Why Japan's environment does not blossom amid population decline as expected

Since 1970, global wildlife populations have declined by a staggering 73%, while the human population has doubled to 8 billion. Research increasingly links these two trends, suggesting that population growth plays a central role in the planet’s biodiversity crisis. But now, a historic demographic shift is underway: populations in 85 countries — mostly in Europe and Asia — will begin shrinking by 2050. Some predict that this will have to benefit the environment, but recent research findings from Japan paint a more complex picture.

Japan began experiencing population decline in 2010, the first country in Asia to do so. Anticipating that depopulation might encourage ecological recovery — a concept some call a “biodiversity dividend” — Japanese researchers sought to examine whether this was actually happening across the island. Their study, recently published in Nature Sustainability and the focus of an article by The Conversation, reveals that the expected environmental gains have not materialized.

Using data from the "Monitoring Sites 1,000" project — a citizen science initiative by the government that has collected over 1.5 million biodiversity records since 2003 — the researchers analyzed trends in birds, butterflies, fireflies, frogs, and nearly 3,000 plant species across 158 sites in wooded, agricultural, and peri-urban landscapes. They then compared these biodiversity trends with changes in local population, land use, and surface temperature over periods of five to twenty years.

The results are sobering. Despite depopulation, biodiversity continued to decline in most areas. Only regions with stable populations showed relative biodiversity stability — but even those areas are rapidly aging and expected to begin shrinking soon, likely triggering further biodiversity losses.

Unlike Chernobyl, where an abrupt evacuation following the nuclear disaster allowed wildlife to rebound dramatically, Japan’s population decline has been gradual. This has resulted in a patchwork of shifting land uses: some farmland remains active, other plots are abandoned, sold for urban development, or transformed into high-intensity agriculture. This mosaic landscape hinders widespread ecological recovery and limits the natural regrowth of forests or wild habitats.

Crucially, the study underscores how traditional human activity has long played a role in maintaining biodiversity. Practices like rice farming, orchard maintenance, and woodland coppicing create habitats and cycles that support diverse species. As rural communities shrink and age, these traditions are fading, and the ecological systems they supported are breaking down. While some species move in, they are often non-native, bringing new problems — such as invasive grasses that dry out once-wet rice paddies.

Vacant buildings, decaying infrastructure, and legal complications — such as unclear property ownership and high demolition costs — make matters worse. Despite nearly 15% of Japanese homes being abandoned (known as akiya), new construction continues. In 2024 alone, over 790,000 new houses were built, driven by changing household structures and internal migration. With each new home comes more roads, shopping centers, sports facilities, parking lots, and convenience stores — all of which shrink wildlife habitat, even as human numbers decline.

What should be done?

The findings show that biodiversity loss won’t reverse automatically with depopulation. It requires active planning and management. Yet Japan has only a handful of rewilding projects. The researchers argue that local governments should be empowered to transform disused land into community-managed nature conservancies, supporting both biodiversity and rural revitalization.

According to the article, nature depletion is more than an environmental concern — it’s a systemic risk to global economic stability. Ecological collapses, like declining fish stocks or rapid deforestation, demand stronger accountability from both governments and corporations. Rather than investing in new infrastructure for a shrinking population, Japanese companies could focus on restoring natural forests, creating both biodiversity value and carbon credits.

Depopulation is emerging as one of the century’s defining global trends. If managed with foresight and care, researchers argue it could ease pressure on ecosystems, lower resource demands, and support climate goals. Japan’s experience and the study shows, however, that without intervention, fewer people don’t automatically mean more nature.

By Nazrin Sadigova