About Tokyo Tech

Cherry Blossom Viewing

Appreciating the Beauty of Tokyo Tech's Cherry Blossoms

Each year in spring, two beautiful rows of old cherry blossom trees bloom on the Ookayama Campus at Tokyo Institute of Technology (Tokyo Tech).

Cherry Blossoms Viewing

Learn More about Tokyo Tech's Cherry Blossom Trees

What is the history of their planting, and what has to be done to keep them in perfect condition? Below are two articles written by a Tokyo Tech faculty member and a group of alumni, in 2005 and 1999 respectively, describing the history and care involved in maintaining the cherry blossom trees on the Ookayama Campus.

The Soul of Cherry Blossoms and the Hearts of Humans

Tokyo Tech Chronicle, No. 402, published in 2005

Kazuyuki Sasajima
Professor, Department of Mechanical and Environmental Informatics, Graduate School of Information Science and Engineering
Planning Officer, Planning Office

As spring arrives, the cherry blossom trees leave an impression of Tokyo Tech's traditions and warmth on that year's graduates while bringing a sense of the Institute's history and an anticipation of campus life to incoming freshmen. These old trees were planted in rows along all the campus roads, with the rows in front of the Main Building the crowning glory. They have been beloved for many years by students, faculty members and administrative staff, as well as local residents and graduates. Cherry blossoms are said to not require pruning, and these trees have been allowed to grow naturally, with only branches that are damaged by the wind and snow and those that grow dangerously long being removed while maintaining the overall shape of the trees. Disease-carrying insects that could harm the trees are also typically exterminated.

As noted in an article written by alumni1, the history of Tokyo Tech's cherry blossom trees starts with the ones planted in front of the Main Building in 1950, those running along the side of the 70th Anniversary Auditorium to the student cafeteria, and those planted around the West Building 1 in 1953. The remainder of the trees was planted at various later dates. Graduates from each of these times expressed a strong collective will to plant the trees in commemoration of their graduation, despite the fact that the economic situation in those days was not as favorable as it is today. They are still looked up to with respect even today.

The majority of the cherry blossoms planted on the Institute's grounds are of the Yoshino (Somei Yoshino) species. In recent years they have begun showing signs of deteriorating vitality, especially the old ones planted in front of the Main Building, as can be seen in Photograph 1. It is said that the life span of a Yoshino cherry blossom tree is 60 years, and the 16 in front of the Main Building, consisting of two rows of eight, which have been an overwhelming attraction for people over the years, have already reached the age of 55 [today, 64]. They are fast approaching the end of their life spans.

Everyone who has come in contact with these trees, including the graduates who originally donated them, the Tokyo Tech community and others in the wider community, as well as the people charged with taking care of them, shares a common wish: that the trees live for a very long time. Activities and initiatives to protect cherry blossom trees are carried out at different levels throughout the country, and the question as to what initiatives Tokyo Tech should adopt has been raised.

As noted in a recent NHK broadcast2, the traditional method of prolonging the life of a cherry blossom tree is now in the process of being overturned after the evaluation of actual results. A new tradition is gradually taking root. This new method, a type of pruning called heading-back cut, claims that even cherry blossom trees should be boldly pruned to remove old branches so that new shoots can appear and grow into new branches. In other words, cutting back the trees is an appropriate method of maintenance. The famous cherry blossom trees in Hirosaki Park in Aomori prefecture have been pruned in accordance with this method since 1955 to allow healthy branches to grow, and they still charm visitors when they are in full bloom each year. Some of these trees are Yoshino cherry trees that are 123 years old.

The heading-back cut is one of the main types of cuts used in pruning and primarily carried out on fruit trees. Long branches are cut off to prevent the shape of the tree from becoming distorted. It is a pruning method carried out to promote the growth of healthy main branches. As the rows of fruit trees planted in orchards grow larger with age, they are forced to compete with neighboring trees. Furthermore, as a tree grows taller it has trouble conveying nutrients to the top of the tree, which leads to a deterioration in its vitality. A lack of sunlight reaching the innermost part of the tree can also result in outbreaks of disease-carrying insects, which can cause serious damage. With heavy pruning, the large branches are systematically cut back to allow new shoots to grow on newly appearing branches each year, which is a kind of heading-back cut. Heavy pruning maintains the shape of the tree and enables good-quality fruit to sprout from young and vital branches.

Having become aware of the various problems mentioned above that can damage Tokyo Tech's old trees, which are more than 50 years old, we decided to study the vitality of the trees to determine what we should do for them in the future. In other words, one of the options we had was to manage them naturally to maintain their beautiful hemispheric shapes and plant young trees to hand over to the next generation when the old trees die. (In actual fact, Somei Yoshino trees are cloned from the roots of the same species.) The other available option was to do as much as we could for the trees centered using the heavy pruning technique in order to extend their life spans. I wrote this article for the sake of obtaining the understanding of the Tokyo Tech community for our decision to prune the cherry blossom trees, as this will result in a drastically different shape in the future for the cherry blossom trees which is explained below. In other words, the heavy pruning method of tree maintenance includes several large problems that are mentioned below. We wonder how the cherry blossom trees feel about our decision. Is it possible that the soul of a cherry tree interacts with our love and care for it?

The main difference between the two methods is the end shape of the tree resulting from heavy pruning as shown in Table 1. First of all, the shape of the tree changes from a hemisphere to a more flattened shape, the height of the tree drops to half or two-thirds of its original height, and the structure changes into a sort of stepped structure, all of which greatly alters the appearance and impression of the tree. Although a different tree shape may be acceptable as long as its life-span is extended, it must also be understood that implementing first-aid maintenance such as this while keeping a close eye on the state of the tree is not always 100 percent successful. The risks that must be understood when implementing heavy pruning are shown in Table 2.

Table 1: Cut-back and their Effects
Tree Shape
Hemispheric shape > Tabular shape
Tree Height
Reduced to half to two-thirds
Structure
Tree shape > Step-shape, roughly speaking
Tree Vitality
Restoring health by growing new branch shoots
Management
Systematic management required at all times

Photograph 1: Cherry blossom trees in front of the Main Building.

Photograph 1: Cherry blossom trees in front of the Main Building.

Table 2: Risks of Cut-backs
Branch cuttings attached to main branches easily snap off
Not all trees can maintain vitality

Great importance is placed on the state of the cherry blossom trees at Tokyo Tech, so we decided to pursue the policy that we thought would extend the life spans of the trees as long as possible, heavy pruning, even if it resulted in the shapes of the trees being changed. Of the 16 trees mentioned earlier, the vitality of one in particular has deteriorated (Photograph 1), and we wondered if this first-aid maintenance after the tree had shed its leaves in the fall would be adequate to save the tree's life. We hope that the Tokyo Tech community will understand why we decided to implement the policy of pruning laid out here to save these valuable assets we inherited from graduates of decades past. We ask for your continuous support as the trees gradually change their shapes in the future.

1.
Cherry Blossoms on the Ookayama Campus: Tale of Those who Supported the Cherry Blossom Trees. Toshio Hori, et al., Tokyo Tech Alumni Association's Kuramae Journal, No. 936, January 1999, p.41.
2.
NHK: Restoring the Cherry Blossoms in our Heart to Life, The Latent Power of the Neighborhood in Solving Problems, broadcast on May 19, 2005.

Cherry Blossoms on the Ookayama Campus: Tale of Those who Supported the Cherry Blossom Trees

Tokyo Tech Alumni Association's Kuramae Journal, No. 936, January 1999, p.41.

Toshio Hori, Class of 1949, Department of Chemistry, School of Engineering
Eizo Suyama, Class of 1952, Department of Chemical Engineering, School of Engineering
Akitaka Matsui, Class of 1952, Department of Textile Engineering, School of Engineering

Photograph 2: Cherry trees had not yet been planted in the early winter of 1949<br />Photo by Eizo Suyama

Photograph 2: Cherry trees had not yet been planted in the early winter of 1949
Photo by Eizo Suyama

The cherry blossom trees in front of the Main Building of the Tokyo Institute of Technology (Tokyo Tech) on the Ookayama Campus have recently become famous. Sitting beneath the trees when they are in full bloom is like entering a world of mysterious profundity where it is possible to forget that one is in a major metropolis.

Those long-ago graduates would have a hard time believing just how large those cherry blossom trees have grown. For recent graduates, these cherry blossom trees in full bloom represent an important memory of campus life.

This article introduces the Institute's cherry blossom trees to the reader through three photographs [only two, Photographs 3 & 4, in this reprint].

Photograph 3: Recently planted cherry trees Photo by Eizo Suyama

Photograph 3: Recently planted cherry trees
Photo by Eizo Suyama

The photograph at the top of this article [not available in this reprint] presents an image of the cherry trees taken in 1997 by Kenjiro Nakamura (Class of 1950, Department of Chemistry, School of Engineering). The photograph to the immediate left (Photograph 3) was taken in 1950 by Eizo Suyama. In this image it is possible to see the small cherry blossom trees which had been recently planted. We are grateful that Mr. Suyama kept this valuable photograph in such good condition.

The photograph immediately below this paragraph to the right (Photograph 4) was taken around 1965 by Eichi Yasuda (Class of 1965, Department of Chemical Engineering, School of Engineering; Class of 1970, Department of Chemical Engineering, Graduate School of Engineering). These three photographs show the cherry blossom trees over approximately 50 years' time up until the present day and provide evidence of the glorious trees they have grown to be.

So, Who Planted these Cherry Blossom Trees?

Photograph 4: Cherry trees around 1965 Photo by Eichi Yasuda

Photograph 4: Cherry trees around 1965
Photo by Eichi Yasuda

Although there are no remaining documents providing conclusive evidence, the graduates of 1950 were the ones who apparently started the custom of planting cherry blossoms in front of the main building, and the cherry blossoms in front of the student canteen are said to have been planted by the graduates of 1953.

Whatever is said, it must have been extremely difficult for volunteer graduates at that time to gather together donations and make sure that the cherry blossom trees remained in good condition. I am sure that the burden involved has changed over the course of the years, but I imagine that the hard work of the school authorities also required much dedication.

Regardless of who made this happen, it must have been extremely difficult for graduates at that time to gather donations and make sure that the cherry blossom trees remained healthy. I am sure that the burden involved has changed over the course of the years, but I imagine that the Institute's administration als​​o dedicated itself to caring for these trees.

Photograph 5: Cherry tree in full bloom in the spring of 2008 Photo by Center for Public Affairs and Communications, Tokyo Tech

Photograph 5: Cherry tree in full bloom in the spring of 2008
Photo by Center for Public Affairs and Communications, Tokyo Tech

It is thanks to the hard work put in by the people who planted the trees and the people who have taken care of them that we are now able to look back on these cherry blossom trees with affection. Aware of this critical situation, I would like to take this opportunity to extend the deep gratitude of Tokyo Tech's alumni to all of the people involved in the care of the cherry blossom trees.

And now, brother and sister alumni, the season for cherry blossoms will soon be upon us. How about quietly visiting the campus and looking back on your old school days? But don't forget that the present professors and students are involved in some very serious research and studies.