(Released on September 9, 2024) We revised the plan taking into account facility plan adaptations and findings of tree research per request received from the Tokyo Metropolitan Government in September 2023. The revised plan calls for more greenery with fewer trees to be removed.
The plan had previously called for an increase of 94 trees over 3.0 meters in height from 1,904 trees to 1,998 trees. Meanwhile, the latest revision calls for 2,304 trees upon completion for an increase of 400 trees.
01Fewer trees to be removed
We plan to remove 619 trees, which is 124 trees fewer than the 743 trees for removal prior to revision, due to the following reasons.
Breakdown of the 124 trees that have been excluded from the scope of removal due to plan revisions
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| Totals | Breakdown | ||||
|---|---|---|---|---|---|
| New rugby facility | Area in front of the picture gallery | Others | |||
| Reclassified from removal to preservation (facility design adaptations) | 66 | 9 | 57 | 0 | |
| Reclassified from removal to transplantation (recovery in tree vitality, etc.) | 16 | 12 | 4 | 0 | |
| Reduction in number of trees to be removed due to plan revisions | 82 | 21 | 61 | 0 | |
| Reduction in number of dead or ailing trees planned for removal | 42 | 6 | 18 | 18 | |
| Total reduction in number of trees to be removed in the project | 124 | 27 | 79 | 18 | |
Area distribution of the 124 trees that have been excluded from the scope of removal due to plan revisions
*1 Specific details on the location of transplanted and newly planted trees are yet to be determined and may be subject to change.
01New rugby facility design adaptations
The number of trees to be removed in the new rugby facility site will decrease by 27 (including 6 dead or ailing trees)
*1 Existing trees shown in the figure for the original plan are based on data from the individual tree research conducted from 2018 to 2019 (hereinafter, “the 2019 tree research”), while existing trees shown in the figure for the revised plan are based on data from the 2023 tree research; tree canopy (shown by size of circle) may differ between the figures due to tree growth, etc.
*2 Preserved trees shown in the figure for the revised plan include trees that have been reclassified from transplant to preservation due to the facility design adaptions.
*3 Only trees 3.0 meters or taller are shown.
*4 Specific details on the location of transplanted and newly planted trees are yet to be determined and may be subject to change.
02Adaptations to plans for area in front of the picture gallery
The number of trees to be removed from the area in front of the picture gallery will decrease by 79 trees (including 18 dead or ailing trees).
*1 Existing trees shown in the figure for the original plan are based on data from the 2019 tree research, while existing trees shown in the figure for the revised plan are based on data from the 2023 tree research; tree canopy (shown by size of circle) may differ between the figures due to tree growth, etc.
*2 Preserved trees shown in the figure for the revised plan include trees that have been reclassified from transplant to preservation due to the facility design adaptions.
*3 Only trees 3.0 meters or taller are shown.
*4 Specific details on the location of transplanted and newly planted trees are yet to be determined and may be subject to change.
POINTDead or ailing treesThe term “dead or ailing trees” refers to withered or decaying trees that need to be removed for safety management reasons.
POINTReasons for tree removal
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| Reasons for removal | No. of trees |
|---|---|
| (i) Priority control invasive alien species | 28 |
| (ii) Close proximity to existing facilities | 270 |
| (iii) Weak tree vitality | 164 |
| (iv) Soil contamination | 2 |
| (v) Other* | 10 |
| Total | 474 |
Reasons for removal of trees in the Scenic District
* The 2023 tree research determined that these trees can be transplanted due to a recovery in vitality or the progress of the project, but they are outside the scope of the redesigned new rugby facility site and the area in front of the picture gallery, so they remain classified as trees to be removed, in line with the original plan based on the 2019 tree research. As the facility designs progress, the classification of these trees will be updated to reflect the latest research results.
Examples of trees unsuitable for transplantation
* Priority control invasive alien species: Species such as the Glossy Privet (ligustrum lucidum), which is designated as a “priority control invasive alien species” in the “List of Invasive Alien Species That May Cause Damage to the Ecosystem in Japan (List of Invasive Alien Species for the Prevention of Ecosystem Damage)” prepared by the Ministry of the Environment and the Ministry of Agriculture, Forestry and Fisheries in 2015.
02More newly planted trees
To create a more abundant green environment, the number of newly planted trees has been increased by 261 trees, from 837 trees to 1,098 trees.
01New rugby facility
On the east side of the site, new trees will be planted in counterpoint to the existing trees in the plaza in front of the picture gallery, giving further consideration to continuity along the green walkway that runs north-south.In addition, plans for the south side of the site call for enhancing integration with the Central Plaza and new woodland areas in creating space for resting and walking as well as distinctive space that strikes a balance among elements such as large volumes of medium-height shrubbery and light thickets of trees.
As a result, the number of newly planted trees has been increased by 131 trees from 81 trees under the original plan to 212 trees.
02Area in front of the picture gallery
The revised plan calls for maintaining the essence of the plaza as it was when initially built. This will involve positioning newly planted trees enlisting an approach that entails planting trees of various species and heights. Moreover, the number of newly planted trees has been increased by 130 trees from 398 trees under the original plan to 528 trees.
Please scroll horizontally to view.
| Totals | Breakdown | |||
|---|---|---|---|---|
| New rugby facility | Area in front of the picture gallery | Others | ||
| Original plan | 837 | 81 | 398 | 358 |
| Revised plan | 1,098 | 212 | 528 | 358 |
| Increase | +261 | +131 | +130 | 0 |
Revisions to the number of newly planted trees
As a result of the above revisions, the number of trees has been changed from the original plan as follows.
Please also refer to the explanatory video detailing a breakdown of these changes.
https://www.youtube.com/embed/p8gKGMprdLE?si=H98g6KQoxBV5jlY3&start=102
*1 The number of trees described on this page only covers trees 3.0 meters or taller.
*2 Transplanted trees include 19 trees under consideration for transplantation.
01Findings of ginkgo tree root study
POINT
In the environmental impact assessment report the criteria for making judgements on the trees has been set as follows. “If root system research results in fewer than four large roots (diameter of at least 30 millimeters) in the surveyed section (1.0 meter x 1.0 meter), the roots may be cut, and if the research finds four or more roots, girdling shall be carried out on the roots. In cases where a tree doctor has judged that there are multiple roots that have an influence on the growth of a tree, then efforts will be made to preserve said tree, including adjustments to facility design, based on the opinion of the tree doctor.”
02Extended setback width for the new baseball stadium and additional root preservation measures
Original Plan
After change
* For specific details on root research findings and additional root preservation measures, please refer to First Root System Research Work – North-South on West Side of Gingko Trees (in Japanese), Report on Ginkgo Tree Vitality Research – Annual Survey (in Japanese), and Second Root System Research Work – North-South on West Side of Gingko Trees (in Japanese).
* For specific details on the second opinion of a third party, please refer to Second Opinion on the Survey of the Westernmost Row of the Four Rows of Ginkgo Trees and Preservation Measures Related to the Jingu Gaien District Type-1 Urban Redevelopment Project (in Japanese).
* For specific details on the second opinion of a third party, please refer to 2. (4) Input from tree doctors and other experts of Further Measures to Preserve Trees and New Measures to Create Greenery in the Jingu Gaien District Urban Redevelopment Project (Supplementary Materials).
Construction work is carried out carefully to avoid damaging the ginkgo tree roots.
01Clearing of hedera and undergrowth
Over the upper layer of the ginkgo tree root system, there is an extremely vigorous growth of hedera. We thoroughly removed this layer of undergrowth, while taking care not to damage any roots, in order to remove the stress on the trees that comes from having to compete for water.
02Using water injection to improve soil
Soil survey results have indicated that some of the soil around the trees is in a compacted state. To mitigate this and realize an environment that makes it easier for the ginkgo tree roots to grow, we used water injection to soften the hardened areas, which improved soil quality while avoiding damage to the roots as much as possible.
03Laying rice straw mulch
We laid a layer of rice straw mulch on the ground to prevent the soil from drying out, particularly in summer, and to keep it warm in fall and winter.
04Installing an irrigation system
We have installed an irrigation system that can provide regular watering automatically in order to ensure the ginkgo tree root system has sufficient water.
05Removing the roadbed of a former road
The roadbed of a former road, which was laid before the current tennis courts were constructed, divides and obstructs the growth of the root system. Therefore, we carefully removed it in a way that does not damage the ginkgo roots and replaced it with good quality soil.
06Installing wood decking in the shops lining the road passing through the ginkgo tree rows
We removed the interlocking blocks used as flooring for the shop terraces and then carried out water injection to improve soil quality and realize a better environment for the ginkgo tree root system. To prevent it from drying out, we laid rice straw mulch and installed an irrigation system. Above this, we installed raised wooden decking as a way of avoiding stress on the root system from pedestrian foot pressure.
01Measuring trunk circumference
In April 2024, we installed dendrometers on eight of the ginkgo trees. Dendrometers are devices for measuring trunk circumference and as the condition of the tree is most noticeable in the trunk, dendrometers can be used to monitor the growth of the ginkgo trees and check if the remedial measures are having an effect. Installing dendrometers has no negative effects on the trees.
02Measuring soil moisture content
We are regularly measuring the moisture content of soil near the westernmost row of ginkgo trees. Through these measurements, we can monitor whether the soil is too wet, appropriately moist, or too dry, as well as whether the timing between watering and the amount of water being used is correct.
Preserving the Four Rows of Ginkgo Trees and the iconic view of the Gallery seen in from the trees for the benefits of future generations.
With new rows of trees to be planted in line at the symbolic 2.5-ha square in front of the Gallery, a new plaza will be developed.
Developing a central plaza between the baseball stadium-- which is annexed with a hotel—and the rugby stadium, thus contributing to an increase in open spaces.
Transplanting existing trees and planting new trees in the neighboring area will create a new woodland that will pair with the wooded area surrounding the iconic hackberry tree, “Gokambei Enoki.”
Developing a path that is rich with green and will run through the district north to south (to be completed in 2028 or later), thus helping people move around with relative ease in the district.
Our efforts to encourage involvement in creating and enjoying the new greenery of Jingu Gaien District include plans to hold events enlisting community involvement as well as implementation of the Reiwa Tree Donation Program, which involves collecting donations from the public for the development of new green spaces.
Click here for more details
About the event
About the Reiwa Tree Donation Program
Refer to the Documents List page of the website for further information and data.