Simulation Carbon Exchanges Based On CoupModel At The Peatland In Permafrost Region Of Great Hing'an Mountains

High latitudes in the north are highly sensitive to climate change in the context of global warming.Since the carbon source/sink problem in high latitudes is still uncertain in response to climate change,it is of great significance to characterize the response of peatland to global climate change by using models.Located in the northeast of China,the Great Hing'an Mountains is the most prominent part of the high-latitude permafrost region in Eurasia to the south,and it is also one of the permafrost regions most significantly affected by climate warming in China.In order to study the response at the peatland carbon cycle to climate change in the permafrost region of the Great Hing'an Mountains,based on the biogeochemical model(Coup Model),the following research contents were completed:The variation characteristics and influencing factors of carbon exchange in the growing season at the peatland in the Great Hing'an Mountains.The determination of model structure and parameters,simulation of water and heat transport and material transport process in growing season;The future prediction datas analysis of different scenarios and the long-term changes simulation of carbon exchanges in the peatland.The main conclusions are as follows:(1)The Net Exchange of Ecosystem CO₂(NEE)and Ecosystem Respiration(ER)in the growing season of 2016 and 2019 of the peatland in the permafrost region of Great Hing'an Mountains showed a good seasonal pattern.The CO₂ absorbed by the peatland ecosystem from the atmosphere mainly occurred from June to August,and the intensity of respiration was the strongest in July.(2)The simulation results of heat and water transfer at the peatland in the permafrost region of Great Hing'an Mountains in 2016 and 2019 showed that the shallow layer simulation results were more accurate than the deep layer;The simulation results of NEE and ER were slightly lower than the measured results,and the frost depth was deeper than the measured results.(3)Under the RCPs prediction scenario at the peatland in the permafrost region of Great Hing'an Mountains from 2021 to 2100,the average temperatures of RCP2.6,RCP6.0 and RCP8.5 reached-2.68°C,-2.04°C and-0.19°C,respectively,which was 1.49°C,2.13°C and 3.98°C higher than those in the past60 years(-4.17°C).The average temperature of the growing season in the next 80 years under the three scenarios is 11.60°C,12.31°C and 13.82°C,respectively,which is 0.99°C,1.70°C and 3.21°C higher than that in the past 60 years(10.61°C).The precipitation in the future scenario showed an increasing trend,and the average values of RCP2.6,RCP6.0 and RCP8.5 were 660.90 mm,674.82 mm and 719.89 mm,respectively.Under RCP2.6,RCP6.0 and RCP8.5 scenarios,the average annual precipitation in the growing season was 529.98 mm,539.86 mm and 572.05 mm,respectively.(4)The annual average humidity at the peatland in permafrost regions of Great Hing'an Mountains showed a downward trend from 2006 to 2100 under RCP2.6,RCP6.0 and RCP8.5 scenarios,which were85.67%,85.58%and 85.10%,respectively.Combined temperature can be speculated that the peatland in permafrost region of Great Hing'an Mountains will develop in the direction of warm and dry.(5)According to the future climate change trend,two vegetation succession schemes are preset,and the overall trends of NEE,ER and GPP of the two schemes were similar.Affected by temperature,the NEE of RCP8.5 showed a decreasing trend at the cut-off point of 2053.ER and GPP increased rapidly in RCP8.5;The simulation results of NEE,ER and GP under the two vegetation schemes showed significant differences(p<0.01).Under the same warming scenario,due to the change of ecosystem vegetation types,photosynthesis,respiration and soil respiration of plants will be affected.The simulation results of NEE,ER and GPP of the Scheme 2 was greater than the Scheme 1.(6)The variance analysis method was used to analyze the influencing factors of NEE and ER under the two vegetation schemes,and the results showed that the NEE,ER and GPP of the two schemes under RCP2.6,RCP6.0 and RCP8.5 scenarios were affected by temperature(p<0.1).In particular,ER and GPP of Scheme 2 in RCP2.6 scenario was only affected by temperature(p<0.1).ER and GPP of Scheme 1 in RCP2.6 scenario and NEE and ER of Scheme 2 in RCP8.5 scenario were also affected by humidity(p<0.1).