Forests for Jingū

The Spring 2025 issue of The Imperial Family (皇室) had a substantial article on the forests from which the wood for the Shikinen Sengū (式年遷宮) at Isë Jingū (伊勢神宮) will be harvested. There will be a lot of articles in this magazine on the process, and they come with colour photographs. (On the other hand, most of the magazine is about, well, the Imperial Family. But if you are in Japan and want to get a subscription, they will be delighted — Jinja Honchō (神社本庁) often talks about the need to get more people buying it.)

There are three forests that will supply a substantial amount of wood for the next Shikinen Sengū. One is the forests around Jingū itself, and that was not the subject of this article. (They have written about it before, and doubtless will do so again.) The program to grow the necessary trees there has only been in progress for 110 years or so, so it is not yet ready to provide the most important timber. That comes from two national forests in the mountains of central Japan.

The first is Kisodani National Forest (木曽谷国有林) in Nagano Prefecture. This forest has been protected for centuries. According to the article, in the Edo period it was controlled by the Owari Domain, and the rule was “one tree, one head” — that is, if one tree were cut down without permission, one person would be executed. It is still protected today — the journalist needed special permission and a guide — but I believe the penalties are a little less draconian.

The article mentions that some of the trees in the forest seem to start in mid-air, with their roots reaching to the ground around an empty space. These trees started life from a seed that fell onto the top of the stump of a felled tree. The old wood provides good nutrition, so you get several saplings growing there, of which one survives to grow into a large tree. As it does so, the original stump decays away, leaving a space in the midst of the roots. This can easily reach a metre or so off the ground.

Another interesting feature of this forest is that the stumps of the trees felled in 1985 at the beginning of preparations for the 61^st Shikinen Sengū (which happened in 1993) are preserved under a wooden shelter, with shimenawa (注連縄) around them. This seems very much the sort of thing that Shinto would do, except that the stumps from the 2005 ceremonies are just sitting in the forest, in a rather less accessible area — although the journalist does visit them. There is doubtless a story behind the different treatment, but the article does not go into it.

The second forest is Urakiso National Forest (裏木曽国有林) in Gifu Prefecture. This forest apparently gets relatively little sunlight, which means that the trees grow slowly. The upside of this is that the wood is fine-grained, and high quality, and this is presumably one reason why it is used for the Shikinen Sengū.

This forest was also protected by the Owari Domain, and set aside for the Shikinen Sengū even in the Edo period. However, in 1839 part of Edo Castle, the home of the Shōgun, burned down, and a large quantity of timber was harvested from it for that rebuilding. The mountains started groaning, wildfires broke out, and the Owari daimyō suffered nightmares. There were even strange events in the women’s quarters of Edo Castle.

They decided that these were curses from the kami of the mountains, put shimenawa around all the timber from that area, and conducted purification ceremonies. A jinja, Moriyama Jinja (護山神社) was then founded, with an inner sanctuary in the mountains and a main sanctuary near the villages, to venerate and pacify the kami. The jinja is still there. Because it was connected to the Owari Domain, it was apparently counted as one of the ten main jinja of Owari Province, despite being in Mino Province.

These forests have, it seems, been used for the Shikinen Sengū since the beginning of the nineteenth century. The plan is for the forests in Isë to supply all the wood in another century or so, which means that they are likely to serve in this role for about 300 years in total.

Note: From this post, I have started including kanji, by popular demand. Literally. One of my patrons asked for them, and when I asked my other patrons, I got lots of responses from people who wanted them, and no real opposition. There may be some adjustments to the number and scope of the kanji, and it is possible that they will disappear again, if people decide that they don’t want them after all.