Page 135 - Photosynthesis: The Green Miracle

bility. When temperatures are low and plants are exposed to extremely
bright light, a great many of them tend to increase their anthocyanin lev-

els. That is why the color red increases in many plants in autumn. These
pigments generally turn color, from yellow to orange and red. In addition
to weather conditions, color change in autumn is to a large extent related
to the individual plant species. The strikingly beautiful scenes we see in
autumn are thus the work of these pigments. 64

Leaf Shedding

Is there any benefit to the falling of the leaves?

Millions of leaves fall every year, and reappear with the coming of
spring. At first sight, it might appear as if all these leaves fall to earth for
nothing. Yet this is a misconception, because the fall of leaves occupies an
important place in the ecological system. Nothing has been created for no

reason. Whichever system or living thing we examine, we find a purpose
and wisdom in its creation. Falling leaves are also a part of this perfect
system. The largest falling leaves replenish the soil with nutrients. In ad-
dition, falling leaves help with the retention and absorption of rain by
forming a humus layer on the forest floor, and many tiny living things
find shelter under them. Finally, fallen leaves become a source of food for
many organisms living in forests.
Every year, as the leaves fall, some 300 million tons of chlorophyll en-
ter the soil worldwide. Every year, 900 million tons of chlorophyll are bro-

ken down in the seas, since seaweeds and algae containing chlorophyll

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