Читать книгу Can You Hear the Trees Talking? - Peter Wohlleben - Страница 14

Just like other living things, trees need water. And because they are the elephants

of the plant

world,

they need a lot of it. On a hot summer day, a large beech

tree can easily drink up three or four bathtubs full of water.

OF COURSE,

THERE

ARE NO

BATHTUBS

in the forest,

which means that beech trees have to get every

drop of water from the ground. They do this

using their roots to feel for the spots where

it's nice and moist.

Once they've found a moist spot, they

quickly suck up all the water. And to make sure

they really do get every last drop, the roots

team up with fungi. Fungi grow fine threads

around the roots of these forest giants and, like

cotton balls, they soak up even more water for

the

trees.

Different salts from the ground are carried

into the tree trunks along with the water. The trees

need these salts to grow, and they like

them.

It's like

when you eat chips–once you start, you can't stop!

We still don't really know how trees get water

all the way up to their crowns. (Maybe you'll want

to research this yourself when you get older.) What

scientists do know is that it takes

a

lot of energy for

trees to do this–more energy than you would need

to blow up

a

balloon as big as a house.

*

In the winter, when the water in the ground freezes,

the trees take a break from drinking. After all, you

can't drink ice cubes. That's why, before they grow

leaves again in the spring, they suck a whole lot of

water up into their trunks in one big gulp. If

you

take

a stethoscope (that thing the doctor uses to listen to

your heart) and hold it up against the bark, you may

actually be able to hear the water rushing up inside

the tree. As soon as the tree leafs out, the water

pressure drops back down.

Trees that belong to the same species usually drink

about the same amount. But some learn to drink

a

little

less.

During a hot summer, the ground can dry out.

If

a

tree keeps trying to suck water from dry

soil,

its

wood may crack. That helps it learn to do

a

better job

of managing its water supply.

Come

the next spring,

instead of drinking up all the water in May and June,

it saves some for July and August.

Some

trees learn more quickly than others. There

are reckless trees that drink a lot, and careful trees

that prefer to conserve water, Fortunately, the careful

trees are very nice to the others. When they notice

that the ground is drying out, they warn their fellow

trees through the fungi that act

as

the forest internet.

(You can read all about this in Chapter 3.) When the

news gets out, even trees that like to guzzle water

begin to cut back.

*

The forest's water supply is constantly refilled by rain

and snow. To catch every possible drop of

rain,

decid-

uous

trees such

as

beech and oak angle their branches

up into the air to act

as

big funnels. The rain runs along

their branches to the trunk, where it shoots down to

the ground. Sometimes so much water runs down the

trunk that it froths up when it hits the ground.

Conifers are not as good at catching

rain.

Many

of them come from colder places, so they're better

prepared for snow

than

for dry weather, After

a

snowfall,

their flexible branches hang down close to their trunks

so the tree doesn't fall over under the heavy snow.

This doesn't work with deciduous trees. Their

branches reach up to the sky, and they would break

off under

a

heavy load of

snow.

That's why these trees

drop their leaves in the

fall.

Then the snow can simply

fall between the bare branches right onto the ground.

The branches of conifers work well to shed snow,

but not so well to catch

rain.

Because conifers are

narrow at the top and their branches angle out or down

rather than up, they act like umbrellas. This means the

ground around the trunks of conifers often stays very

dry, and in the summer the trees can be very thirsty.

Being Thirsty Hurts!

ft

thirsty tree's trunk can tear when

it

tries

to such water from dry ground.

IF IT'S A

VERY

ORY

SUMMER

and

spruces

continue

to

suck water out of the

ground,

especially greedy

trees can split open along the length of their

trunks.

That's a

bad

injury for

a

tree.

Thick drops

of pitch seep out of the wound (pitch is like the

blood of the spruce tree], and the wound never

really heals. That tree will have a

long,

seeping

scar down its bark for the rest of its life.

With their wide crowns, beech trees con capture a

lot of

rain and direct

it

down their trunks

to

the ground.