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00:00Thank you for listening.
00:30The relationship between plants and humans is extraordinary.
00:44We've been adapting to each other for as long as we've been on the planet.
00:52We rely upon plants for almost everything.
00:56The air we breathe, the water we drink, the food we eat, much of the clothes we wear,
01:04and some parts of the world, the very buildings in which we live.
01:09But that relationship is now changing.
01:13How it changes next will shape the future of our green planet.
01:21Some plants have the ability to live alongside us.
01:39Even when we make it extremely difficult for them to do so.
01:47This is Piccadilly Circus in the heart of London.
01:55It will be difficult to imagine a more hostile place for a plant.
02:00And yet, even here, plants will find a way.
02:08Plants like this may seem to follow us wherever we go.
02:23We call them, perhaps a little unkindly, weeds.
02:35In fact, these plants are pioneers.
02:40The ones that are most able to take advantage of new habitats.
02:44Even very harsh ones.
02:52This wall is at least a hundred years old.
02:55It's like a sheer cliff face with no sign of soil.
03:01And yet, this ivy-leaved toad flax thrives here.
03:06How?
03:07The plant grows towards the light,
03:11with its flowers facing outwards to attract pollinators.
03:17But once they've succeeded in doing that,
03:19and the seed pods start to develop,
03:22its behavior changes.
03:26And now, the pods turn and grow away from the light,
03:31seeking the darkest place they can find.
03:34A crevice, perhaps.
03:35Like this one.
03:43It's all the toad flax needs.
03:46It can now germinate and start to produce a new plant.
04:05Other pioneers have a different strategy.
04:11They, instead, distribute their seeds far and wide in great numbers.
04:18Sow thistles are masters of this trick.
04:22Each of its seeds is equipped with a tiny, downy parachute,
04:26boat, which will catch the slightest breeze.
04:31And they can travel extraordinary distances.
04:36They can rise a mile high in the sky,
04:39and reach places hundreds of miles away from the parent plant.
04:43The seeds only need to find the tiniest chink,
04:51and they can take hold.
04:52You barely notice many of these plant invaders.
05:01But here, in the heart of Hong Kong,
05:07strangler fig seeds that landed on a stone wall generations ago,
05:12have spread their flexible branching roots far and wide.
05:16They can be anchored so firmly that they become a part of the city's architecture.
05:26This is, perhaps, the ultimate weed.
05:37But there are places where the extraordinary abilities of fig trees
05:42have created a very different relationship with human beings.
05:46Meghalaya, in northeast India.
06:05A high-altitude plateau riven by dizzyingly steep valleys.
06:10It's home to the Kasi people,
06:21who've learned how to use the remarkable properties of fig trees
06:24to help them live in such difficult country.
06:32As in Hong Kong, the tree's numerous roots anchor it firmly.
06:37Here, to steep mountain sides.
06:40These roots can grow up to two and a half centimetres a day.
06:48They are unusually strong, flexible,
06:52and can develop into a multitude of shapes.
06:57The Kasi persuade them to provide them with stairs.
07:01The monsoon season brings a seemingly insurmountable challenge for Kasi communities.
07:18This is the wettest place in the world.
07:23Nearly 30 centimetres of rain can fall in a day.
07:27Rivers become lethal torrents, dividing communities from each other.
07:41This is when the relationship between fig trees and the Kasi becomes most important.
07:48They deliberately plant fig trees near the rivers.
07:56When they're mature enough to have developed many hanging roots,
08:00Shining Star Kong Thor begins working with them.
08:04The young roots are the best ones for starting their project.
08:12The young roots are the best ones for starting their project.
08:14These roots grow plenty in number.
08:20They are more flexible.
08:24He guides the roots through bamboo tubes
08:27that are pointed towards the opposite river bank.
08:31These strands will combine as they grow,
08:52sharing nutrients and resources
08:54and becoming stronger than a lone strand could ever be.
08:58The roots that are tied together
09:06are like the connection between the Kasi people.
09:11So the roots that are connecting
09:16is like a person who helps each other.
09:20As the years pass,
09:29the growing roots become a living bridge.
09:33As they grow, they become ever stronger and more stable.
09:52As they grow, they become ever stronger and more stable.
09:56As they grow, they become a living bridge.
10:05The living bridge is the lifeline for the Kasi people as a whole.
10:08This unusual relationship has allowed the people here to thrive in an otherwise challenging
10:27landscape, but there are plants that have found a deeper partnership with us and in doing
10:49so have changed landscapes across the globe.
10:56It began over 10,000 years ago with plants that we found especially good to eat.
11:03At first, this relationship created challenges of its own.
11:11Many of the ancestral grasses, like these wild oats, Misrael, have a trick to ensure that
11:18their seeds are planted in the perfect place.
11:22Each seed head at the top carries two long bristles called awns.
11:29And when a seed drops the ground, these awns do something truly extraordinary.
11:36To be continued...
11:43I don't know.
12:13They walk.
12:21The orms twist as they dry out during the day,
12:25and then when they get wet,
12:30they untwist.
12:34Tiny hairs grip onto the ground,
12:37keeping the individual moving forward.
12:43In this way, the seeds work their way along the ground
12:50until eventually they find a rock to hide under,
12:53or a crack to drill into.
12:58This adaptation is useful for the plant, but not for us.
13:07It's hard to collect seeds when they drop off and walk away.
13:11So our ancestors selected plants whose seeds don't drop off,
13:18don't have legs,
13:20and don't bury themselves out of reach.
13:23They also selected those individuals
13:28which put their energy into developing much larger seeds.
13:35Close relationships like this have developed all over the world,
13:41producing the plants that are now our crops.
13:45This may seem a poor deal from the point of view of plants,
13:53but not so.
13:54We eat their seeds,
13:56but in return we cherish and cultivate them.
14:01And now they are widespread and far more abundant
14:05than their wild ancestors.
14:14You might call this a bargain between ourselves and plants,
14:19and over the years it's proved extraordinarily powerful.
14:24In the beginning, the bargain operated on a small scale.
14:47Plant, tend, and harvest by hand in small patches.
14:54Over time, these plants produce more food increasingly efficiently.
15:09And the partnerships became more exclusive.
15:17We started doing more and more for a small number of chosen species.
15:24These few persuaded us to eliminate their competitors,
15:34cure their diseases,
15:37poison their enemies,
15:39and keep them well watered,
15:44even when other species face drought.
15:48Fewer and fewer plant species,
15:52like soy, wheat, and rice,
15:54now occupy more and more land.
16:00So now whole landscapes are dominated
16:02by a single species of plant.
16:09A monoculture.
16:10This is the central valley of California.
16:20The biggest orchard in the world.
16:25A million acres of just one type of tree.
16:30Almonds.
16:31Each flower, if it's fertilized by pollen from a different almond tree,
16:46will produce an almond nut.
16:48The flower's patterns and scent have evolved to attract insects,
17:04and bribe them to do that job for them.
17:07The pollen doesn't have to move far.
17:10It just needs to reach a neighboring tree.
17:17There are about 20,000 flowers on each tree.
17:21And a hundred and forty million trees.
17:33That is billions of flowers,
17:35all calling out at once.
17:42But here, the beauty of the blossom is wasted.
17:44To make way for these almond trees,
17:47the land was in effect wiped clean.
17:54Countless wild species of plants and animals were removed,
17:58including, critically, pollinators.
18:04So now the flowers need help.
18:06And lots of it.
18:17And lots of it.
18:18And lots of it.
18:19And lots of it.
18:20And lots of it.
18:21And lots of it.
18:22And lots of it.
18:43Forty billion honeybees.
18:45The orchard is only in bloom for a few weeks,
19:01so the almonds need the bees to get to work immediately.
19:15Each bee can visit thousands of blossoms a day.
19:28And while they take most of the pollen they collect back to the hive,
19:32they also drop some pollen at each stop.
19:36And so, with luck, the flowers are all eventually fertilized.
19:44Day after day, the process is repeated.
20:01Flower after flower.
20:03tree after tree.
20:09tree after tree.
20:13By the time the petals fall, two and a half trillion flowers have been successfully
20:36pollinated and will now grow into two and a half trillion almonds.
20:45This type of intensive, streamlined agriculture produces amazingly high yields.
20:57But monocultures are fragile.
21:00While they can function effectively when conditions remain stable, it only takes a small change
21:06to create catastrophe.
21:23Lodgepole Pine, a very valuable kimber tree grown extensively in Western Canada.
21:35Hundreds of acres of the same species, all the same age and the same size.
21:42For centuries, lodgepole forests have lived in a natural balance with their enemies, including
21:51this one, the Mountain Pine Beetle.
21:57In summer, female beetles start hunting for a suitable nursery in which to lay their eggs.
22:04The ideal site is a mature lodgepole pine with bark thick enough to feed a female's brood,
22:08and critically, to protect them from the bitter cold of the coming winter.
22:15Once under the bark, she tunnels upwards.
22:21laying her eggs as she goes.
22:28A single female beetle can lay a hundred eggs in a season.
22:34A single female beetle can lay a hundred eggs in a season.
22:55When the larvae hatch, they grow by feeding on the inside of the bark.
23:14As they do, they damage the channels that transport water and nutrients between the roots and needles.
23:20For centuries, the freezing northern winters killed the majority of larvae, so tree and beetle remained in balance.
23:42But now, with the climate changing, the winters aren't cold enough to control the beetle numbers.
23:49Needles turning red are a sure sign that the trees are dying.
23:57The beetle plague spreads like wildfire across a landscape covered by a monoculture of similarly vulnerable trees.
24:14Since the first mass outbreak 40 years ago, trillions of trees in North America have been killed by the Mountain Pine Beetle.
24:26Loss of plant diversity makes any habitat more vulnerable to changing conditions.
24:38Now, with climate changing so fast, we're losing plant diversity just when we need it the most.
24:47Two out of five plants are now facing extinction.
24:56Of course, the loss of any one species is in itself a tragedy.
25:02But such a loss erodes the stability of a whole ecosystem.
25:09And that should be of great concern for all of us.
25:17We need an insurance policy.
25:21A hedge against extinction.
25:26This is Q's millennium seed bank.
25:33Packets of seeds arrive here from all over the world.
25:38These are from a relative of the yucca plant, which grows in central Mexico on the slopes of volcanoes and nowhere else.
25:52Most of the seeds are from plants that are threatened.
25:56Some, indeed, have gone extinct since their seeds arrived here.
26:01But here, at least, those seeds are safe.
26:05When they arrive, they're processed and sealed into airtight jars.
26:18Seeds are then brought underground to be stored in a vault, like this one, at minus 20 degrees centigrade.
26:32Since the bank was founded, two billion seeds from 40,000 different species have been brought and stored here.
26:51Because the seed contains everything it needs to start a new plant, each and every one of them represents a little grain of hope.
27:01Hope that one day we will make it possible for the seeds of these rarities to grow in the wild once again.
27:20The seed bank certainly gives us options when a species becomes rare or even extinct.
27:39But around the world, people are trying ways to keep natural plant populations healthy where they should be.
27:48In the wild.
27:50Hawaii.
28:00Hawaii.
28:01Hawaii.
28:02Hawaii.
28:03Hawaii.
28:04Hawaii.
28:05of the plant species here are found nowhere else in the world.
28:15Many are threatened by a plant invader called Myconia.
28:24It was brought to the island of Maui in the 70s as an ornamental plant.
28:30In its native Mexico, it grows in balance
28:33with a rich variety of predators, competitors and diseases.
28:44It grows taller than most native Hawaiian vegetation
28:48and little can grow beneath it.
28:50On the island of Maui, with nothing to keep it in check, it creates a stifling monoculture.
29:09Myconia, it would appear, is doing very well for itself.
29:13But today, it's under attack.
29:27On level ground, a single dedicated team can keep Myconia in check.
29:32Myconia in check.
29:41But unfortunately, this plant can spread to places impossible for people to reach on foot.
29:46Just one plant can produce around 10 million seeds a year.
29:59Enough to cover this entire landscape.
30:05With so much at stake, the team have come up with an extraordinary plan.
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30:35It's too dangerous to land here, but they don't need to.
31:05A marksman with great skill can shoot the Myconia with paint balls full of herbicide.
31:19The perfect shot is one that hits the stem, so ensuring that the herbicide spreads throughout
31:28the plant.
31:31The method is so precise that with careful flying and accurate aim, they can kill the
31:49intruders without damaging any wild plants.
31:53So, let's go.
32:03Destroying alien invaders is not the only way to help the native plants here.
32:33This is Waikamoi Preserve, the last surviving fragment of a high-altitude Hawaiian rainforest,
32:47and home to one of the world's rarest plants, Holokea.
32:56There are only 57 fully grown individuals left in the wild.
33:07Their peculiar flowers evolved to suit the beak of a bird found only in Hawaii, the i'ivi.
33:17The bird is now so rare itself that today these partners seldom, if ever, meet.
33:26So the chances of Holokea getting pollinated are very slim.
33:31But a strange new partnership might just save it.
33:38I look at losing a plant as flying in a plane and taking a screw out, and yeah, the plane
33:47will fly and you might be able to take a couple of screws out and keep flying, but eventually
33:54you're going to crash.
34:01Hank knows where to find every one of the last 57 plants.
34:13And he returns every year to act as their pollinator.
34:20We have to step in and play that role as pollinator, batch maker.
34:34collects the pollen from the male flower and dusts it onto a female flower of a different plant.
34:44He's currently their life support, but his goal is for Holokea to thrive without him.
34:52So before he leaves, he plays the call of the i'ivi bird.
35:11Hank hopes the sound will attract the living birds, and if they come, that they will reconnect
35:16with the last Holokea and rekindle their vital relationship.
35:34I believe all species are important, and I believe we have a duty to act.
35:45We need to act not only in the wild places, but even in those where we live and where
35:57we farm.
36:04Like much of the world, Kenya is losing thousands of native trees annually, ones that local people
36:11rely on for so much, especially fuel.
36:18But here, people have come up with an ingenious way to reverse some of that loss around them.
36:32At a factory in the outskirts of Nairobi, workers collect and sort waste charcoal dust.
36:45Seeds of carefully selected native trees are mixed with the dust.
36:55This carbon coat will protect the seeds from hungry animals until the rains arrive.
37:11These are seed balls.
37:28In the village of Tebuesi, acacia trees are becoming scarce, cut down by previous generations
37:35to make charcoal.
37:58But the students at this school make forest restoration child's play.
38:05The nutrients in the dissolving charred dust will give each little seed a good start.
38:28If only a handful of these seeds grow into a tree, the effort has been well worth it.
38:42Every mature acacia tree can itself produce thousands of seeds a year.
38:5313 million seed balls have been distributed in Kenya alone.
39:01And the methods by which they are dispersed are ever more inventive, to say the least.
39:23This technique is being repeated around the globe.
39:28Seed ball making workshop.
39:32People are choosing seeds of local native plants, giving them a little initial help,
39:39and bringing some wild plants back into the world around them.
39:44But is it possible, even in our most extreme monocultures, to invite a bit of wildness in?
39:59And with it, a bit of resilience?
40:03I have two different kinds of forage growing in my orchard.
40:09The yellow that you see behind me is a variety of different mustards.
40:15And then after the bloom, we're going to see some clover blossom.
40:19This mix of plants means the bees can feed before and after the brief almond bloom.
40:29And they also get a more balanced, healthier diet.
40:33In the meantime, it's going to provide habitat for all sorts of insects and the bees, probably some rabbits.
40:41It's a step towards establishing a better, more stable system.
40:49It's about finding balance.
40:51That's what we're trying to do here.
40:53Find a balance.
40:58Can humanity, globally, find a new balance between wild plants and those we have domesticated?
41:06Around half the usable land on Earth is taken up by agriculture.
41:16Do we really need that much?
41:19Maybe not.
41:22It's a remarkable fact, but around 80% of all cultivated land is used for raising livestock for us to eat.
41:37Raising animals can be a sustainable way to create food.
41:41But in many places, plants can produce the same amount of protein on a fraction of the land that animals need.
41:52What could it mean for wild plants if the global balance between plant eating and meat eating shifted?
41:59It may sound odd, but the more plants we eat, the more space there will be for wild plants.
42:14Remarkably, it's possible to restock even highly degraded land with wild plants.
42:20In Brazil, the needs of cattle ranching drive most deforestation.
42:32Thirty years ago, the owners of one former cattle ranch wanted to restore their land to the Atlantic rainforest that once covered it.
42:48They had no idea if it could be done.
42:53The land was so bare and eroded.
42:58But they were determined to try.
43:02First, they cleared the introduced African cattle grasses, invasive plants that outcompete most of the native plants.
43:21The grasses were replaced by seedlings grown from seeds gathered in nearby remnants of Atlantic rainforest.
43:28The Earth Institute, or Instituto Terra, as the ranch is known now, was encouraged by early success and expanded its scope and ambition.
43:58In five years, trees covered the land again.
44:12And within ten, it was clear something remarkable was happening.
44:28When rain falls, it now no longer simply runs off the land, leaving it parched.
44:43Instead, it clings to the plants, to every root, stem and leaf, and then slowly filters to the forest floor.
44:58And so, previously dry streams burst into life for the first time in decades.
45:13The Institute never introduced animals or plants other than the trees.
45:18The animals came back on their own.
45:26The small ones came first.
45:31The animals came back on their own.
45:33The small ones came first.
45:36And then, very recently, camera traps left in the forest captured images beyond the hopes of everyone involved.
45:58A maned wolf.
46:05An animal that is being driven from its native habitat by deforestation.
46:11Drawn to its favorite plant.
46:14The wolf fruit tree.
46:19Not only that.
46:21A puma.
46:22A puma.
46:31With cubs.
46:42The arrival of these precious top predators, and their young, shows what can happen when
46:49we make space for wild plants.
46:57We have, for centuries, robbed wild plants of the space and time they need to thrive.
47:06That has certainly not been to their benefit.
47:11Nor, ultimately, is it to ours.
47:20Our relationship with plants has changed throughout history.
47:25And now, it must change again.
47:27Whether it's what we eat and cultivate, or whether it's what we like,
47:32we must now work with plants and make the world a little greener, a little wilder.
47:38If we do this, our future will be healthier, and safer, and in my experience, at any rate, happier.
47:57Plants are, after all, our most ancient allies, and together we can make this an even greener planet.
48:06Throughout the human episode, the green planet crew sought to capture the lives of plants confronted with the human world.
48:28But they also heard the stories of people deeply connected to the plants around them.
48:38Such as those at the front line of the battle, to save Hawaii's native endangered plants from invasive species.
48:46If we don't get a handle on Myconia, we could lose everything that makes Hawaii special and unique.
48:55But before the green planet team could start work, they had to undertake some rigorous preparation.
49:02We're going into somewhere that has a very sensitive ecosystem, they're trying to protect it from invasives.
49:11Filming in a place so ravaged by invasive species meant they had to be 100% sure that they were not spreading any non-native stowaways themselves.
49:22They had to scrub and disinfect every item of equipment.
49:26With kit clean, the team first focus on filming the rare Holokea plant.
49:36Accessible only on foot.
49:42There are a few pristine areas like this left in Hawaii.
49:48Only 40% of the land still has native vegetation.
49:59Most of it wiped out by invasive species, like Myconia.
50:09Next on the list was to film the team waging war on Myconia, known locally as the Purple Plague.
50:16For crew member Asia, the work is not just a physical battle against this invasive species.
50:26It's deeply personal.
50:29I've been to the pristine area, so I know what it looks like and feels like, you know, to be in the presence of all that mana and spirituality.
50:39Those aren't just plants.
50:45Those are ancestors, spirits, you know.
50:50Controlling these invasive plants is a relentless job, and Asia is not just doing this for native Hawaiian ecosystems, but also to protect her ancestral relationship to this fragile landscape.
51:03So going through this, it feels good just to hack them and pull them out and be like, yeah, okay, take that, you know, we can sort of fight back.
51:13Asia's fierce passion to protect these native forests is evident.
51:17But the Purple Plague has spread to places Asia could never reach on foot.
51:24Taking to the sky is the only way to reach the front line of this battleground.
51:30With only enough fuel to stay airborne for two hours, the window for capturing this aerial battle is uncomfortably small.
51:42We have one day of doing the heli operations.
51:46The weather could completely mess us up if we get a system that comes in heli to heli is always dangerous and difficult.
51:56This flight is not just tense for Liz.
51:59For plant sniper Brook Manken, these short flights represent his only opportunity to hold back the invasion.
52:07Myconia left unchecked can be terribly damaging.
52:10The potential for one seeding plant, if it were to get far away from the population, reach maturity and put seeds out,
52:19then it's starting a whole new infestation.
52:22And once it occupies that entire area, then it's completely wiped it out.
52:31The helicopter is really important because you can fly in extreme terrain with these like thousand foot cliffs
52:37and find Myconia that there would be no other way to get to these plants.
52:44The Myconia team are used to the aerial challenges of this battle.
52:49But for producer Liz, the pre-flight talk from the helicopter pilot brings home the lengths that this team go to in order to complete their work.
52:58So you're just going to be in the back here, and it's a hurricane in the backseat, literally a hurricane.
53:03So nothing loose, you don't want to put an arm, a head, a leg or a hand out.
53:08It's just going to blow behind you.
53:10And you don't want to stick your head out because if the headset comes off, then it's into the tail rotor and then it's bye-bye Maui.
53:18Pre-flight checks completed. The clock is now ticking to get into the air.
53:23This matters so much to everyone here. I definitely feel the pressure to get this right.
53:31To get within shooting distance of the plants, the helicopter pilot must carefully maneuver in to one of the area's deepest canyons.
53:45To get within shooting distance of the plants, the helicopter pilot must carefully maneuver in to one of the area's deepest canyons.
53:58The target is in sight. Oh, yep, there he is.
54:14Okay, I'm, uh, I'm live and ready.
54:16With high winds gusting up from the waterfall, getting into position is tricky enough in one helicopter, let alone two.
54:25To give Brooke the best chance of hitting the Myconia, the pilot must get him within 20 meters of the plant and, ideally, at eye level.
54:35Any missed shot threatens to become friendly fire, harming the species he aims to protect.
54:40Ready? Yup, here we go.
54:47Brooke must strike the stem of the plant to have the best chance of completely killing it.
54:54Nice one! Nice one!
54:57Yeah, it worked really, really well. Thanks, guys.
54:58This has been a successful mission for both teams.
55:13The pilot's skills and Brooke's sharpshooting has saved another patch of forest.
55:19And Liz is relieved that she has the shots she needs to do the story justice.
55:23And it's over. It's over.
55:26And it just looked amazing.
55:28Lots of it. Yeah, it looks good. It looks good.
55:32For Brooke and Asia, however, their work doesn't stop.
55:36Just holding back the tide of invasive species in Hawaii is more than a lifetime's work.
55:43But Asia believes that her fight is worthwhile.
55:45Everything we do is for the next generation, just like our ancestors and kupuna's.
55:52It wasn't for them. It was for the next generation.
55:55And just to have my kids go into areas, like, where they can see they're still natives,
56:01where we don't have to go through all this invasive vegetation.
56:05You know, it's not just my responsibility, it's everyone's responsibility.
56:15You know, the earth takes care of us, so we have to do the same.
56:22We can't just let it go by.
56:26We've got to take care, too.
56:28The Open University has produced a poster that explores the vital role that plants have for our planet.
56:46To order your free copy, call 0300 303 4200
56:51or go to bbc.co.uk forward slash green planet
56:58and follow the links to The Open University.
57:06So I'm hearing Sister Monica is feeling a strong presence.
57:10Let's see what this is all about in Call the Midwife.
57:13It's next on BBC One.
57:21The Open University.
57:32The Open University.
57:38We won't continue.
57:40The Open University.
57:43We will.
57:46You.