Effects Of Population Distribution And Land-use Function Changes On Vegetation Carbon Sequestration

Human activity and land use function changes are two important factors affecting regional vegetation sequestration.Jiangxi Province is high forest cover province in our country and one of the ecological civilization demonstration zones.Our study can provide scientific reference for the formulation of regional ecological restoration and sustainable development policies.Based on the multi-source remote sensing data,point of interest,road dataset,and social statistics,the study was established to build a population data set in the four phases of Jiangxi Province in 2005,2010,2015,and 2020to reveal the characteristics of the time and space changes in the population of the province;Based on land use data,social statistics data,point of interest data,Invest model,etc.,the spatial distribution characteristics of the functions of"production-life-ecological"in Jiangxi Province since 2005 were discussed;the data sets of net primary productivity,precipitation and temperature were used to generate the dataset of vegetation carbon sequestration from 2005 to 2020,and the spatiotemporal differentiation characteristics of vegetation carbon sequestration were revealed.Based on the above research,the effects of population spatiotemporal pattern and land use function changes on vegetation carbon sequestration in the study area were discussed.The main conclusions are as follows:（1）The population distribution of Jiangxi Province is"the north is dense,the south is sparse",which is mainly distributed in the Poyang Lake Plain in the north and the Zhejiang-Jiangxi Railway that crosses the region from west to east.During the study period,the total population mainly increased,and the increase rate showed the characteristics of"north-south fast and slow in the middle,slow first and then fast",and the population flow showed a trend of"flowing to dense areas",and there was a trend of"changing from point to sheet"（2）In terms of land use function,the production function showed a trend of"north-south low and the west is slightly high",and gradually enhances,which was manifested as Xinyu and Yichun in western of Jiangxi Province being the highest,and lower in northern Jiujiang and southern Ganzhou.Among them,the production function of Xinyu and Yingtan has increased the most.The living function shows a trend of"bounded by the Zhejiang-Gan line,high in the north and low in the south",and the overall reduction is the mainstay,which is specifically reflected in the provincial capital Nanchang as the highest value of life function,and the lowest in Ji’an and Fuzhou in the south of the Zhejiang-Gan line,among which,the living function of Fuzhou,Ganzhou,Ji’an,Jingdezhen,Jiujiang,Shangrao,Yichun and Yingtan shows a decreasing trend.The ecological function was"high in the northeast"and showed an overall upward trend,except for a small decrease in Ganzhou City,other prefectures and cities showed different degrees of increase,among which Jingdezhen increased the most.（3）The carbon sequestration of vegetation in Jiangxi Province showed a distribution pattern of"high in the south and low in the north,high in the surrounding area,low in the middle",with the high-value areas mainly distributed in the mountainous areas of Gannan and the low-value areas concentrated in the Poyang Lake Plain.During the study period,the carbon sequestration of vegetation fluctuated and increased,and the average annual change rate was 3.54g C m^-2 yr^-1,of which the lowest value was 584.59g C m^-2 yr^-1 in 2010 and the highest value was 654.43g C m^-2 yr^-1in2017.In terms of spatial changes,the proportion of areas with increasing trend of vegetation carbon sequestration was 66.48%,mainly distributed in Jiujiang,eastern Yichun,northern Ganzhou,central Ji’an,central and western Shangrao.（4）The relationship between vegetation carbon sequestration and population distribution in Jiangxi Province was mainly weakly positively located along Zhejiang and northern Jiujiang City,and weakly positively correlated in central and southern area.At the pixel scale,55.67%of the areas with reduced carbon sequestration by vegetation due to population increase were mainly located along the Zhejiang-Jiangxi Line,north-central Jiujiang,and central Ji’an.The increase in carbon sequestration by vegetation accounted for 42.35%of the areas,mainly located in the central and southern parts of Jiangxi Province.Regional statistics show that the areas with strong positive correlation between population change and vegetation carbon sequestration are mainly located in Jingdezhen,Shangrao,Pingxiang,Fuzhou,Ganzhou,etc.,and the areas with strong negative correlation are mainly located in Yichun,Ji’an,Xinyu and other cities in central and western Jiangxi.（5）The amount of carbon sequestration in vegetation in Jiangxi was positively correlated with production function,and it was mainly weakly negatively correlated with living function and ecological function.The area positively correlated with production function accounted for 80.93%,which was located in the whole area of Jiangxi Province,especially in the north of Shangrao and the north of Jingdezhen.On the administrative scale,the most relevant are Fuzhou,Ganzhou and Yingtan.The area negatively correlated with living function accounted for 42.61%,mainly located in the southwest of Fuzhou and the south-central part of Ganzhou.At the regional scale,the city with a negative correlation is Ganzhou,and the correlation coefficient is-0.21.The area with negative correlation with ecological function accounted for 56.24%,mainly located in the central and western regions of Jiangxi.At the regional scale,the cities with negative correlation were Pingxiang,Ganzhou and Xinyu.