Tree Health Survey and Outdoor Area Development at Mita Campus

August 8, 2017

There are many trees on the Mita Campus grounds. With the reconstruction of the South School Building, a large-scale transplantation of commemorative trees around the old building was carried out in the spring of 2009. However, starting two years prior, the Office of Facilities and Property Management had been conducting detailed surveys of the condition of the campus trees, creating a comprehensive maintenance and management plan, and carrying out parallel development of the campus grounds. Here, we introduce this little-known project.

In 2007, there were just over 160 trees on the Mita campus grounds with trunks of 50 cm or more in circumference, of which approximately 30 were designated as protected trees by Minato City. Typically, landscaping contractors would perform gradual maintenance while conducting a "vitality diagnosis" based on visual inspection of leaves, branches, bark, and tree vigor. This was expanded to a survey of a total of 85 trees in high-traffic areas and protected trees. For the 40 trees that showed issues, a second step was taken: a "toppling risk diagnosis," which involved a detailed visual inspection of the trunk and rootstock condition. Furthermore, for 13 of these trees, a third step was implemented: a precision diagnosis using equipment (drilling resistance measurement devices and acoustic wave measurement devices). The results of these surveys were then compiled, the condition of the trees was classified into five levels, and a maintenance plan was formulated.

The trees with the most health issues were the cherry trees (sakura) located in Fukuzawa Park on the eastern side of the campus and along the border with the adjacent property. Somei-yoshino cherry trees are so-called clones from a limited number of original trees, which makes them susceptible to specific diseases and vulnerable to environmental changes. Their lifespan is said to be around 70 years, and those planted after the war were approaching that age.

Furthermore, in the South School Building reconstruction project, securing places for students to spend their time was identified as an important theme. Consequently, the design for the new South School Building incorporated many spaces such as lounges, group study rooms, and student cafeterias. It was also decided to secure space in other locations on campus. While the co-op cafeteria was opened after business hours and more tables and benches were added to the courtyard, it was also decided to create recreational spaces for students in underutilized outdoor areas. For this, advice was received from the Fukuzawa Ikurin Tomo no Kai (Friends of Fukuzawa Forestry). The plan was to preserve many deciduous broad-leaved trees and place tables and benches beneath them, allowing nature to create a comfortable outdoor space where branches and leaves act as a natural roof to block direct sunlight in the summer, and where warm sunlight can pour in during the winter after the leaves have fallen.

Based on this policy, the first area to be developed was around the ginkgo trees to the west of the Research Building, which was paved with water-permeable tiles, and where benches and a beverage vending machine were installed. The next was the area of the former Fukuzawa residence site, where cherry and other miscellaneous trees with a high risk of toppling were cut down to let in more light, and the bare ground was covered with water-permeable tiles.

Through these efforts, Fukuzawa Park, which had been dark and damp and rarely approached by students, was transformed into a comfortable recreational space.

(The Editors)