Why Do Leaves Change Color?

An assortment of fruity colors litter the Adirondack Mountains. Random arrangements of yellow, red and orange leaved trees sparaticly color the forest with a few green leaved trees. I look out my window of the Greyhound bus and I'm in love with the beautiful creation of what nature has made. Yet, as I make my journey back to New York City, I wonder how could nature create such a vivid, lively color to such a boring, dull season.

Trees have to prepare themselves for the winter just like humans do. As the temperatures get colder, the days become shorter. The leaves in trees produce a pigment called chlorophyll. This pigment produces a green color which is absorbed from blue and red light. Chlorophyll is in the cloroplasts part of the cell. This section is where photosynthesis occurs and light energy is converted into chemical energy. It is produced during the summer when there's more light to brighten up a leaf's day.

During the fall, chlorophyll is less present because of less light. In some trees, a pigment called carotene is also produced. This pigment absorbs blue-green and blue light. It combines with chlorophyll when they are in the same leaf. They remove red, blue-green and blue light from sunlight after it hits the leaf. Carotene transfers energy to chlorphyll in photosynthesis. When chlorphyll disappears, carotene is usually still there and it produces a yellow color on its own.

Another pigment that can also appear in leaves is anthocyanin. This pigment is not in the cloroplasts of the cells. A reaction between proteins and sugars in the cell sap form anthocyanins. It doens't occur unless there is a high concentration of sap and it also needs light. It absorb blue, blue-green and green light. It is very sensitive to pH in the cell sap. If the sap is more acidic, the leaf will have a bright red color. If it's not as acidic, the leaf will have a more purplish color.

Trees have so many amazing characteristics about them that make up what they are. They truly change with the seasons and continue to survive through the bitter winter. They liven up the dreary fall mornings with their splash of color even with a lack of light. Who knew that less sunlight could produce something so beautiful.