Response Of Carbon-water Flux To Climate Change In Temperate Coniferous And Broad-leaved Mixed Forests In Changbai Mountain

The research on the variation of carbon-water fluxes in forest ecosystems under global climate change is a hot issue in international studies.Understanding the response of forest ecosystem carbon-water fluxes to climate change will help to further understand the role of forest ecosystems in the carbon-water cycle of terrestrial ecosystems,and to understand the response mechanisms and adaptive mechanisms of carbon-water fluxes in forest ecosystems to climate change.This study will use the EALCO model,which is a comprehensive model for simulating the exchange of carbon and water fluxes between the atmosphere and the underlying surface of the ecosystem,based on physiological and ecological processes.The EALCO model is applied to the temperate conifer and broad-leaved mixed forest ecosystem in Changbai Mountain.Using flux observation data to test the simulation effect of the model on the carbon-water fluxes of coniferous and broad-leaved mixed forests in Changbai Mountains.Simulating and Predicting the Response of Carbon-Water Flux to Temperate Climate in the Mixed Forest of Temperate-Conifer-Hardwood in Changbai Mountains under Future Climate Change Scenarios.With a view to providing reasonable guidance for the future implementation of carbon management and water management.The findings of this paper are as follows:?1?Model carbon-water flux simulation effect:Based on the EALCO model simulation of carbon fluxes in the coniferous and broad-leaved mixed forests of Changbai Mountain in 2003-2005,the correlation coefficients between observed and simulated values of GPP?Gross primary production?,NEP?Net ecosystem production?,and RE?Total ecosystem respiration?are 0.93,0.95,and 0.77,respectively.The daily and seasonal changes of GPP,NEP,and RE are largely simulated.The model's annual aggregate simulation results for GPP,NEP,and RE in 2005 were lower than in 2003 and 2004,probably due to the lower temperature in 2005.At the same time,the simulation results of the EALCO model for evapotranspiration and soil moisture in forest ecosystems show that the simulated values of evapotranspiration during the period from May to August are higher.The correlation coefficients of simulated values and observed values of evapotranspiration and soil moisture reached 0.96 and 0.73,respectively.The model can well show the seasonal variation trend of evapotranspiration and soil water content in the forest ecosystem.Therefore,the EALCO model has good applicability to the Changbai Mountain area,and it can better show the variation of carbon-water flux in the coniferous and broad-leaved mixed forest ecosystem in Changbai Mountains.?2?Analyzed the response of carbon and water flux to the climate change in the mixedforest of temperate conifer and broad-leaved forest in Changbai Mountain:In future climate conditions,the NEP and GPP value of BCC-CSM1.1?m?,GFDL-CM3,and HADGEM2-ES models all show an upward trend.The RE value simulated by the BCC-CSM1.1?m?and HADGEM2-ES models shows a certain increase in the future climate change,while the RE of the GFDL-CM3 model declined in the future.The R_a?Autotrophic respiration?value of the three climate models will show an upward trend in the future.The R_h?Heterotrophic respiration?simulated by the BCC-CSM1.1?m?and HADGEM2-ES models will also increase in the future,while the R_h of the GFDL-CM3 model will decrease.R_h has a negative correlation with CO₂ concentration.The increase of CO₂ concentration may hinder the diffusion of CO₂ and inhibit the heterotrophic respiration of vegetation.The NEP values simulated by the three climate models under the RCP4.5 and RCP6.0 scenarios are compared and it was found that under the RCP4.5 scenario,the simulated values of NEP are BCC-CSM1.1?m?,HADGEM2-ES and GFDL-CM3 from the largest to the smallest.Under the RCP 6.0 scenario,the NEP value of the BCC-CSM1.1?m?model is higher than that of the HADGEM2-ES model.Under the RCP4.5 scenario,the Tr?Transpiration?of the BCC-CSM1.1?m?and GFDL-CM3 models will decrease under future climatic conditions,and the Tr of the HADGEM2-ES model will increase.The HADGEM2-ES model has an increase in Tr under the RCP 6.0 scenario,and Tr is smaller than Tr under the RCP4.5scenario.The Eva?Evaporation?simulated by the BCC-CSM1.1?m?and GFDL-CM3 models shows an increasing trend in the future climatic conditions,while the Eva simulated by the HADGEM2-ES model decreases under the RCP4.5 scenario and increases under the RCP6.0scenario.