All language subtitles for BBC.The.Green.Planet.5of5.Human.Worlds.1080p.HDTV.x265.AAC.MVGroup.org

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,

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 start
to develop,

its behaviour changes.

For 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 north-east 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
2.5cm 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 30cm
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 seed head, 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 on to 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 in to.

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 faced drought.

Fewer and fewer plant species,

like soy, wheat and rice,

now occupy more and more land.

And 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 needs 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.

ENGINE REVS

MACHINERY WHIRS

LOUD BUZZING

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,

2.5 trillion flowers
have been successfully pollinated

and will now grow in to
2.5 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 are 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 seeds 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 volcanoes,

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 in to airtight jars.

Seeds are then brought underground
to be stored in a vault,

like this one, at -20C.

Since the bank was founded,

two 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
native Hawaiian 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 ten 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 paint balls 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

and, yeah, the plane will fly and
you might be able to take a couple

of 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 or 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.

'I'IWI BIRD CALLS

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're dispersed...

..are ever more inventive,

to say the least.

This technique is being repeated
around the globe.

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.

And 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, and
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...

YAPS

..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 a 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 crew member Aja,

the work is not just a physical
battle

against this invasive species,

it's deeply personal.

I've been to the pristine areas,

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 through this, it feels
good to hack 'em

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 Liz,

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,
1,000ft 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
Liz,

the pre-fight 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
ahead, a leg or a hand out

cos it's going to blow behind
you

and 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.

INDISTINCT SPEECH

To get within shooting distance
of the plants,

the helicopter pilot must carefully
manoeuvre in

to one of the area's deepest
canyons.

See the light-coloured rock?
Yep.

Follow that up, to the right.

You see it?

The target is in sight.

Oh, yeah. There it is.

OK, 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? Yeah.
Here we go.

Brooke must strike the stem
of the plant

to have the best
chance of completely killing it.

Whoa! My God, nice fire!

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

This has been a successful
mission for both teams.

The pilot's skills and Brooke's
sharp shooting

has saved another patch
of forest,

and Liz is relieved that she has
the shots

she needs to do the story
justice.

It's over. It's over.

It just looked amazing.

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 kupuna.

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

And just to have my kids go
into areas, like, where they can see

there are 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.

The Open University had produced
a poster

that explores the vital role
that plants have for our planet.

To order your
free copy, call...

or go to...

..and follow
the links

to the Open University.