21 JUL 2026 (TUE) 10:35 - 11:05

Investigating the divergent responses of vegetation spring phenology to warming along urban-rural gradients and their underlying mechanisms

Mr. PENG Zijie    

( Supervisor: Prof Yuyu Zhou )

Abstract:

Urbanization has exerted distinct effects on vegetation phenology, the seasonal timing of recurring plant growth events. Understanding the responses of vegetation phenology to urban warming is critical for assessing the ecological consequences of urban climate change and associated public health risks. Although existing studies have characterized the impacts of urban heat island (UHI) on vegetation phenology at the city scale, fine-scale investigations capturing this phenological heterogeneity along the urban-rural gradient are highly limited. Moreover, the biophysical mechanisms underlying these responses remain insufficiently understood, particularly how UHI and background climate jointly regulate the chilling–forcing balance that controls spring phenology. 

To bridge these gaps, this study proposes an integrated framework combining high-resolution observational data and a process-based phenological model to quantify the phenological response to urban warming and the underlying mechanisms. First, fine-scale indicators of urban vegetation phenology are derived from Landsat imagery on the Google Earth Engine (GEE) platform. Second, the response of spring vegetation phenology to urban warming is examined across the urban-rural gradient using 1-km air temperature data to characterize urban warming. Finally, a process-based phenological model is utilized to estimate the changes in chilling and forcing accumulations associated with UHI and disentangle their relative contributions to triggering the spring onset. 

This study is expected to provide important insights into how urbanization reshapes vegetation phenology and the mechanisms driving these changes. It offers quantitative evidence in fine-scale phenological responses across urban-rural gradients. The process-based mechanism analysis highlights the need to better incorporate forcing-chilling interactions into future phenological models to capture the bidirectional responses of spring phenology to temperature. These findings can further support the development of nature-based solutions and sustainable adaptation strategies for urban ecosystems under a changing climate.