Methane emissions from wetlands in China: effects of wetland type and climate zone

Abstract

Wetlands are the most productive natural ecosystems in the world, and methane (CH4) emissions from wetlands are a significant source of CH4 to the atmosphere. We estimated CH4 emissions from wetlands in China, and analyzed the influence of wetland type and climate zone on CH4 emission. The results indicate that CH4 fluxes were significantly different among different types of wetlands. All types of wetlands other than coastal wetlands were found to be sources of CH4. CH4 fluxes from highest to lowest were as follows: rice paddies > marsh wetlands > reservoirs > riverine wetlands > lake wetlands > coastal wetlands. The interaction between the wetland type and the climate zone was also significant. CH4 emissions from certain types of wetlands differed in different climate zones. Lake wetlands were more sensitive to climate than other types. CH4 fluxes from marsh wetlands were similar in different climate zones, and CH4 fluxes from rice paddies were all very large because they are consistently flooded and shallow. CH4 fluxes were significantly related to both latitude and longitude, but to a greater degree to latitude since latitude is related to climate. In summary, both the wetland type and the climate zone should be considered when estimating CH4 fluxes from wetlands in China as well as in other countries.