Disappearance of Local Charms? Reasons Why Population Decline Affects Biodiversity

1. Introduction—The Illusion of "Nature Returns When People Decrease"

From the end of the Heisei era to the Reiwa era, terms like "marginal villages" and "municipalities at risk of disappearing" in rural areas have been prevalent in the media. At the same time, a positive narrative that "depopulation is a chance for rewilding" has spread. However, the latest international collaborative research pours cold water on these expectations. … (1,038 characters) phys.org

"Population Outflow → Abandoned Farmland → Mosaic Landscape → Biodiversity Decline"

2. Overview of the Research—The Reality Shown by 1.5 Million Big Data

This research analyzes 1,500,000 data collected since 2004 by a total of 5,700 citizen scientists participating in the "Monitoring Site 1000 Satoyama Survey" … (1,128 characters) prtimes.jp

3. The Emerging Pathology of "Mosaicization"

When farmland is abandoned due to population decline, transitions to forests, invasions by alien species, and spot proliferation of urban infrastructure occur simultaneously, causing the landscape to unravel into a patchwork. … (1,234 characters) nies.go.jp

4. Case Studies—"Terraced Rice Fields in Higashikawa Town" and "Yatsuda in Northern Chiba"

In Higashikawa Town, Hokkaido, the aging rate is 46%. As a result of 40% of the fields being left idle, deer frequently appear …
In the Northern Chiba Plateau, the conversion of suburban farmland to residential land continues, and the nesting sites of Little Terns have disappeared. … (1,056 characters)

5. Citizen Science and Data-Driven Conservation

Hashtag #Monitoring Site 1000 was mentioned approximately 42,000 times on X (formerly Twitter) … (856 characters) search.yahoo.co.jp

6. Voices from Social Media—From "Grass Cutting DAO" to "Satoyama Bond"

• Supporters: "Hometown tax + DAO can make Satoyama management costs transparent"

• Skeptics: "Drone grass cutting is not cost-effective" "It will become another alien species business"

• Activists: "Participating in Satoyama conservation only on weekends = a chance to increase 'related population'"
  In the real-time search on X, "Satoyama" and "Biodiversity" ranked within the top 15 trends from June 12 to 13, with the peak number of tweets reaching 18,000.…(732 characters) search.yahoo.co.jp

7. Policy Impact - Nature Positive Strategy and OECM

The Ministry of the Environment's "National Biodiversity Strategy 2023–2030" sets a goal to expand OECM by 1 million hectares by 2030, but … as a solution to the shortage of personnel, the use of special rural districts, satoyama bonds (local government bonds), and corporate hometown tax donations are being discussed. …(1,214 characters)

8. The Cutting Edge of Technology and Finance

Satellite × AI automatic land cover interpretation, real-time eDNA sensors, drone mowing, and blockchain DAO … while technology reduces management costs, it also faces the dilemma of being difficult to quantify the value of cultural landscapes. …(1,097 characters)

9. Conclusion - The Paradox of "Stable Population = Stable Ecosystem"

The greatest implication shown by this study is the fact that regions that are "stable" rather than "decreasing" or "increasing" can maintain biodiversity. …(876 characters)

10. What We Can Do

1. Participate in weekend volunteer activities for mowing and surveys

2. Make small investments in online donations and satoyama bonds

3. Spread local conservation activities on social media

4. Advocate for making satoyama fieldwork mandatory in school education

Resist the simple equation of "population decline = nature recovery" and foster a model of "sustainable coexistence" where people continue to be involved. This is the shortest route to a nature-positive future originating from Japan.

References & Links

• Phys.org “Japan's shrinking rural population linked to ongoing biodiversity losses” (2025/6/12)phys.org

• Japan Nature Conservation Association Press Release “Population decline may also reveal potential biodiversity loss” (2025/6/13)prtimes.jp

• National Institute for Environmental Studies “What is the way to manage Satoyama?” (Kankyo-gi No.82)nies.go.jp

• Yahoo! Real-time Search #Satoyama (2025/6/9–13 Excerpts)search.yahoo.co.jp