1
00:00:01,040 --> 00:00:06,440
Our planet is the greatest
living puzzle in the universe.

2
00:00:06,440 --> 00:00:08,640
A collection of worlds
within worlds,

3
00:00:08,640 --> 00:00:13,680
each one a self-contained ecosystem
bursting with life.

4
00:00:17,160 --> 00:00:19,160
But how do they work?

5
00:00:20,960 --> 00:00:26,560
The intricate web of relationships
and the influence of natural forces

6
00:00:26,560 --> 00:00:32,160
makes each microworld
complex and unique.

7
00:00:33,200 --> 00:00:37,960
So to discover their secrets,
we need to explore them one by one.

8
00:00:39,920 --> 00:00:42,640
Untangle their interlocking pieces

9
00:00:42,640 --> 00:00:46,280
and ultimately reveal
the vital piece,

10
00:00:46,280 --> 00:00:48,000
the key to life itself,

11
00:00:48,000 --> 00:00:54,200
hidden deep within each
of nature's microworlds.

12
00:01:03,040 --> 00:01:08,600
The Amazon.
The largest rainforest on Earth.

13
00:01:10,760 --> 00:01:13,680
Feeding the mightiest
river in the world.

14
00:01:19,920 --> 00:01:24,680
It drains over 40%
of South America

15
00:01:24,680 --> 00:01:29,280
and holds a fifth of
the entire world's river water.

16
00:01:31,200 --> 00:01:35,880
Up to 12 metres of rain falls
in parts of the Amazon every year.

17
00:01:39,880 --> 00:01:45,440
But what makes the Amazon even more
incredible is the life within it.

18
00:01:48,280 --> 00:01:53,040
For sheer diversity of species,
it's unparalleled.

19
00:01:53,040 --> 00:01:58,160
It is estimated to be home
to up to 3 million species.

20
00:01:58,160 --> 00:02:04,440
Over 500 kinds of mammal,
30% of the world's bird species,

21
00:02:04,440 --> 00:02:10,240
and its plants produce
20% of the world's oxygen.

22
00:02:12,720 --> 00:02:16,440
The Amazon River even holds
more kinds of fish

23
00:02:16,440 --> 00:02:18,720
than the whole of
the Atlantic Ocean.

24
00:02:21,640 --> 00:02:26,360
A complex ecosystem with infinite
connections and relationships,

25
00:02:26,360 --> 00:02:31,720
but as we shall discover,
as in all our microworlds

26
00:02:31,720 --> 00:02:36,240
there is one piece that this
entire system relies on to survive.

27
00:02:41,840 --> 00:02:46,240
And without it, the rainforest
would look like this.

28
00:02:47,680 --> 00:02:50,720
Areas that have been
slashed and burned for agriculture

29
00:02:50,720 --> 00:02:56,600
fail rapidly, and before long
the land cannot even support crops.

30
00:02:56,600 --> 00:02:59,360
All our microworlds
rely on nutrients,

31
00:02:59,360 --> 00:03:02,520
they are the
building blocks of life.

32
00:03:02,520 --> 00:03:05,280
Phosphorous, potassium and calcium,

33
00:03:05,280 --> 00:03:09,760
vital elements
that plants need to grow.

34
00:03:09,760 --> 00:03:13,520
But these nutrients are not
a stable part of any ecosystem.

35
00:03:13,520 --> 00:03:17,160
Here they are either locked up
and unobtainable in living tissue

36
00:03:17,160 --> 00:03:21,360
or washed out by the incessant rain.

37
00:03:23,080 --> 00:03:25,880
And it's so poor
in available nutrients

38
00:03:25,880 --> 00:03:30,120
that scientists refer to the Amazon
as a wet desert.

39
00:03:39,520 --> 00:03:43,840
The endless rain affects
the trees, plants and soils

40
00:03:43,840 --> 00:03:48,280
and are constantly washing
the building blocks of life away.

41
00:03:48,280 --> 00:03:51,920
Life here is actually
surprisingly hard.

42
00:03:53,240 --> 00:03:56,160
So how in such a nutrient-poor
microworld,

43
00:03:56,160 --> 00:03:59,160
is there so much diversity and life?

44
00:04:02,920 --> 00:04:07,400
The answer is that in nature,
adversity leads to adaptation.

45
00:04:12,160 --> 00:04:16,120
Animals and plants have carved out
incredible niches

46
00:04:16,120 --> 00:04:17,960
and formed vital relationships,

47
00:04:17,960 --> 00:04:21,920
not just to survive,
but to thrive here.

48
00:04:21,920 --> 00:04:27,240
But is there one that holds the key
to all this success?

49
00:04:33,160 --> 00:04:37,720
Understanding the Amazon,
the most complex ecosystem on Earth,

50
00:04:37,720 --> 00:04:41,880
is one of the greatest challenges
that ecologists have ever faced.

51
00:04:44,520 --> 00:04:47,360
Our only chance is by unpicking
its web of connections

52
00:04:47,360 --> 00:04:50,880
until we can hopefully discover
how the Amazon is able to support

53
00:04:50,880 --> 00:04:54,320
such diversity
on such slim pickings.

54
00:04:57,720 --> 00:05:00,880
The Amazon is so massive
and so intricate

55
00:05:00,880 --> 00:05:03,600
that we are really going to
have to delve deep

56
00:05:03,600 --> 00:05:07,440
and get under this microworld's skin
to search for the pivotal piece.

57
00:05:12,240 --> 00:05:15,600
So in our investigation
we need to start small

58
00:05:15,600 --> 00:05:18,440
and focus on the details first.

59
00:05:24,280 --> 00:05:29,320
Like all microworlds, the Amazon
is a showcase of natural selection.

60
00:05:29,320 --> 00:05:34,200
The inhabitants have evolved
over time to exploit every niche,

61
00:05:34,200 --> 00:05:38,800
every opportunity
that exists within its world.

62
00:05:41,280 --> 00:05:43,040
But what makes the Amazon special

63
00:05:43,040 --> 00:05:46,720
is the vast number of relationships
that have developed.

64
00:05:49,400 --> 00:05:54,160
Particularly compelling is
the interaction between flowers

65
00:05:54,160 --> 00:05:58,360
and one of the most beautiful
groups of birds on the planet.

66
00:05:58,360 --> 00:06:01,080
Hummingbirds.

67
00:06:04,160 --> 00:06:07,080
Like bees,
they are attracted to flowers

68
00:06:07,080 --> 00:06:10,160
for their energy-rich nectar.

69
00:06:12,960 --> 00:06:16,880
But in a world where every nutrient
has to be locked up safely,

70
00:06:16,880 --> 00:06:19,680
the flowers can't give
their valuable resources away

71
00:06:19,680 --> 00:06:22,080
unless they get something in return.

72
00:06:26,280 --> 00:06:29,960
The plants need to be pollinated.

73
00:06:29,960 --> 00:06:34,320
So as the birds feed, they get
their heads sprinkled with pollen.

74
00:06:36,920 --> 00:06:40,160
But this only works if
the hummingbird delivers the pollen

75
00:06:40,160 --> 00:06:43,160
to another flower
of the same species.

76
00:06:43,160 --> 00:06:46,280
And that's the clever bit.

77
00:06:46,280 --> 00:06:51,760
Over thousands of years, the flowers
and the birds have evolved together,

78
00:06:51,760 --> 00:06:55,160
so that only the species of bird
with the right-shaped beak

79
00:06:55,160 --> 00:06:59,160
can get nectar
from their species of flower.

80
00:07:00,600 --> 00:07:02,880
The birds are guaranteed food

81
00:07:02,880 --> 00:07:06,520
and the plant guarantees
it gets pollinated.

82
00:07:11,160 --> 00:07:14,480
Relationships like this
are born out of necessity

83
00:07:14,480 --> 00:07:17,560
but they might not hold the key
to how this world works.

84
00:07:23,560 --> 00:07:26,640
The pivotal piece in many
microworlds is a constant,

85
00:07:26,640 --> 00:07:28,720
something that doesn't change much

86
00:07:28,720 --> 00:07:30,760
so the rest of the world
can keep up.

87
00:07:30,760 --> 00:07:34,040
So to find the key
in this complicated world,

88
00:07:34,040 --> 00:07:38,160
first we need to find this constant.

89
00:07:39,880 --> 00:07:43,160
And there is one thing you can
rely on in a rainforest -

90
00:07:43,160 --> 00:07:44,800
rain.

91
00:07:50,160 --> 00:07:53,000
Massive quantities of rain
fall on the Amazon.

92
00:07:53,000 --> 00:07:58,600
An average downpour can dump
two-and-a-half centimetres of water
on the forest every hour.

93
00:08:02,920 --> 00:08:08,520
This rain usually comes from water
evaporated from the sea.

94
00:08:08,520 --> 00:08:14,160
However, the Amazon is so immense,
it literally makes its own rain.

95
00:08:14,160 --> 00:08:17,080
70% of the rain that falls

96
00:08:17,080 --> 00:08:21,520
has evaporated
from the trees themselves.

97
00:08:23,560 --> 00:08:26,520
And this constant rain
has had a direct effect

98
00:08:26,520 --> 00:08:30,040
on the shapes of things
in the forest.

99
00:08:32,160 --> 00:08:35,280
Plants have developed
leaves with gutters and spouts

100
00:08:35,280 --> 00:08:37,400
to get rid of as much water
as possible

101
00:08:37,400 --> 00:08:40,960
because a leaf that doesn't dry off
will end up rotting alive.

102
00:08:44,040 --> 00:08:46,880
Life can't survive without water,

103
00:08:46,880 --> 00:08:49,520
so the rain is an essential part
of this system,

104
00:08:49,520 --> 00:08:52,280
but as we've seen,
all the good it does

105
00:08:52,280 --> 00:08:56,800
is balanced by the damage it causes,

106
00:08:56,800 --> 00:09:00,280
literally washing away
the rainforest itself.

107
00:09:04,440 --> 00:09:08,440
So if the rain's effect
is to carry the forest away,

108
00:09:08,440 --> 00:09:11,080
what happens to it after this?

109
00:09:13,600 --> 00:09:16,120
Well, it ends up being transported

110
00:09:16,120 --> 00:09:20,680
by the most obvious force
in our microworld, the Amazon River.

111
00:09:32,360 --> 00:09:34,880
It is a huge destructive force.

112
00:09:37,360 --> 00:09:41,720
Each year it removes an enormous
one billion tons of sediment and mud

113
00:09:41,720 --> 00:09:45,480
from the forest basin
on its march to the sea.

114
00:09:47,400 --> 00:09:52,280
During the course of this programme,
it will have dumped the equivalent

115
00:09:52,280 --> 00:09:56,520
of 150,000 Olympic-sized
swimming pools into the ocean.

116
00:10:00,120 --> 00:10:04,080
But the river is not as constant
as you might think.

117
00:10:04,080 --> 00:10:07,440
It is so powerful
that it scours deep channels

118
00:10:07,440 --> 00:10:10,480
barging its way through the forest,

119
00:10:10,480 --> 00:10:15,440
constantly changing course
on its way to the Atlantic.

120
00:10:15,440 --> 00:10:21,680
But as destructive as it seems, it
also creates opportunities for life.

121
00:10:23,960 --> 00:10:26,160
As the river loops
through the forest,

122
00:10:26,160 --> 00:10:28,360
these meanders become very curved

123
00:10:28,360 --> 00:10:33,360
until eventually the neck of the
meander touches the opposite side,

124
00:10:33,360 --> 00:10:38,720
cutting off a big loop
from the main river.

125
00:10:40,680 --> 00:10:43,840
In creating these pools,
known as oxbow lakes,

126
00:10:43,840 --> 00:10:47,680
the river creates a slightly
different habitat to be exploited.

127
00:10:51,800 --> 00:10:54,240
These isolated bodies of water
are the ideal space

128
00:10:54,240 --> 00:10:57,320
for one of the river's
top predators,

129
00:10:57,320 --> 00:10:59,720
the two metre long giant otter.

130
00:11:02,880 --> 00:11:05,880
The lakes are full of fish and
the waters are calm so the otters

131
00:11:05,880 --> 00:11:10,160
use them to rear their young
away from the powerful main river.

132
00:11:11,360 --> 00:11:15,840
So in a microworld where every
available space is to be exploited,

133
00:11:15,840 --> 00:11:18,400
the otters have turned this dead end
feature of the river

134
00:11:18,400 --> 00:11:20,720
to their advantage.

135
00:11:23,440 --> 00:11:27,960
The river is actually a dynamic
element in this environment.

136
00:11:27,960 --> 00:11:30,440
It's not the key to its existence,

137
00:11:30,440 --> 00:11:33,160
but its destructive nature
does open up

138
00:11:33,160 --> 00:11:35,320
a lot of opportunities to life.

139
00:11:38,960 --> 00:11:41,840
Some of the sediment the river
picks up gets dumped again,

140
00:11:41,840 --> 00:11:44,840
forming large banks.

141
00:11:47,560 --> 00:11:51,720
The minute space becomes available,
something is there to exploit it.

142
00:11:51,720 --> 00:11:57,440
Thousands of giant river turtles
use these banks to make their nests.

143
00:12:01,160 --> 00:12:05,800
So many come here that each wave
digs up the nests
laid moments before

144
00:12:05,800 --> 00:12:11,160
and in a world short on nutrients
this bounty is not missed for long.

145
00:12:13,840 --> 00:12:16,320
At every turn,
another opportunity is created

146
00:12:16,320 --> 00:12:22,040
and the black vultures are ready
to jump in and make the most of it.

147
00:12:22,040 --> 00:12:24,600
Like their sea-dwelling cousins,

148
00:12:24,600 --> 00:12:28,560
these turtles have a strategy
that involves producing so many eggs

149
00:12:28,560 --> 00:12:31,720
that they can afford to lose
some casualties along the way.

150
00:12:34,000 --> 00:12:35,840
But in this ever-changing world,

151
00:12:35,840 --> 00:12:40,360
the turtles might have to look
for a new nesting site next year.

152
00:12:43,480 --> 00:12:46,120
So the river is dependent
on the rains,

153
00:12:46,120 --> 00:12:49,520
both are prominent players
in the Amazon's ecosystem

154
00:12:49,520 --> 00:12:53,080
but they both play a role
in removing the most vital piece

155
00:12:53,080 --> 00:12:55,640
of this puzzle, the nutrients.

156
00:12:57,200 --> 00:13:00,680
So how does the forest keep hold of
enough of the good stuff

157
00:13:00,680 --> 00:13:03,240
to stay alive?

158
00:13:08,000 --> 00:13:13,960
In the Amazon, 99% of the nutrients
are locked up in living tissues,

159
00:13:13,960 --> 00:13:18,800
so when any of this becomes
available it's pounced upon.

160
00:13:18,800 --> 00:13:21,000
Nothing goes to waste -

161
00:13:21,000 --> 00:13:27,800
trees, leaves, dung and dead bodies
are recycled almost immediately.

162
00:13:32,160 --> 00:13:35,840
The recycling team are an ungainly
rabble of floor dwellers

163
00:13:35,840 --> 00:13:40,280
that lurk and skulk in the dark,
damp recesses of the forest.

164
00:13:42,800 --> 00:13:45,640
Like this giant metre-long
earthworm.

165
00:13:45,640 --> 00:13:51,640
They methodically race against
the rains to reclaim
as many nutrients as possible.

166
00:13:57,440 --> 00:14:00,080
Even so, commodities are scarce.

167
00:14:00,080 --> 00:14:04,600
Phosphorus, potassium and calcium,
essential elements for life

168
00:14:04,600 --> 00:14:10,920
are hard to find, and because of
the rain can be gone in a heartbeat.

169
00:14:12,520 --> 00:14:15,400
But the recycling teams are good,

170
00:14:15,400 --> 00:14:20,720
so good that sometimes things get
recycled before they're even dead.

171
00:14:24,520 --> 00:14:28,080
Spores of the cordyceps fungus
float through the air

172
00:14:28,080 --> 00:14:32,840
and find their way
inside an insect host.

173
00:14:32,840 --> 00:14:35,080
The fungus attacks them
from inside their bodies,

174
00:14:35,080 --> 00:14:39,240
killing them and consuming them
from within.

175
00:14:41,040 --> 00:14:43,600
The fruiting body then erupts
out of the dead insect

176
00:14:43,600 --> 00:14:47,640
and releases its spores
to float through the air

177
00:14:47,640 --> 00:14:50,880
and infect other
unfortunate individuals.

178
00:14:52,000 --> 00:14:54,640
But even here, there is
a dark interdependency.

179
00:14:54,640 --> 00:14:57,720
Each strain of cordyceps fungus

180
00:14:57,720 --> 00:15:01,640
only infects its own particular
species of insect.

181
00:15:11,000 --> 00:15:13,000
These recyclers play a vital role,

182
00:15:13,000 --> 00:15:18,280
keeping what little nutrients there
are moving around the ecosystem.

183
00:15:18,280 --> 00:15:21,280
But this is certainly not enough

184
00:15:21,280 --> 00:15:25,280
to have created this forest
of giants in the first place.

185
00:15:29,280 --> 00:15:32,600
So where would the trees normally
get their nutrients from?

186
00:15:36,880 --> 00:15:39,920
Here trees can grow
to over 50 metres tall.

187
00:15:39,920 --> 00:15:45,240
There is enough light and water
in the Amazon to fuel rapid growth.

188
00:15:48,040 --> 00:15:52,360
But it is not enough.
These giants like everything here

189
00:15:52,360 --> 00:15:55,640
need those nutrients to grow
to these incredible sizes.

190
00:15:58,160 --> 00:16:01,840
Trees usually get all the nutrients
they need from the soil,

191
00:16:01,840 --> 00:16:04,840
but what is different
in this microworld

192
00:16:04,840 --> 00:16:08,560
is that these are some of
the poorest soils on the planet.

193
00:16:10,840 --> 00:16:14,640
Only 1% of the nutrients in this
ecosystem are found in the soil,

194
00:16:14,640 --> 00:16:17,880
compared to 50% in temperate forests

195
00:16:17,880 --> 00:16:22,520
so the Amazon trees
are really up against it.

196
00:16:24,480 --> 00:16:28,960
Only the top 50 cm
has any nutritional value,

197
00:16:28,960 --> 00:16:33,120
below this there is only clay
that is no use to plants.

198
00:16:37,280 --> 00:16:40,160
So in response, the trees
send their roots not down,

199
00:16:40,160 --> 00:16:44,640
but out through as much
of the fertile top soil as they can.

200
00:16:47,360 --> 00:16:51,880
The only problem with this is that
it makes them pretty unstable.

201
00:16:57,000 --> 00:17:01,720
One way around this
is to create huge buttress roots
that help stabilise them.

202
00:17:04,600 --> 00:17:07,880
And they need a good foundation
because they are competing with

203
00:17:07,880 --> 00:17:11,960
the other trees for the other
vital resource here - sunlight.

204
00:17:13,480 --> 00:17:16,720
The trees are so successful
in exploiting sunlight

205
00:17:16,720 --> 00:17:19,440
that the forest floor is
in constant shade.

206
00:17:19,440 --> 00:17:22,560
Only 2% of sunlight
penetrates this canopy.

207
00:17:24,400 --> 00:17:27,960
So how does a young plant
that's just starting out

208
00:17:27,960 --> 00:17:29,680
get established here?

209
00:17:33,280 --> 00:17:37,400
Cheese plant seedlings have
a strange solution to this problem.

210
00:17:40,640 --> 00:17:44,480
Instead of heading for light,
they search for darkness.

211
00:17:46,520 --> 00:17:52,240
The shadows created by
a buttress root of a big tree.

212
00:17:58,040 --> 00:18:02,080
Once there
and using the tree for support,

213
00:18:02,080 --> 00:18:05,040
they can race upwards
towards the light.

214
00:18:10,080 --> 00:18:14,560
The cheese plant pours its energy
resources into thin and rapid growth

215
00:18:14,560 --> 00:18:20,080
rather than strong stems, and leans
on the tree for a helping hand.

216
00:18:20,080 --> 00:18:24,400
This gives it an advantage in a
world where nutrients are limited.

217
00:18:31,120 --> 00:18:35,600
Other plants don't even bother
to start at the bottom.

218
00:18:37,440 --> 00:18:41,360
Bromeliads grow high up
in the branches of trees

219
00:18:41,360 --> 00:18:44,720
and so start life closer
to the light.

220
00:18:50,720 --> 00:18:53,280
They have ponds in their centres

221
00:18:53,280 --> 00:18:55,920
that fill with up to eight litres
of rain water,

222
00:18:55,920 --> 00:19:01,160
offering a water source
30 metres above the ground.

223
00:19:07,160 --> 00:19:12,920
And where there are ponds,
there are usually frogs.

224
00:19:12,920 --> 00:19:15,880
One of the most poisonous
creatures on earth

225
00:19:15,880 --> 00:19:20,360
relies upon the bromeliads
for their rooftop pools.

226
00:19:20,360 --> 00:19:23,680
This poison arrow frog
carries its tadpole,

227
00:19:23,680 --> 00:19:29,360
hatched from an egg laid on a leaf,
to a pool in a bromeliad heart.

228
00:19:30,480 --> 00:19:36,640
Here the tadpole has its own private
pool, tended by its parents.

229
00:19:36,640 --> 00:19:39,960
So the frogs rely
on the bromeliad for a home

230
00:19:39,960 --> 00:19:45,120
but give the plant nutrients in the
form of faeces and leftover food,

231
00:19:45,120 --> 00:19:49,520
and the bromeliad relies upon the
tree to keep it near the sunlight.

232
00:19:53,400 --> 00:19:56,400
The tree tops are where
it's really at.

233
00:19:56,400 --> 00:20:00,080
So successful are these
high-rise communities

234
00:20:00,080 --> 00:20:03,520
that researchers discovered
a single tree in the Amazon

235
00:20:03,520 --> 00:20:06,880
to be home to nearly 2,000 species
of insect and spider.

236
00:20:06,880 --> 00:20:11,480
Only 100 of these
were already known to science.

237
00:20:14,440 --> 00:20:18,760
With such limited resources
and so many mouths to feed,

238
00:20:18,760 --> 00:20:20,920
once the plants
have secured nutrients,

239
00:20:20,920 --> 00:20:23,480
they have to keep hold of them.

240
00:20:26,840 --> 00:20:30,960
Many Amazon plants use poisons
to protect their leaves

241
00:20:30,960 --> 00:20:33,040
from the hungry vegetarians.

242
00:20:33,040 --> 00:20:36,320
But again nature finds a way.

243
00:20:38,760 --> 00:20:44,120
The piping guan only eats the tender
new tips that hold the least poison.

244
00:20:46,120 --> 00:20:48,360
Most leaf eaters eat some
then move on

245
00:20:48,360 --> 00:20:52,200
before they get too large a dose
from any given tree.

246
00:20:53,920 --> 00:20:55,880
The white faced saki monkey,
however,

247
00:20:55,880 --> 00:20:59,240
has evolved a highly specialised
digestive system

248
00:20:59,240 --> 00:21:03,600
that can cope with virtually
any toxin found in the rainforest.

249
00:21:06,960 --> 00:21:10,000
And there is another primate here,
one of the smallest in the world,

250
00:21:10,000 --> 00:21:13,960
that has found a different way
around the tree's
poisonous defences.

251
00:21:18,440 --> 00:21:22,840
Pygmy marmosets are omnivorous,
eating both plants and insects

252
00:21:22,840 --> 00:21:25,680
but their favourite food
is tree gum,

253
00:21:25,680 --> 00:21:28,360
produced by the trees
when their trunks are damaged.

254
00:21:28,360 --> 00:21:32,360
The marmosets have learnt to keep
this food supply going

255
00:21:32,360 --> 00:21:34,960
by reopening previous wounds
on the tree

256
00:21:34,960 --> 00:21:39,400
and they have evolved
special teeth to do so.

257
00:21:42,480 --> 00:21:45,880
These tiny monkeys,
which could fit inside a tea cup,

258
00:21:45,880 --> 00:21:48,240
have learnt how to exploit
a particular food source

259
00:21:48,240 --> 00:21:50,960
at the tree's expense.

260
00:21:58,480 --> 00:22:00,600
Rather than fighting back,

261
00:22:00,600 --> 00:22:03,800
some plants have developed
relationships with animals

262
00:22:03,800 --> 00:22:05,440
that benefit both parties.

263
00:22:07,600 --> 00:22:10,360
They grow tasty, energy-rich fruit.

264
00:22:11,680 --> 00:22:16,520
44 different species of bird and
monkey can feed on a single tree.

265
00:22:19,320 --> 00:22:23,280
And the benefit for the tree
is that contained inside the fruit

266
00:22:23,280 --> 00:22:26,120
are seeds that cannot be digested.

267
00:22:27,320 --> 00:22:30,760
So as the vegetarians
move off through the forest,

268
00:22:30,760 --> 00:22:33,000
what has gone in has to come out.

269
00:22:34,240 --> 00:22:38,320
And the minute it hits the floor,
in come the forests street cleaners.

270
00:22:41,840 --> 00:22:45,200
Dung beetles detect
the bounty immediately.

271
00:22:46,680 --> 00:22:48,800
The males meticulously ball it up

272
00:22:48,800 --> 00:22:52,640
and roll it away
with their hind legs.

273
00:22:52,640 --> 00:22:57,120
However, it is a lot easier
to steal someone else's

274
00:22:57,120 --> 00:22:58,800
than to make your own.

275
00:22:58,800 --> 00:23:03,080
And the bigger the ball, the better
the chances of attracting a female.

276
00:23:04,680 --> 00:23:07,440
Once he's clear, the beetle
rolls his ball away,

277
00:23:07,440 --> 00:23:12,600
burying it in a safe place so that
the female can lay her eggs inside

278
00:23:12,600 --> 00:23:17,280
and the tree's seed is planted
with its own source of fertiliser.

279
00:23:20,560 --> 00:23:22,640
So in this relationship,

280
00:23:22,640 --> 00:23:26,640
the trees are connected to both the
fruit eaters and the recycling team

281
00:23:26,640 --> 00:23:28,280
and they all benefit.

282
00:23:33,440 --> 00:23:37,520
There is one species of plant that
has taken this one stage further

283
00:23:37,520 --> 00:23:42,200
and developed a much more direct
and surprising relationship
to get ahead.

284
00:23:45,280 --> 00:23:48,240
This might appear to be
a natural forest clearing,

285
00:23:48,240 --> 00:23:53,320
but in fact it is inhabited
by only one species of plant.

286
00:23:54,960 --> 00:23:59,480
One species of plant
and thousands of ants.

287
00:24:01,600 --> 00:24:06,400
In this bizarre relationship, the
plant has enlisted the ants' help

288
00:24:06,400 --> 00:24:08,200
in a very surprising way.

289
00:24:11,360 --> 00:24:14,480
The ants inject formic acid
directly into the leaves and stems

290
00:24:14,480 --> 00:24:17,640
of any other plants that try
and grow in the clearing,

291
00:24:17,640 --> 00:24:20,280
killing off all
but their host plant.

292
00:24:26,720 --> 00:24:31,440
And the ants don't stop there.
They also provide protection.

293
00:24:33,200 --> 00:24:37,120
They attack any animals that try
and feed on the plant's leaves.

294
00:24:40,080 --> 00:24:43,800
Even giants
many thousands of times their size

295
00:24:43,800 --> 00:24:46,920
are not immune to
a bit of ankle biting.

296
00:24:51,280 --> 00:24:54,520
This is a great service
if you are a plant in this
competitive environment,

297
00:24:54,520 --> 00:24:58,400
but what do the ants get in return?

298
00:25:00,640 --> 00:25:03,760
The plant has small openings
and swellings along its branches.

299
00:25:03,760 --> 00:25:07,280
These tiny cavities
provide the ants with a home,

300
00:25:07,280 --> 00:25:12,520
protecting them from predators
and giving them a safe place

301
00:25:12,520 --> 00:25:14,400
to rear their young.

302
00:25:16,520 --> 00:25:19,520
It's a collaboration developed over
millennia and another example

303
00:25:19,520 --> 00:25:23,840
of how to survive out here, by
building a successful relationship.

304
00:25:26,840 --> 00:25:29,920
And it is one of these relationships
that holds the key

305
00:25:29,920 --> 00:25:33,760
to the success
of this entire ecosystem.

306
00:25:33,760 --> 00:25:39,680
But it is not colourful, or obvious,
and happens completely out of sight.

307
00:25:46,840 --> 00:25:51,960
Within the soil, the trees
hide a symbiotic relationship

308
00:25:51,960 --> 00:25:54,480
with a fascinating fungus.

309
00:25:54,480 --> 00:25:57,400
The fungus are attached
to their roots

310
00:25:57,400 --> 00:26:01,280
and absorb the available nutrients
far faster than the trees

311
00:26:01,280 --> 00:26:05,160
because they have
a huge surface area.

312
00:26:05,160 --> 00:26:08,240
They efficiently take elements
like phosphorus, potassium

313
00:26:08,240 --> 00:26:11,160
and calcium out of the soil
and into the tree

314
00:26:11,160 --> 00:26:14,560
before the rain gets a chance
to wash it all away.

315
00:26:15,880 --> 00:26:20,320
But this relationship is mutually
beneficial. Both parties benefit.

316
00:26:21,800 --> 00:26:24,840
In return, the tree supplies
the fungus with sugars and starches

317
00:26:24,840 --> 00:26:27,600
that it can't obtain itself.

318
00:26:29,680 --> 00:26:32,040
One could not survive
without the other

319
00:26:32,040 --> 00:26:36,160
and the rainforest as we know it
would not exist.

320
00:26:40,160 --> 00:26:42,280
The delicacy of this relationship

321
00:26:42,280 --> 00:26:46,400
and the importance it has on this
microworld is clearly demonstrated

322
00:26:46,400 --> 00:26:49,760
where the rainforest has been
cut down for agriculture.

323
00:26:53,640 --> 00:26:57,360
The rain quickly washes away the
little goodness held in the soil,

324
00:26:57,360 --> 00:27:00,320
and the sun bakes the ground solid.

325
00:27:02,680 --> 00:27:06,840
With no trees to shade the ground
or to provide essential sugars,

326
00:27:06,840 --> 00:27:09,000
the fungus in the soil dies out.

327
00:27:09,000 --> 00:27:13,840
Leaving the soil barren,
untenable for trees to recolonise.

328
00:27:15,680 --> 00:27:19,600
Without this partnership
there would be no rainforest

329
00:27:19,600 --> 00:27:23,200
and so many species
rely on this ecosystem.

330
00:27:28,440 --> 00:27:33,200
The Amazon rainforest is
a complex web of inter-connectivity,

331
00:27:33,200 --> 00:27:38,120
where many organisms rely on
the others to survive.

332
00:27:48,120 --> 00:27:52,720
The more diverse the microworld,
the more robust it is to change.

333
00:27:56,000 --> 00:28:00,080
But as we have discovered, even our
biggest and most diverse ecosystem

334
00:28:00,080 --> 00:28:02,040
relies on a fragile balance

335
00:28:02,040 --> 00:28:06,360
between the environment
and the species that live within it.

336
00:28:08,080 --> 00:28:12,480
And without one surprising alliance
between a tree and a fungus,

337
00:28:12,480 --> 00:28:15,600
life in our microworld
would not exist at all.

338
00:28:19,880 --> 00:28:22,080
But it does and it has created

339
00:28:22,080 --> 00:28:27,320
one of the most incredible and
intricate microworlds on our planet.

340
00:28:33,640 --> 00:28:35,680
Subtitles by Red Bee Media Ltd