What causes leaves to change color in the fall?

Autumn splendor

The magnificence of a forest dressed in yellow, orange and red leaves can take your breath away. Each season presents its own pleasures, but none as impressive as the fall. So much so that people cross the oceans to gather in awe where nature offers smorgasbords of autumn colors. Each year, Mother Nature chooses the palette for the glorious display of fine art.

Why do the leaves change color?

According to Native American lore, leaves turn red from the blood spilled when hunters took the life of the Great Bear in the sky. The yellow leaves received their rich color from the splashing of the bear’s fat from the pot in which they cooked it.

Why are trees green in summer?

According to scientists, the green leaves are the providers of energy for the tree’s growth throughout the summer. Sunlight, water and carbon dioxide is changed into energy. They always have yellow and orange pigments, which help with the absorption of sunlight. Together, these processes form green pigment called chlorophyll, which plays the leading role in photosynthesis. During the summer months, the abundance of sun and the longer daylight hours make sure the leaves have maximum green chlorophyll, giving the orange and yellow pigments no time to shine.

Leaves, fall

What causes leaves to change color in the fall?

Toward the end of summer, the shorter days make the trees prepare for a state similar to hibernation. The lack of sunlight and drier air prevent continuing photosynthesizing. The leaves stop absorbing sunlight, and the fiery oranges and brilliant yellows get a turn to show their splendor.

This is also the time for the tree to protect itself from the cold of winter. No sun means no chlorophyll, and the tree begins manufacturing cork-like cells at the joints between the tree trunk and the leaves. This will prevent the tree from drying out in the cold winter. Once this separation process is complete, the leaves begin to drop, often with the help of the wind or gravity.

Leaves, autumn

Why are red leaves so special?

They change their color to red only under specific circumstances. For that reason, they seem extra spectacular. When an unusual amount of sunlight continues into autumn, they form the red pigment to protect them from overexposure. Sunlight at this time encourages the tree to tap into the last bit of nutrients produced by the red pigment. This provides the tree sap with increased sugar concentration. Only after the tree has had its fill will it drop the leaves to conserve energy throughout the cold winter months.

So, in years when the fall is overcast, rainy and with limited sunlight, the chances of seeing red foliage are limited.

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