|
|
|
About a thousand square meters of plane trees can trap 3.5 tons, and pine trees 2.5 tons of pollutants!
|
The
services that plants carry out for other living things are not restricted to
giving off oxygen and water. Leaves at the same time carry out the most highly
developed cleansing and purification functions. The cleaning tools we regularly
use in our daily lives are produced and set in operation as the result of long
studies by experts and after the expenditure of a lot of effort and money. These
need considerable technical support and maintenance both during and after use.
In addition, problems or defects that can arise on a daily basis, and the
necessary staff and the need for other tools and renewals where necessary can
all mean a great many more processes.
There
are hundreds of details to consider even in a small piece of cleaning equipment,
whereas plants do the same job as these tools in return for just sunlight and
water, and perform the same cleaning service with the guarantee of greater
efficiency. They also give rise to no waste product problem, because the waste
product they give off after cleaning the air is oxygen, which all living
creatures need!
Leaves
Catch Air Pollutants
Tree
leaves possess tiny filters that catch pollutants in the air. There are
thousands of tiny hairs and pores, invisible to the naked eye, on the surface of
a leaf. The individual pores trap pollutants in the air and send them to other
parts of the plant to be absorbed. When it rains, these substances are washed to
the ground. These structures on the surfaces of leaves are only of the thickness
of a film; but when one considers that there are millions of leaves in the
world, it becomes clear that the amount of pollutants trapped by leaves is not
to be underestimated. A 100-year-old beech tree, for example, has about 500,000
leaves. The amount of pollutants caught by these leaves is more than one might
guess. About a thousand square metres of plane trees can trap 3.5 tons, and pine
trees 2.5 tons of pollutants! These materials then fall to the ground with the
first rain. The air in a forest two kilometers from a settlement area is some 70
percent cleaner than that in the settlement area. Even in winter when trees lose
their leaves, they still filter out 60 percent of the dust in the air.
Trees
can trap dust weighing 5 to 10 times more than their leaves: bacteria levels in
an area with trees is considerably less than in one with no trees [1].
These are very important figures.
As
a food resource and cleaning tool scientists showed that leaves are protected by
another perfectly planned mechanism. With the approach of winter the air grows
colder and the days shorter, and less light reaches the Earth from the Sun. This
reduction causes changes in plants, and the aging process in leaves, or leaf
fall, begins.
Before
trees lose their leaves, they begin to absorb all the nourishing substances in
the leaves. Their aim is to prevent substances such as potassium, phosphate, and
nitrate from disappearing with the falling leaves. These substances are directed
through the pipelines that run through the layers of bark and the centre of the
trunk. The collection of these substances in the xylem makes it easier for them
to be digested by the tree.
The
Leaf Fall Process
Trees must shed their leaves because in cold weather the water in the soil
increasingly solidifies and becomes more difficult to absorb. But the
perspiration in the leaves continues, despite the cold weather. A leaf that
continues to perspire at a time when there is less water starts to become a
burden on the plant. In any case, the cells in the leaf would freeze and break
up in the cold days of winter, for which reason the tree acts early and frees
itself of its leaves before winter arrives, and in this way its limited water
reserves will not be wasted [2].
This
leaf fall, which looks like a purely physical process, actually comes about as
the result of a sequence of chemical events.
In
the cells in the palm of the leaf are pigments called phytochromes that are
sensitive to light and give color to plants. It is these molecules that allow
the tree to realize that the nights are growing longer and that less light is
reaching the leaves. When phytochromes sense this change they cause various
changes within the leaf, and begin the leaf's aging program.
One
of the first signs of leaf aging is that the cells in the palm of the leaf begin
to produce ethylene. The gas ethylene begins to destroy the chlorophyll that
gives the leaf its green color, in other words the tree withdraws the
chlorophyll from the leaves. Ethylene gas also prevents the production of
auxine, a growth hormone that delays the falling of the leaf. Together with the
loss of chlorophyll, the leaf also starts to receive less energy from the sun
and produces less sugar. Furthermore, carotenoids, which have hitherto been
suppressed and that give the leaf its rich color, reveal themselves and in this
way the leaf begins to change color[3].
A
short while later, ethylene has spread to every part of the leaf, and when it
reaches the leaf stalk, small cells there start to swell up and give rise to an
increase in tension in the stalk. The number of cells in that part of the stalk
that join onto the trunk increases, and they begin to produce special enzymes.
First, cellulose enzymes tear apart the membranes formed from cellulose, and
then pectinase enzymes tear apart the pectin layer that binds the cells to one
another. The leaf can no longer bear this rising tension and starts to split
from the outer part of the stalk in.
The
processes we have been describing so far may be described as the cessation of
food production and the first stages of the leaf's split from the stalk. Rapid
changes go on around the developing split, and the cells immediately begin to
produce suberin. This substance slowly settles over the cellulose wall and
strengthens it. All these cells leave behind them a large gap replacing the
fungus layer and die [4].
 |
|
What
has been described so far shows that a string of interlinked events is necessary
for just one leaf to fall. Phytochromes determining that there is a reduction in
sunlight, all the enzymes necessary to the falling of the leaf moving into
action at the appropriate time, the cells beginning to produce suberin just at
the place where the stalk will break off: it is clear what an extraordinary
chain of events it takes for a leaf to detach itself. "Chance" cannot
be offered as the explanation of this series of processes, all planned and
following one another in perfect order. The leaf fall plan functions in a
perfect manner.
Before
the leaf is completely separated from the trunk, it no longer receives any water
from the transport tubes, for which reason its grip on the place it is attached
to grows progressively weaker. A moderate wind becomes all that is needed to
break off the leaf stalk.
Contained
in the dead leaf that falls to the soil are food substances that fungi and
bacteria can make use of. These food substances undergo changes brought about by
micro-organisms and become mixed with the soil. Trees can take these substances
up again from the soil by their roots as nutriments.
Each
and every process that occurs in leaves can be described as an individual
miracle. These systems in green leaves, in the superb planning as in a
microscopic factory, are proof of the creation of God, the Lord of all the
worlds, and have come down to our day after hundreds of thousands of years in
the same perfect state with no changes and no defects.
References:
[1]
Bilim ve Teknik Dergisi (Science and Technology Journal), August 1998, p.92
2
Lathiere, S. Science & Vie Junior, November 1997
3
Lathiere, S. Science & Vie Junior, November 1997
4
Malcolm Wilkins, Plantwatching, New York, Facts on File Publications, 1988,
p.171
*
The
author,
who writes under the pen-name of Harun Yahya, has published many books on
political, faith-related and scientific issues. Some of the books of the author
have been translated into English, German, French, Spanish, Italian, Portuguese,
Albanian, Arabic, Polish, Russian, Bosnian, Indonesian, Turkish, Tatar, Urdu and
Malay and have been published in the countries concerned. Visit his website at www.harunyahya.com
or contact him at info@harunyahya.com
|
