Analysis of carbon source/sink capacity and climate driving factors in different ecological regions of Jilin Province

This study is based on an improved CASA model and uses multi-source data from MODIS,meteorology,and land use classification from 2000 to 2022 to estimate the net ecosystem productivity (NEP) of vegetation in different ecological regions of Jilin Province.The spatiotemporal variation characteristics and climate driving factors of NEP are explored.The results indicate that on a monthly scale,the NEP in the study area is positive from March to October,showing a natural carbon sink state,while the remaining months exhibitcarbon source characteristics.On an interannual scale,the average annual NEP is 383.8 gC·m^-2·a^-1,exhibiting a fluctuating upward trend.On a spatial scale,the NEP in the study area shows a gradual decreasing trend from east to west.During the study period,the cumulative carbon sequestration was higherin the eastern coniferous and broad-leaved mixed forest ecological zone than in the central farmland ecological zone and the western grassland ecological zone.The area with improved vegetation NEP accounts for 90.38% of the total area,and the areas with significant improvement are mainly distributed in the western ecological zone.The vegetation NEP in the study area is mainly positively correlated with precipitation and solar radiation,and negatively correlated with temperature.The dominant climate factor affecting NEP in the western ecological zone is precipitation,while that in the central and eastern ecological zones is solar radiation,and NEP in the western ecological zone is more sensitive to changes in precipitation and solar radiation.When precipitation is less than 700 mm,vegetation NEP is more sensitive to precipitation;When the temperature is between 5.7 and 6.9 ℃,the sensitivity of vegetation NEP increases with rising temperature.