All language subtitles for E05 - Human Worlds_Track7

The relationship between plants

and humans is extraordinary.

We've been adapting
to each other

for as long as we've been
on the planet.

We rely upon plants
for almost everything.

The air we breathe,

the water we drink,

the food we eat,

much of the clothes we wear,

and in some parts of the world,

the very buildings
in which we live.

But that relationship
is now changing.

How it changes next

will shape the future
of our green planet.

Some plants have the ability
to live alongside us...

...even when we make it
extremely difficult

for them to do so.

This is Piccadilly Circus

in the heart of London.

It would be difficult
to imagine

a more hostile place
for a plant.

And yet, even here,

plants will find a way.

Plants like this may seem
to follow us wherever we go.

We call them -
perhaps a little unkindly -

weeds.

In fact, these plants
are pioneers,

the ones that are most able
to take advantage

of new habitats,
even very harsh ones.

This wall is
at least 100 years old.

It's like a sheer cliff face,

with no sign of soil.

And yet, this ivy-leaved
toadflax thrives here.

How?

The plant grows
towards the light,

with its flowers
facing outwards

to attract pollinators.

But once they've succeeded
in doing that

and the seed pods
have started to develop,

its behaviour changes.

Now the pods turn

and grow away from the light,

seeking the darkest place
they can find.

A crevice, perhaps,

like this one.

It's all the toadflax needs.

It can now germinate and start
to produce a new plant.

Other pioneers have
a different strategy.

They, instead, distribute
their seeds far and wide

in great numbers.

Sow thistles are masters
of this trick.

Each of its seeds is equipped
with a tiny downy parachute

which will catch
the slightest breeze.

And they can travel
extraordinary distances.

They can rise a mile high
in the sky

and reach places
hundreds of miles away

from the parent plant.

The seeds only need to find
the tiniest chink...

...and they can take hold.

We barely notice
many of these plant invaders.

But here,
in the heart of Hong Kong,

strangler fig seeds

that landed on a stone wall
generations ago

have spread their flexible
branching roots far and wide.

They can be anchored so firmly

that they become a part
of the city's architecture.

This is, perhaps,
the ultimate weed.

But there are places where
the extraordinary abilities

of fig trees have created
a very different relationship

with human beings.

Meghalaya,
in northeast India...

...a high-altitude plateau

riven by
dizzyingly steep valleys.

It's home
to the Khasi people...

...who've learned how to use

the remarkable properties
of fig trees

to help them live
in such difficult country.

As in Hong Kong,

the tree's numerous roots
anchor it firmly,

here, to steep mountainsides.

These roots can grow
up to 2.5 cm a day.

They are unusually strong,

flexible

and can develop
into a multitude of shapes.

The Khasi persuade them
to provide them with stairs.

The monsoon season brings

a seemingly insurmountable
challenge

for Khasi communities.

This is the wettest place
in the world.

Nearly 30 cm of rain can fall
in a day.

Rivers become lethal torrents,

dividing communities
from each other.

This is when the relationship
between fig trees and the Khasi

becomes most important.

They deliberately plant
fig trees near the rivers.

When they're mature enough

to have developed
many hanging roots,

Shining Star Kongthaw
begins working with them.

He guides the roots
through bamboo tubes

that are pointed towards
the opposite river bank.

These strands will combine
as they grow,

sharing nutrients
and resources,

and becoming stronger than
a lone strand could ever be.

As the years pass,

the growing roots
become a living bridge.

As they grow,
they become ever stronger

and more stable.

This unusual relationship
has allowed the people here

to thrive in an otherwise
challenging landscape.

But there are plants

that have found
a deeper partnership with us,

and in doing so, have changed
landscapes across the globe.

It began over 10,000 years ago

with plants that we found
especially good to eat.

At first, this relationship
created challenges of its own.

Many of the ancestral grasses,

like these wild oats
from Israel,

have a trick to ensure
that their seeds

are planted
in the perfect place.

Each seedhead, at the top,

carries two long bristles
called awns,

and when a seed drops
to the ground,

these awns do something
truly extraordinary.

They walk.

The awns twist as they dry out
during the day,

and then, when they get wet...

...they untwist.

Tiny hairs grip
onto the ground,

keeping the individual
moving forward.

In this way, the seeds work
their way along the ground

until, eventually, they find
a rock to hide under

or a crack to drill into.

This adaptation is useful
for the plant

but not for us.

It's hard to collect seeds

when they drop off
and walk away.

So our ancestors
selected plants

whose seeds don't drop off,

don't have legs

and don't bury themselves
out of reach.

They also selected
those individuals

which put their energy into
developing much larger seeds.

Close relationships like this

have developed
all over the world...

...producing the plants
that are now our crops.

This may seem a poor deal

from the point of view
of plants,

but not so.

We eat their seeds

but, in return,

we cherish and cultivate them

and now they are widespread
and far more abundant

than their wild ancestors.

You might call this

a bargain
between ourselves and plants,

and over the years

it's proved
extraordinarily powerful.

In the beginning...

...the bargain operated
on a small scale.

Plant, tend,
and harvest by hand

in small patches.

Over time,

these plants produced more food
increasingly efficiently...

...and the partnerships
became more exclusive.

We started doing more and more

for a small number
of chosen species.

These few persuaded us

to eliminate
their competitors...

...cure their diseases,

poison their enemies...

...and keep them well watered,

even when other species
face drought.

Fewer and fewer plant species,
like soy, wheat and rice,

now occupy more and more land.

So now whole landscapes

are dominated
by a single species of plant.

A monoculture.

This is the Central Valley
of California,

the biggest orchard
in the world.

A million acres
of just one type of tree.

Almonds.

Each flower, if it's fertilised

by pollen
from a different almond tree...

...will produce an almond nut.

The flowers' patterns and scent
have evolved

to attract insects

and bribe them to do that job
for them.

The pollen
doesn't have to move far.

It just has to reach
a neighbouring tree.

There are about 20,000 flowers
on each tree...

...and 140 million trees.

That is billions of flowers,

all calling out at once.

But here, the beauty
of the blossom is wasted.

To make way
for these almond trees,

the land was, in effect,
wiped clean.

Countless wild species
of plants and animals

were removed, including,
critically, pollinators.

So now the flowers need help,

and lots of it.

40 billion honeybees...

...trucked in from all over
the United States.

The orchard is only in bloom
for a few weeks,

so the almonds need the bees
to get to work immediately.

Each bee can visit
thousands of blossoms a day.

And while they take
most of the pollen they collect

back to the hive,

they also drop some pollen
at each stop.

And so, with luck,

the flowers are
all eventually fertilised.

Day after day,

the process is repeated.

Flower after flower.

Tree after tree.

By the time the petals fall,
two-and-a-half trillion flowers

have been
successfully pollinated

and will now grow into

two-and-a-half trillion
almonds.

This type of intensive,
streamlined agriculture

produces amazingly high yields.

But monocultures are fragile.

While they can function
effectively

when conditions remain stable,

it only takes a small change

to create catastrophe.

Lodgepole pine.

A very valuable timber tree

grown extensively
in Western Canada.

Millions of acres
of the same species,

all the same age

and the same size.

For centuries,
lodgepole forests

have lived in a natural balance
with their enemies,

including this one.

The mountain pine beetle.

In summer, female beetles start
hunting for a suitable nursery

in which to lay their eggs.

The ideal site is a mature
lodgepole pine,

with bark thick enough
to feed a female's brood

and, critically,
to protect them

from the bitter cold
of the coming winter.

Once under the bark,

she tunnels upwards...

...laying her eggs as she goes.

A single female beetle

can lay 100 eggs in a season.

When the larvae hatch,

they grow by feeding
on the inside of the bark.

As they do,
they damage the channels

that transport water
and nutrients

between the roots and needles.

For centuries,

the freezing northern winters
killed the majority of larvae

so tree and beetle
remained in balance,

but now,
with the climate changing,

the winters aren't cold enough
to control the beetle numbers.

Needles turning red

are a sure sign
that the trees are dying.

The beetle plague spreads like
wildfire across a landscape

covered by a monoculture
of similarly vulnerable trees.

Since the first mass outbreak
40 years ago,

trillions of trees
in North America

have been killed
by the mountain pine beetle.

Loss of plant diversity
makes any habitat

more vulnerable
to changing conditions.

Now, with climate changing
so fast,

we're losing plant diversity
just when we need it the most.

Two out of five plants

are now facing extinction.

Of course,
the loss of any one species

is in itself a tragedy.

But such a loss
erodes the stability

of a whole ecosystem,

and that should be
of great concern for all of us.

We need an insurance policy.

A hedge against extinction.

This is Kew's
Millennium Seed Bank.

Packets of seed arrive here
from all over the world.

These are from a relative
of the yucca plant

which grows in Central Mexico

on the slopes of volcanos
and nowhere else.

Most of the seeds are from
plants that are threatened.

Some, indeed,
have gone extinct

since their seeds arrived here.

But here, at least,
those seeds are safe.

When they arrive,
they're processed

and sealed into airtight jars.

The seeds are then
brought underground

to be stored in a vault,

like this one,

at minus 20 degrees centigrade.

Since the bank was founded,

2 billion seeds,
from 40,000 different species,

have been brought
and stored here.

Because a seed contains
everything it needs

to start a new plant,

each and every one of them

represents
a little grain of hope.

Hope that one day
we will make it possible

for the seeds of these rarities
to grow in the wild once again.

The seed bank
certainly gives us options

when a species becomes rare
or even extinct.

But around the world,
people are trying ways

to keep natural plant
populations healthy

where they should be -

in the wild.

Hawaii.

90% of the plant species here

are found nowhere else
in the world.

Many are threatened
by a plant invader

called miconia.

It was brought
to the island of Maui

in the '70s
as an ornamental plant.

In its native Mexico,

it grows in balance

with a rich variety
of predators,

competitors
and diseases.

It grows taller than most
Hawaiian native vegetation,

and little can grow beneath it.

On the island of Maui,

with nothing
to keep it in check,

it creates
a stifling monoculture.

Miconia, it would appear,

is doing very well for itself.

But today, it's under attack.

On level ground,
a single dedicated team

can keep miconia in check.

But, unfortunately,

this plant can spread to places

impossible for people to reach
on foot.

Just one plant can produce

around 10 million seeds
a year -

enough to cover
this entire landscape.

With so much at stake,

the team have come up
with an extraordinary plan.

It's too dangerous
to land here.

But they don't need to.

A marksman with great skill

can shoot the miconia
with paintballs full...

...of herbicide.

A perfect shot
is one that hits the stem,

so ensuring that the herbicide
spreads throughout the plant.

The method is so precise

that with careful flying
and accurate aim,

they can kill the intruders...

...without damaging
any wild plants.

Destroying alien invaders

is not the only way to help
the native plants here.

This is Waikamoi Preserve,
the last surviving fragment

of a high-altitude
Hawaiian rainforest...

...and home to one of
the world's rarest plants.

Holokea.

There are only 57 fully grown
individuals left in the wild.

Their peculiar flowers evolved
to suit the beak of a bird

found only in Hawaii -
the 'i'iwi.

The bird is now so rare itself

that today these partners
seldom, if ever, meet.

So the chances of holokea
getting pollinated

are very slim.

But a strange new partnership
might just save it.

I look at losing a plant
as flying in a plane

and taking a screw out.

Yeah, the plane will fly,

and you might be able to

take a couple screws out

and keep flying,

but eventually,
you're going to crash.

Hank knows where to find

every one
of the last 57 plants.

And he returns every year
to act as their pollinator.

We have to step in
and play that role as...

...pollinator, matchmaker.

Hank collects the pollen
from the male flower

and dusts it onto a female
flower of a different plant.

He's currently
their life support,

but his goal is for holokea
to thrive without him.

So before he leaves,

he plays the call
of the 'i'iwi bird.

Hank hopes the sound
will attract the living birds,

and if they come,
that they will reconnect

with the last holokea

and rekindle
their vital relationship.

I believe all species
are important.

And I believe
we have a duty to act.

We need to act
not only in the wild places,

but even in those
where we live

and where we farm.

Like much of the world,

Kenya is losing thousands
of native trees annually,

ones that local people rely on
for so much, especially fuel.

But here,
people have come up

with an ingenious way
to reverse

some of that loss around them.

At a factory
in the outskirts of Nairobi,

workers collect and sort
waste charcoal dust.

Seeds of carefully selected
native trees

are mixed with the dust.

This carbon coat will protect
the seeds from hungry animals

until the rains arrive.

These are seed balls.

In the village of Kibwezi,

acacia trees
are becoming scarce,

cut down
by previous generations

to make charcoal.

But the students at this school

make forest restoration
child's play.

The nutrients
in the dissolving char dust

will give each little seed
a good start.

If only a handful of
these seeds grow into a tree,

the effort has been
well worth it.

Every mature acacia tree
can itself produce

thousands of seeds a year.

13 million seed balls
have been distributed

in Kenya alone.

And the methods
by which they are dispersed...

...are ever more inventive,
to say the least.

This technique is being
repeated around the globe.

A seed-ball-making workshop.

People are choosing seeds
of local native plants,

giving them
a little initial help,

and bringing
some wild plants back

into the world around them.

But is it possible,

even in our most extreme
monocultures,

to invite a bit of wildness in?

And with it,
a bit of resilience?

I have two different kinds of
forage growing in my orchard.

The yellow
that you see behind me

is a variety
of different mustards,

and then after the bloom,

we're going to see
some clover blossom.

This mix of plants
means the bees can feed

before and after
the brief almond bloom.

They also get a more
balanced, healthier diet.

In the meantime,
it's going to provide habitat

for all sorts of insects,
and the bees,

probably some rabbits.

It's a step towards
establishing a better,

more stable system.

It's about finding balance.

That's what we're trying to do
here.

Find a balance.

Can humanity globally find
a new balance

between wild plants

and those
we have domesticated?

Around half the usable land
on Earth

is taken up by agriculture.

Do we really need that much?

Maybe not.

It's a remarkable fact,

but around 80%
of all cultivated land

is used for raising livestock
for us to eat.

Raising animals can be
a sustainable way

to create food,
but in many places,

plants can produce
the same amount of protein

on a fraction of the land
that animals need.

What could it mean
for wild plants

if the global balance
between plant eating

and meat eating shifted?

It may sound odd,

but the more plants we eat,

the more space there will be
for wild plants.

Remarkably,
it's possible to restock

even highly degraded land
with wild plants.

In Brazil, the needs
of cattle ranching

drive most deforestation.

30 years ago, the owners
of one former cattle ranch

wanted to restore their land
to the Atlantic rainforest

that once covered it.

They had no idea
if it could be done.

The land was so bare
and eroded.

But they were determined
to try.

First, they cleared
the introduced

African cattle grasses,
invasive plants

that outcompete
most of the native plants.

The grasses were replaced
by seedlings

grown from seeds gathered

in nearby remnants
of Atlantic rainforest.

The Earth Institute,
or Instituto Terra,

as the ranch is known now,
was encouraged by early success

and expanded its scope
and ambition.

In five years,
trees covered the land again.

And within ten, it was clear

something remarkable
was happening.

When rain falls,

it now no longer
simply runs off the land,

leaving it parched.

Instead,
it clings to the plants,

to every root, stem and leaf...

...and then slowly filters
to the forest floor.

And so previously dry streams

burst into life
for the first time in decades.

The Institute never introduced
animals or plants

other than the trees.

The animals came back
on their own.

Small ones came first.

And then, very recently,

camera traps left in the forest

captured images beyond
the hopes of everyone involved.

A maned wolf.

An animal that is being driven
from its native habitat

by deforestation,
drawn to its favourite plant,

the wolf fruit tree.

Not only that...

...a puma.

With cubs!

The arrival of these precious
top predators and their young

shows what can happen

when we make space
for wild plants.

We have for centuries
robbed wild plants

of the space and time
they need to thrive.

That has certainly not been
to their benefit.

Nor, ultimately, is it to ours.

Our relationship with plants
has changed throughout history.

And now it must change again.

Whether it's what we eat
and cultivate

or whether it's what we like,

we must now work with plants,

and make the world
a little greener,

a little wilder.

If we do this,
our future will be healthier,

and safer,

and in my experience,
at any rate, happier.

Plants are, after all,
our most ancient allies,

and, together, we can make this
an even greener planet.

Throughout the Human episode,

the Green Planet crew sought
to capture the lives of plants

confronted
with the human world.

But they also heard the stories

of people deeply connected
to the plants around them...

...such as those
at the front line

of the battle to save Hawaii's

native endangered plants
from invasive species.

If we don't get a handle
on miconia,

we could lose everything

that makes Hawaii
special and unique.

But before
the Green Planet team

could start work,
they had to undertake

some rigorous preparation.

We're going into somewhere

that has very... It's a very
sensitive ecosystem,

they're trying to protect it
from invasives.

Filming in a place so ravaged
by invasive species

meant they had to be 100% sure
that they were not spreading

any non-native stowaways
themselves.

They had to scrub and disinfect
every item of equipment.

With kit clean, the team
first focus on filming

the rare holokea plant...

...accessible only on foot.

There are few pristine areas
like this left in Hawaii.

Only 40% of the land
still has native vegetation...

...most of it wiped out
by invasive species

like miconia.

Next on the list

was to film the team
waging war on miconia,

known locally
as the purple plague.

For crewmember Aja,
the work is not just

a physical battle
against this invasive species -

it's deeply personal.

I've been to the pristine area,

so I know what it looks like
and feels like, you know,

to be in the presence

of all that mana
and spirituality.

Those aren't just plants.

Those are ancestors' spirits,
you know?

Controlling these invasive
plants is a relentless job,

and Aja is not just doing this
for native Hawaiian ecosystems,

but also to protect
her ancestral relationship

to this fragile landscape.

So going to do this, it feels
good just to hack them,

and pull them out and be like,
"Yeah, OK, take that,"

you know?
We can sort of fight back.

Aja's fierce passion
to protect these native forests

is evident.

But the purple plague
has spread

to places Aja could never reach
on foot.

Taking to the sky
is the only way

to reach the front line
of this battleground.

With only enough fuel
to stay airborne for two hours,

the window for capturing
this aerial battle

is uncomfortably small.

We have one day of doing
the heli operations.

The weather could
completely mess us up

if we get a system
that comes in.

Heli-to-heli is always
dangerous and difficult.

This flight is not just tense
for Lis.

For plant sniper
Brooke Mahnken,

these short flights

represent his only opportunity
to hold back the invasion.

Miconia left unchecked
can be terribly damaging.

The potential for

one seeding plant,

if it were to get far away
from the population,

reach maturity
and put seeds out,

then it's starting
a whole new infestation.

And once it occupies
that entire area,

then it's completely
wiped it out.

The helicopter
is really important

because you can fly
in extreme terrain

with these, like,
1,000-foot cliffs,

and find miconia that
there would be no other way

to get to these plants.

The miconia team are used
to the aerial challenges

of this battle,
but for producer Lis,

the pre-flight talk
from the helicopter pilot

brings home the lengths
that this team go to

in order to complete
their work.

So you're just going to be
in the back here,

and it's a hurricane
in the back seat.

Literally a hurricane.

So nothing loose, you don't
want to put an arm, a head,

a leg or a hand out.

It's just going to blow
behind you.

You don't want
to stick your head out

because if the headset
comes off,

then it's into the tail rotor
and then it's bye-bye, Maui.

Pre-flight checks completed,

the clock is now ticking
to get into the air.

This matters so much
to everyone here.

I definitely feel the pressure
to get this right.

The first thing I want to do is
get some close-ups of the HBT,

because that's going to be
the most challenging thing.

Let's go find
some plants, please.

To get within shooting distance
of the plants,

the helicopter pilot
must carefully manoeuvre

into one of the area's
deepest canyons.

See this light-coloured rock?

- Yep.
- Follow that up

to the right to see it.

The target is in sight.

Yeah, there he is.

OK, I'm, uh...
I'm live and ready.

With high winds gusting up
from the waterfall,

getting into position is tricky
enough in one helicopter,

let alone two.

To give Brooke the best chance
of hitting the miconia,

the pilot must get him
within 20 metres of the plant,

and ideally at eye level.

Any missed shot threatens
to become friendly fire,

harming the species
he aims to protect.

- Ready?
- Yes.

Here we go.

Brooke must strike
the stem of the plant

to have the best chance
of completely killing it.

Oh, my God! Nice one!

Yeah, it worked really, really
well. Thanks, guys.

This has been
a successful mission

for both teams.

The pilot's skills
and Brooke's sharp-shooting

have saved
another patch of forest,

and Lis is relieved that
she has the shots she needs

to do the story justice.

It's over!

It's over.

It just looked amazing.

Lots of...

Yeah, it looks good.

It looks good.

For Brooke and Aja, however,
their work doesn't stop.

Just holding back the tide
of invasive species in Hawaii

is more than a lifetime's work.

But Aja believes
that her fight is worthwhile.

Everything we do
is for the next generation,

just like our ancestors
and kūpunas.

It wasn't for them,
it was for the next generation.

And just to have my kids
going to areas, like,

where they can see
there's still natives,

where we don't have
to go through

all this invasive vegetation.

You know, it's not
just my responsibility,

it's everyone's responsibility.

You know,
the Earth takes care of us,

so we have to do the same.
We can't just...let it go by.

We've got to take care, too.