Tokyo’s urban tree challenge: Decline in tree canopy cover in Tokyo from 2013 to 2022

Abstract

The important contributions of urban trees and green spaces to climate moderation, disaster mitigation, and public health have been widely recognized. Tree canopy cover is one of the simplest proxies for assessing the extent of urban forests and their associated benefits. Many cities are targeting increases in the extent of their urban canopies as a means of mitigating the impact of urbanization and climate change. This is the first study to examine the spatiotemporal changes in tree canopy cover over 9 years from 2013 to 2022 in the 23 wards of Tokyo, Japan. It aims to clarify the main spatiotemporal characteristics of urban tree cover. We extracted tree canopy cover from satellite imagery using object-based image analysis incorporating land-use data. Topography, historical green spaces, and social geography have variously influenced the distribution of tree cover among Tokyo’s 23 wards. Tree canopy cover declined by 1.9% from 9.2% in 2013 to 7.3% in 2022. Tree cover loss amounted to 38.0% on public land and 57.0% on private land. The highest percentage of tree cover loss occurred in residential areas: single-family houses (39.8%), followed by roads (14.7%), educational and cultural facilities (10.8%), and parks (10.4%). The main factors responsible for tree cover loss are private housing developments, urban redevelopments, and the removal of trees in parks, along streets, and in educational and cultural facilities. Tokyo is currently facing significant challenges related to tree cover loss and it is crucial to integrate urban forestry into the urban planning framework.