A method for evaluating the temperature-reducing effects of urban green spaces: A case study from central Tokyo

Abstract

Summertime temperature reduction is an important ecosystem service of green spaces in urban ecosystems. However, many urban green spaces are formed by non-native plants, which have the potential to negatively influence local biodiversity. Unfortunately, due to the difficulties of evaluation, there have been few studies comparing differences in the temperature-reducing effects of native- and non-native species. In this study, we attempted to establish a method for comparing differences in temperature-reducing effects between native- and non-native species. Using aerial photographs taken in summer in a heavily urbanized area of Tokyo, we compared radiant temperatures between green spaces comprised of native and non-native trees, and in areas varying in the number of species and various other factors. Although we were not able to obtain sufficient data for statistical analysis in this case study, the results indicated some differences in temperature-reducing effects among different species of plants. Additional case studies performed using our method may allow us to derive other ecosystem services from green spaces formed only by native plants.