Abstract:

【Objective】As an indicator of urban ecosystems, plant phenology can visually reflect the changes of ecosystem under the process of urbanization. In this study, we investigated the response pattern of flowering phenology of five common flowering woody species to the heat island effect in Nanjing, and provided data supplement for the response mechanism of vegetation phenology to the heat island effect in East China. 【Method】Based on Landsat 8 remote sensing data to invert the surface temperature of Nanjing, the urban heat island radio index (URI) was used to characterize the heat island intensity, and the combined with the flowering phenology observation data to quantitatively study the effect of urban heat island effect on the flowering phenology of plants.【Result】Nanjing showed a significant urban heat island effect. Heat island intensity ranking: central city > suburban area > remote suburban area. The sensitivity of the same plant to the heat island effect differed at different points. Among the five plants, Yulania denudata was the most affected by the heat island effect, with the flowering period advanced by four to 11 days and the flowering period duration shortened by up to 50%; Cercis gigantea, Malus halliana and Prunus yedoensis were affected to a similar extent and were at a medium level; Loropetalum chinense var. rubrum was the least affected, with the flowering period advanced by about two to four days and the flowering period duration shortened by about 19%. 【Conclusion】The heat island effect has a significant effect on the onset and duration of flowering periods of plants, and as the heat island effect increases, the onset, bloom and last flowering periods of plants tend to be earlier and shorter.

Key words: urban heat island effect, flowering phenology, urban heat island radio (URI) index, Landsat8, surface temperature, Nanjing City