The Magical Forest (BBC Documentary 2012)
-
0:06 - 0:11Ten million species live on planet Earth-
-
0:11 - 0:15Each one is remarkable-
-
0:15 - 0:21But none can survive on its own-
-
0:21 - 0:26All life depends upon connections.
-
0:26 - 0:29Unexpected, invariably complex,
-
0:29 - 0:38beautiful relationships between
millions of plants and animals. -
0:38 - 0:41This time, in our seasonal forests,
-
0:41 - 0:45why does this lynx need a caterpillar?
-
0:45 - 0:49Why does the tree need the fish?
-
0:49 - 0:54And why does this truffle fungus
need one of these? -
0:54 - 0:58Flying squirrel!
-
0:58 - 1:04Connections like these
form the planet's great ecosystems- -
1:04 - 1:08They're vital for all life-
-
1:08 - 1:53I want to show you our world
as you've never seen it before. -
1:53 - 1:56New England in autumn.
-
1:56 - 2:01There really can't be a more magical place
anywhere on Earth -
2:01 - 2:10to appreciate that dramatic transition
between summer and winter. -
2:10 - 2:14But we mustn't get blinded
by this natural fiesta, -
2:14 - 2:20because such an extreme transformation
is a huge challenge for life, -
2:20 - 2:29and autumn is just one of many
transformations the forest must face- -
2:29 - 2:34From summer to winter, this land of plenty
will appear to collapse, -
2:34 - 2:53before attempting to rebuild itself
all over again in the spring- -
2:53 - 2:55To see how, 1'm going to what is, for me,
-
2:55 - 3:07the greatest seasonal forest
on the planet- -
3:07 - 3:14The wooded wilderness that stretches
right across North America- -
3:14 - 3:16From the land of the Canadian lynx
-
3:16 - 3:25to the land of the grizzly bear-
-
3:25 - 3:39Our story begins in autumn-
-
3:39 - 3:48As the days are drawing shorter,
less light is feeding the forests- -
3:48 - 3:54Deciduous trees are shedding their leaves-
-
3:54 - 3:59Many creatures are burrowing away
to escape the cold- -
3:59 - 4:05And others are simply leaving-
-
4:05 - 4:10But there's one animal
with a crucial job to do, -
4:10 - 4:14now, before the winter sets in-
-
4:14 - 4:201t's a job the entire forest depends upon-
-
4:20 - 4:25The best time to see them is in
the first couple of hours after dark. -
4:25 - 4:28And what I'm hoping is
that if I stand here -
4:28 - 4:35and stay really quiet,
I'll be in for a real treat. -
4:35 - 4:491t's a creature 1've waited all my life
to see, but they move so fast! -
4:49 - 4:530h! Did you see that?!
-
4:53 - 4:56That was amazing,
it went right past my face! -
4:56 - 5:04Flying squirrel!
-
5:04 - 5:14They really are expert gliders-
They can glide for up to 2OO metres! -
5:14 - 5:18When I was a kid, I was obsessed
with things that were, you know, -
5:18 - 5:19not meant to fly.
-
5:19 - 5:23Flying fish, flying frogs,
flying lizards, flying squirrels. -
5:23 - 5:25And this is the first time
I've ever seen them. -
5:25 - 5:34It was worth a 45-year wait - honestly!
-
5:34 - 5:36Did you...? 0h! Did you see that?!
-
5:36 - 5:42I felt it, it went right through my hair!
Seriously! Centre parting! -
5:42 - 5:44It was like having a sheet of A4
coming right over my face, -
5:44 - 5:51and as soon as they hit the tree,
they're running and up they go. -
5:51 - 5:55They're just crisscrossing
all of the trees. -
5:55 - 5:59And they immediately scamper up to the
top and then take off and glide again, -
5:59 - 6:12and sometimes, I've noticed, they can
even change direction during flight. -
6:12 - 6:16Urgh! 0ne hit me in the chest!
-
6:16 - 6:18It doesn't come better than that, does it?
-
6:18 - 6:20It doesn't get more exciting.
-
6:20 - 6:25But what on Earth
have they got to do with our story? -
6:25 - 6:28Well, at the moment,
these flying squirrels are out and about -
6:28 - 6:30in the woods trying to find
as much food as possible -
6:30 - 6:33before the weather turns nasty
and the winter kicks in. -
6:33 - 6:40But what are they after?
Well, they're after these - truffles. -
6:40 - 6:42They're the fruiting bodies of fungi
-
6:42 - 6:48and they appear in the damp cool
of autumn- -
6:48 - 6:501n preparation for winter,
-
6:50 - 6:55the hungry squirrel needs to hoard food
such as truffles- -
6:55 - 7:06But the truffles also need
the squirrel to eat them- -
7:06 - 7:15As the squirrel moves through the forest,
the spores are dispersed- -
7:15 - 7:17And that's crucial-
-
7:17 - 7:26Not just for the truffle,
but for the trees- -
7:26 - 7:30What's so special about these truffles?
-
7:30 - 7:32They certainly don't look much,
-
7:32 - 7:35and the smell can be said to be
an acquired taste. -
7:35 - 7:38And they're not just here
as another organism to be eaten -
7:38 - 7:41by hordes of hungry squirrels either.
-
7:41 - 7:43Because without these truffles
-
7:43 - 7:46and all of the other fungi
here in the wood, -
7:46 - 7:51this woodland simply couldn't function.
It couldn't exist. -
7:51 - 7:52Why?
-
7:52 - 8:01Well, take a look beneath the soil
down here. -
8:01 - 8:05Each truffle has thread-like roots
extending from it- -
8:05 - 8:21The threads extract nutrients in the soil
from rotting material, like the leaves- -
8:21 - 8:23And, cunningly,
-
8:23 - 8:29they also tap into the roots of the trees
to siphon off sugars- -
8:29 - 8:33But this is not a one-way relationship,
because the tree -
8:33 - 8:44can now tap into the nutrients
extracted by the fungal threads- -
8:44 - 8:48This symbiotic relationship
between the trees and the fungus, -
8:48 - 8:53where each is dependent on the other,
clearly helps the tree grow, -
8:53 - 8:57but it's not only that.
It greatly extends the reach of its roots. -
8:57 - 9:02Because in effect, they become
as extensive as the fungal network -
9:02 - 9:06that they're connected to.
-
9:06 - 9:101n autumn, throughout the northern
hemisphere, trees use fungi -
9:10 - 9:15to extend their roots
and absorb sufficient nutrients -
9:15 - 9:24for the big freeze ahead-
-
9:24 - 9:271 love this little web of relationships-
-
9:27 - 9:29The squirrels, the fungi, the trees-
-
9:29 - 9:431t ensures that they're all ready
to face the winter- -
9:43 - 9:48But for me, one of the most
magical relationships of all -
9:48 - 9:51is seen on the far west coast of Canada,
-
9:51 - 10:08as one of the world's most ancient forests
prepares for the oncoming challenge- -
10:08 - 10:13Here, 1 can stand at the foot
of thousand-year-old cedars -
10:13 - 10:25and 9O-metre tall sitka spruce trees-
-
10:25 - 10:29The combination of large mountains
and ocean winds -
10:29 - 10:32generates unusually heavy rainfall,
-
10:32 - 11:09earning this place the title
the Raincoast- -
11:09 - 11:18There's so much rain in autumn
that the rivers are swollen- -
11:18 - 11:31And that is vital
to the forest's survival- -
11:31 - 11:34There's a significant event happening here
-
11:34 - 11:39which allows the whole forest
not only to survive the winter, -
11:39 - 11:42but also to flourish throughout
the course of the year. -
11:42 - 11:44But, you know,
the really incredible thing is -
11:44 - 11:49that this key to life is not here
in the forest at all at the moment, -
11:49 - 12:02but it will be soon.
-
12:02 - 12:05After years at sea,
salmon are returning to spawn -
12:05 - 12:13in the same forest streams
in which they were hatched- -
12:13 - 12:16And the swollen rivers
make it easy for them -
12:16 - 12:22to swim deep into the forest-
-
12:22 - 12:30But the scent of home also draws them
irresistibly towards danger- -
12:30 - 12:48Predators make the most
of this banquet of seafood- -
12:48 - 12:58But none of them compare
to the most formidable fish-eater of all- -
12:58 - 13:01Grizzly bears!
-
13:01 - 13:02Just look at this.
-
13:02 - 13:08There's a female here,
about 40 metres in front of me, -
13:08 - 13:12in the shallows fishing for salmon.
-
13:12 - 13:16Behind her, on the bar over there,
she's got three cubs. -
13:16 - 13:18They're not struggling
to catch the fish here, -
13:18 - 13:22there's such a tremendous surfeit
of tired salmon out there. -
13:22 - 13:25All she really has to do
is wander into those shallows -
13:25 - 13:26until one comes close.
-
13:26 - 13:33And then she can grab it,
much to the delight of her cubs. -
13:33 - 13:37For these cubs, it's the first salmon run-
-
13:37 - 13:45They've got to learn how to catch fish
by watching their mother- -
13:45 - 13:49Look at this, look!
-
13:49 - 13:54This is the adult grizzly
that's just leapt off of the island there, -
13:54 - 13:58and caught a salmon, look at that,
right in its mouth. -
13:58 - 14:00Overjust six weeks in autumn,
-
14:00 - 14:04tens of millions of salmon
are going to return to these rivers- -
14:04 - 14:07And during the course of a day,
one adult bear like this can eat -
14:07 - 14:1340kg of salmon, and during the course
of the salmon run, 1,400kg. -
14:13 - 14:19That's just one bear's intake.
-
14:19 - 14:47But every salmon caught by these bears
increases their chances of survival- -
14:47 - 14:50And they are incredibly important
to these bears, -
14:50 - 14:52particularly at this time of year
-
14:52 - 14:55when it's essential they bulk up
as quickly as possible -
14:55 - 15:01before they slip into hibernation
with the winter coming. -
15:01 - 15:05This cub hasn't quite
got the hang of it yet- -
15:05 - 15:14But he hasn't got long- The salmon run
has only got a couple of weeks to go- -
15:14 - 15:23Until they learn,
Mum has to work even harder- -
15:23 - 15:37Every salmon caught
makes a real difference- -
15:37 - 15:40These bears, those that are close
to a huge amount of salmon, -
15:40 - 15:44grow 80%/ larger than those in other areas.
-
15:44 - 15:46They have 25%/ more cubs
-
15:46 - 15:49and occur at densities 50 times greater.
-
15:49 - 16:13So salmon, frankly,
are great news for bears. -
16:13 - 16:15Exciting as it is to watch,
-
16:15 - 16:21there's a lot more going on here
than simply bears catching fish- -
16:21 - 16:33And the reason
is thanks to what happens next- -
16:33 - 16:37And the only way to see it
is with remote cameras -
16:37 - 16:53positioned deep in the forest-
-
16:53 - 16:59These younger bears have carried fish
3O metres from the river- -
16:59 - 17:06Because here they're less likely
to be challenged by hungry adults- -
17:06 - 17:11So they can eat in peace-
-
17:11 - 17:15There's so much fish available,
they just eat the richest bits -
17:15 - 17:19to lay down enough fat for hibernation-
-
17:19 - 17:26The rest appears to be wasted,
abandoned on the forest floor- -
17:26 - 17:34Along with our camera-
-
17:34 - 17:39The aftermath of this feast
is unbelievable- -
17:39 - 17:47Up to four tonnes of carcasses are left
in an area the size of a football pitch- -
17:47 - 17:55But what have dead fish got to do
with the forest preparing for winter? -
17:55 - 17:58Well, this is where it starts
to get really intriguing, -
17:58 - 18:02because the catching of the salmon
is just the start of it. -
18:02 - 18:08Bears aren't the only creatures
attracted by such a feast- -
18:08 - 18:18A banana slug- At 25cm long, it's one
of the largest slugs in the world- -
18:18 - 18:26And masses of insects-
-
18:26 - 18:29These flies won't survive the winter,
-
18:29 - 18:32but if they plant their eggs
in the salmon's flesh, -
18:32 - 18:40their offspring might-
-
18:40 - 18:46This flurry of activity eventually breaks
the flesh down into simple nutrients -
18:46 - 18:57that are absorbed into the soil-
-
18:57 - 19:00The significance
of all of this decaying fish -
19:00 - 19:04goes far beyond it being
just a feast for scavengers. -
19:04 - 19:09Without all of these rotting salmon
accumulating here every autumn, -
19:09 - 19:14this forest would be
a very different place. -
19:14 - 19:23The salmon nutrients in the soil
are taken up by the fungi- -
19:23 - 19:29So this ancient forest is better equipped
to face the almighty change -
19:29 - 19:44that's fast approaching-
-
19:44 - 19:53For forests in the northern hemisphere,
time has run out- -
19:53 - 20:29Every day, the sun sinks lower in the sky-
-
20:29 - 20:31Winter.
-
20:31 - 20:33And on the face of it,
all of the life here -
20:33 - 20:37seems to have just gone away.
-
20:37 - 20:39Those truffles and the seeds,
-
20:39 - 20:42they're locked away
underneath all of this snow. -
20:42 - 20:44The salmon run is over.
-
20:44 - 20:49The vegetation - look at it -
it appears just to have shut down. -
20:49 - 20:54Even the water is in short supply.
It's all frozen. -
20:54 - 21:01All of those connections
appear to be broken. -
21:01 - 21:06The fungi have reduced their recycling
to a bare minimum- -
21:06 - 21:15And the trees they're connected to
are producing little in return- -
21:15 - 21:19The deciduous trees pre-empted
the winter by shedding their leaves- -
21:19 - 21:23The conifers are slowing down too-
-
21:23 - 21:33The waxy coating on the needles
protects their leaves from the cold- -
21:33 - 21:38But not everything here can exist
in a state of suspended animation. -
21:38 - 21:41Some of the animals
have to remain active, -
21:41 - 21:56and surviving in conditions like this
isn't easy. -
21:56 - 22:04The icy cold is the cue for the bears
to leave the forest altogether- -
22:04 - 22:05With the salmon run over,
-
22:05 - 22:10they are retreating to their winter dens
up in the mountains- -
22:10 - 22:15They must spend the entire winter
living off their fat reserves -
22:15 - 22:21gained by feeding on all of those salmon-
-
22:21 - 22:28The squirrels and other small mammals
must keep their activity to a minimum--- -
22:28 - 22:39---only occasionally venturing out
to retrieve their autumn caches- -
22:39 - 22:46The lower the temperature falls,
the more vulnerable creatures become- -
22:46 - 22:50Winter has been too brutal
for this young white-tailed deer, -
22:50 - 22:58but at least it's an opportunity
for some nocturnal scavengers- -
22:58 - 23:01A racoon-
-
23:01 - 23:06Out of the forest, a fisher,
a relative of martens and weasels- -
23:06 - 23:25And it's smart enough
to keep this meal to itself! -
23:25 - 23:38But there is more to this lifeless-looking
forest than just the scavengers- -
23:38 - 23:46For most creatures,
winter is a brutal and unforgiving time. -
23:46 - 23:51But others actually thrive
in these conditions. -
23:51 - 23:56You see, for animals
that have adapted to live in winter, -
23:56 - 24:22this stripped-down forest ecosystem -
well, it's a wonderland. -
24:22 - 24:261n winter here,
there are beautiful connections -
24:26 - 24:38between some of the forest's
most enchanting characters- -
24:38 - 24:43There is one predator here,
an incredibly important animal -
24:43 - 24:46that has no intention
of avoiding the snow, -
24:46 - 24:50because, unlike me,
it's perfectly adapted to it. -
24:50 - 24:54But it's an enigma,
a really, really shy animal, -
24:54 - 24:56one that's difficult to study.
-
24:56 - 24:59Having said that,
scientists have been tracking them -
24:59 - 25:12through the forest here
for more than a decade. -
25:12 - 25:16Researchers from the Maine Department
of Fisheries and Wildlife -
25:16 - 25:32have set a trap to catch one alive-
-
25:32 - 25:40With those distinctly pointed ears,
it can only be a Canadian lynx- -
25:40 - 25:49Lynx are the world's
most northerly dwelling cats- -
25:49 - 25:56And this particular lynx is well known
to chief scientist Jen Vashon- -
25:56 - 26:00The ear tags are blue with white.
-
26:00 - 26:03- That indicates it's L1 -1 1 .
- (LYNX BARKS) -
26:03 - 26:17He's called L 1-1 1
and was born in May 2OO4- -
26:17 - 26:26They've discovered that he is just one
of hundreds of lynx living here- -
26:26 - 26:44JEN: It's too intimidated
with everybody right there. -
26:44 - 26:481n fact, there are more lynx
living in these eastern forests -
26:48 - 27:10than anywhere else in North America-
-
27:10 - 27:17Now, the fact that L1 -1 1 has lived
all of his life in this frozen forest -
27:17 - 27:22has to mean that this is
a perfect place for a lynx to live. -
27:22 - 27:27But how can a top predator
like this survive -
27:27 - 27:29in such a stripped-down environment
-
27:29 - 27:46when there appears to be
so little else here? -
27:46 - 27:49The tracks of their prey are everywhere,
-
27:49 - 27:53but actually finding one
is a real challenge, -
27:53 - 28:17because its winter camouflage is perfect-
-
28:17 - 28:23It's taken some finding,
but it's there - the snowshoe hare. -
28:23 - 28:27You can just make out
its beady little black eye -
28:27 - 28:29and the black tips to its ears.
-
28:29 - 28:34And these things form 80%/
of the lynx's diet, -
28:34 - 28:39but as you can see,
they don't make it easy for that lynx. -
28:39 - 28:42Their camouflage is astonishing.
-
28:42 - 28:44In the summertime, they're brown,
-
28:44 - 28:47but in the winter,
they moult through to a white coat. -
28:47 - 28:50But they also use this thick brush.
-
28:50 - 28:54It provides them with excellent cover
to hide from the lynx, -
28:54 - 28:56also hide from the elements,
-
28:56 - 28:59but it's also crucial
in keeping them alive, -
28:59 - 29:05because they climb on top of the snow and
nibble at all of the shoots and the bark -
29:05 - 29:13growing from all of this brush.
-
29:13 - 29:16Look at that - beautiful!
-
29:16 - 29:18And with those big snowshoe feet,
-
29:18 - 29:33it just sort of floats across
the surface of the snow. -
29:33 - 29:37What the snowshoe hare needs most
to survive the winter -
29:37 - 29:41is a specific type of vegetation-
-
29:41 - 29:431t must be the right height to eat
-
29:43 - 29:50and provide enough cover
to hide from all of those lynx- -
29:50 - 30:01So the vegetation here must be perfect-
-
30:01 - 30:05And the reason that it does grow into
this perfect environment - -
30:05 - 30:12well, you could never guess-
-
30:12 - 30:18The most beautiful thing about this story
is that the lynx, the hare, -
30:18 - 30:21patches of cover like this
amongst the forest -
30:21 - 30:24didn't happen by chance.
-
30:24 - 30:28They're all controlled
by the most unlikely of creatures, -
30:28 - 30:34a tiny thing, less than the size
of one of my fingernails. -
30:34 - 30:36And at the moment, it's hiding,
-
30:36 - 30:39having burrowed into the bark
of one of these trees, -
30:39 - 30:44or perhaps in a crack in a log
lying on the forest floor, -
30:44 - 30:46covered with frozen snow.
-
30:46 - 30:49But it's there and it's waiting.
-
30:49 - 31:14It's waiting for springtime.
-
31:14 - 31:17As the hours of daylight increase
and the ground thaws, -
31:17 - 31:45as if by magic,
the northern forests change again- -
31:45 - 31:50As new leaves appear,
trees start producing sugars, -
31:50 - 31:53and that's good for fungus in the soil-
-
31:53 - 32:00Entwined with the trees'roots,
they can siphon off some of these sugars- -
32:00 - 32:04But not everything appears
so harmonious- -
32:04 - 32:111n the land of the lynx, something
extraordinary is happening to the forest- -
32:11 - 32:14These trees may have endured the winter,
-
32:14 - 32:19but now it's spring, they're under attack-
-
32:19 - 32:24Some are even dying-
-
32:24 - 32:27But what's happening here now is vital
-
32:27 - 32:34for how this ecosystem functions
over the year- -
32:34 - 32:38This defoliation is entirely natural.
-
32:38 - 32:41And I might be able to find
one of the culprits down here, -
32:41 - 32:44although they're quite tricky to spot.
-
32:44 - 32:49They live in these fresh, green shoots.
-
32:49 - 32:50Yes, here we are.
-
32:50 - 32:55Now, wrapped delicately in these leaves
-
32:55 - 32:58is a species that is single-handedly
-
32:58 - 33:03influencing the ecology
of this entire forest. -
33:03 - 33:07Inside this nest is the caterpillar
of the spruce moth - the budworm. -
33:07 - 33:11And it hasn't only wrapped itself up
in those leaves -
33:11 - 33:14to hide from predators,
because it's eating them as well. -
33:14 - 33:16And it doesn't just eat the leaves.
-
33:16 - 33:25It also eats the buds, the flowers
and the cones on the tree here. -
33:25 - 33:28Up in the canopy,
a tiny budworm caterpillar -
33:28 - 33:31has just emerged from hibernation
-
33:31 - 33:43and it's racing to fatten itself up-
-
33:43 - 33:48When it's finished on one branch,
it releases a strand of silk -
33:48 - 34:12and abseils down to the next-
-
34:12 - 34:151t's a risky business
being a juicy, fat caterpillar- -
34:15 - 34:30You're in danger of being spied by all
of those birds just back from migration- -
34:30 - 34:32But the caterpillar has a plan-
-
34:32 - 34:451t uses its silk to weave the needles
together and hide in a dense web- -
34:45 - 34:49Now, the springtime assault
by these caterpillars -
34:49 - 34:51is bad news for the trees-
-
34:51 - 34:55But for other inhabitants
of these forests, -
34:55 - 35:00these caterpillars are heroes-
-
35:00 - 35:03It's thanks to the behaviour
of this species -
35:03 - 35:07that one of North America's most elusive
and charismatic predators - -
35:07 - 35:09the Canadian lynx -
-
35:09 - 35:14is enjoying a bit of a renaissance
in forests like this one. -
35:14 - 35:20But the caterpillar lives all the way
up there, in the canopy. -
35:20 - 35:24Whilst the cat with the pointed ears
is prowling around down here. -
35:24 - 35:28So how can a humble insect like this
-
35:28 - 35:31have any impact
on a formidable thing like that? -
35:31 - 35:34I bet the lynx never even sees
the caterpillar -
35:34 - 35:37throughout the course of its life.
-
35:37 - 35:42Why does the lynx need the caterpillar?
-
35:42 - 35:50The clue is how they affect
the lynx's prey on the forest floor- -
35:50 - 35:55For decades, scientists have studied
budworm caterpillars, -
35:55 - 35:57and a remarkable pattern has emerged-
-
35:57 - 36:03They've discovered that the population
of caterpillars fluctuates dramatically- -
36:03 - 36:07And at the peak of the cycle,
-
36:07 - 36:18there can be tens of thousands
of budworms in a single tree- -
36:18 - 36:26And this has devastating consequences-
-
36:26 - 36:29Whilst these dramatic natural events
-
36:29 - 36:32might be a catastrophe
for the established trees, -
36:32 - 36:37for anything trying to grow on the
forest floor, they are an absolute bonus. -
36:37 - 36:39In here, where it's dark,
there's very little, -
36:39 - 36:44very poor diversity -
just some mosses and a few ferns. -
36:44 - 36:46But as soon as
there's a break in the canopy -
36:46 - 36:51and the sunlight can flood in -
well, look at the difference. -
36:51 - 36:54Lots of wild flowers, there's young maple
coming through here, -
36:54 - 37:03mountain ash and, most importantly of all,
regenerating spruce and fir. -
37:03 - 37:10Now, the hares essentially need
these regenerating conifers as shelter. -
37:10 - 37:17And, of course, what's good for the hares
is also good for the lynx. -
37:17 - 37:221t's such an elegant connection-
-
37:22 - 37:25Without the spring emergence
of the hungry caterpillars -
37:25 - 37:27to chew holes in the dense canopy,
-
37:27 - 37:31there wouldn't be enough light
flooding the forest floor- -
37:31 - 37:33And with less light down here,
-
37:33 - 37:39there would be less growing for
our snowshoe hare to forage and hide in, -
37:39 - 37:42and then there would be nothing
-
37:42 - 37:47for L 1-1 1 and all of those
hundreds of other lynx to eat- -
37:47 - 37:52And that's why the lynx
needs the caterpillar. -
37:52 - 37:55And now it's spring,
there's no better time -
37:55 - 38:16to see what the future holds
for the lynx population- -
38:16 - 38:21Wildlife biologist Jen is doing a count-
-
38:21 - 38:42She's detected a signal
from a radio-collared female- -
38:42 - 38:44There she is-
-
38:44 - 38:52But there might be something else here-
-
38:52 - 38:58Safe inside a den, a lynx cub-
-
38:58 - 39:00He's just a few weeks old-
-
39:00 - 39:12(CUB SQUEAKS)
-
39:12 - 39:15His eyes aren't even open.
-
39:15 - 39:36Jen must work fast before Mum returns-
-
39:36 - 39:41Thanks to the timing of the budworm
opening the canopy this spring, -
39:41 - 39:48there's going to be enough prey
for these lynx to hunt next winter- -
39:48 - 40:02(CUB SQUEAKS)
-
40:02 - 40:21Far away to the west, the Raincoast forest
is coming back to life- -
40:21 - 40:25Thanks to the richness
of the autumn salmon run, -
40:25 - 40:33the bears have survived the winter-
-
40:33 - 40:38They've now returned to the forest,
looking for something to eat- -
40:38 - 40:47They'll survive on vegetation
until the next salmon run- -
40:47 - 40:49The emergence of the bears
-
40:49 - 40:54is a cue for scientists to conduct
a rather risky experiment- -
40:54 - 40:59They need a large, hungry bear-
-
40:59 - 41:011t's the only way to measure
-
41:01 - 41:05the impact of
all of those salmon on this ecosystem -
41:05 - 41:18and to understand why this vast,
ancient forest has thrived for so long- -
41:18 - 41:20For such a big question,
-
41:20 - 41:29the methods employed by senior researcher
Chris Darimont seem a bit curious- -
41:29 - 41:32He's equipped
with a can full of old salmon guts, -
41:32 - 41:38effusing probably
the most disgusting smell known to man- -
41:38 - 41:44CHRIS: This is wonderful stuff.
-
41:44 - 41:49But he hopes
the bears are going to love it- -
41:49 - 41:51He's made an aerial lure,
-
41:51 - 41:57so the wind will carry this distinctive
perfume deep into the forest- -
41:57 - 42:05The wind - extra boost.
-
42:05 - 42:10Now they surround the area
with barbed wire- -
42:10 - 42:15And it's this that they hope will collect
what they're so interested in - -
42:15 - 42:20- a single hair from a visiting bear-
- (CAMERA BEEPS) -
42:20 - 42:27Now the site is prepared,
it's time to set some remote cameras--- -
42:27 - 42:34---and beat a hasty retreat-
-
42:34 - 42:38Personally, 1'm very happy to watch
from a safe distance- -
42:38 - 42:451t's not the smell -
some of those bears are huge- -
42:45 - 42:53Look at the size of this bear!
-
42:53 - 42:56As a trap, this is the perfect bait,
it's working brilliantly. -
42:56 - 42:58The bears have come in
-
42:58 - 43:01and they're snagging themselves
on the wire there. -
43:01 - 43:06You can see it vibrating about.
And that's justwhat we want. -
43:06 - 43:08Fresh out of hibernation,
-
43:08 - 43:12it seems they can't resist
this pile of stinking salmon. -
43:12 - 43:16This one's even rolling around
in the stuff now. -
43:16 - 43:23No doubt it values the scent -
I'm not sure we would. -
43:23 - 43:26The bear's coat has been growing
for nearly a year, -
43:26 - 43:32but soon it will be moulted and lost-
-
43:32 - 43:46The more bears we can attract, the better-
-
43:46 - 43:48Now the coast is clear,
-
43:48 - 43:58and it's time to retrieve any fur
from the barbed wire- -
43:58 - 44:11So what on Earth can hair tell us
about this forest ecosystem? -
44:11 - 44:13Well, hair is made of protein
-
44:13 - 44:29sourced from whatever the bear
has been eating over the last year- -
44:29 - 44:31And by analysing this hair,
-
44:31 - 44:44science can reveal an astonishing level
of detail about a bear's life- -
44:44 - 44:49We can learn so much
from a single bear's hair. -
44:49 - 44:53So I know, for instance, that this one
has come from a female grizzly. -
44:53 - 44:56I know exactly what it's been eating
even on a week-by-week basis, -
44:56 - 45:01where that food has come from and even
the impact on the quality of its life. -
45:01 - 45:04So this bear has been getting
most of its protein, -
45:04 - 45:06not from the forest around here
-
45:06 - 45:10but actually from the deep ocean,
via the salmon. -
45:10 - 45:13And we know that,
throughout the course of the year, -
45:13 - 45:1780%/ of that bear's protein
has come from these salmon. -
45:17 - 45:19And that's surprising, because, remember,
-
45:19 - 45:24they're only available to the bear
for a few weeks during the autumn. -
45:24 - 45:28And yet the impact
is clearly lasting all year. -
45:28 - 45:44So how come the bears appear to be
so full of salmon? -
45:44 - 45:45Well, back in autumn,
-
45:45 - 45:58we saw the bears scattering fish carcasses
all around the forest floor- -
45:58 - 46:01As the protein
in those rotting salmon broke down, -
46:01 - 46:05nitrogen from it accumulated in the soil-
-
46:05 - 46:13And this salmon nitrogen
is like fertilizer- -
46:13 - 46:17So in spring,
nutrients all the way from the ocean -
46:17 - 46:23gradually appear
in all the vegetation growing here- -
46:23 - 46:31Just in time for the hungry bears to eat
as they emerge from hibernation- -
46:31 - 46:34And hungry bears have huge appetites -
-
46:34 - 46:40they'll eat a third of their body weight
every day- -
46:40 - 46:54That's why their bodies
appear to contain so much salmon- -
46:54 - 46:58But the impact
of this ocean-borne nitrogen -
46:58 - 47:04extends far beyond bears and their food-
-
47:04 - 47:09This particular form of nitrogen
can be found in almost all of the animals -
47:09 - 47:22and plants that appear here in the spring-
-
47:22 - 47:27These rufous hummingbirds
have migrated to the forest to breed- -
47:27 - 47:31They're drinking nectar from plants
that have been fertilized by rotted fish- -
47:31 - 47:35So they'll carry the same salmon nutrients
with them -
47:35 - 47:45as they fly through the forest-
-
47:45 - 47:49And many of the insects
pollinating the plants now -
47:49 - 47:55were incubated in that decaying flesh
back in the autumn- -
47:55 - 47:56As they themselves are eaten,
-
47:56 - 48:04the salmon nutrients
are spread even further- -
48:04 - 48:07Thanks to the bears, the insects
and the birds, -
48:07 - 48:12this salmon fertilizer is spread
deeper and deeper into the forest, -
48:12 - 48:16sometimes as much as 800 metres
from the river. -
48:16 - 48:19And this pulse of nutrients
-
48:19 - 48:25then allows the organisms which define
the forest itself to prosper... -
48:25 - 48:42...its trees.
-
48:42 - 48:47Dr Tom Reimchen
can measure exactly how much -
48:47 - 48:52these vast old trees need the fish-
-
48:52 - 49:07The secret is to look inside the tree
by taking a core sample- -
49:07 - 49:18Written on it is the entire story
of this 3OO-year-old tree- -
49:18 - 49:23T0M: The rings I see are two, three,
even four millimetres, -
49:23 - 49:31which continues back to even the early
parts of the 1 800s, late 1 700s. -
49:31 - 49:36Tom has taken similar samples
from thousands of trees- -
49:36 - 49:40An entire forest is lined up in his lab,
-
49:40 - 50:03each tree waiting to tell its own story-
-
50:03 - 50:141n this seasonal climate, annual rings
are created as the tree grows- -
50:14 - 50:17From these rings, he can determine
not just the age of the tree -
50:17 - 50:22but also the amount of growth
in each year- -
50:22 - 50:25Some of the rings are thicker than others,
-
50:25 - 50:34showing that the tree has grown more-
-
50:34 - 50:39Like the bear fur,
each annual ring can be analysed- -
50:39 - 50:42Tom can search
for the same type of nitrogen -
50:42 - 50:44that's found in the bears'hairs -
-
50:44 - 50:56it comes from the ocean
and it's called nitrogen-1 5- -
50:56 - 50:58And the data will tell us
-
50:58 - 51:10just how much nitrogen in those trees
comes from all those salmon- -
51:10 - 51:13I think this is really exciting.
-
51:13 - 51:16You see, the annual growth rings here
-
51:16 - 51:19show the presence
of the stable isotope nitrogen-1 5, -
51:19 - 51:23which significantly comes from the oceans.
-
51:23 - 51:26It could only have been carried here
by the salmon. -
51:26 - 51:29Now, look. Here is the present,
-
51:29 - 51:33the bark on the outside of a tree.
So these rings here represent perhaps -
51:33 - 51:36about the last 1 5 years
and they're very closely packed together. -
51:36 - 51:41But here, back in the 1 980s,
the rings are twice as thick. -
51:41 - 51:46The trees have been growing twice
as much during the course of a year. -
51:46 - 51:49So perhaps the salmon runs then
were even more productive -
51:49 - 51:52than they have been recently.
-
51:52 - 51:53But that's not the best thing.
-
51:53 - 51:55Come and have a look at this.
-
51:55 - 52:00By measuring the abundance of that
nitrogen isotope in this material, -
52:00 - 52:05I can tell you that majestic old giants
like this beauty here -
52:05 - 52:15are actually composed of up to
85%/ material that's derived from salmon. -
52:15 - 52:21Now, when I was a teenager, I remember
learning that I was made of carbon, -
52:21 - 52:24and carbon could only be formed
when stars died. -
52:24 - 52:29Effectively, I was made of dead stars,
and that struck me as terribly romantic. -
52:29 - 52:36But look at this.
This is a forest made of the ocean! -
52:36 - 52:42That's why the tree needs the fish.
-
52:42 - 52:46Without this
unlikely sounding relationship, -
52:46 - 52:53this magnificent ancient forest
just wouldn't be the place it is today- -
52:53 - 52:56But there is one more relationship
-
52:56 - 53:00crucial to seasonal forest
all around the world -
53:00 - 53:05when it comes to surviving
constant change- -
53:05 - 53:09And it's one that reaches
its greatest intensity now, -
53:09 - 53:14at the height of summer-
-
53:14 - 53:211t's the driest time of year,
and the trees need water- -
53:21 - 53:24Fortunately,
united with their fungal partners, -
53:24 - 53:28the trees
have massively extended their roots- -
53:28 - 53:31Fungal threads in the soil
are absorbing water -
53:31 - 53:35and passing it to the tree-
-
53:35 - 53:38But what has only recently
been discovered -
53:38 - 53:44is the sheer scale
of these fungal root networks- -
53:44 - 53:48A single cubic centimetre of the soil here
-
53:48 - 53:53can have a mile of these
white fungal threads running through it - -
53:53 - 53:56they're called mycorrhizae.
-
53:56 - 53:58And for me,
-
53:58 - 54:05it's these organisms that are
the real secret of the forest here. -
54:05 - 54:061n the lab,
-
54:06 - 54:18the genetic fingerprints of individual
mycorrhizae have been identified- -
54:18 - 54:22By mapping an area 3O metres across,
it's been discovered -
54:22 - 54:29that individual fungi
connect to more than a single tree- -
54:29 - 54:30Just one fungus
-
54:30 - 54:37can be joined to 8O%
of all of the plants growing here- -
54:37 - 54:40And, amazingly, these physical links
-
54:40 - 54:46enable different species of plants
to exchange nutrients- -
54:46 - 54:51Older established plants
are even nurturing younger weaker ones- -
54:51 - 54:561t acts like
an underground welfare system- -
54:56 - 55:01These giant webs connect all of the trees
in this forest, -
55:01 - 55:07and keep them, and all of the things
that are dependent upon them, alive. -
55:07 - 55:24That's why scientists
are calling this the wood-wide web. -
55:24 - 55:281t's thanks to this natural phenomenon,
the wood-wide web, -
55:28 - 55:34that together the trees
in the forest ecosystems are resilient- -
55:34 - 55:38Resilient enough to cope
with the dramatic changes -
55:38 - 55:49they encounter every year-
-
55:49 - 55:57And what's really amazing
is how the web is built- -
55:57 - 56:01It's thanks to hungry mammals
like our flying squirrels -
56:01 - 56:07that this essential life-support system
is effectively maintained. -
56:07 - 56:12It's actually fair to say that these trees
wouldn't be standing here, -
56:12 - 56:18wouldn't be thriving,
unless a squirrel had eaten a truffle. -
56:18 - 56:24And thatis fantastic!
-
56:24 - 56:251t is fantastic-
-
56:25 - 56:291t's fantastic to think
that what animals do in one season -
56:29 - 56:38influences the forest ecosystem
throughout the year- -
56:38 - 56:471t's almost as if all of these stories
are choreographed- -
56:47 - 56:50The arrival of the salmon
at exactly the right time -
56:50 - 56:54to fatten the bears for winter.
-
56:54 - 56:57Then the emergence
of the lush green vegetation -
56:57 - 57:03fertilized by those salmon to sustain the
bears when they emerge from hibernation. -
57:03 - 57:08The squirrels foraging for truffles
in the autumn time, -
57:08 - 57:10and sowing their spores
throughout the forest -
57:10 - 57:16to grow a fungal network that joins
all of the trees and all of the plants, -
57:16 - 57:20and provides them with nutrients.
-
57:20 - 57:25The budworm chewing a hole
in springtime in the canopy, -
57:25 - 57:30so that in summer, sunlight floods down
to the forest's floor -
57:30 - 57:35and produces the perfect hunting habitat
for lynx. -
57:35 - 57:38It's all in the timings.
-
57:38 - 57:41And it's this that makes
these temperate forests -
57:41 - 58:02such magical places.
-
58:02 - 58:06If you'd like to know more about the
fascinating web of links between species, -
58:06 - 58:12the 0pen University has produced some
material both to inform and inspire you. -
58:12 - 58:22For your free copy, or to find out more
about 0pen University programmes, ring... -
58:22 - 58:270r go to the website...
-
58:27 - 58:31And then follow the links
to 0pen University. -
58:31 - 58:35And join me next time
when 1'll be travelling -
58:35 -to some of the world's
greatest water habitats-
- Title:
- The Magical Forest (BBC Documentary 2012)
- Description:
-
Please Subscribe To The Evolution Documentary YouTube Channel:
http://www.youtube.com/EvolutionDocumentaryBroadcast 2012. In this episode, Chris travels to North America to witness the annual miracle of the temperate forest: the destruction of its ecosystem in winter, followed by it rebuilding itself in spring. Chris marvels at the exquisite timing that is necessary in two particularly wonderful stories - the story of how the Canada lynx depends for its prey on a caterpillar high up in the canopy, and the story of why the giant trees of the north-west are dependent on bears and salmon.
Secrets of Our Living Planet showcases the incredible ecosystems that make life on Earth possible. Using beautifully shot scenes from all over the world, naturalist Chris Packham reveals the hidden wonder of the creatures that we share the planet with, and the intricate, clever and bizarre connections between the species, without which life just could not survive. For him, what is really beautiful about nature is not the amazing animals and plants that we share the planet with but the hidden relationships between them. Discover why a tiger needs a crab; or why a gecko needs a giraffe. Each week Chris visits one of our planet's most vital and spectacular habitats and dissects it, to reveal the secrets of how our living planet works.
- Video Language:
- Sinhala
- Duration:
- 59:01
![]() |
Amara Bot edited English subtitles for The Magical Forest (BBC Documentary 2012) | |
![]() |
Amara Bot added a translation |