Responses Of Greenhouse Gases Emissions From Alpine Wetland Soil To Different Water Level

Under the background of global climate change, the temperature and precipitation changes have caused the qinghai-tibet plateau alpine wetland water level change.Qinghai-tibet plateau alpine meadow ecosystem is an important part of alpine grassland ecosystem,extremely sensitive to climate change,Researching the relationship between the release of greenhouse gases and the water level change is advantageous to the deep understand the grassland ecosystem affected by climate change and its response to climate change and speculating the future trend, to promote the national response to climate change, adaptive management of grassland ecological restoration policy provide a scientific basis. In order to clarify the effects of water table drawdown on greenhous gases emissions from Alpine wetland in Qinghai-Tibetan Plateau, a simulated research was carried out,in which we set two treatments: natural water WN(about 0 cm soil surface) and lower water level WD(natural fell to about 40.00 cm below the soil surface). Determination the emissions of carbon dioxide(CO2), methane(CH4) and nitrous oxide(N2O) of the wetland system under different water level and calculating the global warming potential(GWP), we got the following results:(1) There are different effects on the emissions of CO2, CH4 and N2 O of the wetland system under different water leve: There is no significant effect on the emissions of CO2 of the wetland system under different water leve, the cumulative CO2 emission of WD and WN treatment was 23.52g·m-2and 20.97g·m-2respectively, CO2 release rate were not significantly associated with a water level; There is a significant effect on the emissions of CH4 and a significant correlation was discovered between CH4 release rate and water level, Alpine wetland soil acted as a sink of CH4 under the WD treatment. Alpine wetland soil acted as a source of CH4 under the WN treatment; the cumulativeCH4 emission of WD and WN treatment was 6.72mg·m-2and-7.36mg·m-2respectively. Water level is the key factor for affecting N2 O release and a significant correlation was discovered between N2 O release rate and water level. A certain degree of decline in water level is beneficial to N2 O release, alpine wetland water levels fall further, will reduce N2 O release rate.(2) There was a positive correlation between the cumulative CO2 emissions and soil DOC concentration, significant positive correlations was observed between the cumulative N2 O emissions and soil NO3--N concentration.(3) There was a close relationship between CO2 release and temperature of the alpine wetland ecosystem and reduce the water level to improve the soil respiration sensitivity to temperature; The CH4 released from Alpine wetlands was significantly influenced by the soil temperature, and reduce the water level increased CH4 released sensitivity to temperature; In wetland meadow ecosystem,the N2 O fluxes were very small,and they were influenced by many factors. The influence of temperature and soil moisture on N2 O fluxes were easily masked by the effects of otherf actors. We found no correlationin temperature and N2 O fluxes,the same ashumidity and N2 O fluxes.(4) At the same time scale, the variation of global warming potential(GWP) of the WD treatment was lower than the WN treatment, suggesting alpine wetland water level is beneficial to weaken the global warming potential of greenhouse gases.