Abstract: As a crucial component of the Belt and Road initiative, the tropical and subtropical coastal zones of Eurasia are subject to the dual pressures of complex climate change and intense human activities. Investigating the evolution of their forest ecosystems and their responses to driving factors under this background is of great significance. Based on kNDVI (kernel Normalized Difference Vegetation Index) data from 2000 to 2020, this study employed Theil-Sen Median trend analysis, Mann-Kendall test, and partial correlation analysis to analyze the spatial distribution and spatiotemporal changes of vegetation in the coastal forest regions of tropical and subtropical Eurasia. It further explored the response mechanisms to climatic and human activity factors. The results indicate that:(1)The distribution of kNDVI in the tropical and subtropical forest regions of Eurasia generally shows a decreasing trend from low to high latitudes. Coastal forests in the tropical zone exhibit kNDVI values close to 0.6, while those in the subtropical zone have values around 0.4.(2)With the exception of some areas showing a decreasing trend in kNDVI along the Southeast Asian coast, coastal forests in other regions displayed an increasing trend.(3)Regarding influencing factors: Solar radiation showed a decreasing trend in coastal forests of East Asia, Southeast Asian islands, South Asia, and West Asia; Temperature exhibited an increasing trend across all coastal forest regions; Precipitation displayed a decreasing trend in coastal forests along China's coast, the western regions of Southeast Asian countries bordering the mainland, and the eastern Atlantic coast of Southern Europe, while showing an increasing trend elsewhere; The overall population density in the study area exhibited a decreasing trend.(4)Solar radiation and population density primarily showed partial negative correlations with coastal forest changes (represented by kNDVI trends). Rising temperatures were generally conducive to the improvement of coastal forests. The relationship with precipitation transitioned from predominantly partial negative correlations at lower latitudes to predominantly partial positive correlations at higher latitudes. Population density mainly exhibited partial negative correlations with coastal forest changes.

Key words: kNDVI, climate change, population density, coastal forests, spatiotemporal changes