Response of Vegetation Phenology to Seasonal Land Surface Temperature in the Beijing-Tianjin-Hebei Region Under Urbanization Background

The rapid development of global urbanization has underscored the need to understand how vegetation phenology (VP) responds to land surface temperature (LST) for the sustainable development of regions. Most previous studies have focused on the seasonal spatial distribution or temporal trends of regional VP. However, the specific impact of LST on VP along the urban–rural gradient remains insufficiently explored. This study investigates the response of VP to LST in the Beijing–Tianjin–Hebei (BTH) region from 2004 to 2023, with a particular emphasis on the role of urbanization. The findings reveal that: 1) VP and LST exhibit significant spatial and temporal variations across different urban–rural gradient levels. Since 2014, the duration of the vegetation growing season has notably declined, with an average reduction of 13 days per year over two decades. 2) Elevated temperatures during summer, autumn, and winter may lead to an earlier cessation of the growing season. 3) The urban–rural gradient has a pronounced influence on VP trends. Except in spring, urbanization intensifies the marginal impact of daytime LST on the length of the growing season (LOS), while reducing the marginal impact of nighttime LST. This study provides a comprehensive analysis of how seasonal daytime and nighttime LST variations influence VP, particularly in the context of urbanization. The quantitative assessment improves our understanding of the mechanisms driving changes in the vegetation growing season under urbanization. In addition, it offers scientific insights to optimize ecological and agricultural benefits and promote sustainable regional development.