All language subtitles for BBC.Natures.Microworlds.07of13.Canadas.Coastal.Forests.720p.HDTV.x264.AAC.MVGroup.org Eng

Our planet is the greatest
living puzzle in the universe.

A collection of
worlds within worlds.

Each one a self-contained ecosystem,
bursting with life.

But how do they work?

The intricate web of relationships

and the influence of natural forces

makes each microworld

complex and unique.

So, to discover their secrets,

we need to explore them one by one,

untangle their interlocking pieces

and ultimately reveal
the vital piece -

the key to life itself,
hidden deep within

each of Nature's Microworlds.

In the remote temperate region
of the Pacific Northwest,

there's a remarkable ecosystem.

Canada's coastal forest has
some of the largest trees on Earth,

and they reach right down
to the shoreline.

But that's not all.

This place is also
jam-packed with wildlife.

This coastline is an extraordinary
merging of land and sea

which showcases some of nature's
greatest living spectacles.

The forest is home to iconic species
like bears...

..eagles

and wolves.

In fact, these coastal areas

are such great habitat
for these top predators

that they're here in some of the
highest densities on the continent.

Winters here can be harsh

with blanketing snow
and very little sunlight.

Yet this forest is one of
the most productive in the world.

The sheer volume of plant material
this forest accumulates

outweighs even some of
the world's tropical rainforests.

So, where do
all the nutrients come from

that allow the trees of this forest
to get so big?

This coastal forest stretches
for thousands of kilometres

along the North American coast -

from Northern California right up to
Canada and southern Alaska.

It's a landscape forged by glaciers

and bordered by a mountain range
stretching right along the coast.

And to its west
sits the Pacific Ocean.

Thousands of kilometres of water

that floods in to fill
sheltered inlet and bays.

This microworld
is more than just a forest.

And to see just what it is
that makes this place tick,

we'll need to explore
all of these parts.

In the North American Coastal
Forest, there's one thing -

or rather a few million things -
that dominate the landscape.

Spruce, cedar,

fir trees and redwoods
tower above the forest floor.

These trees are huge.

Many are 70 metres tall

and some are over 1,000 years old.

But the great coniferous forests
of North America

are more than just trees.

They're homes for squirrels...

..rich hunting grounds
for pine martens...

..and nest sites for
Great Grey Owls to raise a family.

There are top predators here too,

and the generally solitary
brown bear

can live here in surprising numbers.

These brown bears
managed to put on so much weight

that they've become
the largest in the world.

Another top predator
thrives here too - the grey wolf.

This population
has become particularly adapted

to living in this unique
forest environment.

Each in their own way, these animals
depend on the giant trees

that stretch for thousands
of kilometres along this coast.

These trees are actually
some of the largest living things

on the planet,
and they're still growing.

But how do they get so big?

Trees need nutrients in the form
of phosphates and nitrates to grow.

These are essential building
blocks that fuel growth -

and WHAT growth!

Each tree can weigh
over 150,000 kilograms.

And to get to this size, more than
a million kilograms of nutrients

are drawn up by the trees
in this forest every year.

But with so many trees, the
available nitrates and phosphates

are soon locked up
in the forest's living tissue.

So where do these building blocks
come from to make giant trees?

It's too wet for forest fires that
might release nutrients in ash,

so the only way trees
get recycled here

is when strong winds and old age
put an end to a giant's life.

CREAKING

CRASHING

The nourishing chemicals locked up
in its tissues provide a feast

for decomposing lichens and fungi,
which gradually break it down

and return the life-giving
elements into the soil.

Thanks to the nutrients
provided by these decomposers,

these small seedlings might still
be standing in 500 years' time.

This slow process of death, decay
and recycling feeds the new life

that colonises gaps
on the forest floor.

But the death of one or two trees

cannot justify this microworld's
prolific growth.

The nutrients that feed these trees
must be coming from somewhere else.

To find it,
we need to go beneath the canopy

and get to know some
of the animals in this forest.

Our journey begins in November

when the ice-cold grip
of winter is setting in.

The cold can make this one
of the toughest times of year

for the animals in this forest.

But there's still life here.

SQUAWKING

Bald eagles weather out the winter
months in this coastal forest.

The eagle is another of the forest's
top predators.

And in winter, these eagles
group together around

the open waterways on the lookout
for carrion and live prey.

These are the largest congregations
of bald eagle

found anywhere on Earth.

The flowing rivers full of fish
provide food year-round,

allowing the eagle to prosper
in the freezing conditions.

But few other animals are so lucky.

Amongst the trees,
bears are nowhere to be found.

They've escaped the brunt
of the weather and have retreated

to dens in the mountains.

But this freeze
doesn't last forever.

With the arrival of spring,

the North American days
begin to lengthen.

Up in the mountains
on the eastern flank of the forest,

the bears are now emerging
with their newly born cubs.

BEARS BARK

The cubs were born
in the heart of winter,

and this is their first journey
outside the den.

They're still finding their feet
on the slippery slopes

that descend down to the forest.

The adult bears might not have
eaten for over half the year,

yet in the next few months,
they can pack on

an impressive 100 kilograms,
and in this forest, they thrive.

Bears are capable predators,
but they're also opportunists,

able to eat a massive range of food.

And they even eat grass.

But for the bears, perhaps the
best thing about these forests

is that they're right on the coast.

Bears that are after any protein
they can find

are able to walk right down
to the sea to find food.

BEAR SNUFFLES

Here, bears can find valuable
protein from clams

that they dig up on the sandy shore.

And there's plenty more food
available on the shoreline.

As the tide goes out,

other forest creatures
take advantage of the shallows.

With forest cover just metres away,

racoon families catch crabs
in the draining pools.

These morsels of food gathered along
the shoreline by forest creatures

are a hint to the potential
nutrients that the Pacific Ocean

can offer this forest.

For now, bears and raccoons
must resign themselves

to foraging at low tide.

But the ocean has an important part
to play in this forest's story.

And its great productivity
may just hold the key

to the nutrients
that feed this forest.

To understand this,

we need to take a look at just
how spectacular this ocean is.

And this will help us see

just how the ocean nutrients
might be getting onto land.

It's now early spring, and the
warming waters attract herring

from the open Pacific Ocean to
the bays and inlets along the coast.

And they gather in their millions.

It's an event that doesn't escape
the attention of predators.

Sea lions head towards
the commotion...

..and dolphins move into position.

The herring attempt to confuse
their assailants

by schooling together
in great shoals.

But attack comes from all angles.

Herring are considered a keystone
species along this coast,

a species so important that
the whole system could collapse

if they were removed.

SEA BIRDS CRY

One massive creature has travelled
over 4,000 kilometres to be here.

The humpback whale.

Although thousands of humpbacks
migrate here in the spring,

only a few have developed
a neat predatory trick.

WHALES SING TO EACH OTHER

Working together, these humpbacks
use circular streams of bubbles

and loud calls to corral the fish
into tighter and tighter balls.

WHALES CALL OUT TO EACH OTHER

Lunging up from beneath,
their huge mouths engulf their prey.

Humpbacks have to eat 1,500 tonnes
of food a day.

And these herring provide
about 20% of the food they eat

along this coast
over the spring and summer.

The whales don't feed over winter,

and the herring
provide essential energy

before they begin their long
migration back to the tropics.

With such a swathe of predators,

it seems madness that the herring
come to this coast at all.

But they need this coastline
for the future of their species.

The coastal winds pull nutrient-rich
water from the ocean depths

into the inlets and bays...

..and these fertile waters turn
green with the plankton bloom.

These vast quantities
of microscopic plants and animals

are potential food
for thousands of tiny mouths.

This is why the herring are here.

But the adult herring
haven't come here

so that they can eat the plankton,
but so that their offspring can.

They're here to breed.

In a spawning frenzy,
females coat the leaves and rocks

along this coast with eggs

and the males follow with
a fertilising liquid called milt.

The small eggs are just over
a millimetre across

and with each fish producing
up to 130,000 of them,

they can coat rocks and vegetation
more than 20 layers thick.

Coastal birds are quick to respond.

Gulls pluck eggs from the shallows.

And huge flocks of migrating birds
feast as they journey northwards.

The herring and their eggs
provide huge amounts of food

for animals along this coast,

allowing the nutrients in the open
ocean and the plankton bloom

to reach the land.

But the fish and eggs are just
a thin layer of potential nutrients

that sit right on the shoreline.

Their influence doesn't travel
far into the forest.

Forest animals like bears and wolves
unable to join in the herring feast

can only wait patiently
on the beaches.

For hungry forest animals, life
can become a bit of a waiting game.

As the summer arrives, the surviving
herring move off into deeper waters.

But the key to this microworld
is still out at sea

waiting for the rains.

As the sea warms, the Pacific winds
carry water drawn up into clouds

towards the North American coast.

WIND BLOWS, THUNDER RUMBLES

The gathering clouds
hit the coastal mountains

and release their moisture as rain.

And lots of it.

The forest is showered with three
to five metres of rain every year...

..filling the rivers into torrents.

WATER ROARS

Their tributaries spread
like arteries

winding deep into the forest.

The flowing rivers carry the
nutrients that trees need to grow

out of the mountains, out of
the forest and into the ocean.

So there must be
one last piece to the puzzle.

The key that allows
the nutrients to flow

from the highly-productive ocean
into the forest.

It's a fish that's building up
in numbers

along the North American coast.

Salmon.

These five species of Pacific salmon
may have travelled

more than a thousand kilometres
from the open ocean

and are reaching
the end of their journey.

These mature salmon have spent
their adult lives in the ocean,

building up their muscles
and fat reserves

for this one final
reproductive moment.

Mature salmon come to this coast
every year to breed,

but unlike the herring,
which spawn along the coast,

these salmon adopt a bizarre
reproductive strategy.

A strategy which underpins the
productivity of this entire forest.

They switch their biology,
moving out of the ocean

into the freshwater streams
along the North American coast.

These fish will travel sometimes
hundreds of kilometres in land

to the rivers of their birth and
only there will they lay their eggs.

But the rivers running through
these forests can be treacherous.

Such huge parcels of protein
from the ocean don't go unnoticed.

Bears line the rivers.

These normally solitary predators
congregate in huge numbers.

You can find 25 individuals
on a single waterfall.

But space at these busy falls
is at a premium.

Mothers with cubs
are often relegated

to the quieter sections
of the river,

where young bears can learn
the art of catching a salmon.

Catching salmon in deep water
can be a challenge,

even for the experienced.

Most of the salmon arrive in autumn
when the bears are preparing

to retire to the mountains
for another year.

This is the bears' big chance

to put on body fat
before the winter sets in.

The fish feast is the key reason

why these bears do so well
in this forest.

There's no coincidence
that there are so many bears here.

Without the salmon, nine out of
every ten bears in this forest

would probably not be here at all.

Bears are messy eaters,

and their scraps become food
for other forest creatures.

Grey wolves which normally hunt
animal like deer

join the bears feeding
along the riverbanks.

They're more than capable
of catching salmon themselves,

but often let the bears do the
hard work and turn to scavenging.

The wolves of this forest have
developed such a strong relationship

with the coast that they barely
venture beyond its limits.

This isolation could start them
on the slow path

towards becoming
a new wolf species -

the coastal wolf.

These wolves are not isolated
on an island or in a valley,

but instead isolated
by their unique behaviour.

It's a life that's centred
around the coast

and the habits are passed on
from mother to young.

It's just another reminder
about the importance

of the marine ecosystem
to the thriving of life here.

But it isn't just the bears
and wolves that rely

so heavily on the salmon.

Larger life forces in this forest
depend on the salmon too.

But the bustling rivers full of fish
are no use to them yet.

The forest's waiting game continues.

The surviving salmon move on...

..driven by raging hormones which
have now turned many of them red.

They travel far into the forest,

some for over 1,000 kilometres,
into the tiniest streams.

Their incredible sense of smell
carries them to the stream

where they themselves were born
and where now,

they'll mate and lay their eggs.

This is their ultimate sacrifice.

With their eggs safely tucked away
on the riverbed,

their one-way journey is at an end.

They've exhausted themselves
to get here

and invested
all their energy reserves.

Their wasted bodies
can swim no more.

Salmon carcasses
sprawl across the river,

but this seemingly useless death
is not wasted.

These carcasses represent
the massive injection of nutrients

that the forest ecosystem
has been waiting for -

the nutrients
that are the elements of life.

Even in death, the salmon
feed the animals of the forest.

Carried onto land by scavengers,
salmon become soil.

Their nutrients
seep into the water table

and it's now the trees' turn
to feast on the salmon.

These are the nutrients
that drive the coastal forest

and the super-sized trees
grow fast, tall and strong.

But the death of the salmon
is not a completely selfless act.

The nutrients in their bodies
feed the streams,

they feed algae and insects...

..that will be a miniature feast
for the tiny baby salmon

that will emerge the following year.

The next generation of nutrient
messengers that will live out

their adult lives in the ocean

and will one day return to this
same spot in the riverbed

to make the ultimate sacrifice
of their own.

Life on every level, from mosses
to lichens, trees to animals,

flourish in this coastal rainforest.

The trees close to salmon streams
grow taller and faster.

The forest animals have more food

and live in higher densities
in these forests.

Some have even become
so tied to the ocean

that they are truly becoming
coastal specialists.

The secret of this forest's success
doesn't come from the land at all,

but from the riches of the Pacific
Ocean sitting just offshore.

This is a forest
fuelled by the ocean.