Opinions are divided on the role of street trees. In recent years, promoting greenery has become essential from the perspective of carbon neutrality. Street trees play a part in this. Street trees block the strong summer sun and play a role in preventing heatstroke and mitigating the heat island effect. According to data from the National Institute for Land and Infrastructure Management, the number of street trees nationwide was 3.71 million in 1987. In 2002, the number of street trees increased by 80% to 6.79 million. In the 10 years since 2002, the number has remained stable. However, something troublesome has started to happen. Street trees planted in the 1950s and 1970s during the period of high economic growth have now become aging after more than half a century. These old trees are falling over and causing various problems.
In response to the street tree accident, the Ministry of Land, Infrastructure, Transport and Tourism conducted the first nationwide survey of damage caused by fallen trees and branches targeting municipalities that manage parks and roads. A total of 1,732 cases of human and property damage were reported over the approximately three and a half years from April 2021 to November 2024. Of these, there were a total of 110 cases of human damage, eight of which required more than 30 days to heal, and one death in Hino City. In September 2024, about 10 branches of Icho fell on a promenade in a green space in Hino City. A man (36 at the time) who was crushed by the fall lost his life. Prior to that, someone had died from a fallen tree in Mihara City, Hiroshima Prefecture. In Mihara City, two people were killed and injured in a fallen tree accident in 2014. Therefore, a system was introduced that allows photos and location information to be sent to the city by smartphone. Mihara City has created a system that allows residents to contact the city by smartphone if they find a tree that is about to fall. There have been 19 reports from residents so far, and city officials are quickly heading to the scene to deal with the situation.
There is a term called the financial strength index. This refers to the ratio of a town’s tax revenue to the costs required to provide administrative services. The higher this index, the healthier the local government. In times when the productive labor force was large, cities continued to spread to the suburbs in a disorderly manner. Street trees also spread along with this trend. As can be seen in recent years, this spread has created areas that are vulnerable to disasters. The limitations of urban policies that have always focused on growth have become apparent. Many local governments are drawing up budgets that are constantly increasing, as in the era of high economic growth. However, investing budgets in places that do not produce profits will be a waste if there is no return. The conflict of shrinking local governments seems to be seen in microcosm in the treatment of street trees.
