Post-WWII reforestation with monoculture sugi and hinoki plantations now causes $1.6B/day economic damage from hay fever each spring.
Key Takeaways
1950s government planted fast-growing Japanese cedar (sugi) and cypress (hinoki) across stripped mountains; both produce heavy, city-drifting pollen at maturity (30+ years).
Economic impact peaks at $1.6B per day from sick days and reduced consumer spending during pollen season.
Japan declared allergies a national social problem in 2023 and targets 50% pollen reduction in 30 years, starting with 20% reduction in sugi plantation area.
Kobe’s 180-hectare pilot selectively clears sugi/hinoki and lets broadleaf species regenerate; biodiversity indicators (badgers, turtles, rare insects) already improving at the halfway mark.
A new 1,000 yen/year national tax (2024) funds replanting, but only 30-40% of newly harvested land is being replanted per 2023 Forest Declaration Assessment data.
