Different Urbanization Levels Lead to Divergent Responses of Spring Phenology

Abstract

Urban vegetation phenology is important for understanding the relationship between human activities on urban ecosystems and carbon cycle. The relationship between urban and rural vegetation phenology and environmental and meteorological factors were studied across urban-rural gradients. However, the relationship of intra-urban urbanization intensity (UI) gradients on vegetation at the start of season (SOS) is unclear. Here, we used remote sensing data to quantitatively assess the relationship of vegetation SOS to UI gradients at mid-high latitudes in the northern hemisphere. The results showed that urban area vegetation SOS widely presented earlier than for rural area vegetation. Across the cities we investigated the extent UI gradient was prevalent as a threshold (33.2% ± 2.3%) of surface temperature to SOS advance enhancement and offset. At low urbanization enhanced surface temperature on sos advances, while at high urbanization offset surface temperature on SOS advances. Overall, UI demonstrated a nonlinear relationship with sos. The results of this study suggest that there may be thresholds of impact on vegetation SOS in future global climate and environment change processes, where opposite effects can occur below and above thresholds.