A Study On Risk Assessment And NPP Status Based On BIOME-BGC Model In Xilin River Basin

Ecosystem is of great significance to the survival and development of human beings.Due to the large area of grassland ecosystems,the global study of grassland ecosystems is more important.Xilin River Basin has always been regarded as a representative area of Inner Mongolia typical grassland,but in recent years,the ecological environment of the Xilin River Basin has also deteriorated.Therefore,there wre many studies on carbon sources?carbon sinks and the impact of climate change on the environment of grassland ecosystems,which are more conducive to the scientific assessment of grassland functions It can provide better climate change solutions for grasslands.This article analyzes the climate change over the past 40 years and the next 40 years in the Xilin River Basin.The BIOME-BGC model was used to simulate the cycling of carbon and nitrogen in the Xilin River Basin ecosystem and describing the interaction between the external environment and the net primary productivity of vegetation.Finally,the research analyzed the changes in the NPP over the past 40 years and predicted the possible risks to the Xilin River Basin based on the climate change over the next 40 years.The main results are as follows(1)During the period from 1976 to 2016,the temperature change showed an upward trend in the Xilin River Basin,while the precipitation did not increase significantly,and there was a trend of warming.The warmth index(WI)showed a significant increase trend in the hydrothermal index,and the cold index(CI)showed a slight increase.After2005,the humidity index(HI)and the dryness index(DI)were significantly changed in the hydrothermal index.There was no obvious trend of change,but it has been extremely volatile in the past 40 years.The number of consecutive days of drought showed a significant decrease,and the number of summer days increased.(2)The correlation coefficient increased from 0.47~0.74 to 0.77~0.82 after optimizing the parameters of the four communities.The mean value of the community IV was the largest among the four communities,and the standard deviation was also the largest,indicating that the community was affected by the community in the past 40 years.The external environment has a greater impact,and the NPP value of community III is the least affected by the environment.In the past 40 years,net primary productivity was the highest in 1996,and 1983 was the lowest net primary productivity in the past 40 years.The trend of NPP in the Xilin River Basin was mainly related to moisture andgreater than the effect of temperature on NPP.The impact on NPP is mainly through the process of affecting the carbon cycle.(3)The average annual temperature in the Xilin River Basin under the two RCP4.5and RCP8.5 future climate scenarios shows a significant upward trend.The average temperature of RCP in 4.5 years is slightly lower than the average temperature of RCP8.5 years,and is higher than the previous 40.The average temperature of the year.The rate of temperature increase in the context of RCP8.5 is greater than the rate of temperature increase in the context of RCP4.5,and the climate warming rate is slower in the context of RCP4.5.Rainfall in the RCP4.5 and RCP8.5 future climate scenarios showed a slight upward trend,with weak changes but large fluctuations between years.The annual rainfall of RCP4.5 is lower than the annual rainfall of RCP8.5 in the next 40 years,which is higher than the average annual precipitation in the past 40 years.(4)In the next 40 years,the baseline annual average NPP under the RCP4.5 scenario is almost equal to the NPP annual average of the Xilin River Basin in the past 40 years.Under the RCP8.5 scenario,the NPP is lower than the baseline NPP,RCP4.5 The NPP in the context is higher than the NPP in the context of RCP8.5.Under the context of RCP8.5,this also results in the larger variation of the NPP in the Xilin River Basin under the RCP8.5 climate scenario.(5)In the next 40 years,the NPP in the Xilin River Basin faces certain risks,but most of the risks are mainly concentrated after 2040.In the context of RCP4.5,the risk level is mainly due to the higher probability of occurrence of low-risk in the RCP8..5The level of risk in the context is higher,and the probability of risk in the RCP4.5situation is higher than that of RCP4.5.