The Mystery of the Dying Bamboo

Bamboo: a plant that is integral to Japanese culture.

Bamboo often appears in Asian myths and stories.

It's a versatile plant that can be used for crafts, daily necessities, and food.

Right now, something drastic is happening with bamboo!

Over here, over there, all over.

I've never seen this before.

Looking in the direction they're pointing reveals what looks like a white scar on the mountainside.

This is where most of the mountain's bamboo forest is said to have withered away.

Upon closer inspection, we find that the bamboo trees have indeed faded and withered!

Moreover, this strange phenomenon is reportedly occurring all over Japan.

Experts say that the cause is an interesting phenomenon that happens just once every 120 years!

Later, we'll also examine new research on how bamboo may be vital to space exploration!

In this episode, we'll look at the strange phenomenon in bamboo that has captured researchers' attention, and bamboo's new potential as a space material!

Hello, and welcome to Science View, where we cover the latest advances in Japanese science and technology.

I'm your host, Tomoko Tina Kimura.

Today's topic is "bamboo."

Bamboo is a very common plant in Japan.

And it seems that once every 120 years or so, bamboo withers all over the country.

Why does this happen?

Research has recently uncovered the reason.

Joining us today is Mr. David Hajime Kornhauser, director of Kyoto University's office of Global Communications.

Hello Mr. Kornhauser.

Pleasure to be here.

Now, apparently, bamboo plants seem to be dying all over Japan around the same time.

Yes, and in fact, this phenomenon of bamboo dying at the same time occurred during the late 1800s in Japan's Meiji period.

Newspapers back then described how this caused a huge blow to the businesses that dealt in lanterns and bamboo swords.

Bamboo was used as a material to make so many things.

So, to not have that must have been very difficult.

What's going on with Japan's bamboo?

Let's find out what causes bamboo forests to die.

What causes bamboo forests to die?

We headed out to a village in Hiroshima Prefecture where the strange phenomenon occurred.

The residents also seem confused...

I don't understand why it's dying...

We continued to ask around.

It withers when its flowers bloom.

What?

The bamboo withers when it blooms?

Next, a bamboo research expert accompanied us to inspect the withered bamboo forest.

Oh, wow! It's blooming, here.

Actually, the brownish areas around the branches are all flowers!

These are from a type of bamboo called "Hachiku."

Right now, the flowers are blooming all at once, stretching 1,000 kilometers from east to west, from Kyushu in the south to Tohoku in the north.

There are even similar reports from neighboring Korea!

Such a large scale flowering is said to occur only once every 120 years.

We decided to try recording the very moment bamboo starts flowering by filming in time-lapse.

Here's the footage!

The yellow parts popping out are the "stamen."

Bamboo flowers do not have so-called "petals."

The white fluttering part at the base of the stamen is the "pistil."

Bamboo pollen is said to be carried by the wind to pollinate and produce fruit.

It's thought that every 120 years, hachiku bamboo blossoms all over its branches, then runs out of energy and dies due to the enormous effort expended in trying to reproduce.

There's a record of a flowering
at the end of the Meiji period, making it a once-in-a-century event.

This flowering, scientists say, is a once-in-120-years chance to uncover the mysterious biology of bamboo!

With flowering that leaves seeds only once every 120 years, how does bamboo ensure its survival?

Here's the secret: an "underground stem" that stretches beneath the ground surface.

It's from these stems that the bamboo shoots, or clones of the plant, grow.

The underground stem grows at a speed of two meters per year.

And the bamboo shoots can grow to a height of 15 meters in just a few weeks.

These underground stems give bamboo a means of propagating without needing to frequently produce seeds.

I did know that bamboo grows very fast, but I never knew that it only blooms once every 120 years.

The plant can spread its clone to a place with a good environment via its underground stems.

In the course of a few decades, the forest may move!

That is quite incredible.

But there's no genetic exchange with clones to allow for diversity in the species.

That's why flowering with occasional genetic exchange is necessary to make a strong species.

I see.

But why does it bloom in this unusual cycle?

The leading theory is the "predator satiation hypothesis."

When a bamboo plant bears seeds, it is a feast for the animals.

If they bloomed separately, the seeds would be eaten up.

So, the theory goes, they try to avoid being completely eaten by flowering all at once.

So, that's actually quite clever!

But why do they all die at once?

The most likely explanation is that they are trying to avoid intergenerational competition between parents and children.

If the parent generation remains, it will be difficult for the new sprouts to get light and they will be competing for nutrients.

By dying all at once, they are making a way for the next generation.

So, they're successfully passing the baton.

In addition, research is being conducted on the possibility that the "genes" of bamboo have a mechanism that measures time over 120 years.

When the genes of flowering bamboo and newly grown bamboo were compared, differences were found in certain areas of the DNA.

In the genes of the flowering bamboo, a modification called methylation has accumulated in part of the C base of ATGC, which may hold the switch for flowering.

So there may be a gene that acts like a natural "alarm clock" when 120 years have passed.

Since we can only study the flowering of bamboo once in 120 years, this long cycle means the phenomenon of bamboo flowering is still shrouded in mystery.

The key to solving this lies in a tropical jungle!

Next, a rather innovative research approach.

There are said to be 1,200 species of bamboo in the world.

It's thought that their ancestors were actually born in this sort of jungle-like environment.

This is tropical bamboo!

It's growing densely in a small area on the ground.

This is clumping bamboo.

The underground stems do not grow long horizontally.

Also, unlike Japanese bamboo, the flowering cycle is "short," and some bloom once every few years.

Compared to Japanese bamboo, it looks like this.

The underground stem length seems to be related to the flowering cycle length.

However, no one has been able to prove this.

Doctor Yuuya Tachiki is working on this challenge.

He's trying to unravel the process of bamboo evolution through simulation.

It's difficult to track bamboo evolution
over a period of 100-200 years when you're in an actual forest.

By running virtual simulations in the computer,
we can do many iterations.

Here's one simulation.

It's based on observation data of actual bamboo, including the spread of underground stems and the germination rate of seeds.

The "circles" represent individual bamboo, and the "colors" represent the same clones.

On the left are bamboo with short underground stems.

Circles of the same color are concentrated in a small area, reproducing a tropical bamboo "clump."

Yet in bamboo with "long underground stems," circles of the same color are located far apart from each other.

This also simulated the way bamboo grows in temperate zones.

Now, here's the key part!

We'll examine the relationship between underground stem length and flowering cycle.

The vertical axis of the graph shows bamboo plants with different flowering cycles, ranging from one year to 139 years.

A simulation was run to see which would survive over 1,500 years.

First, short underground stems, as in tropical bamboo.

The plant that survived was bamboo with an 11-year cycle.

Indeed, the shorter the underground stem, the shorter the flowering cycle remained!

But what about long underground stems, as in temperate bamboo?

The last plant left was bamboo with a long 129-year cycle!

This is the result of one simulation, but Tachiki says that the same result will still be obtained over multiple simulations.

So, why is the underground stem length related to the flowering cycle?

Tachiki speculates that it's the result of competition between plants for density and light.

When the area with light is small, such as in the tropics, it's more advantageous for plants to concentrate their growth in that limited area.

Even if the underground stems grow long, there's a high possibility that the area where the bamboo shoots emerge will not get enough sunlight.

However, eventually the bamboo shoots would be overcrowded, so bamboo plants that can flower frequently, produce seeds, and spread to distant places will survive.

On the other hand, in temperate zones such as Japan, where light penetrates a large area and the leaves fall in winter, bamboo can grow by extending its underground stems.

Bamboo with a long flowering cycle may have survived because they did not need to use energy to produce seeds frequently.

So the plant's environment affects both the flowering cycle and the underground stems.

Yes, and it's also amazing that this was understood through simulations.

What would have taken about a hundred researchers to do can now be done by computer in a matter of seconds.

The results of the simulation still need to be verified, but accuracy should increase as more data becomes available.

If flowering occurs only once every 120 years, it will be very important for the current researchers to "pass the baton" to the next generation.

Next, we'll take a closer look at the amazing qualities of bamboo as a "material"!

Bamboo is considered to be the fastest growing plant in the world!

It's also incredibly strong!

This bamboo shoot seems unaffected by 20 kilograms of weights.

What's even more unique is that bamboo manages to be both strong and flexible at the same time.

The secret to that property turns up in a bamboo cross-section.

Looking closely, we see countless holes amidst the white cross-section.

These are the "vascular bundles" - a collection of tubes that suck up water and nutrients.

The key part is here!

A "vascular bundle sheath" surrounds the tubes.

In fact, this part here is as strong as iron.

In addition, the white part surrounding the vascular sheath is called "parenchyma," which is characterized by its many pores and softness.

The combination of these two tissues creates bamboo's unique strength and flexibility.

Bamboo has long been a material used in the past, but it may now find a new application in...

Space Development!

In fact, bamboo may be the solution to a serious problem facing spacecraft.

That problem is "outgassing."

Space is a harsh environment.

Not only is it a vacuum, the temperature between a surface in the sunlight and a surface in the shade can differ by hundreds of degrees.

When the plastic parts and adhesives used in spacecraft are exposed to such an environment, some of their volatile components may leak out.

This can cause problems with sensors and other equipment.

One of the most famous examples is a camera on board NASA's Cassini spacecraft.

This image of a star became hazy - a problem thought to be caused by outgassing.

Doctor Taro Kinumoto of Oita University is trying to use bamboo to solve this problem.

Let's check out his approach!

He's prepared thinly split pieces of bamboo and... a pressure cooker!

The bamboo is put inside and cooked for several hours.

After the bamboo has softened and broken into fibers, it's put into a blender!

Applying a special chemical to it turns it into a white liquid!

These are cellulose nanofibers made from bamboo.

Cellulose nanofibers Here they are up close.

Under a microscope, we can see very fine fibers intertwined together.

These fibers are cellulose, the carbohydrate that makes up the plant body.

The fibers' thickness is about 20 nanometers.

That's only about 1/50,000th of a millimeter.

Kinumoto says that if the water content is drained out of the cellulose and it's made into boards for use in place of plastic, the problem of outgassing could be reduced.

First, let's compare strength.

While the plastic completely deformed after 12 kilograms of force, cellulose nanofibers were able to withstand up to 27 kilograms, more than twice as much!

Cellulose nanofibers are made up of extremely thin fibers that are intertwined with each other at the nano level.

As a result, a tremendous number of bonds are created, resulting in high strength.

Cellulose is also more stable against heat than plastic and does not easily produce gas.

As a solution to the outgas problem, bamboo-derived fibers may one day be used in space.

We're excited that it might be used in space.

It'd be neat to see something we made flying around.

Like something out of Japanese folklore.
A dream come true.

It's exciting that a common plant like bamboo could be a useful material in space.

Yes, cellulose nanofibers can be made from other plants too, but bamboo seems like it might yield better performance.

Research is still underway, but some results have highlighted the possibility of making bamboo nails that are stronger than steel nails.

Really!

I imagine that there could be strong demand for bamboo nails.

Moving on to our next topic, "Visualizing Underground Infrastructure."

In the ground, underneath the roads we use every day lie many objects such as water pipes and gas pipes laid out in complex arrangements.

This means a long time is usually required in surveying for construction and infrastructure improvement.

Our Takumi on today's J-Innovators has streamlined this process with this latest technology.

We’ll head out into the field to find out how.

A man is standing on the sidewalk.

And wearing goggles.

For some reason, he is looking at the ground.

Believe it or not, he is able to see things that are buried under the ground, such as water pipes and gas pipes.

These goggles can actually "see through" the ground, making buried objects visible.

This is today's 'Takumi,' developer Hiroshi Tomita.

Construction workers don't know exactly
where things are underground.

This technology helps them know what's really there,
reducing unnecessary or dangerous work.

Electricity, water and gas works often require digging up the ground.

That's where this Underground Infrastructure 3D Map comes into play.

Accurately knowing the situation in advance helps workers avoid accidentally damaging underground objects and makes the work more efficient.

This is the latest underground radar,
which uses 3D to detect underground objects.

This technology developed by Tomita and his team can survey underground objects in three dimensions.

It uses microwaves.

The waves pass through the surface, hit any underground objects, and reflect.

Different materials, such as metal or concrete, reflect the waves in different ways.

Data is then analyzed to provide a picture of the underground objects.

However, microwaves can only provide information in two dimensions.

This is the horizontal data and the cross-sectional data.

An underground pipe can be seen, but exact details are unclear.

So Tomita and his team installed several antennas that emit microwaves.

The details are a trade secret, but this allows simultaneous scanning at intervals of one centimeter in depth, five centimeters in cross-section, and eight centimeters in longitudinal-section.

With this 3D information, it's now possible to check the bends and overlaps of underground objects, and to create a 3D map of the underground infrastructure.

There's a reason why Tomita started to develop this technology.

In 1990, an accident in Tokyo's Okachimachi district occurred which involved a sinkhole that collapsed a road.

Tomita, then developed an "under-road cavity investigation system" which might help to prevent such a collapse from occurring again.

Then Tomita received an unexpected request.

This is a plastic land mine brought by Brigadier General Blagden from the UN.

It's diameter is five centimeters.

It was a request to help develop technology to remove landmines in Cambodia.

At first, we were just going to go and do a test,
but I learned about the suffering landmines cause.

My sons were three and five years old then, so I felt I had to do something
because children were also suffering.

It started with this righteous indignation.

The landmines were so small that developing a detector was extremely difficult.

Tomita came up with the idea of increasing the accuracy of the antenna to obtain three-dimensional information.

It took ten years to finally put it into practice.

We did everything without charge, and eventually
it evolved into the technology we have today.

Development based on making a profit or not
does not necessarily produce good results.

It's really motivating to help save people's lives,
and I think that's when I become most creative.

Tomita is now trying to use this technology in the construction of "pole-free areas" in which power lines are buried underground.

During natural disasters such as typhoons and earthquakes, utility poles can fall over, blocking roads, and hindering evacuation and emergency services.

However, because there are many underground objects, it would take about seven years to convert 400 meters of road into a "pole-free area."

Tomita has developed a vehicle that can survey roads and sidewalks in 3D.

By doing this, the construction period can be shortened by more than two years, leading to a significant reduction in costs and more "pole-free areas."

Tomita is continuing his research to make our lives safer and more comfortable.

This system to "see" underground is truly fascinating.

It is surprising that the technology was originally developed to find landmines.

It truly is.

Tomita says he'll continue his research to improve the efficiency of construction work and to protect human lives.

And that's all for this week's Science View.

Thank you very much for joining us, and please stay tuned for our next episode.