[Spatiotemporal Evolution of Carbon Sources/Sinks and Analysis of Multi-factor Driving Mechanisms in the Weihe River...

Net ecosystem productivity (NEP) is an important indicator for measuring the carbon source/sink function of an ecosystem. As an important ecological corridor connecting northwest and central-eastern China, the study of the variation characteristics and driving factors of NEP in the Weihe River Basin is of great significance for the ecological restoration of the basin and the realization of carbon neutrality goals. The improved CASA model and soil respiration empirical model were used to estimate the NEP of the Weihe River Basin from 2003 to 2023 in combination with MODIS remote sensing data and meteorological data. Trend analysis and optimal parameter-based geographical detector were used to explore its spatiotemporal variation and driving mechanism. The results showed that: ① The annual average NEP (in terms of C, same as below) in the Weihe River Basin from 2003 to 2023 ranged from 154.69 to 239.59 g·(m²·a)^-1, showing an overall fluctuating upward trend, with an average annual change rate of approximately 3.36 g·(m²·a)^-1. The area with increased NEP accounted for 36.14% of the total area of the basin, and the area with decreased NEP accounted for 13.78% of the total area of the basin. ② The carbon sink area in the Weihe River Basin expanded year by year, and the carbon source area decreased accordingly. The high carbon sink area and the medium carbon sink area were mainly distributed in the areas with high vegetation coverage in the southern and central parts of the basin, and the high carbon source area and the low carbon source area were mainly distributed in the Loess Plateau in the north of the basin and the Guanzhong Plain in the central and southern parts of the basin. ③ The optimal spatial scale for the analysis of driving mechanisms was a 3.5 km grid. Vegetation coverage and land use type were the core influencing factors of NEP changes in the Weihe River Basin. Annual precipitation, solar radiation, and carbon dioxide concentration were secondary influencing factors of NEP in the Weihe River Basin. ④ The interaction between different driving factors was higher than the impact of a single factor on NEP. Among them, the interaction between vegetation coverage and land use type had the strongest explanatory power for NEP changes. Enhancing vegetation cover and optimizing land use structure were key strategies for strengthening the carbon sink function of the Weihe River Basin and achieving regional carbon neutrality goals.