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00:28Transcribed by —
00:49The Boreal Forest
00:50This is the Boreal Forest.
00:57The largest forest on earth.
01:02750 billion trees.
01:08Smothered by snow throughout the winter.
01:16This is the northernmost boundary of an extraordinary world.
01:25I'm standing at the edge of the Arctic Circle.
01:30To the north of me lies a land dominated for most of the year by snow and ice.
01:363,000 miles to the south, the tropics bathed the year round in warm sunshine.
01:43And in between, a very different world dominated by relentless change.
01:57An endless cycle of four distinct seasons, each with its own challenges.
02:05The short freezing days of winter give way to the urgent awakening of spring.
02:14And the long hot days of summer yield to the cooling of autumn.
02:26Opportunities will be brief.
02:36To survive these extremes, plants have not only got to be hardy and resilient, but many
02:43of them have developed special strategies in order to meet the demands of this seasonal world.
02:52To succeed, they must get their timing just right.
02:59For months now, this world has been asleep.
03:05But change is coming.
03:22Spring is on its way.
03:25Spring is on its way.
03:48In Canada, the forests are starting to stir.
03:55Earth descending into the winter.
03:55Over the winter, the sugar maples here have kept stores of nutrients ready for this moment.
04:05Now, as temperatures start to rise, those nutrients must be brought up from the roots.
04:20Sap is on the rise..
04:28...fuel for new green growth.
04:41But just as growth reaches full speed...
04:46...robbers arrive.
05:07A sapsucker. A thief in search... ...of maple syrup.
05:32The tree can tolerate hundreds of wounds.
05:42But if they completely encircle the trunk...
05:46...the tree will eventually die.
05:56The sapsucker's break-in hasn't gone unnoticed.
06:10Hummingbirds...
06:12...squirrels...
06:14...and insects...
06:16...all invade the sapsucker's territory...
06:20...trying to steal a meal.
06:26But unwittingly...
06:28...they help the tree.
06:35Time spent chasing the competition...
06:39...means less time to drill new holes.
06:42The only one of those will be killed.
06:43Can I borrow hands for those?
06:58You're doing this.
07:02I don't know what you're saying.
07:03We're doing this all.
07:04I know that we've made out of my own lives.
07:04Though you're going to work.
07:05I've been under the Pentangief.
07:05Here's my most amused.
07:05The Pen Soapes...
07:12The tree gets a chance to repair its wounds, and the sap can rise freely again.
07:28So this year at least, the tree will once more produce its leaves.
07:38Hundreds of miniature solar panels that collect energy from the sunlight.
07:47Each leaf is covered by millions of microscopic pores, stomata.
07:57They take in carbon dioxide, and release oxygen and water vapor,
08:04in a process that produces high-energy fuel.
08:20All the trees here can now use that fuel to grow over the coming months.
08:45As spring proceeds, the power of the sun increases.
08:54On riverbanks across Europe, many plants have been lying dormant underground, waiting for
09:03the earth to warm.
09:10And now a race begins.
09:20Among the first to start are Nettles, the sprinters.
09:31Then, only just behind come the brambles.
09:36They're much more aggressive, and have backward-pointed hooks with which to scramble over their rivals.
09:45Last to come, the climbers.
09:52Hops, and briny.
10:00They see the inflicted little containers from M respect to M pride.
10:01They lasseoe their way towards the light.
10:19Morden, mine is not a link from M λ.
10:21Level Is the slightest thing to decrease in them?
10:21No, in horsement, I need to lift them up to your妈
10:23Well, in horsement, I need to repeat in thesedamn regenerate.
10:25It's a special place among females who have captured all things.
10:32Soon, every inch of space and every patch of light has been claimed.
10:40But hidden in the shadows, another plant has been waiting to make its move.
10:57This... is Dodder.
11:07A hunter...
11:11with an exceptional sense of smell.
11:21Moving swiftly, it searches for its prey.
11:27It detects the scent of a young nettle.
11:49The Dodder punctures the nettle stem
11:52and sucks out the nutritious sap.
11:59And it doesn't stop at just one victim.
12:04With its energy supply assured, it multiplies.
12:19It's a parasite, with an insatiable appetite.
12:2300,00,000
12:2800,00,000
12:2900,00,000
13:24But, remarkably, its victims can now exploit the dodder.
13:31When other springtime enemies appear.
13:40Caterpillars.
13:52When under attack a leaf sends out a signal telling the rest of the plant to start building defenses.
14:03Foul tasting toxins that deter the caterpillars.
14:10In an extraordinary twist, the stems of the dodder interconnecting the plants are now being used as lines of communication.
14:19To relay these warning signals from plant to plant.
14:30They respond by producing their own protective chemicals.
14:38Eventually the whole riverbank becomes one huge defensive network.
14:45And the one time rivals are now better off together.
15:10The first warm days of spring encourage some plants to flower.
15:16And get ahead of the competition.
15:21Creating beautiful displays throughout the seasonal world.
15:28From the spectacular cherry blossoms of Japan.
15:34To the goldfield flowers of California.
15:42But spring flowering is risky.
15:45If they flower too early, it may not be warm enough for pollinating insects to be active.
15:52But the common daisy gives them every opportunity.
16:00The warmer the flowers are, the more attractive they are.
16:04And they have a remarkable strategy in order to maximize this.
16:10They were closed up tightly throughout the night as a protection against the elements.
16:16But once they feel the warmth and the light of the sun, they spring into action.
16:36It's a behavior called heliotropism.
16:41They turn to keep facing the sun.
16:46Absorbing as much heat as they can.
17:04This is a thermal camera.
17:08And it will tell me the difference between the surrounding temperature.
17:13And the temperature in the center of a daisy flower.
17:18The surroundings, 12 degrees.
17:23In the center of a flower, 21.
17:31Pollinators, such as bees and wasps, prefer the warmed up flowers.
17:36Because they can get a share of the heat for themselves.
17:41As a consequence, they can collect more nectar from more flowers, pollinating as they go.
17:50And the daisies, with the help of their pollinators, are able to have a particularly long flowering season.
18:00But when the window of opportunity is brief, even more ingenious tactics are necessary.
18:19Here in southwest Australia, summer temperatures can soar to up to 40 degrees Celsius.
18:37Now, for a brief moment in the cooler spring, flowering plants must get busy.
18:47And this hammer orchid, with its strange flower, is doing exactly that.
18:56It needs to attract a pollinator, but has no nectar and doesn't even look like a flower.
19:06Unlike these neighboring huge grass trees.
19:15These produce thousands of tiny white flowers, all dripping with nectar.
19:26But the orchid has a different strategy.
19:32It synchronizes its emergence with the brief mating season of the tinnid wasp.
19:45The flightless female wasp produces pheromones to attract males.
20:00This male detects a scent that seems to be hers.
20:12Yet flies right on by.
20:21The orchid not only has the same shape and color as a female wasp, but it sits at the same
20:27height as she does.
20:30It even mimics her smell.
20:34And the beguiled male attempts to mate with it.
20:55It hammers against the orchid's pollen sacs.
21:03And the wasp leaves, doubtless a little shaken.
21:10Only to be duped once again.
21:23The pollen on his back now sticks to this different orchid.
21:28And the deception has worked.
21:34The orchid's imitation is even more intoxicating, it seems, than the real thing.
22:02Eventually, the male wasps tire of the orchid's enticements.
22:10And now the wasps, both male and female, find the flowers of the grass trees to feed.
22:19And there, at long last, they mate.
22:32And as for the hammer orchid, pollination is complete.
22:51As summer approaches, the need to flower becomes more urgent.
22:57And nowhere more so than here, in South Africa.
23:07This is the Fanebos, part of the Cape Floral Kingdom.
23:12A great expanse of open heathlands, just north of the Cape.
23:20Here, there are more different species of plant than anywhere else in the world.
23:27Nearly 9,000 many leading pollinators.
23:34They compete with one another for such help by flaunting extravagant shapes and vivid colors.
23:44All promising nectar as a sugary reward.
23:52But there is a plant here that avoids this crowded competition.
23:59And the rising temperatures of summer bring just what it needs.
24:28This is the first fire here for 15 years.
24:42Nearly all of the plants are destroyed.
24:51Incinerated.
25:01It might seem from the smoke and the still smoldering embers,
25:05that no plant could survive such an inferno.
25:18But just four days after the flames.
25:23Rising from the ashes.
25:30A far lily.
25:40It has been lying dormant underground for 15 years.
25:44But now, awakened by the smoke, it flowers.
25:59The blooms may be small and unchowy, but that's all they need to be.
26:07In this charred landscape, pollinators such as these sunbirds can spot these little red beacons from great distances.
26:21They're the only source of nectar around.
26:35And the more visitors the flowers attract, the more likely they are to be pollinated.
26:54It's just in time.
27:01Within a few months, the whole landscape is alive once more.
27:10In fact, all these plants need fire to survive.
27:20And as competitors return, the fire lily fades.
27:34It now returns underground and will rest there as a bulb until another fire awakens it.
27:52By the time the long hot days of summer arrive, wildflower meadows are bursting with life.
28:02But autumn is not far away.
28:07So now, pollinated plants must use their remaining energy to produce the next generation.
28:16Seeds.
28:26A dandelion clock contains around 200 seeds.
28:35Each with its own tiny parachute.
28:44Few seeds can fly as far as these.
28:47Some are known to have traveled over 60 miles.
28:58But to travel any distance at all, they need the wind to be just right.
29:09However, before they can get away, there is a risk.
29:14Voracious hunters live in this meadow.
29:41Tiny harvest mice.
29:45Tiny harvest mice.
29:47Dandelion seeds.
29:49T All, wait.
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29:56But they don't like to share.
30:09Finally, the sun warms the ground.
30:13And a gentle breeze blows in,
30:16Teasat Kae 잘en-
30:17seeking a slade egg protein veteran.
30:17an ideal updraft.
30:32Air flowing between the bristles creates a vortex that lifts the seeds up.
30:42Heading off on a gentle breeze,
30:45this seed now starts its travels.
31:17Plants use a variety of different techniques to spread their seeds as far as possible from themselves.
31:24And one of the most remarkable is this one.
31:27It's called ecballium and it's a relative of the cucumber.
31:31For several weeks now, pressure has been building up inside the pods.
31:37And so now they're as taut as a well-pumped up bicycle tyre.
31:41All they need is just a slight nudge.
32:02The further the plant can fire its seeds, the better.
32:08If a seedling germinates close to its parent, the two will have to compete for nutrients and light.
32:19This Himalayan balsam has seed pods that react rather differently, like catapults.
32:27As they dry out, they begin to strain along precise depositioned lines of weakness.
32:33And then just the slightest disturbance, even a single raindrop, is enough to trigger the mechanism.
32:40And that happens, God gets all the dichos again.
32:57It's enough to know what is the meaning of the triangle of the traders,
32:59which means we need to destroy the triangle of the traders.
32:59The end is the same as you think.
33:01It's enough to show up.
33:01So it's time to show up unless a giant plummet,
33:02which means we need to support the tree.
33:02If you can't do it all, you never depend on what you do.
33:03What is the decaying of this tree here?
33:04It appears all on theừng.
33:13The east coast of South Africa.
33:18Summer here brings scorching temperatures.
33:32This ceratocherium has to get its seeds underground before it gets too hot.
33:39And it has acquired somewhat unlikely allies.
33:49Dung beetles.
33:54They have a particular fondness for antelope droppings.
34:03At this time of the year, these beetles bury the dung and lay their eggs on it.
34:15And the fresher, the better.
34:27Ceratocherium's spindly stems send their seeds flying.
34:54They're the same size, shape, and even smell.
34:59Remarkably like antelope dung.
35:17The beetles simply can't resist them.
35:39Dung beetles always bury dung balls at the same depth, and it's one which suits the seeds very well.
35:57So effective is the seeds' deception that the beetles come back for more time and time again.
36:19Most of the ceratocherium's seeds get safely buried.
36:29Exactly where they need to be.
36:50As the sun begins to retreat, so autumn arrives.
36:59The cooler, shorter days are the cue for many seasonal florists to prepare for the winter shutdown.
37:10The trees start to divert their nutrients back into their roots, and there other organisms await them.
37:28Fungi.
37:28Fungi.
37:30Fungi.
37:36Fungi.
37:41Fungi.
37:51Fungi.
37:57Fungi.
37:58Fungi.
37:59Fungi.
38:06Fungi.
38:08Fungi.
38:09Fungi.
38:10Fungi.
38:10Fungi.
38:11Fungi.
38:11Fungi.
38:11Fungi.
38:11Fungi.
38:12Fungi.
38:12Fungi.
38:12Fungi.
38:13Fungi.
38:14Fungi.
38:28Fungi.
38:28contain several thousand meters of their microscopic filaments. It's only recently that we have
38:36discovered the extraordinary role that these fungi play in a forest like this. Their filaments
38:47plug into the tips of the tree's roots and nutrients pass between tree and fungus throughout
38:55the year. Some fungi have the ability to link with not just a single tree but with a whole group
39:05of
39:05trees so that the entire forest may be linked together by these microscopic threads to form
39:12what you might call a wood-wide web.
39:24Hundreds of trees can be interconnected by these webs. Scientists call it the mycorrhizal network.
39:34And it might look something like this. They've discovered that trees not only send nutrients
39:49along it but chemical and electrical signals, allowing them to communicate with one another.
39:57But some trees can also be selfish and steal from their rivals. Or even wage war by sending
40:06out toxins that will harm competitors.
40:16It seems however that most trees do try to help each other.
40:24They raise the alarm when attacked by leaf eaters, giving other trees time to produce defensive chemicals.
40:36Those that are dying may send their food reserves to their neighbors. And some individuals, known
40:45as mother trees, recognize their own offspring and will channel resources to them.
40:57So giving their young the best possible start in life.
41:22As the harshness of winter approaches, temperate woodlands from Russia to Canada are now in a race to shut down.
42:04The green pigment of the leaves starts to break down.
42:08And nutrients are withdrawn into the branches.
42:14The chemical substances that are left behind then create one of the most spectacular displays of color in the whole
42:23of nature.
42:54The chemical substances that are left behind by fossiles are not destroyed.
43:21The first freezing nights of winter
43:23bring with them a killer, frost.
43:37Stems, when frozen, rupture, and flowers of ice form in the chilly air.
44:21For some, winter
44:23brings dormancy.
44:27For others, it brings death.
44:41Another cycle of the seasons comes to an end.
45:01Plants all across the seasonal world have developed many different strategies for success.
45:07But they all depend on the seasons changing reliably year after year.
45:15Doesn't matter whether you live for 3,000 years or just a few months.
45:21Everything depends on you getting the timing just right.
45:29But in our changing world, this is becoming a greater challenge every year.
45:37And even the most hardy and resilient of plants are starting to struggle.
45:52These sequoia trees are the giants of the natural world, the largest living thing on the planet.
46:01They can grow to almost 100 meters tall and 11 meters across.
46:09Their bark alone can be over a half a meter thick.
46:13They are also among the oldest, some living to over 3,000 years.
46:21And to achieve such age and size, they need very particular living conditions.
46:27such as are found here in the Sierra Nevada mountains of California.
46:38Not only do they need energy from the sun, but critically, they also require up to 4,000 liters of
46:46water a day.
46:47So they are almost entirely reliant on the seasonal snow melt.
46:59But recent years have brought longer, hotter summers.
47:03And their source of water is becoming increasingly unreliable.
47:15Scientists are discovering that even these seemingly indestructible giants are now starting to show signs of vulnerability.
47:27Some are shedding their needles and branches as a way of conserving precious water.
47:44But for others, climate change has already been fatal.
47:50Ten percent of them have been lost in just the last few years.
48:05A single giant sequoia in its lifetime can produce a hundred million seeds.
48:13These in my hand from one cone are more than enough to start a completely new forest.
48:22But they can only do such a thing in a world where the seasons change with some reliability.
48:31Today, our climate is changing, bringing an unprecedented level of unpredictability all across the seasonal world.
48:43The question is, can we curb time change sufficiently to ensure that the seasons will continue?
48:53Only if we can do that will the future of seasonal plants, including these magnificent trees, be assured.
49:01We can't afford to eat, but we're definitely not –
49:08We can to prepare different structures for the whole world itself.
49:31The increasing unpredictability of the seasons made it frustratingly difficult for the crew to be in the right place at
49:38the right time.
49:40Whether the height of summer...
49:42We are in the middle of a biblical rainstorm.
49:48...or a quiet autumnal afternoon.
49:51This is crazy. Hurricanes are no joke.
49:54They were always kept on their toes.
49:57That's really scary.
49:58Three! Four!
50:01Sometimes very numb ones.
50:05It's been the most snow they've had for 38 years.
50:08And I think this is now our fifth filming trip in a row, where the seasons haven't done what they're
50:15predictably meant to do every year.
50:18And these challenges continue in attempting to find and film an elusive plant with a remarkable survival strategy.
50:28The far lily.
50:40Somewhere out there is a tiny, tiny red plant in all of that.
50:56Traveling to South Africa at the height of summer...
51:01...the crew witness many extraordinary flowers bursting into bloom.
51:08But if they are to see a fire lily, they need a fire.
51:15None of the team have filmed wildfire before, not something to be underestimated.
51:22In most cases with wildfires is that when they go wrong, they go wrong radically.
51:26And it's very unforgiving.
51:28If you get caught on the wrong side of a fire because you want to get that special shot,
51:32there's a possibility you can get killed.
51:33But that's really what it comes down to.
51:35And after some understandably studious note taking, it's time to put their training to
51:42the test.
51:53The fire is just racing up a gully behind me, the heat is intense, you just can't even stand
52:00to be like five meters far.
52:01It's insane.
52:09This is what any fire lilies here should be waiting for.
52:25But feindloss wildfires are starting to become fiercer than in the past.
52:31Something fire chief Reinhard Gildenhuis knows first hand.
52:36Nowadays we're experiencing more extreme temperature conditions and more extreme wind conditions,
52:42which exacerbates a feindloss fire.
52:48Feindloss fire in full tilt with a strong wind behind it is an animal that's just running wild.
52:55It's a very frightening sight if you're standing in front of it.
53:14It has given me a complete new appreciation for fire, how intensely it burns and how quickly
53:23it roars through this environment.
53:26And the fact that any plants can survive afterwards is just, yeah, it's crazy.
53:36As destructive as it seems, the fire has been part of this ecosystem for millennia.
53:42Fires should refresh and regenerate the landscape.
53:47Worryingly however, this fine balance between plant and fire is beginning to shift.
53:54More extreme wildfires may spell disaster.
53:59If you disturb the soil in a feindloss system, you're going to lose a lot of species.
54:04Bigger, hotter fires can burn the soil there and burn out all the seeds.
54:10And for the species that have these really intricate strategies like the fire lily, it really
54:15is a difficult game.
54:18Every year is getting hotter and potentially drier.
54:22So it's kind of becoming Russian roulette for a lot of the species here.
54:37In the fire's aftermath, the crew must now try to find a tiny flower, but have any survived
54:45the blaze?
54:46It just looks completely dead.
54:48The whole valley.
54:55There's nothing for it but to get their hands dirty.
55:01Searching in the ash is a grubby business.
55:10I feel disgusting.
55:14After scouring this mountainside just days after it burned, they finally find the first
55:22signs of regeneration.
55:27Wow.
55:28That's what it's all about.
55:29That's the fire lily.
55:31It's like a pop of bright red against all the black.
55:35I mean, that's amazing.
55:37There's another one over there and there's another one behind us.
55:42This place hasn't burned for 15 years.
55:44So, they've been sat underground waiting for this precise moment for that entire time.
55:49And then within two weeks, they're up and they're flowering.
55:52It's incredible.
55:54This time, the fire lilies here succeeded in flowering.
55:58But in the 15 years since they last bloomed, the Earth has experienced 10 of the warmest years
56:05on record.
56:07You know, there's huge debates about climate change.
56:10How real is it really?
56:11And so on.
56:13We experience it in the fire.
56:15It's more intense, burns easier, burns longer.
56:20In the past, we used to have one big fire per season and we said, yeah, that was a big
56:25one.
56:26Now we have five to six big ones per season.
56:30If we don't change our ways, we are going to reach a point where fires are burning with
56:35such ferocity that it will destroy the landscape.
56:40And in recent times, a rapidly changing climate has led to some of the biggest fires in living
56:46memory, not just in South Africa, but around the world.
56:51The next five to ten years are going to be pretty scary to actually see what this has
56:57done to the ecosystem.
57:00Let's hope that the next time this fire lily blooms, it will find a world in which it
57:06can still survive.
57:12Next time on the green planet, desert worlds, a landscape of extremes where water equals life.
57:29It only takes a drop.
57:34The Open University has produced a poster that explores the vital role that plants have for
57:42our planet.
57:43To order your free copy, call 0300 303 4200 or go to bbc.co.uk forward slash green planet
57:54and follow the links to The Open University.
58:02Find some headspace with David Attenborough's The Green Planet Mindful Mix.
58:07Listen now on BBC Sounds.
58:09Unexpected news means Lucille might need a little headspace of her own here on BBC One.
58:14Call the midwife, next.
58:17.
58:17.
58:17.
58:18.
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