| In this experiment,greenhouse gas emissions of non-native mangrove species,Sonneratia apetala and native mangrove species,Kandelia obovate,were measured to explore their responding mechanisms to sea level rise and temperature change during the processes of global change.The marsh organs were set to simulate the future sea level rise scenarios of four water levels(HW,MW,LW,LLW).Through experiments in three study sites,Aojiang,Yunxiao and Haikou,different latitudes of three sites are used to simulate different temperature.Firstly,in this experiment,judging from NPP of plant productivity and plant height index,the non-native mangrove species,Sonneratia apetala,is the dominant species in Hainan and Yunxiao compared with native mangrove species,Kandelia obovate.It has stronger adaptability to sea level rise.Secondly,this experiment studies sea level rise and temperature change.Temperature changes are simulated by latitude instead.The results showed that the emission rates of CO2 and CH4 from different mangrove communities in Hainan,Yunxiao and Aojiang were significantly different.The higher the latitude is,the lower the emission rate is.Under the simulated sea level rise treatment,there is no significant difference in the emission rate of CO2 and CH4 in different water level treatment.But the interaction of latitude,water level and season has a significant impact on the emission rate of greenhouse gases.Thirdly,the data of CO2 emission rate in Hainan explains that in spring is higher than it in summer.The CO2 emission rate in spring and summer are larger than the rate in autumn and winter.The CO2 emission rate of the Sonneratia apetala group was higher than Kandelia obovate group.The rate of the Kandelia obovate group was larger than control group.In Hainan,the CO2 emission rate of HW level is higher than MW level in spring and summer.In summer,the CO2 emission rate in Hainan HW level of control group(11246 μmol m-2 h-1),Kandelia obovate group(12000 μmol m-2 h-1)and the Sonneratia apetala group(17279 μmol m-2 h-1)is orderly.In spring,the CO2 emission rate in Hainan HW level of control group(6545μmol m-2 h-1),Kandelia obovate group(91 17 μmol m-2 h-1)and the Sonneratia apetala group(9990 μmol m-2 h-1)is also orderly.In YunXiao,the CO2 emission rate in spring is close to summer.The CO2 emission rate in spring and summer is larger than the rate in autumn and winter.The CO2 emission rate of Sonneratia apetala group was higher than Kandelia obovate group.The CO2 emission rate of Kandelia obovate group was larger than control group.In spring,the CO2 emission rate of Sonneratia apetala group(14272μmol m-2 h-1)was larger than Kandelia obovate group(10711 μmol m-2 h-1)and control group(1593 μmol m-2 h-1).In summer,the CO2 emission rate of Sonneratia apetala group(12876 μmol m-2 h-1)was larger than group(3697μmol m-2 h-1).Finally,there was no significant correlation between the CO2 emission rate of two mangrove seedlings and the measured external factors(Eh and pH).Considering that the DNDC model divides greenhouse gases into six sub modules,the next experimental direction can further integrate environmental factors according to the wetland-DNDC model. |
