Friday, October 14, 2016

Attack of the Clones? Bamboos, bamboos …

When I was a simple hiker visiting city forests occasionally, I thought Niiharu is probably one of the best maintained forests in Yokohama. Now I realized there still are lots of things to be improved. Take bamboo shoots harvesting. For more than a month this year, weekly volunteering by about 60 people yielded hundreds of shoots that could be sold at a good price if marketed. But when the shoots had become commercial products, the elderly landlords must have thought about management issues and taxes which are too much for them. That was the original reason why such a rich bamboo forest is a part of Citizen Forest, and volunteers are inundated the weekly supply of shoots. There must be some policy solution for the situation … Taking care of bamboo forest requires all-year-round labor intensive tasks. Some trees become prematurely yellow any time. The others are broken due to storms. The broken bamboos can be a danger for visitors who must pass under the precariously hanging broken limbs. They must be taken away ASAP, if the forest receives lots of weekend hikers. Even if the location is not open for the public, abandoned bamboos could pose another problem. Bamboos are very elastic. When they collapse and wither, their bottoms are still attached to the rhizome underground. The tethered “net” of broken bamboos obstructs the new growth of shoots from the jumble-covered ground, let alone sunshine for the other vegetation to sprout. Furthermore, a network or bamboo rhizome occupies only top soils. The bamboo “mesh” is not strong enough for the impact of rapid torrential rain, or large earthquakes, especially where the rhizomes completely dominates the ground and the soil in-between is washed away. A neglected bamboo forest becomes a good candidate for the next large landslide. Meanwhile, for example, in Niiharu Forest all the bamboo fields are private properties of several landlords. Majority of them are households of senior citizens. I realized how labor intensive digging bamboo shoots is. Maintaining the soil of bamboo field is not a lonely job for an abuelita of 75+ years old. We return to the land management issue in aging society … the spread of neglected bamboo forests is becoming serious ecological problems.

The problem may not be so pressing when the plant takes their time to grow as the other trees do. Bamboo spreads ferociously similar to herbaceous. The secret why bamboos can grow so fast is in the sections of its trunk. They are apical cells of bamboo. When a bamboo gets taller, all the cells in the sections grow at once. A healthy bamboo can have 60 sections with lots of apical cells, and hence the tree can become 20m high in less than 2 months. Their rhizome also has a similar structure and can grow 7-8m long underground. In addition, it is ever-green, which makes them possible to photosynthesize and grow during the winter. A vigorous bamboo forest in Satoyama consists of only one sequence of DNA explosively started by one bamboo shoot transplanted from somewhere. They are clones. Once established, without a proper control in humid Japan, they can cover a wide forest floor with the shadow of canopy, thick fallen leaves below, and a network of its rhizome beneath, all of which impede growth of the other plants. In addition to disaster risk reduction, controlling a bamboo forest is important to protect the other forests from the attack of the clones.

er … those clones are cute.

In Japan, the bamboos we can find easily are either pubescens with 1 ringed section, or bambsoides with 2 sections. Legends say phyllostachys pubescens was imported from China in 801 or 1228 by Buddhist monks who studied in China. It is almost sure that pubescens became “vegetable” when in 1736 the lord of Kagoshima ordered his subordinate to bring its seedling from Okinawa where already the Okinawan dynasty had introduced them to eat from the continental Qing dynasty. In standard “farming” of bamboo shoots, we cut the phyllostachys pubescens when it reaches 5 years or so old in order to stimulate more new shoots in spring. Moreover, before plastics the large trunks of pubescens provided lots of materials for the tools in daily lives, such as bucket, kitchen gadgets, utensil, and dishes all of which required almost annual replacement. Cutting them frequently was natural for bamboo farmers. On the other hand, some think phyllostachys bambsoides is Japanese native bamboo. The garden structures we can find in traditional Japanese gardens are often made of bambsoides. Bambsoides are thinner than pubescens. Their shoots are also edible; there are lots of gourmands who prefer bambsoides to pubescens. Unlike pubescens, the shoots are harvested when they are 30-40cm tall above the ground and still so soft that they can be broken from the root by hands. Immediately after the harvesting, the shoots of bambsoides do not require preparations for cooking as pubescens. Do you remember we encountered a BBQ party in Jike Citizen Forest last year? The landlords entertained the visitors with freshly harvested shoots of bambsoides by roasting them over charcoal fire, just like sweet corns. The slender bambsoides can provide smaller amount of materials for crafts. In addition, bambsoides are not that much vigorous for shoots as pubescens. There wasn’t strong demand to cut bambsoides as for pubescens. The traditional way of dealing with bambsoides is leaving the trees to be old enough for creating a gnarled trunk or odd shapes, in order to be appreciated as a material of Japanese traditional art. Especially when it sprouts from a steep slope and shot up in a curved way, the form of the trunk becomes ideal for shakuhachi flute. Older arched bambsoides with a large cavity surrounded by thick old trunk wall can fetch a fortune to be a “Stradivarius” of shakuhachi. Unfortunately, the long-terminalism for maintaining bambsoides forest has a hidden danger: they are easy to be neglected, especially in Japan these days with lots of senior citizen landlords.

It’s a bambsoides forest in Ikego.
The reason of neglect here would not be aging society,
but … international politics?

Niiharu is situated almost in the center of Tama Hills. This part of Japan has been famous since the 18th century for bamboo shoots cultivation, catering megalopolis of Tokyo. So, Niiharu Forest has lots of bamboos. Compared with the other places in Yokohama, Niiharu’s bamboo forests are really kept well in general, especially where we can harvest the large bamboo shoots, i.e., the forest of phyllostachys pubescens. Even though, Niiharu has problem spots of one or two. A forest of phyllostachys bambsoides was the one.  They were damaged by heavy snow 2 years ago when lots of trees were broken and fell. The landlord does not have resource to tackle the problem. Uber busy Niiharu Lovers finally found time to attend the issue this spring.  A Niiharu’s bambsoides forest is small and surrounded by the pubescens. My seniors assessed the field and concluded that there is a strong possibility that the weakened bambsoides will be invaded and dominated by pubescens eventually … “Any way, let us see if we can restore the bambsoides forest by first clearing the broken and dead trees.”

A bambsoides forest in disarray

A disaster such as unusually heavy snow can first bend the bamboos. If it occurs in a neglected bamboo forest, too much density makes a mesh of bended and broken tops of bamboos whose weight eventually causes the whole a net to fall down to cover a wide space. It was a mess. To sort out the situation, we had to wade in the heap of entangled, pointed, and dry branches of bambsoides. We then cut the end of dead tree, undid the complication and made bamboo logs for disposal. The bamboos logs dried in this way were too damaged to be material of crafts or gardening, other than being crushed for mulch. That’s really wasteful …

Could you see the top of the bamboos were entangled
and drugged the entire trees to the ground?
Let’s tackle the fundamental problem over there.
As long as it stood upright,
yellowish leaved trees were left for the forest restoration.
My seniors decided to stop clearing here,
and to wait and see how the forest cures itself.
They said the place would be a good playing ground
for corvus macrorhynchos meanwhile.
Logs of dead bamboos.
We have to carry them out from the site later
in order to prevent arson, and other nuisance.

Even though, I noticed Niiharu’s phyllostachys bambsoides fairs better. One of the requirements for Forest Instructor Course by Kanagawa Prefecture is accumulating the experience in the forests of entire prefecture. One weekend, I joined an event to take care of a forest owned by the City of Kamakura. Due to a heavy rain, the planned forestry exercise was changed into a stroll in the forest that is not officially open. We walked in a forest hill which was once the property of Nomura Research InstituteIn 1989, they moved out the place and donated the entire land to the City of Kamakura … The buildings Nomura used are still standing although the concrete of the outer wall is crumbling. “Please do not go near to the structure. They are dangerous.” The people from the Prefectural government warned us. The hill is covered completely with overgrowth from the top to the ground. The donated hill looked abandoned as a whole. The messy forest with which we could have done the job was of a phyllostachys bambsoides … The bamboo trees stand too close each other which makes lean phyllostachys bambsoides even leaner than in a healthy forest … That was a sad scene. … Hmmmmm, the place surely needs lots of helping hands, as the lecturers for the Forest Instructor Course told us …

A former office building of NRI.
It could be another site for 007 adventure someday …
The entire hill is covered with overgrown everything
… asphalted roads are also crumbling, actually.
Although they are too short,
the bamboos are already getting yellow.
It is definitely impossible to walk
in this forest with an opened umbrella.
(Oh, yes, the metric for thinning bamboos is
“making space between the trees
that is wide enough for a person
with opened umbrella to walk.”)
That pointed cutting of a bamboo in the middle is
a prohibited way of thinning the forest …
probably somebody cut the bamboo just for fun …

If you find a problem in the Niiharu Forest, please make a contact with

Office for the Park Greeneries in the North 北部公園緑地事務所
Yokohama Municipal Government Creative Environment Policy Bureau 横浜市環境創造局
Phone: 045-311-2016 (I guess in Japanese only)
FAX: 045-316-8420 (I hope there is somebody who can read English …)

Niiharu Administrative Office / Satoyama Exchange Center 新治管理事務所・里山交流センター
Phone: 045-931-4947
Fax: 045-937-0898

The contact address for Kanagawa Green Trust かながわトラストみどり財団 is

Phone: 045-412-2255

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