All language subtitles for E01 - Tropical Worlds_Track7

The biggest living thing

that exists on this planet
is a plant...

...like this giant sequoia tree
in California.

Plants, whether they are
enormous, like this one,

or microscopic,
are the basis of all life,

including ourselves.

We depend upon them for every
mouthful of food that we eat

and every lung full of air
that we breathe.

Plants flourish
in remarkable ways,

yet, for the most part,

the secrets of their world
have been hidden from us...

...until now.

Now we have new ground-breaking
technology that enables us

to enter their extraordinary
world

and see their lives
from their perspective.

This series will reveal
the extraordinary

and dramatic ways in which
plants behave...

...and we will explore
the challenges demanded by

the very different landscapes
in which they live.

The tropics.

The richest
and most competitive place

in which to survive.

The bizarre water world...

...where giants
fight ferocious battles,

and plants eat animals alive.

Deserts...

Agh!

A world of extremes.

Seasonal lands...

...where survival depends
on precision timing.

And everywhere,
we will explore the critical

and intimate relationships
between plants and animals,

including ourselves.

Join me in a world
that takes you by surprise...

...and see our planet
as never before...

...from
the plants' perspective.

This is The Green Planet.

I'm in Costa Rica,
in the heart of a rainforest,

the richest and most dynamic
environment on Earth.

Rainforests only cover
a very small proportion

of the Earth's surface,

yet they contain over half
of all known

species of animals
and plants.

Up here, the forest's canopy is
bathed by life-giving sunlight.

The branches of the great trees

carry rich, flourishing
sky gardens...

...home to countless different
kinds of beautiful plants.

Each species has evolved
its own exquisite solution

to the challenges of survival.

This forest world
may look peaceful,

timeless and unchanging,

but that is far from the truth.

This is a battlefield.

Throughout this forest, plants
are competing ferociously

with one another
to claim the light.

The battle is at its fiercest
on the forest floor...

...where only 2% of
the sunlight filters through.

Plants here have to
bide their time.

Their opportunity comes
when an old tree dies.

When that happens, sunlight
floods the forest floor

for the first time
in perhaps 100 years.

The seedling's wait is over.

It must now race skywards

and claim a place
in the canopy.

But it's not alone.

Rivals are everywhere,

each with its own
survival strategy.

Some plants,
like this monstera,

stretch out divided leaves
to collect what light they can.

This vine is groping blindly
around with its tendrils.

It attempts to reach the light
by hitching a ride.

Its tendrils are highly
sensitive to touch.

And a suitable target
is in range.

Got it!

The vine tightens its grip

and begins to haul itself
upwards.

But it's now overtaken

by the forest's
fastest-growing tree.

A young balsa.

Its giant leaves are already
40 cm across

and are stealing the light
from its rivals below.

But the balsa's battle
is not yet won.

Other, different vines
are lying in wait.

Each is armed with dozens
of claw-like hooks.

If just one hook gets a grip,

the vine will be able to
smother its victim.

But the balsa is defended by
a shield of slippery hairs.

The vine's hooks
just can't get a hold.

The balsa brushes them aside...

...and continues to rush
skywards...

...leaving the losers
in its shadow

to fight among themselves.

This balsa has won its battle
for the light.

And it's done so
in a little over a year.

Most trees would have grown
an inch or so in that time,

but this one is already
30 feet - 10 metres - tall.

Balsas owe their success

to the special character
of their wood.

If this section of tree trunk
came from a hardwood tree,

it would be really quite heavy.

But as it is,

it's from balsa,

and it's really very light,

and that's because of
its internal structure.

Under the microscope, balsawood
looks like a honeycomb.

It contains more air than wood,

so not only
can it grow very fast,

but it gets the maximum height
for minimum weight.

But fast growth needs
something else.

Fuel...

...and lots of it.

That fuel is created in
a plant's leaves,

as they soak up the sun.

It's a process called
photosynthesis...

...a chemical reaction that is
the basis of all life on Earth.

Leaves are covered by thousands
of microscopic pores

called stomata.

When open, they extract
carbon dioxide from the air,

and using energy from the sun,

combine it with nutrients
to build the plant's tissues.

And critically for us, the
process releases the oxygen

that we and all animals need
in order to breathe.

But for plants,
there is a downside.

These precious, energy-packed
leaves attract predators...

...in every shape...

...size...

...and agility.

A sloth can only move slowly,

but you don't need speed
to gather leaves,

and it eats nothing else.

The plants here are under
constant attack

from all kinds of leaf-eaters,

but the most voracious by far
is hardly ever seen.

It consumes 50,000 leaves
every day.

It's created this great
clearing in the forest...

...and it lives
just beneath my feet.

It's called leucoagaricus.

It's neither animal nor plant.

It's a fungus.

It lives five metres
underground,

far from the leaves
that it devours.

To get them,

it employs the best
leaf-gatherers in the tropics.

Leafcutter ants.

Millions of them provide
the fungus with its food,

and in return, the fungus
cultivates tiny mushrooms

as food for the ants.

The fungus releases
chemical signals

that tell the worker ants what
type of leaf it wants to eat.

Scouts are sent out
with the latest orders.

Worker ants will travel
hundreds of metres

to find the right kind.

Today's crop is being taken
from a young bixa tree.

Just a few years old and still
battling to reach the canopy,

it can ill afford to lose
any of its leaves.

Between them, the ants can
demolish a large leaf

in a matter of minutes.

The sound of cutting attracts
more ants.

Now the pieces are carried back
to the underground fungus.

The ants can run at speeds
of two metres a minute.

And each can carry a load
ten times its own weight.

It's a river of leaves across
the jungle floor...

...part of a vast network
that extends for miles

through the forest.

To avoid congestion,

worker ants dig trenches
around obstacles.

Thousands of pieces
are delivered every hour

to the waiting fungus.

Fed by
such a continuous supply,

the fungus grows rapidly,

filling the chambers
in which it lives...

...so the ants excavate
more space.

It seems that the fungus has
the upper hand...

...and the bixa tree
will not survive.

But it fights back...

...using chemical warfare.

The bixa tree floods its leaves
with toxins

that could kill
the distant fungus.

As the ants carry the fragments
back, they are themselves

poisoning the fungus
on the tree's behalf.

It's a long-distance attack.

As the poison takes effect,
the ants sense

that their fungus
is weakening...

...and they respond to
its signals

by changing to another
source of leaves.

So the plant's
chemical response

forces the ants to constantly
switch from tree to tree.

Strike and counterstrike.

And that ensures that enough
leaves remain uneaten

for each tree to recover.

Once a plant becomes adult,

it can switch its energies

from growth to reproduction.

The tropical forests of the
Americas stretch from Mexico

to the southern reaches
of the Amazon.

They contain more than 100,000
different species of plants,

each with its own particular
survival strategy.

One species that has adopted
a grow-fast lifestyle

flourishes throughout
this vast region.

The balsa.

But it has to pay a high price
for doing so.

The lightweight wood
that enables it

to grow at such speed
is not strong

and is easily broken.

Few balsas live
longer than 20 years.

This one is approaching the end
of its brief life,

so the time has come for it
to reproduce.

It has used a huge amount
of energy to produce

some of the most extravagant
flowers in the forest

in immense numbers.

Each is the size
of a human hand.

As night falls,

the tree prepares
an enticing treat.

This is a kinkajou,

a kind of fruit-eating
raccoon.

Each flower is filled with
huge quantities

of exceptionally rich nectar,

supercharged with sugar.

Irresistible!

The kinkajous drink so greedily

that they get pollen
all over their faces.

So, as they move from
tree to tree,

they carry pollen with them.

But the balsa
leaves little to chance.

The nectar might appear
to have run out,

but this is just
the first round.

Now the balsa refills
its flowers,

enticing the kinkajous back
to repeat the process...

...seven times a night.

Pollination is complete.

And the kinkajous -
they also get well served,

with over 100 pints of nectar
in just a few weeks.

Both plant and animal do well
out of this arrangement.

But in the tropical world,
that isn't always so.

Borneo.

Here, on the slopes
of Mount Kinabalu,

live plants that eat animals

using pitcher-shaped leaves
full of water.

Insects are attracted by
the expectation of nectar,

but tumble into the pitcher,

where they are drowned
and absorbed.

On the lower slopes
of the mountain,

a plant grows
that has no leaves at all.

Or even a stem.

All that can be seen is this -

a bud.

It is a parasite.

The rest of its body lies
within the tissues of a liana,

on which it feeds.

After about five years,

the bud finally opens into
a monstrous flower.

It now has only a day or so
in which to be pollinated

before it starts to wither.

Its petals are
the colour of blood.

Their surface is tough
and warty.

It appears to have fur.

Even whiskers and teeth.

At first sight, it might be
mistaken for a dead animal.

This is rafflesia,
the corpse flower.

A metre across, it's
the world's biggest flower.

And this one is a male.

From its centre comes
the pungent odour of death.

It's a scent that might not
appeal to every animal.

But it's very attractive to
carrion flies.

They lay their eggs
on rotting flesh.

The scent lures the fly
deep into the flower

in search of meat.

The fly finds nothing.

The rafflesia, however, has the
fly exactly where it wants it.

It's stuck pollen
to the fly's back.

If this male rafflesia's
strategy is to work,

the fly carrying its pollen
must now visit

a female corpse flower...

...such as this one.

Success!

Once pollinated, plants are
able to produce seeds,

the next generation,

but once again, there are
animals all over the forest

that are eager to make
a meal of them.

The Malay Archipelago,

a vast tropical world
of 1,000 islands.

It's home to giants -

the tallest trees
in the tropics,

many of which live
for centuries.

They produce seeds
in enormous numbers,

but only do so
when the time is right.

This individual hasn't produced
a single seed

for nearly a decade,

but in the last weeks,
it has become festooned

with more than 10,000 of them.

Each seed has the potential to
produce a giant,

like its parent.

But success will depend...

...on timing.

Seed-hunters are gathering.

Bearded pigs.

But these seeds have been
produced by a dipterocarp...

...trees that create
the tropical world's

largest seed nursery.

After years of waiting,

thousands upon thousands
of individual dipterocarps

have synchronised to produce
the next generation,

all at exactly the same time.

And now these seeds will face
the dangers below together.

By releasing billions of seeds
all at the same time,

they swamp the pigs
and any other animals

with more than they could
possibly eat.

And that buys time for
some of the seeds to take root

and sprout.

The tree's strategy has worked.

But a seedling will have to
overcome many more dangers

over the years if it, too,
is to become a giant.

And there are many ways
in a tropical forest

by which a tree's life
can be ended

before it reaches its prime.

The northernmost tip
of Australia.

This is the world's
most ancient rainforest.

Battles between animals
and plants

have raged here
for 180 million years.

So the plants have had time
to develop effective defences.

This is a poison arrow tree,

one of the tropical world's
most heavily defended plants.

Its trunk is tall and slippery

and exudes a poisonous sap.

It appears to be
almost invulnerable.

But even so,

just as this individual
reaches maturity,

its life has become endangered.

Each monsoon season,

it is invaded from above.

It attracts
hundreds of shining starlings.

Its immense smooth trunk makes
its high branches above

a safe place to nest,

but over the years,

this has created
a major problem for the tree.

After feeding, the starlings
return to the nest

to digest their food,

with inevitable consequences.

Every year,

they produce almost a quarter
of a tonne of droppings.

The toxic chemicals
they contain

create a dead zone that
completely surrounds the tree.

The toxins are absorbed
by its roots

and travel up through the trunk
and into every leaf.

Branch by branch,

the tree is slowly dying.

It has become a victim
of its own success.

It has been poisoned.

Now a new battle begins...

...one to claim the tree's
dead body

and the vast amount
of nutrients that it contains.

It's a battle that is fought
throughout the natural world...

...involving a group
of organisms

that we rarely notice.

Here, on the floor
of a tropical rainforest,

it's dark, it's humid

and it's hot -

ideal conditions for fungi.

We normally think of fungi
as things like this.

Mushrooms of one kind
or another.

But these are just
the fruiting bodies.

They exist for most of the time

hidden in the leaf litter
and the earth

as a network
of fine white threads.

The threads of competing fungi
envelop their victim's body,

releasing enzymes which digest
the tree's tissues

and unlock the nutrients
within.

There are a million or so
different species of fungi

in the tropics.

Some feed on dead plants.

Others eat them alive.

And some reveal their existence
in an eerily beautiful way.

In Africa, in the Congo,

this is known
as chimpanzee fire.

The mysterious
bioluminescent glow

becomes brighter as the fungus
digests the tree.

When fungi have fed
sufficiently,

they develop
their reproductive organs.

Each can produce
literally billions of spores...

...the tiny particles

that carry the species'
genetic blueprint.

Each spore like this

has the potential
to kill a tree.

The spores are so light

they can be carried by
the slightest air currents.

At least a billion

float above every square metre
of rainforest.

Recently, it has been
discovered that these spores

do far more than just bring
death and decay.

They are, in fact,

at the very centre

of the rainforest's
life support system.

High in the humid air,

the spores combine
with molecules of water.

Gradually,
they collect into droplets,

which,
when they are heavy enough,

fall...

...as rain.

Over two-and-a-half metres
of rain falls every year

in a rainforest.

And in the centre of almost
every raindrop,

there is a fungal spore.

The world's rainforests
are the richest

and most dynamic environments
on Earth,

built on complex connections
and relationships.

But these connections,

competitive or collaborative,

are now becoming
increasingly fragile.

When Charles Darwin was
exploring the tropical world

nearly 200 years ago,

he wrote this in his diary.

"Among the scenes which are
deeply impressed on my mind,

"none exceed in sublimity

"the primeval forests undefaced
by the hand of man."

He would struggle to find
such a place today.

Today, 70% of all the world's
rainforest plants

grow within a mile of a road
or a clearing

that we have
cut into the forest...

...and this is creating
new battlefields

in the tropical world.

Alien armies of identical
cultivated plants

now stand where thousands
of different species once grew.

We have planted
vast regiments of crops

in order to provide ourselves

with food
and other commodities...

...and the ancient forest
has been reduced

to ever fewer
isolated fragments.

All, however, is not lost.

The fragments
can still be sanctuaries,

keeping alive the intimate
relationships within them.

Their size is
nonetheless critical.

This is the seven-hour flower.

This plant produces its flowers
at night.

They open about six o'clock,

and each blossom only lasts
that night.

It opens for about seven hours

and then it dies.

But during that time,
it provides food

for one particular animal.

A bat.

And here it is.

During the seven-hour flower's
flowering season...

...Underwood's bat feeds almost
exclusively on its nectar.

It is the plant's
primary pollinator.

It might seem that this is

a fairly evenly balanced
relationship,

but not so.

The bat likes this nectar
because it's sweet,

but it's not very nourishing.

So the bat must visit
hundreds of flowers a night...

...and it pollinates them
as if feeds.

But if a patch of forest
becomes too small,

with too few flowers,

the bats will disappear,

and without the bats,
the flowers can't reproduce

and will soon die out.

The partnership is broken.

Life in the forest depends on
countless close relationships,

but they are increasingly
under threat

as forests
become more fragmented.

The solution, of course,

is to join these remaining
fragments together again.

30 years ago,

I came to this exact spot.

This land belonged to

a scientific research
establishment

and it was covered with grass
being grazed by cattle.

The scientists
got rid of the cattle

and allowed nature
to take its course.

Just look at it now!

This new forest
has become a bridge

that connects several
fragments,

allowing plants and animals

to both renew old connections

and create fresh ones.

Of course,
we urgently need to protect

what healthy forests
still remain.

But looking forward,

we must take what may well be
our last chance

to re-establish
the lost rainforest...

...and help the tropical world
to heal itself.

It will take the co-operation
of nations around the world,

but it is the only way in which
we'll be able to

preserve the treasures
of the tropical rainforest

for future generations.

And with it,

ultimately protect all life
on this,

our green planet.

The aim of The Green Planet
team was to take the viewer

into the world of plants,
so that it could be seen

from the plants' perspective

in a way that had not been
possible till now.

That meant developing
an entirely new camera system.

And this is the game-changer -

a specially designed
robot camera

that we affectionately call
"the Triffid".

The Triffid started life in
the garage of an American

ex-military engineer,
Chris Field.

I'd seen quite a few of these

Planet Earth style
documentaries,

and they always absolutely
blew my mind,

especially the botanic
time-lapse really spoke to me.

In his spare time,
Chris spent a decade

building elaborate
motion-controlled

time-lapse camera rigs

and teaching himself
how to film plants.

Plants often behave like
animals in so many ways,

and being able to see it
through time-lapse is one thing

but using the motion-control
brings you into that timescale.

We could really see
the potential

in how we could use

this sort of movement
to bring plants alive

and film them in the same way
that we film animals.

Soon, Chris joins the team

in a quiet corner
of the Devon countryside

and the robot army begins
to take shape.

After 40 years
of filming time-lapse,

these rigs have opened up
a whole new world for us.

So it'll be like
hovering around something

with a drone or helicopter,
but in a time-lapse speed.

The Holy Grail for us is being
able to take this technology

out into the wild, try and get
the same sorts of dynamic moves

in some of the most extreme
environments in the world.

So what we needed to do

was to develop this technology
even further.

Six months later,
the Triffid is born...

...and with slight trepidation,
they hand me the controls.

That makes it go away...

and this makes it come back...

...and this sends it up...

Ooh!

I think I'd better hand it over
to the experts.

Now it's time to put this new
member of the team

properly through its paces.

The aim here

is for Ollie to find a target,
aim for it

and fly through it,
as if he is a tiny fly

going through a hole in a leaf.

Easier said than done.

- Oops!
- I'm trying to find a target.

Whether the kit's going to

stand up to that sort of use

and the abuse that we throw
at most pieces of kit

has yet to be seen.

In the studio, it seems to be
working pretty well.

But this is only
a dress rehearsal.

It's time for the Triffid
to face the challenges

of the Costa Rican rainforest

and leafcutter ants.

We want to film their journey
all the way

down the trunk
and along this buttress root

and down to their nest.

The team and the Triffid
need several days

of dry weather,

but a storm can hit
at any moment...

...and rain is one thing
the Triffid does not like.

The conditions
that we're working in now

are a little bit more
challenging than the studio.

All the ground is really bumpy.

We've got loads of plants
in the way.

I know we're making a series
about plants,

but sometimes they're
a complete pain in the neck.

The Triffid needs to be
programmed

to capture images from 7,000
different camera positions

of the ants' trail.

Just one drop of rain
on the lens,

or a wobble,

and the whole process
will have to start again.

I think this is when
we're going to find out

if our ambition
outweighs our ability.

For the crew,
the ambition is certainly high.

Fortunately, it's all down
to the Triffid now.

We've been filming the ants
with the Triffid

for eight days now,

and we're on our third set-up.
It's pretty slow going.

While the Triffid seems to be
handling the pressure well,

for the crew, trying to take
a tree's-eye view of ants

is turning into
a bit of a nightmare.

Wake up, film ants,
go to sleep, dream of ants.

Wake up, film ants, sleep,
dream of ants.

Wake up, film ants,

go to sleep, dream of ants.

After two weeks in the jungle,

ambition and ability
finally come together...

...for the Triffid, at least.

Thousands of individual images

creating a single
extraordinary time-lapse...

...one that follows
a river of leaves

across the jungle floor
from a unique perspective.

For the Triffid,
this was just the beginning.

Take a bow, Triffid.