Simulation And Projection Of Grassland Carbon Balance In Western Sichuan Plateau Under Climate Change Based On IBIS Model

Grassland in the western Sichuan plateau is an important wetland protected area in China,and has abundant ecological resources.Its carbon balance plays an important role in the regulation of ecosystem.The special ecological environment in the western Sichuan Plateau is sensitive to climate change,and the carbon balance of the grassland is also affected.In this paper,we use IBIS model to simulate and project the carbon balance of grassland ecosystem in the western Sichuan Plateau under climate change.On the one hand,the suitability of IBIS model for the study of the West Sichuan Plateau is tested.On the other hand,the carbon balance of the grassland in the western Sichuan Plateau in the past and future was mastered through the simulation study,which provided a scientific basis for the further study and protection of the grassland.The main research methods and conclusions of this paper are as follows:(1)The climate change in the West Sichuan Plateau during 1990-2018 and2019-2050 was analyzed through meteorological data interpolation and Arc GIS,and temperature and precipitation were selected as the main variables of climate change.The results showed that the average annual temperature and annual precipitation in the two study periods decreased from southeast to northwest.The interannual variation law of temperature and precipitation is different,and the increase of temperature fluctuation is more obvious than that of precipitation.Generally speaking,the climate of the West Sichuan Plateau tends to be warm and humid.(2)For the two research periods of 1990-2018 and 2019-2050,Arc GIS and Matlab programs were used to process the input data of IBIS model,and then the corresponding parameters of IBIS were adjusted in VMware virtual machine software and the output data program modules needed in this study were added.Then run the IBIS model.After the operation of the model,the output data were collated and calculated to obtain NPP and soil heterotrophic respiration data,and then their accuracy was verified by the following verification methods: measured data verification,remote sensing data verification,calculation verification of other models and comparison verification of other research results.The results showed that the simulation accuracy of NPP and soil heterotrophic respiration was high,which indicated that the IBIS model was suitable for the simulation of grassland ecosystem in the western Sichuan Plateau.(3)Based on the validation of the model simulation study,the changes of NPP and soil heterotrophic respiration in the two study periods were analyzed.From the perspective of spatial distribution law,the spatial distribution law of NPP and soil heterotrophic respiration in the two study periods and the spatial distribution law of climate change showed a certain correlation,that is,the better the hydrothermal conditions,the higher the NPP and soil heterotrophic respiration.From the perspective of time variation,the annual mean values of NPP and soil heterotrophic respiration fluctuated slightly from 1990 to 2018.At the seasonal scale,the seasonal variations of NPP and soil heterotrophic respiration were stable.The annual mean NPP showed a slight upward trend during 2019-2050,while the soil heterotrophic respiration showed a slight downward trend.(4)In this paper,net ecosystem productivity(NEP)was used as the quantitative index of carbon balance,and NEP was calculated by NPP and soil heterotrophic respiration.The results show that there are ecological regions of carbon sink and carbon source in the study area in both time periods,and the NEP value in the northeast region is higher than that in other regions during the period of 2019-2050.In terms of time scale,the annual mean value of NEP in the two study periods was positive,but the fluctuation of NEP value from 1990 to 2018 was smaller than that from 2019 to 2050.Therefore,the carbon sink function of grassland ecosystem in the western Sichuan Plateau was stronger than that from 1990 to 2018 in the next 32 years,and the carbon sink function of grassland ecosystem in the western Sichuan Plateau was gradually increasing.