slightly higher than that of the cellulose C (38.23%-43.86%). The total disappearing rates of the plant carbon were 53.8%, 60.03% and 55.18% respectively in the three communities. The amount of C retained in soil from litter after 1 and 2 years of decomposition was 30 g·m-2 and 25.5 g·m-2 respectively, while the amount retained in the residual roots was 179-223 g·m-2 and 161-208 g·m-2 respectively. These results indicated that residual plant roots was the main source of soil organic carbon and the amount of organic carbon flow was large because of the higher biomass in wetland ecosystem in Ruoergai Plateau.