Effects of Urban Warming on Plant Phenology

The Prunus yedoensis Flowering Date in Kumagaya City

Abstract

Recent changes in plant phenology such as budding, flowering, and change in color and falling of leaves are related to global warming and heat islands developing in city areas. Some studies have evaluated how secular urban climates influence the flowering dates of cherry blossoms (Prunus yedoensis). However, few studies have observed both the spatial urban climate and the flowering dates of P. yedoensis at the same time in a city. In this study, the authors researched the relationship between the spatial urban climate and the flowering dates of P. yedoensis in Kumagaya City, Saitama Prefecture, Japan. It was clear that the flowering dates of P. yedoensis corresponded to urban temperatures. It is concluded that heat island effects influence the flowering dates of P. yedoensis, and therefore those flowering dates are possible indicators of climatic change and urban warming. Moreover, it is possible to evaluate the effects of urban warming by applying the spatial variation in Kumagaya City to the year-to-year variation in flowering dates of P. yedoensis at the Kumagaya Meteorological Observatory.
The authors analyzed the urban climate in Kumagaya City, including a comparison with urban climate data from 1956. The horizontal and temporal changes of heat islands were closely related to degree of urbanization in the urban area and the physical nature of surface coverage (values of 1/cρ√κ)