Sanbon Sugi gets a physical.

If you've been following my blog, you may know that visitors can no longer see Jomon Sugi from the "front," because a health exam a little over a year ago found that the overhanging limb is hollow -- as it may have been for hundreds of years -- and was deemed hazardous to those standing below. But just how do you go about evaluating the health of a tree that's older than Jesus?

This January, I went to the local Forestry office and asked. Fully expecting to be shown a stack of papers and research reports, I was thrilled by the answer:

Why don't you come along and see for yourself?

平成24年11月、縄文杉の正面の枝が空洞だ（←たぶん大昔から）とわかって、下の展望デッキに立っている登山者の安全を確保するため、林野局の判断に従って、展望デッキの半分が立入禁止となった、とごご存じでしょうか。でも、縄文時代から生きてきたものの場合、健康診断はどうやって行われているでしょうか。林野局の保全センターに聞いてみたら、その答えは、

 調査結果を読んでもいいけど、その代わりに、今度、見学に行ったら？

The Patient: Sanbon Sugi

The next examination coming up was for a tree named 三本杉 -- Sanbon Sugi, or, literally, Three Sugi Trees, in English. This tree isn't on the list of milleniarians, but, according to the head of the research team, it received its name well before any of its famous Yakusugi associates. Not only does this threesome of inosculated (I'm impressed if you don't have to google inosculation!) trees stand along the

That's a bottle of
Mitake shochu behind
the inscribed stone.

Kusukawa Trail used by Edo-period loggers to access Yakushima's interior, but it's a holy tree. In fact, there is a small shrine recognizable by the carved stone nestled among the trunks. Over hundreds of years, the tree has grown up around this stone, so that the dedication is only partly visible.

次の調査の対象は三本杉でした。まだ屋久杉と呼ぶほど古くない杉ですが、現在屋久島の他の著名杉の名前が決まった断然前に、この不思議な杉は三本杉と名づけられました。三本の大きな杉が合体してるかたちで、江戸時代にも伐採のために使われた楠川歩道に立っています。数百年渡って、幹と幹の間においてある碑の字を二つしか見えないほど木が成長しています。

Sanbon Sugi, measurement sticks
in place.

Once there, the head scientist bowed to the shrine, and then they set up tools for standard measurements, laying out tape measures and standing a ten-meter-high pole next to one of the trunks. We all backed away and tried to estimate the height of the tree -- not an easy feat in a dense forest. I counted out 24 meters to a space where I could see both the top and bottom of the tree, and then took out my cell phone (got to love smartphone apps!) to measure the angle. Others estimated how many ten-meter poles would be required to reach the top. The team leader, a local well-versed in both about nature and local lore, took out a surveying device that looked a bit like a mini-telescope that measured both and angles to calculate height. Most estimates fell around 24 meters, although both my cellphone and the surveying device gave something closer to 30m. The leader jotted down the height and environmental conditions and sketched the tree on the long form he carried.

班長がお参りをしてから、研究者達はメジャーなどを広げたり立てたり、様子を確認しました。そうして、皆さん、三本杉から下がって樹高を推測しようとしました。木々が密生している森の中には、大した技です。10メートルの棒を水準にして推測したり私は携帯のアプリを使って、角度と距離で推算しました。班長はそれを自動的に図って計算する装置を出してが、意外に高い数字（約30m）が出ました。（目で推測すろと、24mぐらいではないかと思っていました。）

Circumference is measured at the highest point 1.3 m above the ground. Coins removed and returned to the shrine. Did you know one-yen contain aluminum, which is bad for the environment? Soil Observations: Testing the firmness of the soil. Note the book of swatches on the ground.

The next measurement was circumference (and thereby diameter) of each trunk. This is measured at 1.3 meters from the ground, so that the sprawling roots don't overblow the measurements. Then parameter of the roots. What trees (epiphytes) had taken up root on Sanbon Sugi. (It's not easy to identify a plant that's 12 meters up the side of another tree trunk!) and what plant species were growing in the area. The depth of hollow openings above the roots. A sound-test for hollowness. (All three trunks are hollow.) Estimating how far the branches extend in all directions. The presence of fungus on decaying limbs. (The form called for identification of the fungus, which is something I couldn't do with the fungus in front of my nose, and this fungus was probably 15 meters above.　サルノコシカケ, polyporaceae, seemed like a good bet.) Things like that. 次は各幹の胸高周囲（地面から1.3mの高さで周囲を図る）、根っこの周囲、着生植物の種類（難しい！）、付近に生えている植物、空洞状態のテスト（各幹、皆空洞です。）、枝の延長、菌類の有無と週類。（感動しますは。菌類のわからない私は、十数メートル頭上の菌類の種類の判断は無理です。サルノコシカケかな。）などなど。 Lunchtime was the most interesting for me. I'd racked up a bunch of questions I wanted to ask, but found it was much more interesting to let the group talk about things I hadn't even considered. 昼ご飯の会話もかなり面白かったです。いろんな聞きたい質問がありましたが、皆さんの話しが面白すぎて、ほとんど聞き忘れました。特に班長は自然についても里についても詳しいです。 In the afternoon we started the soil measurements, which take the most time. A couple holes were dug and the leader expertly documented the soil layers including color, granularity, stiffness, and a bunch of other factors I didn't understand. Apparently these things have been recorded for soils all over Japan, and you can look up the color in this little booklet that must be the world's most expensive book of swatches (to untrained eyes, just like you get for free from the paint store!) to find out the stage of erosion. While the leader concentrated on that the rest of the team took turns boring meter-deep holes by dropping a weight on the end of a sharp-tipped pipe. With each drop, the pole sank a few milleters or maybe even a couple centimeters, and the depth was recorded. The weather forecast had called for partly cloudy skies, but it was much chillier than most of us had anticipated, and I found myself cheering for the pole to sink faster as a shivered and waited.

午後になったら地質を調べました。結構時間がかかりました。穴を掘って、土壌の色、硬さ、粒子の大きさ、などなど。日本の各地でこれらがすでに研究されているため、（めちゃくちゃ高い）本で色を検索したら、土壌の腐食度合いを調べられるらしいです。班長が詳しい観察を行いながら、残りは重りの付けられている棒で4つの穴を作って、土壌貫入式を行いました。重さを上げて、落とす度に棒が少しずつ地面に入り込んで行きます。その深さを記録しながら１mの深さまで繰り返す作業です。天気予報は晴時々雲でしたが、とっても寒かったです。その土壌貫入式棒を見つめながら手が震え始めそうになりました。

While the team was documenting all the flora in the area, (omg, they're supposed to know the names of all those ferns?? Wow.) a family of monkeys -- apparently aquaintances of our leader -- stopped by to chat as they foraged nearby.

研究者達が植物の種類の記録していた時、（皆さんはとても詳しいです。特にシダの区別が難しそうです！）数匹のサルたちがよってきました。班長の知りたいみたいに、遊び声をかけたり、うちたちが研究作業に励みながら、サルたちは採食行動に励んで、面白かったです。




Sanbon Sugi (according to Yakusugi Museum texts)
Height: 23.4m
Circumference (of largest trunk): 4.9m
Elevation: 550m

Special thanks to the kind and knowledgeable folks in the forestry office and at the Yakushima Forestry Conservation Center.

林野局や屋久島森林生態系保全センタの方々にとても感謝しています。