[Spatiotemporal Patterns and Driving Forces Analysis of Ecological Carbon Sink from 2001 to 2022 in Qinling-Daba...

The Qinling-Daba Mountain area, an essential ecological conservation zone in China, occupies a pivotal position in the pursuit of carbon neutrality. Using diverse data sources, including temperature, precipitation, solar radiation, and the Normalized Difference Vegetation Index, we refined the CASA model by replacing model indicators. This enhanced model simulated the net primary productivity of vegetation in the Qinling-Daba Mountain area from 2001 to 2022. Additionally, we employed a method that subtracts soil respiration （Rh） from the simulated vegetation net primary productivity to calculate the regional net ecosystem productivity （NEP）, thereby characterizing the ecological carbon sink. Employing techniques such as linear regression analysis, MK trend testing, partial correlation analysis, and composite correlation analysis, we examined the spatiotemporal evolution characteristics of NEP over the past 22 years in the Qinling-Daba Mountain area and assessed the degree of influence of various factors. Our findings revealed that： ① Over the past 22 years, the vegetation NEP in the Qinling-Daba Mountain area displayed a fluctuating upward trend, with an average annual increase of 168 g·m^-2·a^-1, resulting in a total increase of 52.2 Tg in regional vegetation NEP （in terms of C） over the 22-year period. ② Spatially, the Qinling-Daba Mountain area predominantly functioned as a carbon sink, with only 0.3% of the area serving as a carbon source, primarily concentrated in a punctate pattern on the eastern side of the Qinling-Daba Mountain area. ③ Changes in the carbon sink in the Qinling-Daba Mountain area were the consequence of the interaction of multiple factors, with 60% of the contribution stemming from climatic factors. The combined weak driving force of temperature, precipitation, and solar radiation accounted for as much as 29%, distributed in a scattered manner across the central and eastern regions of the Qinling-Daba Mountain area.