The Indians of North America have attempted to explain the mysterious beauty of fall foliage. According to legend, hunters in the sky killed the great bear every fall. The spilled blood, they said, splashed red in several layers as the fat from the hunter's pot turned another yellow.
This explanation probably won't do much to satisfy your curiosity about roving colors this fall. What really goes on in the colored leaves? Why do some turn red, some yellow or orange or purple, and others brown? What causes the same tree to take on different colors? And why do only some parts of the world enjoy spectacular fall shows?
You might be surprised to learn that much of the color is in the leaves all summer! You can't see. The excess of green chlorophyll in the leaves during the summer masks the other colors. But in the fall, something happens to the chlorophyll in deciduous trees. It is important to understand why the leaves change color in the process.
These deciduous trees shed their leaves every year, unlike evergreen plants. The annual increase in fall colors only reflects the physical and chemical changes that occur during this process. The colors signal the viewer that a magnificent leafed seal is being made. How is it?
Well, in a little-known chemical reaction, the chlorophyll in the leaves uses sunlight in the summer to make food (sugar) from water and carbon dioxide in the air. To do this, the leaves remove water from the soil and much of it evaporates into the atmosphere.
However, very little water is available in winter. It is often suspended from the ground. Therefore, the loss of vital water through the leaves must be stopped. Trunks and branches must also be protected from winter cold. For the good of the tree, its leaves should disappear. When the sunlight goes down in winter, most of the deciduous trees start to close the camp.
A seal that reveals
As the days get shorter, a layer of specialized cells begins to form between the leaf stem and the branch it grows from. This absorbent cork layer gradually reduces the water supply from below and stops the flow of sugar from the leaves to the tree. When the sealing is finally complete, the weight of the sheet and its twisting in the wind is enough to make it float on the ground. But remarkable in the meantime. to make things happen.
The large chemical laboratory loses its raw material access to water and summer sunlight without raw material. The unstable chlorophyll in the leaves begins to break down and fade, making the color pigments already present visible. These are mainly carotenoids, pigments responsible for colors ranging from light yellow (xanthophylls) to the color of carrots (carotenes). Carotenoids are much more stable than chlorophyll, so they stay on the leaves of poplar, birch, poplar and others to brighten up the landscape with golden tones.
But what about the bright reds, purples and even blues that make the drop so spectacular in some parts of the world? They are anthocyanins. They also give red apples, cabbage to purple, violets to blue, etc. Anthocyanins are so dominant in some trees like Japanese maple (red) and purple plum that they can be seen all summer. In most plants, however, this pigment does not form until fall.
Anthocyanins are much more sensitive to external influences than other leaf pigments. When leaf fluids are acidic, they appear red; when the fluids are neutral, purple; and if it's alkaline, blue. Therefore, any variation in the chemical composition of anthocyanins or in the acidity of the leaf can result in a large number of colors.
Since these pigments are made of sugar and clear sunny days enable good sugar production, fluctuations in the autumn weather can also affect the brightness of the leaf screen. While clear days are followed by cool, cool nights, the cold of the night slows the movement of sugar from the leaves to the trees. Sugar concentrations increase, which increases color production. But when the autumn weather is cloudy or hot nights, the colors are much softer.
Anthocyanin production in some plants is so sensitive to light that when one leaf casts a shadow over the other, a picture of the upper leaf looks like green or yellow at the bottom, outlined in red where the sun is shining! It also explains why parts of a tree that are most exposed to the sun may be slightly colored, while other parts of the same tree are slightly red.
Finally, there are browns that are often combined with yellows to form the beautiful golden yellow and golden brown that further increase case exposure. Brown tones often occur in aged cells, similar to what happens when a sliced apple turns brown in the open air. It is light brown in beech and some oaks because the leaf cells still live a lot, even if they age as brown forms.
On the other hand, some leaves do not turn brown until they are almost dead or on the ground. These brown and some yellow are the only autumn colors seen in most of the world, where there are some deciduous trees. Why do so few places have bright autumn displays with a wide range of colors?
A show for a few
Only limited regions of the world are blessed with the conditions under which these dazzling representations can occur. First, there must be a large number and different deciduous trees. It must have the genetic ability to produce pigments that make the leaves so colorful. Many varieties simply do not produce anthocyanins. Another important factor is the clear and cool autumn. Only a few regions in the world meet these requirements and they are mainly in the northern hemisphere.
The British Isles and western Central Europe have large deciduous forests, as do eastern China, Korea and parts of Japan, and these have a beautiful autumn color. But many believe that the most spectacular color displays occur in the eastern United States and southeastern Canada. The largest range of tree varieties with red potential and perfect fall conditions seem to work together to give truly impressive results.
In some states, the autumn leaves attract people from distant places as an annual tourist attraction. Newsletters are also published that describe the color phase in different areas. The traffic blocks roads in the normally sleepy landscape, with what residents often call "leaf monsters".
But these beauty lovers are in awe of what they see. It is an incomparable chemist, the Creator Himself, who can make this splendor part of what would otherwise be a routine for tree survival.
Nice article Dear