Spatiotemporal evolution and driving factors of vegetation NPP in Jialing River Basin

Abstract

[Objective] Vegetation net primary productivity(NPP) is a crucial component in the carbon cycle of terrestrial ecosystems. Investigating its spatiotemporal evolution and driving factors is of great significance for promoting regional ecological civilization development. [Methods] Taking the Jialing River Basin as the study area, the spatiotemporal evolution patterns and driving factors of vegetation NPP were analyzed based on the coefficient of variation, Theil-Median trend method, Mann-Kendall statistical test, R/S analysis, geodetector, and PLS-SEM model. [Results] NPP showed a fluctuating upward trend, with spatial variation increasing and then decreasing with elevation. The overall trend remained stable, with fluctuations characterized by “higher in the south and lower in the north”. Historically, extremely significant increases predominated, while future trends were divided into two types: continuous increase and shift to decrease. Spatial differentiation was mainly dominated by natural factors such as temperature(Temp), normalized difference vegetation index(NDVI), and digital elevation model(DEM), while anthropogenic factors such as GDP also had significant effects. In interaction detection, Temp∩Pre, NDVI∩GDP, and Temp∩NDVI demonstrated the strongest explanatory power. PLS-SEM revealed that topography indirectly promoted NPP the most by inhibiting climate deterioration and promoting vegetation growth. Climate directly inhibited NPP but indirectly exerted a positive regulatory effect through vegetation growth, while indirectly inhibiting NPP through human activities. Human activities had negative effects both directly and indirectly. Based on future risk zoning, vegetation and urban landscapes should be optimized in the Sichuan Basin. A synergistic artificial-natural restoration system should be constructed in the northwest alpine area. Ecological redlines and corridors should be strengthened in mountainous and hilly areas. Ecological compensation and soil and water conservation projects should be coordinated across the entire basin. [Conclusion] Vegetation NPP in the Jialing River Basin is mainly increasing, with spatial differentiation dominated by natural factors. Temp∩Pre, NDVI∩GDP, and Temp∩NDVI have the strongest explanatory power. Topography indirectly promotes NPP by inhibiting climate deterioration and promoting vegetation growth. Climate directly inhibits NPP but indirectly regulates it positively through vegetation growth. Human activities inhibit NPP both directly and indirectly. Future strategies should focus on zoned management.

Keywords

vegetation NPP / spatiotemporal evolution / future trends / geodetector / PLS-SEM / Jialing River Basin / influencing factors