海外「とてもラッキーなウーバーイーツさん」

There is a lot of news that street trees suddenly fall down.
In some cases, natural disasters such as the giant typhoon the other day have exceeded expectations, but in recent years, there have been quite a few cases of aging street trees and root rot.

Many of the street trees in Japan were planted during the period of rapid growth.
There are various types of street trees such as ginkgo, zelkova, and cherry blossoms, but their lifespan is set to be 100 years or hundreds of years, and it is a little too early to say that they will age in about 50 years.

According to research, the biggest factor is the environment.
In the first place, street trees have aspects such as improving the scenery, suppressing temperature rise, and other measures such as car noise and natural disasters such as fires and typhoons, so we are thinking of improving our lives properly.

However, unlike forests and parks, the roadside is a harsh environment for trees.
Street trees are paved with asphalt and concrete, and lifelines such as drains run through the ground, making it impossible to take root freely.

In a normal environment, the moisture and nutrients that are supposed to rain and penetrate the ground spread through the roots, but in the case of street trees, they cannot do so, so they age faster than usual.

Nagoya City Street Tree Regeneration Guidelines (City Information)
Nagoya City Street Tree Regeneration Guidelines (City Information) From the website

The current replanting work creates a gentle environment, such as separating trees from trees to make space around street trees easier to root, but 50 years ago, when many street trees were planted, the growing environment of trees may not have been so conscious.

Also, it’s easy to touch people’s hands because it’s on the side of the road.
Pedestrians may step on the roots without realizing it and damage street trees.
Then, from where the wound came from There is a problem that bad bacteria get in and rot the roots and trunks of street trees.

In particular, it is a kind of mushroom, the baeko mushroom, that is often parasitic on street trees.
It is said that it is not parasitic on healthy young trees, but is especially parasitic on withered and weak trees, and “street trees that are damaged by lack of nutrients” are my favorite food.

white-spotted woodpecker
Yokohama City Highway Bureau Facilities Division Consignment of street tree maintenance work data (about bekko mushrooms) From the website

If you are parasitic on this bekko mushroom, the inside of the trunk will rot, but the trouble is that it doesn’t change much in appearance.

If there is a bekko mushroom at the root of a street tree, it is a parasitic landmark, but it is hard to tell from the ground because it is buried in the ground, and even if it looks green, there is a street tree called Scuska in the trunk, so there is a risk of falling trees.
It means that there are no mushrooms, so it’s not safe.

Local governments are taking measures to deal with street trees in this situation.
Among them, the Tokyo Metropolitan Government is the first local government to adopt “street tree diagnosis.”
About 20 years ago, a roadside tree collapsed and began investigating major roads in Tokyo.
At that time, few people were called “tree doctors” and it took time to confirm, but later, local governments prepared a “street tree diagnostic manual” to diagnose street trees based on it.

Nagoya City has also introduced a “Guidelines for the Regeneration of Street Trees” to replace street trees that have been planted for more than 40 years with trees that are one size smaller and more resistant to disease than conventional trees.

In addition, more and more local governments are introducing a street tree supporter system, which is led by local governments to protect street trees with the hands of residents.
It is a beautification activity such as cleaning fallen leaves and weeding by volunteers, and an activity to protect the greenery of the town with the hands of residents to inspect street trees.

However, the task of diagnosing all street trees in the area, removing them if necessary, and replanting them into new trees is decades-long, and maintenance costs billions.

In the first place, street trees are under the jurisdiction of local governments, and each local government responds differently.
There are some places that make diagnostic manuals or ask tree doctors to check them, and there are cases where they rely only on visual inspection, or they rarely respond.

The Ministry of Land, Infrastructure, Transport and Tourism is also conducting a survey on fallen trees of street trees and local governments’ responses, but many of them are already aging, so they are now left to local governments.
Fifty years after the high-growth period, what we can do may be a familiar approach that does not hinder the growth of street trees and does not damage street trees.