Work with clients for 20 years to conserve urban biodiversity with the indigenous landscaping concept “Gohon no Ki” (five trees)


OSAKA, Japan, Dec 3 2021 / PRNewswire / – Sekisui House, Ltd. has been pursuing biodiversity conservation since 2001 by creating green networks in urban residential neighborhoods as part of its indigenous landscaping concept “Gohon no ki” (five trees). In collaboration with the University of Ryukyus (* 1), the company analyzed the results of the Gohon no ki project that it implemented with one million customer households (* 2) in the space of 20 years, and designed the first quantitative assessment mechanism for urban biodiversity. He published this qualitative assessment mechanism as a nature-positive methodology to promote biodiversity conservation.

Since the 1970s, relentless urban development has dramatically reduced the amount of habitat available for flora and fauna in cities. Sekisui House started its Gohon no ki project in 2001 as an initiative to conserve biodiversity through environmentally friendly landscaping and greening of its clients’ gardens. Based on the concept of planting five local native trees, three for birds and two for butterflies, the Gohon no ki project proposes to green gardens and local communities with native tree species adapted to the local climate and benevolent for birds, butterflies and local wildlife. . The project is inspired by the landscaping of the gardens on the model of the traditional Japanese “satoyama” (which roughly translates to village forest).

In the 20 years from 2001 to 2020, more than 17 million trees were planted as part of the project. The company has also promoted urban greening through Japan by incorporating the Gohon no ki concept into its green space planning in its condominium and community development initiatives.

  • Quantitative assessment of biodiversity

Sekisui House has been working since 2019 with the Kubota Laboratory, the Faculty of Science, the University of Ryukyus and Think Nature Inc. to quantitatively assess the contribution of this network-like greening to urban biodiversity. Based on the Japan Biodiversity Mapping Project (J-BMP), a website managed and operated by Think Nature Inc., created by Professor Yasuhiro Kubota, the partners analyzed data on the number of trees, species and locations accumulated over the 20 years of the Sekisui House Gohon no ki project to quantitatively assess the project’s effectiveness in conserving and restoring biodiversity.

Results of the quantitative evaluation analysis (1):

Results of the quantitative evaluation analysis (2):

This quantitative assessment revealed the following biodiversity benefits of planting native tree species in accordance with the Gohon no ki project as opposed to planting conventional horticultural and exotic species in gardens in urban areas where biodiversity has greatly increased. decreases (from Japan three large metropolitan regions) (* 3).

  • The number of native tree species in each region – the foundation of regional biodiversity – has increased tenfold.
  • The number of bird species that residential areas can attract has doubled.
  • The number of butterfly species that residential areas can attract has quintupled.
  • Biodiversity in the three metropolitan areas has returned to 30% of the 1977 level for which the first reliable data relating to biodiversity exist.

It is the first mechanism in the world for the quantitative assessment of urban biodiversity and its application to a real case. Digital data disclosure allows biodiversity to be expressed in terms of financial value, thus providing a way to visualize the private sector’s contribution to biodiversity.

  • Positive methodology for nature

In recent years, increased efforts have been made to conserve biodiversity. In June this year, the Taskforce on Nature-related Financial Disclosures (TNFD) was launched, and in October, the 15th Conference of the Parties to the Convention on Biological Diversity (COP15) took place. In Japan, too, a discussion began in earnest on other effective area-based conservation measures (OECMs) to gain private sector support to drive urban greening.

In this societal context, Sekisui House makes its 20-year biodiversity conservation initiative available to the public as a positive methodology for nature. The positive nature methodology of the Gohon no ki Project represents a means of expressing urban biodiversity. Sekisui House makes this methodology available to the general public with the aim of raising awareness and enabling their knowledge and expertise to be used by others to promote greening and contribute to biodiversity conservation.

Nature-positive methodology website:

Based on a joint review of the available data, Sekisui House and its partners fixed the number of tree, bird and butterfly species, the diversity index and the number of trees, birds and individual butterflies in 1977 at 100%, and using 2000, the year before the launch of the Gohon no ki project, as the base year, the simulated change to 2070 in from Japan three largest metropolitan areas (Kanto including Tokyo, Including Kinki Ossaka, and Chukyo including Nagoya) which have suffered the greatest decline in biodiversity. This simulation indicated that the planting of native tree species likely to benefit local fauna (Gohon no ki concept) compared to 2000, the year before the launch of the Gohon no ki project, would allow biodiversity to recover. 37.4% of 1977 levels by 2030 (target year for international biodiversity conservation), 40.9% by 2050 and 41.9% by 2070.

If the Gohon no ki concept of native tree planting was applied to 30% of all newly built properties in Japan in the future, urban biodiversity is expected to reach 84.6% of 1977 levels. Sekisui House believes this indicates that if the private sector works with the general public, the decline in biodiversity can be reversed to achieve the goal of recovery of biodiversity post-2020 which is the theme of COP15, and that his Gohon no ki concept can contribute to this goal.

The company has received comments of approval from the following people. For more details, please refer to the attached document:

  • Sir. Makoto haraguchi, Fellow, MS & AD InterRisk Research Institute and SVP Sustainability Section for TNFD, MS & AD Insurance Group Holdings
  • Mr. Teppei Dohke, Executive Secretary General of the Japanese Committee for the International Union for Conservation of Nature
  • M / s. Mariko Kawaguchi, specially appointed professor, Rikkyo University / Executive Advisor to the CEO, Fuji Oil Holdings Inc.
  • Sir. Yasuhiro Kubota, Professor, Faculty of Science, Ryukyu University / Representative Director, Think Nature Inc.


(* 1) This is a joint research with the Kubota laboratory, Faculty of Science, Ryukyus University.

(* 2) Cumulative number of households built from February 2001 To January 2021 is 1,001,977.

(* 3) Comparison of the continuation of the planting of conventional species of garden trees with the planting of species according to the Gohon no ki concept over the 20 years from 2001 to 2020

SOURCE Sekisui House, Ltd.


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