Spatiotemporal variation of vegetation coverage and the response to typhoon disturbance in National Park of Hainan Tropical Rainforest.

The fractional vegetation cover (FVC) is a key indicator for characterizing ecosystem changes. Combined multi-source remote sensing data from 1995 to 2024, with Theil-Sen-Median trend analysis, geographic detector and XGBoost methods, we systematically investigated the spatiotemporal variations of FVC, driving factors, and the impact of typhoon disturbances. The results showed that the average FVC reached 0.92, with an average annual growth rate of 0.4% from 1995 to 2024. The year of 2007 was identified as a significant turning point in FVC, with the average area proportion of high vegetation cover throughout the study period being 75.0%. The spatially change trend was predominantly characterized by significant improvement, accounting for 75.3%, mainly concentrated in the high-altitude core zones. The explanatory power of single climate and terrain factors on FVC changes was relatively weak, while the interactions among factors exhibited a notable nonlinear enhancement effect, particularly the interactions between altitude and slope, altitude and aspect, and temperature and aspect. XGBoost analysis indicated that the distance to the strongest monitoring point of Typhoon No. 0518 "Damrey" (DNEAR_1), the distance to the weakest monitoring point (DNEAR_3), and the digital elevation model (DEM) were main influencing factors for the decline in FVC, while the distance to the moderately strong monitoring point, aspect, and slope was relatively weak. As DNEAR_1 got closer, the decline in FVC became more significant, and the impact weakened after exceeding 140 km. DNEAR_3 and DEM were positively correlated with FVC. The impact of DEM exhibits a "V-shaped" pattern, with lower elevations below 500 m experiencing greater effects, the weakest influence between 500-900 m, and severe vegetation damage in areas above 1000 m. Our results could provide support for the formulation of ecological protection strategies.