why do deciduous trees turn different colors in the fall?

Answer 1

Scenes of stately sugar maples turning shades of orange and red, or red oaks ablaze with crimson leaves accented by a bright blue autumn sky are indelibly etched in the memories of many Iowans. However, have you ever wondered how the leaves of trees and shrubs are able to create such a colorful display? And why is fall color better in some years than in others? There is no simple formula to predict fall color for a given area of the state. Instead, intensity, type and duration of color, and date of peak color are determined by complex environmental factors and the genetic makeup of the plants themselves.
A summer leaf is green because of the presence of a group of pigments known as chlorophylls. Chlorophyll pigments, which help the plant manufacture food, are plentiful in leaf cells during the growing season, and their green color masks the colors of other pigments present in the leaf. But as autumn approaches, shortening daylength causes the supply of chlorophylls to dwindle, and their ability to mask other pigments is greatly diminished. Then other pigments like the carotenoids, which actually have been present in the leaf all summer, begin to show through.

Carotenoids, responsible for the colorations of yellow, brown, orange, and many intermediate hues, give characteristic color to carrots, corn, daffodils and bananas, as well as the fall leaves of deciduous trees like ash, aspen, birch, ginkgo, hickory and honeylocust.

Reds and purples, and their blended combinations that color the autumn leaves of red maple, white ash and red oak come from another group of pigments called anthocyanins. Unlike the carotenoids, anthocyanins are not present in the leaf during the growing season. Instead, they develop in late summer in the sap of leaf cells. Not all trees are capable of producing anthocyanin pigments, and even those that are, depend on the breakdown of sugars in the leaf in the presence of bright light. In fact, when the days of autumn are bright and cool, and the nights are chilly but not freezing, the most brilliant colorations usually develop. Wet, cloudy, warm weather or exceptionally low temperatures in early fall tend to mute the much anticipated autumnal display. Finally, trees growing in dense shade usually do not develop the vibrant colors that trees of the same species produce in full sun.

Each fall, thousands of Iowans and visitors alike enjoy the dazzling leaf display in our state. "Knowing when and where the fall colors are going to be most brilliant, is kind of a roll of the dice," according to John Walkowiak, Urban Forester with the Department of Natural Resources. "But in general, the northern 1/2 of Iowa has prime fall colors during the last week of September to the second week in October, and the southern 1/2 of the state has prime fall colors during the second to the fourth weeks of October," he said. For current leaf conditions across the state, individuals can call [phone]. Callers will receive a recorded message detailing leaf conditions and best color locations. The information is updated weekly and is available from mid- September through late October.

Answer 2

We all enjoy the colors of autumn leaves. Did you ever wonder how and why a fall leaf changes color? Why a maple leaf turns bright red? Where do the yellows and oranges come from? To answer those questions, we first have to understand what leaves are and what they do.

Leaves are nature's food factories. Plants take water from the ground through their roots. They take a gas called carbon dioxide from the air. Plants use sunlight to turn water and carbon dioxide into glucose. Glucose is a kind of sugar. Plants use glucose as food for energy and as a building block for growing. The way plants turn water and carbon dioxide into sugar is called photosynthesis. That means "putting together with light." A chemical called chlorophyll helps make photosynthesis happen. Chlorophyll is what gives plants their green color.

autumn leaf


As summer ends and autumn comes, the days get shorter and shorter. This is how the trees "know" to begin getting ready for winter.

During winter, there is not enough light or water for photosynthesis. The trees will rest, and live off the food they stored during the summer. They begin to shut down their food-making factories. The green chlorophyll disappears from the leaves. As the bright green fades away, we begin to see yellow and orange colors. Small amounts of these colors have been in the leaves all along. We just can't see them in the summer, because they are covered up by the green chlorophyll.

The bright reds and purples we see in leaves are made mostly in the fall. In some trees, like maples, glucose is trapped in the leaves after photosynthesis stops. Sunlight and the cool nights of autumn cause the leaves turn this glucose into a red color. The brown color of trees like oaks is made from wastes left in the leaves.

It is the combination of all these things that make the beautiful colors we enjoy in the fall.

Answer 3

Interestingly, many of the colors are there during the warm season, but appear only as nourishment to the leaves wanes in the Fall. Do an internet search for "fall colors." Explanations as well as colors vary with species and environment.

Answer 4

because of changes in the length of daylight and changes in temperature, the leaves stop their food-making process. The chlorophyll breaks down, the green color disappears, and the yellow to orange colors become visible.

Answer 5

You will get a better answer than this, but the sap drops down in the tree and the in the leaves dying process a chemical process makes the beautiful colors. I don't know your answer, but live in the woods and they are beautiful right now. This is the simple answer that we were taught, but not the scientific one that I am sure you seek.