| Wetland ecosystem could fix carbon from the atmosphere, play an important role in the global carbon cycle, which is considered to be one significant carbon sink by its carbon sequestration effect. However, because of the emission of carbon dioxide and methane, the coastal wetland ecosystem is likely to be ‘carbon source’. So in the process of global carbon cycle balance calculation, we need to measure the CO2 and CH4 emission to further calculation. In order to explore the Liaohe Delta wetland of CO2 and CH4 emission flux among different vegetation types and identify different environmental factors in different wetland vegetation types on the effects of CO2 and CH4 emission. The method of static box in the growing season(from April to November) in three kinds of typical vegetation type of Liaohe Delta wetlands(seablite wetland, reed wetland and rice wetland) was used to make a CO2 and CH4 flux monitoring for each month. The monitoring lasted for three years since 2012. At the same time, environmental factors such as the temperature in the chamber, soil temperature at 5 cm, soil moisture content and soil bulk density, soil redox potential, the ground biomass, p H, salinity and water concentration of HCO3–were collected during each measurement, which determine the correlation of CO2 and CH4 emission. Find out the various environmental factors and the correlation of CO2 and CH4 emission. Three typical vegetation types for the estimation of Liaohe Delta wetlands in emission of CO2 and CH4, evaluation of Liaohe Delta wetlands provide basis for carbon sequestration ability and potential accessment.The main factors controlling the emission of CO2 and CH4 in different vegetation types of wetland are the temperature and water level, the influence of biomass was not expected. The main reason is that the water content of plant reducted in the end of growth, then respiration is abate. All show obvious seasonal variation characteristics that high summer release quantity and low winter release.The CO2 and CH4 emission in seablite wetland in Liaohe Delta range from-24.96 to 1903.49 mg/m2? h-1 and from-0.25 to 1.74 mg/m2? h-1respectively. The release of CO2 and CH4 varies significantly in different seasons, which means CO2 and CH4 have a high emission in summer and low in other seasons. The emission is restricted by the various environmental factors and the temperature, biomass and the change of water level are main factors in seablite wetland.The CO2 and CH4 emission in reed wetland in Liaohe Delta range from-39.27 to 4381.82 mg/m2? h-1 and from-3.6 to 98.28 mg/m2? h-1,Methane emission flux showed obvious temporal and spatial heterogeneity, high emission in the summer, winter and spring season is extremely low. This characteristic is affected by the environmental factors, such as temperature, water level and reed types.The CO2 and CH4 emission in rice wetland in Liaohe Delta range from-143.74 to 2135.53 mg/m2? h-1 and from-0.004 to 24.51 mg/m2? h-1. As the growth of rice plant after rice transplanting, flux of CO2 and CH4 released continuously rise, after rice mature CO2 and CH4 emission flux is decreasing. The changes of temperature and rice growth process are the main environment factors.The data from the 30 min incubation in 2012 is significantly below the real-time monitoring data in 2013 and 2014 so CO2 and CH4 emission flux were undervalued.In winter, the CO2 and CH4 emission declined relatively after cutting plant. But some plot increased, this may be the exposure area of soil surface increased which makes the CO2 and CH4 in the soil to release. |
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