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00:0310 million species live on planet earth each one is remarkable but none can survive on its own
00:18life depends upon connections unexpected invariably complex beautiful relationships
00:28between millions of plants and animals
00:38this time in our grasslands i want to show you why these antelope need these rhino
00:47why this lone wolf needs an ant
00:53and the incredible secret that lies buried beneath them all
00:59connections like these create the planet's great ecosystems they're vital for all life
01:08i want to show you our world as you've never seen it before
01:34central kenya
01:38and this is whistling acacia grassland
01:51the whistling actually comes from the breeze blowing across the holes in these hollow gauls
01:59and they're home to one of the grasslands most intriguing creatures
02:17this lizard is the aptly named dwarf gecko and this one has laid a couple of eggs
02:25down here in this gall on the tree the perfect place for a nest you might think
02:34but this tiny lizard can only safely lay its eggs here thanks to one of africa's
02:40largest most iconic and bizarre animals the giraffe
03:01the story of why the gecko needs the giraffe is wonderful
03:07and it will take us on a journey across the world to some of our most breathtaking grasslands
03:29they are habitats which occupy a quarter of the land surface of our planet
03:50they support some of our most spectacular wildlife
03:58and yet grasslands lack one of the basic ingredients for life
04:07a truly precious element
04:13it's this
04:17nitrogen
04:19a colourless tasteless gas
04:22it's only when we chill it down to 196 degrees below zero that we can actually see it
04:30we can see it
04:31i can tell you that almost everything that happens out here in this grassland ecosystem
04:37is governed by a craving for this rare resource
04:41in fact i'd go so far as to say that grasslands can only function
04:46because they can cope so ingeniously with so little of it
04:51so for once perhaps this will make the ecologist's job a little easier
04:55because to understand how grasslands work all we need to do is follow the nitrogen
05:14australia
05:30the grasslands here have some of the lowest levels of nitrogen on the planet
05:37which makes the local wildlife perfect for demonstrating why it's so important
05:48nitrogen is the magic ingredient
05:51when you add it to carbohydrate you get protein and protein is what you need to make living tissue
05:59protein is the building block for life all life
06:12a baby eastern grey kangaroo
06:20when he was born he weighed less than a one pence piece
06:33his dad on the other hand is one of the heaviest marsupials in the world
06:41which means that joey has a lot of growing up to do
06:54in fact from birth to adulthood he'll increase his body size by one hundred thousand times
07:07and all of that will be built with protein
07:13and you can't make protein without nitrogen
07:23right now he gets most of his protein from his mother and she gets all of her protein
07:31from a diet of grass
07:37at the moment these kangaroos are just hanging out
07:41and they look like a typical population of kangaroos
07:44and i can assure you they're not because this is not your typical australian grassland
07:54it's anglesea golf club near melbourne
08:07kangaroos were here when the golf course was built 60 years ago
08:12but since then their population has boomed
08:19at a recent count there were 359 of them
08:24that's nearly 20 for each hole
08:32and the secret of their success is down to these immaculate fairways
08:43this grass is so green and so lush because it's had something added to it
08:51this nitrogen fertilizer and i know it's a product of the industrial revolution that's therefore
08:59led to all of this lushness but it certainly proves a point the power of nitrogen in a grassland
09:13it's added once a month it seeps into the soil is quickly taken up by the roots
09:20and then converted into proteins for stronger healthier grass
09:29great for golf
09:31but perfect for the joey
09:36the extra protein means that he can grow faster become healthier and live longer
09:45and that's the power of nitrogen
10:05on the plains of east africa there's an animal that you might think is the least
10:12likely to be affected by nitrogen levels in the grassland
10:28nitrogen or indeed the lack of it plays a decisive role in any grassland ecosystem
10:33it's even intrinsically entwined with the ecology of large predators like these lions
10:45this close and i'm in no doubt that these animals are at the very top of their food chain
10:54but to find out how nitrogen affects predators
10:58i need to start at the bottom of the food chain
11:09and it all begins with a very special plant
11:15one of the great unsung heroes of our planet
11:21grass
11:26the really great thing about grass is that it's simple compared to other flowering plants shrubs
11:33and trees it requires a minimal protein to build so it can take all of the nitrogen from its roots
11:40and
11:40put it not into bulky structures but organize it efficiently yet simply to maximize photosynthesis
11:47to produce its food so grass leaves have protein at much lower concentrations
11:56but this gives grazing animals a real problem
12:03impala are one of africa's commonest antelope a favorite prey of big cats
12:16but their biggest challenge is a much more basic one
12:22how to survive on nothing more than grass
12:28the key is being very fussy about the sort of grass you eat
12:32because some grass is richer in nitrogen than other grass
12:38this impala is actually cherry picking the leaves with the highest concentration of nitrogen
12:47even so she'll have to work hard to extract it
12:54just watch her neck closely
12:58any moment now she's going to regurgitate a ball of partially digested grass
13:08and she'll process it all over again
13:16it's called chewing the cud
13:20by digesting grass not once
13:24but twice these animals can extract as much of the nitrogen as possible
13:30but it still only works on the very best grass
13:34antelope like these impala can only survive on a diet of grass which is relatively high
13:40in nitrogen grass like this we call it sweet grass
13:47this long grass on the other hand is known as sour grass because the nitrogen in its leaves occurs at
13:56even lower concentrations
14:02antelope can't live here they simply can't get enough nitrogen out of sour grass to survive
14:23antelope
14:24but there is an animal here that can change that
14:28a very rare one
14:30this is what i've been looking for
14:36the animal that has deposited this dung
14:39processes grass through its gut in a very different way than
14:42antelope and i'm sure i can demonstrate that here
14:47is some antelope poo and if i take just one of these and break it open here
14:54you can see that what remains is pretty much nothing more than dust
15:02whereas this on the other hand is very different
15:06it's very different if i break this one in half the grass is still very visible
15:40it's very helpful
15:45The white rhino.
15:47What an animal.
15:53Their sheer scale.
15:54I mean, they're the closest thing perhaps that we have on the planet to mammalian dinosaurs.
15:59And of course, they have a reputation for being pretty feisty.
16:03So I'm being very careful and not moving too quickly and keeping my voice down.
16:09In fact, this one's getting a little bit close.
16:12So I'm going to stop moving and talking altogether.
16:19Their eyesight is poor.
16:21So, if I'm still, they may not notice me.
16:31But they do have a great sense of smell.
16:40If the wind changes, they could charge.
17:03Absolutely fabulous things.
17:15Now, one of these animals has got no horns.
17:18It hasn't lost them in a scrap.
17:20They've been deliberately removed by the park rangers here as these horns can have a tremendous value.
17:30Rhinos with horns are prized by poachers.
17:33The month before I arrived, they killed one in this very park.
17:40Cutting off her horn could save her life and it's hoped that this practice will save the entire species.
17:52Losing a species like this would have a drastic impact on the entire grassland ecosystem.
18:02Her huge size allows her to live on grass where antelope just can't.
18:09Her body houses a massive gut, a fermentation chamber, so she can make up for the low quality of sour
18:17grass by digesting vast quantities of it.
18:27All of which means she produces a lot of dung.
18:37Which she drops in a very specific place, a midden.
18:44For rhinos, this is important.
18:46It's how they communicate.
18:48It's how they communicate.
18:54Rhinos come here from far and wide.
18:58By smelling the pile, they can tell who's around, how they're doing, and who is ready to mate.
19:09It's a sort of faecal face book, but with added value.
19:17It brings nitrogen-rich manure from all over the grassland to one place.
19:27So the grass growing here becomes increasingly sweeter, until, as if by magic, rhinos have created a grazing lawn of
19:38sweet grass, perfect for fussy eaters like Impala.
19:56Rhinos are ecosystem engineers, upon which many other animals depend.
20:03That surely is their true value, that's why they're worth much more alive than dead.
20:20Right across the world, it's sweet grass that is crucial for most grassland grazers.
20:28And it's this quest for sweet grass that drives one of the largest movements of animals on our planet.
20:47Every year, one and a half million wildebeest migrate 3,000 kilometres, all because of nitrogen.
20:58And this is when its impact reaches the top of the food chain.
21:52So what has a lion kill got to do with nitrogen?
21:56Well, basically, two things.
21:59You see, the lions here have identified the richest source of nitrogen available out here in the grassland, large herbivores.
22:09You see, their bodies are made up of principally proteins, and that protein is where the nitrogen is.
22:18Then, it's the sweet grass which dictates where lions like to hunt.
22:29King of beasts they may be, but their lives are ruled by nitrogen.
22:37But how would a grassland predator survive if there were no sweet grass to hunt in?
23:06Depending on where you are in the world, the grassland always has a special name.
23:10In Africa, the savannah.
23:12In the US, it's the prairies.
23:15Here, in South America, it's the cerrado.
23:23There's one animal that lives here that I'd love to show you.
23:26It's really special.
23:27I've never seen one in the wild, but it's a truly fantastic animal by anyone's standards.
23:36This is MS National Park.
23:42The name comes from the Brazilian for this bird.
23:47The rear.
23:57But it's not a rear that I'm after.
24:02What I'm after is a wolf.
24:09Maine wolves are one of the largest predators in South America.
24:13But their home ranges, their territories, are huge.
24:17So they're not easy to find or see.
24:34This wolf has a problem on her paws.
24:43You see, these grasslands are so low in nitrogen that they can't support herds of grazing animals like impala or
24:53wildebeest.
25:01In fact, the wolf's survival here is all thanks to a relationship with one of the cerrado's smallest inhabitants.
25:11It's this, an ant.
25:14And the story of why the wolf needs the ant is an amazing one.
25:19And it's all down to the way that grassland ecosystems survive against the odds.
25:27Other species of canids, dogs, wolves, hunt in packs.
25:33But her life is a lonely one.
25:39There's just not enough nitrogen here for even two main wolves.
25:45So one of them has to go.
25:50One of them has to go.
26:17Hunting on her own means that even the odd deer is off the menu.
26:24Instead, she has to catch more modest prey.
26:52She has to catch more than the deer.
26:56She has to catch more than the deer.
27:22She may have walked miles just for that mouse.
27:29And such meagre pickings won't sustain a wolf.
27:35So, she has put herself on a bizarre dietary supplement.
27:51This is a lobeira fruit from the word lobo which means wolf and wolves love these things.
28:03They make the perfect midnight snack.
28:16Libera fruit make up about half of her diet.
28:20True, they don't have much nitrogen but they are packed with vitamins and carbohydrates.
28:28So, eating fruit means she needs to catch fewer mice.
28:33And that actually means that she can survive in this nitrogen-starved grassland.
28:45But it gets even better.
28:50The maned wolf is also helping the fruit.
28:56Wolves like to mark their territory.
28:59And maned wolves are no exception.
29:01And they like to choose high spots to do so.
29:04But of course, here on the flat Cerrado, such places are in short supply.
29:09So, the one they turn to is this.
29:11And this mound of soil here is the nest of leaf-cutter ants.
29:21When the wolf poos on the mound, it has an immediate effect.
29:38Soon, most of the colony are out in force.
29:49The ants will salvage anything.
29:52They'll even try what's left of a mouse.
30:05But one of them has just found the real prize.
30:11A seed from the libera fruit.
30:32The nutrient-rich coating from these seeds will be fed to the ant larvae.
30:57And buried in the safety of the nest, those seeds will germinate.
31:02They've even got added fertiliser.
31:06So, what we have here is an interaction between three totally disparate species.
31:12The ant, the fruit and the wolf.
31:15Now, the ants, they get food delivered straight to their door.
31:19The fruit has found something to disperse its seeds and something else to ensure that they germinate perfectly.
31:26And the wolves, well, they're effectively farming their own food.
31:32What a story. What a story.
31:35It's stories like that that mean that you can always entertain a lifelong fascination with nature.
31:40And, you know, every single leafcutter ant nest out here on the Cerrado has a libera fruit tree growing next
31:48to it.
31:49It works.
31:51And, you know, the most exciting thing for me is that none of the players in this system, the ant,
31:57the fruit or the wolf, has any knowledge or regard for what it's doing.
32:01And yet it works perfectly. Fantastic.
32:13These connections are not just important for the creatures concerned.
32:18Because of the way they move precious nitrogen around, they are crucial for the entire grassland ecosystem.
32:47But they can be destroyed in just a matter of years.
32:53And it's happened a lot in Australia's grasslands.
33:09This is Mount Rothwell Research Centre in Victoria.
33:15It's 400 hectares of high-security grassland.
33:26Scientists here are trying to restore animal relationships and thus mend a broken ecosystem.
33:38It's surrounded by 11 kilometres of fencing.
33:457,500 volts protect the perimeter.
33:55And it's patrolled every day.
34:03I'm feeling a little imprisoned.
34:05But then this fence is not designed to keep things in.
34:09It's actually designed to keep things out.
34:12You see, in here is the largest piece of native Australian grassland left in this region.
34:19And this fence is helping keep out a whole load of animals that they don't want in here.
34:28This Moggy is, or was, someone's pet.
34:32But she's also an alien predator that didn't evolve in this ecosystem.
34:41You see, Australia has no native cats of any kind.
34:46Down under, she's an unstoppable killer, along with feral dogs and foxes.
34:58These carnivores would do anything to get their jaws and claws on what's in here.
35:15This is a brush-tailed rock wallaby.
35:19And because of these introduced predators, he is now one of the rarest mammals in the world.
35:25And the extinction of just a few key creatures like him has had a catastrophic impact.
35:33Crucial ecological relationships are in tatters here.
35:37And as a result, this native grassland is now far more endangered than any tropical rainforest.
35:45The question is, if you remove all of the alien animals and reintroduce the key native ones,
35:52could Australia's grasslands be brought back to life?
35:56On the inside of this fence, a relatively small community of animals and plants has been saved.
36:03But I've got to say, some of them really are pretty odd.
36:07And to stand any chance of seeing them, I'm going to have to wait until after dark.
36:32Welcome to the weird world of the native Aussie night.
36:58This is a southern brown bandicoot.
37:03And I'm getting a superb view of it.
37:05I'm so close that I can actually see the saliva glistening in its mouth as it's chewing its food.
37:15It's one of about 20 different species of bandicoot.
37:18And they all come equipped with this long pointed and sensitive snout.
37:24And they're principally insectivores, meat eaters.
37:29But they do play a very important role when it comes to maintaining the plant community in this ecosystem.
37:37He spends all of his time digging for food.
37:42By the end of the night, he'll have covered the grassland with lots of snout-shaped conical pits.
37:50Here's one of the pits here.
37:53And when the wind blows, grass seeds are caught in here.
37:57Along with a lot of other detritus.
37:59All of which is rich in nitrogen.
38:02So they become a perfect place for germination.
38:27This is a baton, otherwise known as a rat kangaroo.
38:32They're herbivores.
38:34At the moment, if you listen carefully, you can hear it munching on some roots or tubers that it's eating.
38:46All of these animals are so tame that it's no wonder foreign cats and foxes have almost wiped them out.
38:57As it feeds, it effectively ploughs this hard soil.
39:02Allowing air and water in.
39:04Vital for the plants that live here.
39:11But so that the herbivores don't do too much damage,
39:15this miniature Serengeti also has its own mini lion.
39:42This is an eastern quoll.
39:46A pocket-sized marsupial predator.
39:51Don't be fooled by size.
39:53He can take prey much larger than himself.
39:58What's important is that unlike cats and foxes, quolls have co-evolved with their prey.
40:04So they are a critical part of this ecosystem.
40:13The Rothwell experiment is working.
40:17Rare species of plants, birds and mammals.
40:20The entire grassland is making a comeback here.
40:31The secret to healthy grasslands is having the right species in the right place.
40:39And there's one animal that benefits grasslands more than any other on Earth.
40:54These monoliths dominate the Cerrado in South America.
40:59There can be as many as 40,000 in one square kilometre.
41:08From the outside, these things appear entirely lifeless.
41:12In fact, you could sit down here alongside one and see nothing move all day.
41:19But living on the inside is perhaps the most important animal in this entire ecosystem.
41:31They are grassland's secret weapon in the battle for nitrogen.
41:43Termites.
41:44Half-blind, distant cousins of cockroaches.
41:51There are so many millions living in this grassland,
41:55that their combined weight is far greater than that of all the mammals living here put together.
42:03And yet, you would have no idea they were even here if they didn't build these huge mounds.
42:13They build them as cooling towers to keep the temperature of the colony on the inside at an optimum 30
42:20degrees centigrade.
42:21And they're remarkably efficient, normally accurate, plus or minus a single degree.
42:28Not bad for a colony of primitive insects.
42:31But then, building these mounds all over the landscape is the least of their accomplishments.
42:41Because one way or another, termites are fundamentally important to almost all life here.
42:58Especially the strangest of all, the giant anteater.
43:05These animals are related to armadillos and sloths.
43:09They're part of a group called edentates, which basically means without teeth.
43:14But whilst armadillos and sloths do have rudimentary teeth,
43:18if you were to perform a dental examination on one of these guys,
43:22which would be difficult because their mouth is so small,
43:24you'd find no teeth at all.
43:29But it's not teeth he needs to unlock the termite's secret.
43:37If you look at its front feet, you can see it's got these two huge claws on each one of
43:43them.
43:43And they can break into just about any substrate.
43:46It also uses them for defence.
43:49It's said that if it's attacked by a larger predator,
43:51it will stand back on its tail and lash out with those claws.
44:00He uses his tongue, which is over 50 centimetres long,
44:05flicking it in and out at around 150 times a minute.
44:16Giant anteaters eat 35,000 termites a day.
44:22Nevertheless, you could be forgiven for thinking that no matter how many they hoover up,
44:26or how quickly, they could never sustain an animal this size.
44:31But they do.
44:33By weight, termites are the most protein-rich food that you can find.
44:38There's more protein in these little insects than there is in beans,
44:42nuts, cheese, chicken, even roast beef.
44:46And what's interesting is that termites occur in ecosystems all over the world.
44:52And wherever they do, there are creatures like this
44:55that have evolved to feed exclusively on termites.
45:09The reason termites are so rich in protein is all down to some very intimate relationships.
45:18The first is with a fungus.
45:21Deep within the mound, the fungus breaks down dead grass so the termites can digest it.
45:29Not much else could eke a living out of this stuff.
45:41The second is more remarkable still.
45:45You see, termites can obtain nitrogen directly from the air.
45:53And they achieve this through another symbiotic relationship, an even more intimate one.
45:59Because living inside their digestive systems are amazing nitrogen-trapping bacteria.
46:05And it's this that gives termites their special powers.
46:09So using the nitrogen they get from that bacteria, the nutrients they get from the fungus,
46:15they're able to turn this dead woody material into a productive food source.
46:23This stuff which is so low in nitrogen, so low in protein, they can turn into edible protein.
46:30And that's how they can form these vast colonies.
46:37The termite mound becomes a nitrogen hotspot.
46:41That's good for anteaters, but also for all the surrounding plants and for all the other animals living here.
47:01The incredible actions of termites nurture grasslands all over the world.
47:10Including Kenya's whistling acacia savannah.
47:31Here, the impact of termites goes right to the top.
47:37All the way to the world's tallest land animal.
48:05When I was a child, we thought there was just one type of giraffe.
48:10But now we know there were six different species.
48:15This one's a reticulated giraffe.
48:30He can reach anything.
48:32But of all the plants here, he's chosen to eat the whistling acacia tree.
48:42But just look at it.
48:44It's one of the best offended plants in the whole of Africa.
49:05But why are these trees so well armed against browsing animals like these giraffes?
49:13Well, the answer, you won't be surprised, comes down to nitrogen.
49:19You see, these trees' leaves are absolutely packed with nitrogen.
49:26That's why they are the botanical equivalent of Fort Knox.
49:32At the base of many of these acacias are colonies of African termites.
49:37The acacia's roots are boring under the mounds, tapping into a rich well of nitrogen.
49:44As a result, these acacias become an oasis in a nitrogen desert.
49:50So it's really no wonder that the thorns alone don't deter giraffes from tucking in.
49:59So not to be beaten, the tree employs another line of defence, its own private army.
50:08Now just watch this.
50:10I'm going to pretend to be a giraffe browsing on this branch here.
50:15So I'm going to pull at the leaves, shake it about a bit.
50:19Try and not get jabbed by the thorns here.
50:23But just look at this.
50:25Very quickly, a whole mass of these crematogaster ants swarms out and covers my hand.
50:34And I can tell you that if you were a giraffe browsing on this,
50:38you wouldn't want these things all over your tongue.
50:42Each ant is armed with a chemical weapon.
50:45It's capable of squirting venom.
50:50Each gall houses a separate colony of ants.
50:54And each branch might have a dozen or more of these galls.
51:07So the only way a giraffe can get an ant-free meal is to grab a quick snack and then
51:13move on.
51:32The tree has evolved to produce these hollow thorns and they are the perfect structures for the ants to make
51:39their colonies inside.
51:41And in return for the plant's investment, it gets these insects as vigorous defenders.
51:56But this is just the beginning of a truly amazing web of relationships.
52:12These are patas monkeys.
52:23As grassland specialists, they're the fastest running primates in the world.
52:29In the 100-metre sprint, they'd beat any Olympian by three seconds.
52:45To fuel their energetic lifestyles, their favourite food is chromatogaster ants and their larvae.
52:59The trick is finding them in just the right position.
53:06He could easily have his eye out on those thorns.
53:09near the 100s.
53:51Once ripped open, the ants abandon the gall.
53:55But this act of primate vandalism only serves to enrich this mini-ecosystem.
54:04You see, a short while later, a new occupant has moved in.
54:15Here, protected from predators and the harsh sun, a dwarf gecko has laid two eggs.
54:32Because she isn't a threat to either them or the acacia, the ants mostly ignore her.
54:45After four months, a perfect miniature gecko hatches out.
55:03It's completely defenceless, but luckily, it's found itself in the perfect nest.
55:16It couldn't possibly appreciate all of the creatures here on the grassland that have come together to put a safe
55:25roof over its head.
55:34The giraffe eats the acacia trees, so it continually produces those galls which form the gecko's home.
55:41The acacia tree needs the ants to protect its leaves and keep it healthy.
55:46And in turn, the patas monkey needs those ants and their larvae as food.
55:51And all of this can only happen because the tree has managed to accumulate nitrogen from a grassland that's evolved
56:00to prosper despite the fact that this element is always in short supply.
56:12It's often said that you can only tell who your real friends are in times of need.
56:20This is also true in nature.
56:26You might ask if it really matters if an animal becomes extinct.
56:34Well, so intricate are the connections in the natural world that there's no way to predict the impact of adding
56:42or removing species until it's too late.
56:53Who would have thought that a baton would need a bandicoot?
56:58That a leafcutter ant would need a maned wolf?
57:02Or indeed, that a gecko would need a giraffe?
57:06Now, the complex web of relationships that we've seen have evolved over millions of years, but we've only scratched the
57:15surface of a myriad of stories that, when they come together, make these grasslands functional ecosystems.
57:25And it's here that I've learned to see the real beauty in nature.
57:30You see, for me, it's not in the minute detail.
57:34It's in the bigger picture.
57:36Because this works perfectly.
57:40That is beautiful.
58:00If you'd like to know more about the fascinating web of links between species, the Open University has produced some
58:07material both to inform and inspire you.
58:11For your free copy, or to find out more about Open University programmes, ring 0845 366 0254.
58:21Or go to the website, bbc.co.uk slash nature, and then follow the links to Open University.
58:30And join me next time, when I'll be travelling to the world's greatest seasonal forest.
58:40Nicky Chapman helps a couple escape to the country in North Wales tomorrow afternoon, seeking out the dream home at
58:4620 past four.
58:47For now though, we're all done here on BBC HD, so good night.
58:52We'll see you next time, ma'am.
58:56We'll see you next time.
58:58And next time, please.
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