Radiation from nuclear disasters continues to threaten traditional ways of life in northeastern Japan

Tetsuzo Tsuboi, who has worked to prevent shiitake growing strains from absorbing radioactive cesium by placing them on blocks, covering them with fleece, and other measures, is seen in the Miyakoji district of Tamura, Fukushima Prefecture on September 5, 2021 (Mainichi / Rikka Teramachi)

FUKUSHIMA – When the Fukushima Daiichi nuclear power plant was hit by a triple meltdown in March 2011, it spat radioactive material over much of the forests in northeastern Japan. Even now, more than a decade after the disaster, the effects of the cesium still present in the trees in the region are enormous.

One area hardest hit by the fallout’s effects is the Abukuma Mountains in eastern Fukushima Prefecture, which were once one of Japan’s premier sources for growing shiitake mushrooms and have now practically stalled. Ten years after this ongoing disaster, locals and experts have worked hard to find ways to revitalize traditional industries in hopes of passing on to the next generation the mountains’ rich natural resources and the life associated with these landscapes.

“Once a log gets that thick, it’s not really good as a log.” We are located in the forest in the Miyakoji District of Tamura, Fukushima Prefecture, about 20 kilometers west of the Fukushima Daiichi Plant. Kazuo Watanabe, the 59-year-old head of the Miyakoji office of the Fukushima Central Forestry Union, stands with a sigh by a grove of Konara oaks for shiitake cultivation.

Watanabe says the oaks for the shiitake business are harvested when they are about six inches in diameter. And it takes about 20 years to get that big. If the stems are too thick, it will be difficult for new growth to sprout from the stump. But logging in Konara stagnated severely due to the nuclear disaster, which led to a halt in deliveries.

In tree trunks from Miyakoji and other parts of the Abukuma region, radioactive cesium has been detected that exceeds the maximum of 50 becquerels per kilogram set by the government. Even 10 years after the core meltdown of the Fukushima Daiichi reactor, tests have shown a cesium content in the logs between 100 and 540 Becquerel per kilogram.

To grow shiitake, mushroom mycelia are inserted into holes drilled in sawtooth oak, konara oak, and other tree trunks. In 2010, Fukushima Prefecture was Japan’s third largest producer of these logs and supplied around 4.78 million pieces. But the nuclear disaster changed that, and even now the prefecture only produces about 140,000 of the cultivated strains annually.

According to the forest authority, shipments of shiitake logs to 93 communities in Fukushima, Iwate, Miyagi, Ibaraki, Tochigi and Chiba prefectures were restricted due to cesium contamination at the end of 2020. Along with Fukushima Prefecture, Miyagi Prefecture and other jurisdictions also voluntarily restrict shipping of the tribes.

Cesium-134 has a radioactive half-life of about two years, which means that it has almost disappeared in the past 10 years. However, the half-life of cesium-137 is around 30 years, which means that after 50 years it will retain 30% of its original radioactivity in disaster and 10% after a century.

The problem is the cesium in the trees, which, shortly after the meltdown, absorbed the disaster through their bark and roots. When plants are low on potassium, an essential element for growth, they ingest cesium, which has similar chemical properties. This has resulted in farmers spraying their fields with potassium fertilizer as a countermeasure. However, this is difficult in the vastness of the forest.

About 70% of Fukushima Prefecture is covered with forest. In principle, however, only certain areas come into question for the decontamination of nuclear disasters, such as residential areas and their immediate surroundings. The government and researchers believe that decontamination has limited its effectiveness in reducing external exposure to local residents, is very costly, and there is a risk of soil spilling from scraping the topsoil. And while cesium-137 does indeed become less radioactive over time, it will take 150 years for the emanations to drop to a few percent of their current level.

And so the stem production of shiitake cultivation is essentially frozen, as is the local traditions of distributing wild edible plants, mushrooms and the like. In order to preserve these natural resources and this way of life for future generations, local forest workers and experts founded the “Abukumayama no kurashi kenkyujo”, or the Abukuma Mountain Way of Life Research Center, in January 2020. Its purpose: to create a vision for the Abukuma region for the next 150 years. The participants study forest culture at former industrial sites associated with mushroom cultivation. Research center director Kazunori Aoki, 60, told Mainichi Shimbun, “The nuclear accident changed the value of the mountains and our connection with them has become rather fragile.”

Aoki once raised Wagyu cattle and grown vegetables in Miyakoji, but closed his business after the nuclear disaster. As he watched growing farmlands become overgrown, Aoki said he had decided “to change the landscape a little at a time and bring it back to the mountains”. He has been planting 100 to 300 maples and other trees every year since 2012, a project that helped establish the Abukuma Research Center.

In April this year, the center brought together 40 people in and outside Tamura City to plant 90 mountain cherries, Kobushi magnolias, and other trees in Miyakoji. However, some elderly residents of the district fear that there will be no one to take over the community and that there is no hope of a future associated with the mountains.

“We want to work with the local community to consider how the next generation can live with the natural wealth of the mountains,” said Yumeko Arai, 35, the center’s administrative director.

(Japanese original by Rikka Teramachi, Fukushima Bureau, and Shuji Ozaki, Minamisoma Local Bureau)