The Living Planet

I am sitting surrounded by the greatest proliferation of life

anywhere on the surface of the earth.

I'm up in the canopy of the jungle, the tropical rainforest.

Here there is a greater bulk of life, both animal and plant -

and a greater diversity too - than can be found anywhere else.

This huge proliferation comes from two main causes: Warmth and wetness.

The wetness comes from the abundant equatorial rains,

the warmth from the tropical sun.

Between them, those two factors have created the jungle,

which stretches in a broken green band right round the earth.

This particular patch lies in South America, right across the equator,

stretching for 600 miles both north and south of it

in a vast blanket, almost unbroken except for the rivers.

Here there is probably more unexplored territory than anywhere else in the world.

Travel east from here along the course of that greatest of rivers, the Amazon,

and you reach the Atlantic.

Continue along the line of the equator, across the ocean,

and you come to the west coast of Africa,

another gigantic river, the Zaire - that used to be called the Congo -

and another vast tract of jungle.

Eastern Africa doesn't get as much rain and the jungle dwindles into savannah,

but across the Indian Ocean the great green rainforest reappears

along the western edge of India and Sri Lanka.

It covers south-east Asia, Burma, Thailand and Malaysia,

the huge islands of Borneo and Sulawesi and the smaller archipelagos of Indonesia,

and farther east still, New Guinea.

Beyond lies the vastness of the Pacific,

for the most part empty of land except for scatterings of tiny islands,

until, having girdled the earth around the equator,

you come back to the greatest expanse of all, the Amazon jungle.

The kind of tree I've climbed doesn't grow in groups but as isolated individuals,

and it's by far the tallest tree in this particular jungle.

It's a kapok, and it grows to over 200 feet high.

If the canopy of leaves formed by the rest of the jungle

can be called a sea of leaves, then the crown of the kapok

is an island which rises above that sea, and it has a climate all of its own.

There is more sunshine up here than below and there's also wind,

which is virtually unknown in the depths of the forest.

The wind causes some problems.

It can rob a tree of its moisture by evaporation from the surface of its leaves,

so the kapok has very small leaves.

The wind also brings a benefit -

it distributes the kapok seeds, which are extremely fluffy.

They float gently across the top of the canopy for mile after mile.

The crowns of these giant trees are the home

of the biggest and most fearsome of all jungle birds.

There are flying hunters very like this one in most jungles.

In South America the harpy, in Africa the crowned eagle,

and here in Malaysia the hawk eagle.

All patrol above the surface of the canopy, occasionally plunging down into the leaves

at great speed to seize a squirrel, a bird or even a monkey.

All produce just one nestling

which they must feed with meat for almost a year

until it too is big enough to hunt.

These high outposts above the jungle are excellent vantage points

from which to scan life in the canopy below.

Few other creatures dare fly above that sea of leaves when there are eagles about.

Coming down from the airy sunlit branches of the kapok,

you leave the breeze and the dazzling sunshine and enter a different world.

Here the warm still air is heavy with moisture,

there's hardly a breath of breeze,

the leaves above cut out much of the sunshine.

The canopy - millions of leaves stretching in a vast endless mosaic of green,

each leaf exactly angled to collect the maximum amount of light.

Many have a special joint at the base of their stalk

that enables them to twist and follow the sun as it swings overhead.

It's an isolated world, many of whose inhabitants

are born here and will die here, without ever leaving it.

Insects are everywhere.

There seems no limit to the variety of their shapes and colours.

Some prey on others, most derive their sustenance from the trees,

collecting the seeds, sipping the nectar, sucking the sap and munching the leaves.

Weaver ants use the leaves as walls for their nests.

Workers, feet hooked on one leaf, lock their jaws on the edge of another

and haul the two together.

While they hold the leaves in position,

other workers use the colony's grubs as tubes of glue, gently squeezing them

so that they produce threads of sticky silk

which they weave back and forth across the junction.

Eventually they produce an enclosed globe within which they can rear their young.

The insubstantial green terraces of the canopy are the pastures of the jungle

and a multitude of creatures graze on them.

These in South America are squirrel monkeys,

but every jungle has its monkey troops that scamper with total confidence

through the branches, fastidiously selecting the right kind of tree,

the juiciest bud... or the particular shoot that most takes their fancy.

There are no seasonal changes here comparable to winter and summer in the north,

so there is no one time for the shedding and the renewal of leaves.

Neither is there any particular season for flowering.

In this eternal summer, trees vary greatly in their flowering cycles.

Some bloom every ten months, others every fourteen.

A few may only flower once in a decade. But the rhythm is far from haphazard,

for all the individuals of one species produce their flowers at about the same time,

as they must if they are to cross-pollinate one another.

With so little breeze within the canopy, the trees can't rely on the wind to pollinate.

Most depend on insects and other animals,

bribing them with lavish feasts of pollen and nectar.

Bigger creatures have to be persuaded to transport the heavier seeds.

Their rewards are the fruits.

Birds do much of this work during the day, swallowing the entire fruit,

digesting the flesh and voiding the seeds later and elsewhere.

At night, other creatures take on the job.

The majority of bats eat insects, but in the tropics many have specialised

in collecting fruit and live on nothing else.

There are a great number of different kinds of figs in the jungle,

each with its own fruiting rhythm.

Since the bats are such accomplished fliers, they can range far over the jungle

and can always find figs of some kind, ripe somewhere.

Some feast on them in the trees, many prefer to carry them away

and feed in the familiar safety of their roosts.

Trees can be cropped in many different ways.

The pygmy marmoset has specialised in collecting sap.

The front teeth in its lower jaw project forward,

and with them it scrapes away the bark causing the sap to run.

Marmosets live in families, each with its own territory in the branches,

and each has at least one of these sap wells

which the family keeps open and productive and vigorously defends.

Still though the air is, it carries the microscopic spores of ferns and mosses

which lodge in the crevices of the tree bark and sprout.

As they flourish and decay, their remains accumulate into a compost

on which other plants can grow.

Their dangling roots collect moisture from the humid air,

and so the broad branches become balconies loaded with orchids and bromeliads.

Bromeliads are relations of the pineapple

and each one has its own population of animal lodgers.

The rosette of leaves forms a chalice that is always full of water,

a useful drinking place for the canopy animals.

For some frogs, it's more than that. It's a nursery.

This little female arrow poison frog laid her eggs on a leaf.

As they hatched, she allowed a tadpole to wriggle up onto her moist back.

Now she must find a pond for it to swim in.

She reverses into the water and allows the surface tension to pull her tadpole off.

Several species of arrow poison frogs use bromeliads like this,

and most regard their parental responsibilities as being over at this stage.

Mosquitoes are likely to lay here,

so with luck, there should be some wriggling larvae for the tadpole to feed on.

But this frog doesn't take that chance. Every three or four days,

she returns to every plant where she left a tadpole and in each she lays more eggs.

But these are not fertile. They are food for the tadpole

and will sustain it until it's big enough to catch insects for itself.

For such frogs, like so many creatures up here,

the canopy is a complete world, suspended above the surface of the earth,

that they never need leave.

When you descend from the canopy,

you leave behind the most densely populated part of the jungle

and enter a kind of aerial halfway house of spindly saplings,

hanging lianas and bare branchless trunks.

Here, I am about halfway down, about 70 feet above the floor,

midway between the ceiling of leaves in the canopy and the carpet of leaves below.

Up here, there are very few leaves - these huge tree trunks don't sprout many.

There's nothing much but empty space, so very few creatures come here to feed,

and apart from birds and some flying insects, the only creatures I'm likely to see

are those that use these huge tree trunks and the dangling lianas

as vertical highways between the world above and the world below.

Snakes with no legs and claws with which to hold on

might not seem to be well suited to climbing, but in fact

some can ascend the vertical trunks with astonishing ease.

The paradise tree snake of Borneo maintains its grip

by pressing sideways with its coils and propels itself upwards

by sending ripples down the line of angled backward-pointing scales on its underside.

But it has an even more unexpected accomplishment.

By pulling its ribs forwards, it flattens its body, turning it from a rod into a ribbon

so that it catches the air, and by waving its coils it can, to some extent,

control the direction of its glide.

But in these Borneo forests there are even better gliders.

This squirrel has a cloak of furry skin that stretches from its wrist to its ankle.

When it's about its normal business, the skin looks a bit untidy,

as though the animal were rather sloppily dressed, but when the squirrel leaps,

then it becomes the very summit of gliding grace.

Most other mammals in this midway zone travel from tree to tree along the lianas.

Marmosets are capable jumpers and confidently leap a yard or so.

But they are not always convinced that they can make it.

The uakari is not nearly so athletic.

It sometimes avoids too big a jump by throwing its weight back and forth on a sapling,

so that it sways and carries it across to the next tree.

Few large creatures visit this middle part of the jungle to feed,

for there are comparatively few leaves here,

but lizards scuttle up and down the trunks, for there, as almost everywhere else,

there are insects to be collected.

Spiders hunt here too.

These termites collected their food from rotting vegetation on the ground.

They are laboriously carrying it all up here because it's up here, within the trunks,

that they have built their nest.

Other termites hang their nests from branches

and these are often commandeered by others.

A bird originally dug this hole, but the bat took it over

and now uses the termites' work as a convenient roost

from which to hawk for insects.

The pillar-like trunks of the huge trees provide homes for a few birds.

A big bird like a macaw needs a nice open approach to its nest,

and the hole is relatively safe, for few non-flying robbers can reach it.

This hole started when a dead branch fell, but the macaws have enlarged it greatly.

They usually have just two chicks,

but keeping them properly fed is a considerable labour,

for they will stay in the nest hole for over three months.

Like all parrots, macaws feed their young

by regurgitating chewed-up fruit from their crop.

Both parents labour away, bringing loads of fruit throughout the day,

for it's bulky food and the youngsters need a great deal of it.

Holes in tree trunks are very valuable properties.