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.

中文翻译：

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东京的城市树木挑战：2013 年至 2022 年东京树冠覆盖率下降


城市树木和绿地对气候调节、减灾和公共卫生的重要贡献已得到广泛认可。树冠覆盖度是评估城市森林范围及其相关效益的最简单指标之一。许多城市的目标是扩大城市冠层范围，以此作为减轻城市化和气候变化影响的手段。这是第一项研究日本东京23个区2013年至2022年9年间树冠覆盖度时空变化的研究。旨在明确城市树木覆盖的主要时空特征。我们使用基于对象的图像分析并结合土地利用数据，从卫星图像中提取树冠覆盖度。地形、历史绿地和社会地理对东京 23 个区的树木覆盖分布产生了不同的影响。树冠覆盖率下降了 1.9%，从 2013 年的 9.2% 下降到 2022 年的 7.3%。公共土地上的树木覆盖率损失达 38.0%，私人土地上的树木覆盖率损失达 57.0%。树木覆盖损失比例最高的是住宅区：独栋住宅（39.8%），其次是道路（14.7%）、教育文化设施（10.8%）和公园（10.4%）。造成树木覆盖损失的主要因素是私人住房开发、城市重建以及公园、街道沿线以及教育和文化设施中树木的砍伐。东京目前面临着与树木覆盖损失相关的重大挑战，将城市林业纳入城市规划框架至关重要。