Original subtitles

[♪ dramatic music playing]

In the largest forest on Earth...

life can be brutal...

and bone-chilling.

Here, animals have evolved superpowers...

...and trees talk to each other beneath the soil!

This forest holds a magic so potent, it can tame wild beasts,

join forces with predators,

and ultimately determine the future of our entire planet.

This is the story of our Boreal Forests.

Take a journey

through our planet's kaleidoscope of forests realms.

From the frozen boreal in the north...

to the tropical jungles that hug our equator...

from mountain peaks...

to the ocean depths...

Marvel at the magic and drama,

that unfolds...

as we reveal the Secrets of the Enchanted Forests.

[enchanting music]

[majestic music]

In the far Northernmost reaches of our planet,

on the edges of the Arctic circle...

...a swathe of evergreen forest

wraps around the Earth like an emerald crown.

This is the 'taiga', or Boreal forest.

named after Boreas, the Greek god of the harshest of winds.

This wild and brutal realm is home to the reindeer,

an icon of the boreal snowscape.

[reindeer puffs]

This is no ordinary herbivore.

These arctic specialists

are equipped with seemingly supernatural abilities,

enabling them to conquer their frozen world.

[birds tweet]

The reindeer have spent the winter months among the trees.

Soon, this heavily pregnant herd

must leave the forest's protective embrace,

and embark on an epic migration.

They have three weeks to reach their birthing grounds,

Hundreds of kilometres away in the mountains.

But before they leave their wooded sanctuary,

they must build up their reserves.

Beyond the forest,

the reindeers' passage across the tundra

lies under an expanse of white.

There will be little to eat here during wintertime.

[wind blows]

But within the trees,

the conditions are just right to grow a precious superfood.

An all you can eat buffet of lichen.

This exquisite combination of fungi and algae

creates the perfect blend of nutrients and carbohydrates,

to fuel the reindeer on their journey.

[enchanting music]

The trees act as willing hosts to the lichen,

in return for a powerful, life-giving substance

captured from thin air.

Lichen spins nitrogen from the atmosphere

into a form that the trees can absorb.

A rare treat in this frozen landscape.

Much of the lichen lies shrouded in snow,

but that's not a problem for the reindeer...

They have evolved a special kind of vision.

Their eyes see a spectrum of light

that few other mammals can see.

Anything that absorbs ultraviolet light from the sun,

appears black to the eyes of the reindeer.

All they need to do is uncover this hidden bounty.

With reserves replenished,

the herd begin their exodus to their summer pastures.

[reindeers grunt]

Without the protection of the forest,

the pregnant reindeer are now exposed and vulnerable...

And predators know it.

Now that the reindeer are out in the open,

the forest's allegiance has shifted.

The trees that once offered the herd protection,

now provide cover for the enemy.

This pack of wolves is poised for an ambush.

But their pale fur,

their secret to blending in against the snow,

is rendered useless when it comes to outsmarting reindeer.

Their coats absorb UV just like the lichen.

In reindeer vision,

a wolf stands out as a black shape against the white snow...

Eliminating any chance of a surprise attack.

The reindeer's superpowered vision

gives them the edge in this wintery realm,

and sets them apart from every other species of deer.

It feeds them and ensures a safe passage for the herd

and the unborn calves they're carrying.

[soft music]

Finally, after a perilous 240 kilometres,

these reindeer have arrived, exhausted but safe.

A nutritious banquet of herbs,

grasses and sedges now awaits the hungry herd.

[reindeers grunt]

This marks the start of new beginnings.

The newborn calves will fatten up on the tundra,

their summer paradise.

Within a few months they'll have gained the strength

to accompany their mothers on the return journey home.

Back to that same boreal forest

that has sheltered the herd for generations.

They'll need its shielding embrace

if they're to survive their first winter

in the frigid North.

These evergreen trees, draped in their winter finery,

are as far north as trees get.

Their ability to survive here is nothing short of miraculous.

Their classic look and graceful shape belies their true grit.

Each trademark characteristic...

each minuscule detail...

has evolved to take on the Arctic's icy powers.

For some of these evergreens,

100 years might bring only 20 centimetres of growth.

Height isn't the goal for these trees.

Instead, it's shape and substance that really matter.

The trees' leaves, or 'needles', are dark and narrow,

designed to absorb as much

of the weak winter sunlight as possible.

Their waxy texture

helps retain what little liquid water there is.

Inside, special proteins work as an antifreeze,

keeping the trees' internal mechanisms functioning

when temperatures drop well below zero.

And that classic Christmas tree shape we know and love

is there for a reason.

Their flexible branches slope downward,

so any heavy bouts of snow... simply slide off.

Unfrozen,

unbroken

and unrelenting,

these trees are the hardcore tough guys of our boreal forest.

For most, winter is the toughest period of all

in a boreal forest.

But for one tiny resident, it can't last long enough.

During the long, cold season,

a blanket of thick snow carpets the entire forest floor.

For this deer mouse, it's his favorite time of year.

He is at the bottom of the food chain in this forest,

and lives his life in hiding.

But in winter, the forest gives him a helping hand.

Beneath the hardened snow,

undulating tree roots and shrubs form air pockets,

creating a labyrinth of mouse-sized tunnels.

Down here it's much warmer,

and any sound he makes is muffled by his icy walls.

He has plenty of roots and stems to feed on

and can happily stay stashed away all season.

The only thing his bunker lacks is fresh air,

so he must make sure his home is well ventilated.

But in this forest, an open door is seen as an invitation.

This pine marten uses his keen sense of smell

to locate the mouse's burrow.

But the mouse has prepared for this.

[ominous music]

The mouse uses the tangle of tunnels to outwit his pursuer.

All it takes is one wrong turn

for the marten to come out empty handed.

Safe... for now.

But, when spring arrives...

everything changes.

The forest's cloak of protection melts with the snow.

Now a mouse's every move,

every sound,

is music to the ears of nearby predators.

[dramatic music]

And there is no longer anywhere for them to hide.

[squeaking]

For the great grey owl, this reversal of fortune

couldn't have come at a better time.

Their newly hatched chicks will be raised on a diet

of the now exposed mice and voles.

[chicks tweeting]

The change in season

has drastically altered the playing field.

Now, these aerial predators hold the power.

But maybe not for long.

As the days warm up,

ground plants will begin their short growing period,

and the forest will once again be able to provide

just enough cover for all their ground scurriers.

As long as they keep quiet...

There's more than one hidden labyrinth in this forest.

Beneath the soil

lies an even greater network of connections.

A secret place where trees talk, share.

and sometimes even try to poison each other.

Trees may appear as silent, impassive sentinels,

but underground lies a very different story.

The trees' roots

are plugged into a vast web of fungal strands,

stretching out below the entire forest.

The fungi provide the trees

with nutrients absorbed from the soil,

and in return the trees feed them sugars.

But the trees are using this 'wood wide web',

for a far greater purpose...

To talk to each other.

Using their own social network,

older, more robust trees can send food and water

to those in need of a boost.

They even use this underground matrix

to protect each other from harm.

Distress signals are dispatched through their roots

to warn surrounding trees of impending dangers,

triggering them to launch their own internal defences.

These seemingly selfless exchanges are life-sustaining.

But like our own internet...

the forest has a Dark Web,

where users exploit the system for their own selfish gains.

Bilberry plants maliciously spread toxins,

sabotaging their rivals in a quest for more light and space.

And others, like this orchid,

use these connections to steal food from their neighbors,

offering nothing in return.

But, for the majority of trees,

this vital partnership turns a group of individuals into

a thriving woodland community.

Even the quietest forest is as bustling as a city -

just under the surface!

[enchanting music]

At the southerly edge of the boreal forest,

the dominance of the pine tree starts to wane.

Here, species such as Birch and Aspen

are welcomed into the boreal family,

and could even be responsible for turning a top predator...

into a teddy bear.

[bear growling]

Just south of the Canadian border,

some wide-eyed residents are out exploring

for the very first time.

The lives of these playful cubs will be shaped

by their forest environment...

[cubs barking]

...just like the lives of their parents!

Their whole character has been shaped by it too.

Could it be that a black bear's tree-dwelling lifestyle

has made them less aggressive than their brown bear cousins?

Caring for vulnerable cubs

is the ultimate test of a bear's personality.

Over the next few years,

this bear mum will devote her life to raising her little ones.

There are two pressing life skills that she must teach them.

The first is to find food wherever you can.

Like all forest dwellers,

bears know that the best food is seasonal.

In this mix of broadleaf and pine forest,

they couldn't be better provisioned for.

Non-native dandelions are a particular favorite -

highly nutritious, succulent,

and easy for a young bear to digest.

But their picnic is about to be interrupted.

This lone male has picked up the family's scent.

[bear growling]

At this time of year,

he is only concerned with two things...

food... and mating.

He wouldn't hesitate to kill the cubs

if it meant he could breed with their mum.

So mum distracts the determined suitor,

giving her cubs the time

to implement their second life skill:

climbing!

Within seconds, the cubs are out of immediate danger.

And mum can calmly deflect any unwanted attention

without a fight.

Black bears are incredibly adept climbers.

Their curved claws,

strong forelimbs and comparatively small size

mean they can find sanctuary or a playground

amongst the trees.

Unlike their larger brown bear relatives,

who prefer to keep their feet firmly on the ground.

Their temperaments are very different too.

Brown bears prefer the richer food sources

of the open prairies and meadows.

So, when a brown bear faces a threat, with nowhere to hide,

their only option is to stand their ground and fight.

[bears growling]

Whereas the black bears stick to the forest,

where cubs can flee to safety

and mama bear can afford to be a little more relaxed.

Each species of bear has developed a different approach

to protecting their family, based on their chosen habitat.

By sticking to the forest with its easy escape routes,

black bears don't have to be as aggressive

in the face of danger.

Here amongst the trees,

the best mothers prove to be the climbers, not the fighters.

[enchanting music]

If the boreal forest wields enough power to placate a bear,

what could it do for us?

When you wander through a pine forest,

you can be forgiven for thinking there's magic in the air.

The scent of pine not only smells great,

but it can also influence the weather,

and improve our own physical and mental wellbeing.

That distinctive pine fragrance is made from special compounds

known as terpenes, in the tree's resin.

But that heady aroma is merely a by-product.

On hot sunny days,

these terpenes are released into the atmosphere.

The tiny floating particles refract

and scatter the sun's rays in all directions.

Ensuring the sun hits

as many of the trees' needles as possible...

doubling their chance of capturing its energy.

And if it gets too hot,

the particles can also react with rising water vapor,

conjuring up clouds...

...and providing the forest with its own bit of shade.

Collectively, the trees are changing the Earth's atmosphere

to suit themselves.

But it can benefit us humans too.

Stretching out into the breeze,

pine needles dramatically increase a tree's surface area.

Thousands of needles

act like a giant air conditioning unit for the north,

trapping pollen and pollutants on their surfaces,

and absorbing dangerous gases through their pores.

Filtering the atmosphere in the process.

It's so effective, that every year,

one square mile of forest

can remove up to 20 tons of particulate matter.

As we inhale that clean air,

we are also receiving a dose of complementary medicine

straight into our lungs.

The terpenes produced by coniferous trees

are proven to reduce inflammation,

increase antibodies to fight off disease

and ease stress and anxiety.

So take a deep breath...

a walk in these woods has never felt so good.

One of the boreal's largest

is on his yearly mission to bulk up,

and build a set of antlers, forged from salt.

After a lean winter, the forest springs back to life.

For this bull moose, it's all about getting in shape,

as this year he's keen to find himself a mate.

He uses the forest like a living kitchen pharmacy,

purposefully seeking out the nutritious meals,

supplements and remedies

that will help him to reach peak condition.

First, he spends his days building body mass...

devouring tender young saplings,

tearing off newly sprouted foliage,

and freshly grown stems.

But beefing up is only a part of the job.

To really impress the females it's all about his antlers.

The bigger, the better.

Antlers are made from fast-growing bone.

They expand at the rate of an inch a day,

and are fueled by large quantities of salt.

To find this vital mineral,

he leaves the trees and heads to the ponds.

[splashing]

As aquatic plants contain more sodium

than any land plants.

And to give him an extra edge over his rivals,

he ventures out on the highway.

He's learned that the roadside vegetation here

has been sprayed with salt by the gritter trucks

throughout the winter,

providing a sneaky boost for his growing rack.

By the height of summer,

his fur coat covering his now muscular frame,

makes this an uncomfortable time of year.

Moose do not sweat,

so he splits his time

between chilling in the meltwater pools...

and looking for plants rich in calcium,

which he now needs to strengthen his new antler growth.

By the time autumn arrives,

the benefits of his carefully balanced diet have paid off.

He and his antlers are in tip top condition.

Ready to warn off rivals and impress potential mates.

Well, they would be...

if he could find a female interested enough

to fight over...

[moose vocalising]

After all that effort,

his mating season...

has been woefully uneventful.

There's always next year.

He discards his precious antlers

to save energy over the leaner winter

and heads into the hills.

Up here, he targets sapling bark and needles,

as they're far sweeter than the old growth pines.

But once denuded of their protective outer layer,

the young trees are unable to recover in the cold.

To fuel their seasonal demands,

moose are gradually transforming the face of this forest.

Every sapling eaten, means one less tree.

And a forest needs to regenerate to survive.

It's an age-old balancing act

between healthy growth, and hungry residents.

To help maintain that balance, the forest needs an ally...

There is a special group of animals

that can counteract a moose's voracious appetite,

and in doing so, can revive the forest

and even the planet!

In the dead of winter...

herbivores will consume every last bit of sustenance

a tree has on offer.

But too many mouths browsing in one place

can devastate a tree beyond repair.

The forest needs the herd to move on.

[wildlife sounds]

And there is one thing...

that never fails to get them moving.

[ominous music]

Predators.

Their presence casts a spell over the forest,

creating a landscape of fear.

Herbivores are forced to live their lives on the run.

This fear of getting caught helps the forest.

A fleeing herd spreads its grazing further afield,

giving plants and trees the respite they need to recover.

And the predator's own need to feed

means fewer mouths for the forest to support.

This predator-prey relationship

could even be part of the solution

to some of our man-made problems.

In North America, a boreal forest with wolves

can capture more harmful carbon from the atmosphere,

than one without.

Their presence can be likened to removing the emissions

of 71 million cars from the roads, every year!

Simply by chasing their prey.

[majestic music]

Far from being the bad guys,

these predators contribute a great deal more to life on Earth

than they take.

The boreal ecosystem in perfect harmony is a powerful force.

As a healthy, flourishing forest,

it can offer sanctuary,

sustenance,

a wealth of opportunities,

and a brighter future for our planet.

[music]