[Quantitative Analysis of the Drivers of Spatial and Temporal Evolution of Vegetation Cover in the Beijing-Tianjin-Hebei Ecological Barrier Area].

The Taihangshan-Yanshan Region （TYR） is an important ecological barrier region for Beijing-Tianjin-Hebei. The effectiveness of its ecological protection is of great significance to the ecological security pattern of Northern China. In this study， based on the 22 a long time series of fractional vegetation cover （FVC） data from 2000-2021， we explored the spatial and temporal succession process of vegetation cover in the TYR by using methods such as spatio-temporal heterogeneity analysis and correlation analysis and quantitatively separated the contributions of climate change and human activities to the impact of the FVC. The results showed that： ① The FVC in the TYR showed a slowly fluctuating upward trend，with an average growth rate of 0.022 2 a. FVC is increasing more than stabilising and decreasing， especially in the western Yanshan and the central and western Taihangshan， with a highly significant increasing trend and a spatial distribution of 'high in the north-west and low in the south-east". ② The results of the partial correlation analysis indicated a positive correlation between vegetation cover and precipitation in most areas of the TYR. However， there was a negative correlation with temperature， although it was not statistically significant. The correlation analysis suggested that meteorological factors alone or in combination had limited ability （no more than 14.00%） to influence the evolution of the FVC， so it is likely that other factors were involved. ③ The residual results indicated the significance of anthropogenic factors and supported the compound correlation findings. Climate change and human activities together affected 74.25% and 69.75% of the improved and degraded areas， respectively. The area that had improved due to human activity accounted for 80.80% and was mainly distributed in the north-central TYR. The degraded area was mainly concentrated in the south-central Yanshan and eastern Taihangshan， where the human activity-driven area accounted for as much as 76.78%. The conclusions of the study can provide an important reference for ecological environmental protection and restoration.