Japan has begun replacing nearly two million acres of forests to help reduce seasonal allergies.

Planting trees like large forests can be unhealthy! Seems counterintuitive! Wrong trees?

"After World War II, Japan’s government encouraged widespread planting of fast-growing sugi cedar and hinoki cypress trees to supply the country with timber. Unfortunately, the pollen from those trees has since contributed to a national epidemic of hay fever afflicting over 40 percent of the population.

The Japanese government is now accelerating the removal of those forests and replacing them with a variety of local trees, including sugi varieties selectively bred to produce less pollen. The long-term goal is to halve cedar pollen emissions within three decades."

"... In 2023, the Japanese government announced a solution: Fell 750,000 hectares of sugi and hinoki trees in a bid to cut the problem off at the root.

After decades of work, researchers have developed more than 30 strains of low-pollen and no-pollen sugi trees, which will replace some of the trees cut down. ...

The trees were first distributed widely across Japan during the Meiji era, a period of rapid industrialization that ran from 1868 to 1912.

But it was the post-World War II period that accelerated the conversion of natural forests into planted forests dominated by sugi and hinoki. ... explaining that several intersecting shifts in the second half of the 20th century pushed Japan to favor sugi and hinoki trees.

Between 1950 and 1985, Japan’s planted forests grew to account for some 10 million hectares (24.7 million acres) — more than a quarter of the country’s total land area — with much of it converted from natural forests. Deciduous species formerly used for firewood like kunugi (Quercus acutissima) and konara (Quercus serrata) fell out of favor as fossil fuels became widely available. ...

Meanwhile, the construction industry drove demand for timber from sugi and hinoki trees. By the war’s end, aggressive bombing campaigns by the U.S. had left the country in need of some 4.2 million homes, according to a 2021 case study. Japan rebuilt at a staggering pace, spending as much as 40% of the national budget on construction projects. By 2020, the construction industry had built more than 76 million apartments and houses, the study found, with detached single family homes made of wood accounting for the largest share of new housing units. ..."

Doomslayer: Progress Roundup - by Malcolm Cochran

As hay fever sufferers grow in Japan, the country is looking to plant no-pollen trees

A cloud of tree pollen emanates from a sugi tree