Demystifying spatiotemporal NDVI change in county-scale for vegetation cover evolution analysis and geographical-ecological-economic driving factors quantification in Shandong Province, China

County-level units play a pivotal role in harmonising economic activities with ecological and environmental conservation efforts. Analysing the NDVI at the county level yields precise data for guiding regional environmental conservation initiatives and fostering sustainable development. In this study, an integrated spatiotemporal NDVI change assessment model was proposed for vegetation cover evolution analysis and driving factor quantification under a county-level perspective combined with the Sen and Mann-Kendall test, OPGD, and MGWR. This model was applied to a case study in Shandong Province, China, covering 137 counties from 2000 to 2020. The results reveal a general decline in vegetation NDVI between 2000 to 2020, with only 13% of the whole area in central and northern regions showing an increasing trend. The key elements driving the shift in NDVI were evaporation, land use/cover, and net primary productivity. The vegetation became increasingly reliant on both human activities and natural influences. These findings improve our understanding of the connection between the environment and vegetation in the study area and constitute a crucial guide for managing regional ecosystems.