Evaluating The Impacts Of Climate Change On Carbon Sequestration Services Of Ecosystem On The Tibetan Plateau

The impact of climate change on the interaction between vegetation and atmosphere is one of the main factors of the change of regional carbon cycle.As a climate sensitive area,how the carbon sequestration potential of the Tibetan Plateau distributes in space and changes under the influence of climate change has important research value for how to respond to climate change in the future.This study provides a reference and understanding of carbon management under the background of urbanization for understanding the regional carbon sequestration services and for facing with the climate change of the Tibetan Plateau in the future.In this paper,ANUSPLIN method is used to calculate the temporal and spatial distribution and trend of precipitation and temperature in the Tibetan Plateau from 1960to 2018 through 218 weather stations.Then,the process based dynamic vegetation model IBIS is used to simulate and analyze the spatial and temporal variation characteristics and trend of net primary productivity and net ecosystem productivity in the Tibetan Plateau from 1960 to 2018,and based on different climatic zones,the results are analyzed.Finally,the spatial and temporal variation characteristics of net primary productivity and net ecosystem productivity in the Tibetan Plateau are analyzed by using CMIP6 Multiple models are used to analyze the future climate change trend,vegetation carbon sequestration potential and carbon use efficiency of the Tibetan Plateau in the long-term future time series from 2015 to 2100,and to explore the impact mechanism in the long-term future time series.The main conclusions are as follows:(1)From 1960 to 2018,the climate of the Tibetan Plateau becomes warming and humidification.The precipitation shows an overall increasing trend.The average annual precipitation in most climatic regions shows an upward trend on time scales.In northern of Yunnan,Bomi,Western of Sichuan and Sichuan regions with higher precipitation,the precipitation shows a slight downward trend,and the spatial distribution range of the change rate is-6.09-12.39 mm/10a.The spatial distribution of the annual mean temperature is between-14.89?and 21.49?,and the change of the temperature in the whole region almost shows an upward trend.The spatial distribution of the change rate is between-0.03?and 0.07?/10a.(2)The ecosystem carbon sequestration service function of the Tibetan Plateau in the historical period shows an upward trend in time,and gradually decreases from southeast to northwest in space.The dynamic change of carbon sequestration potential is heterogeneous in space.The spatial distribution of NPP in the Tibetan Plateau is gradually increasing from northwest to southeast,which is consistent with the spatial distribution of water and heat.The rising trend of NPP is in the hinterland of the plateau,the east and southeast of the plateau,while the declining trend is in the northwest and the southwest valley.The declining regions are mainly located in the north of Qaidam and Northern Tibet,but the regional average level of NPP in the whole region and each region shows an increasing trend in the long-term time series.The net ecosystem productivity of the Tibetan Plateau gradually increases from northwest to Southeast.In the regional carbon cycle,it is generally shown as carbon sink.In the spatial distribution,it is shown as carbon sink in most regions.In the north and southwest regions,it is shown as carbon source.The climate regions of carbon source mainly include Qaidam region and the connecting regions of northern,central and southern Tibet.The spatial distribution of the temporal variation trend of net ecosystem productivity shows a certain spatial heterogeneity,which is different from the distribution of the variation trend of net primary productivity.The spatial distribution of the temporal variation trend of net ecosystem productivity shows a downward trend in the eastern and southern marginal areas of the plateau and the southwest part,and an upward trend in the central hinterland and the western part of the plateau.The decreasing areas were mainly distributed in Dawang-Chayu area,Northern Yunnan area,Sichuan area and Qaidam area.The overall change trend of Dawang-Chayu area is decreasing,while the overall level of net ecosystem productivity in other areas is increasing.(3)The carbon sequestration potential of the Tibetan Plateau predicted by multiple models under the three future climate scenarios increases significantly.Under the three future climate scenarios,the net primary productivity and total primary productivity of the Tibetan Plateau ecosystem predicted by multiple models all shows an increasing trend,and the increasing trend of total primary productivity is higher than that of net primary productivity with the increase of radiation forcing.On the monthly scale,NPP and GPP show a significant seasonal trend of high in summer and low in winter,and the difference between scenarios is mainly in summer.NPP and GPP increase with the enhancement of radiation forcing in summer.The results show that the carbon use efficiency of the Tibetan Plateau will decrease on the future interannual scale,and the decreasing trend will increase with the increase of radiation forcing;on the monthly scale,it is found that the future carbon use efficiency of the Tibetan Plateau has the characteristics of high in summer and low in winter.Temperature,precipitation and CO₂ concentration have different effects on the carbon use efficiency of the Tibetan Plateau ecosystem.Temperature plays a leading role in the carbon use efficiency relative to precipitation and CO₂ concentration.