Spatial-Temporal Analysis and Multi-Scenario Forecasting of Land Use and Net Primary Productivity in Qingdao

To enhance regional carbon sequestration capacity and achieve carbon neutrality, it is crucial to accurately estimate the net primary productivity (NPP) of vegetation and its response to changes in land use/land cover (LULC). Based on remote sensing data, the study estimated the NPP of Qingdao, a typical coastal city in eastern China, from 1990 to 2020 using the CASA model and examined its spatiotemporal dynamics. The Geographic Detector was used in the study to measure the impact of anthropogenic and natural factors on variations in NPP. Additionally, the Markov–PLUS model was utilized to forecast future LULC patterns and NPP changes for 2030 under three development scenarios: natural development, cropland protection, and ecological protection. The results indicate considerable regional variation and an initial decrease followed by an increase in Qingdao’s NPP. It is distributed in a strip-like pattern from northwest to southeast, with the regions around Jiaozhou Bay showing the lowest levels. The changes in NPP are driven by multiple interacting factors; among these, LULC, DEM, and slope exhibit significant spatiotemporal correlations with NPP, with LULC playing a dominant role in this process. In addition, interaction analysis demonstrated that the synergistic effects between LULC and other factors constituted the principal driving force behind NPP dynamics, and the interactions between the two factors that contribute show bivariate or nonlinear enhancement effects. The ecological protection scenario produces the greatest NPP values among the three scenarios. Optimizing LULC may significantly increase carbon sequestration capability, as evident in the NPP forecast, which is higher than that of 2020 in all scenarios. This study demonstrates that the ability of vegetation to store carbon can be effectively enhanced through land-use optimization informed by remote sensing technologies. The results provide a scientific basis for adjusting LULC policies and conducting carbon-neutral spatial planning in coastal urban areas.