Effects of heat island on the flowering dates of Prunus yedoensis: Case study in the wards of Tokyo

Abstract

This study examined the effects of heat island on the flowering dates of Prunus yedoensis in the wards of Tokyo in 2004. The main results were summarized as follows. 1) The distribution of the flowering dates of P. yedoensis corresponded well with the mean temperatures in March 2004. The flowering dates in the central urban area were earlier than those in the suburbs. This clarifies that heat island influences the flowering dates of P. yedoensis. 2) The relationship between flowering dates and monthly mean temperatures in March was confirmed through the flowering process mechanism using an accumulated temperature model. 3) The authors tried to estimate the monthly mean temperatures in March using the flowering dates. The difference between estimated values and actual values of the monthly mean temperatures in March was less than 0. 3°C at most observation points, and the root mean square error was 0. 2°C at all observation points. Therefore the flowering date of Prunus yedoensis is an indicator of local climate such as urban heat island.