I have mentioned before that the magazine The Imperial Family also carries articles about jinja that are not directly connected to the Imperial family. The Summer 2023 issue had such an article, about the forests at Jingū.
As readers of this blog are probably at least vaguely aware, Jingū rebuilds all the main sanctuaries once every twenty years, and moves the kami from the old to the new, in the Sengū. The old sanctuaries are then disassembled, and sent to jinja around the country that need new ones. However, even if the materials are recycled and used for decades somewhere, Jingū still needs enough wood — primarily hinoki — to rebuild everything, every time. In total, they need about 10,000 cubic metres of wood, in about 12,000 tree trunks. The main trees need to be about 60 cm in diameter, while some need to be 100 cm. The latter trees typically need to be about 200 years old.
Originally, this wood was sourced from the mountains around Jingū. However, the Indigenous people failed to manage their sacred forest sustainably, and by the Kamakura period (around the thirteenth century) it was no longer possible to find the necessary trees there. Instead, the wood was sourced from elsewhere in Japan — currently from national forests in the mountains of central Japan.
About a hundred years ago, the people at Jingū realised that this approach was also unsustainable, and that they needed to plant and nurture forests that would sustainably produce the wood necessary for the Sengū. These forests cover 5,512 hectares around Jingū (as compared to 183 for the sacred forests strictly speaking).
This plan was carried out, and, as I have mentioned before, at the last Sengū, in 2013, some wood from the forests around Jingū was used for the first time in seven centuries. The forestry techniques used are non-standard, because the aim is not to maximise profit, but to ensure a sustainable supply of large trees from the forests. As a result, the trees are growing better than predicted — they expect to use more local wood at the next Sengū, and they might be able to supply everything a bit earlier than 2133. However, things are moving into completely unknown territory. Commercial forestry does work on a longer timescale than most industries, but even they only have a one century horizon. No-one knows anything about managing a forest in its second century of life, so the department at Jingū will have to develop its own techniques as they go along.
A substantial part of the article was about a training session for the people who will cut down the trees for the most sacred parts of the sanctuaries. These are cut down using traditional techniques, with axes, that no-one uses commercially any more. Thus, even though the people recruited work in forestry, they are novices at these techniques.
The axes that are used have three or four lines engraved on the heads, and these are wards against ill fortune. Several stories were offered for the meaning: they might represent the offerings made to the kami of the trees, or they might be a pun on “keep danger away from me”. After the tree has been felled, a slit is cut in the top of the stump and a small branch from the tree fixed in it, before all the workers pay their respects. At least during Sengū, the kami of the trees are venerated at all stages of the process.
It seems that the people who served at the last Sengū are almost all going to be too old to do it next time, so they are currently training up their successors. For now, they will still be working far from Jingū, but that will change.