What makes trees change color

In unusual cases, sometimes in winterberry holly, a fair amount of chlorophyll is left in the leaves when they fall. Such leaves are a pale green in color, or perhaps yellow-green from the mixture of chlorophyll and carotenoids. Most interesting are leaves that turn red, because this color is the result of the active synthesis of anthocyanin pigments just before the leaves fall from the trees.

In these leaves, the actual shades of red are the consequences of the amounts of anthocyanin, the retention of carotenoids or even a little chlorophyll. Anthocyanin and chlorophyll produce brownish colors. Since the leaves are no longer able to produce food for the tree, they break down chlorophyll, and orange and yellow pigments, called carotene and xanthophylls, surface.

These pigments emerge in leaf cells to protect chlorophyll from damage. The vivid reds come from pigments called anthocyanins which are manufactures from sugars in the leaf. The sugars are stored in the twigs for next spring when leaves emerge again. This cyclic pattern repeats itself every September in countries that experience seasonal weather. Although it might seem trivial, fall colors are one of those intangibles that make life exciting.

The quantity and quality of the color vary depending on weather, sunlight and soil moisture. An article by the department of Biology at Appalachian State University states that trees are extremely sensitive to environmental shifts. Ah, autumn—the air is crisper and the trees are turning brilliant shades of gold , red, and brown.

In the temperate areas of the world, it gets very cold in the winter and there is not much sunlight, which the trees need to feed themselves. This preparation process is what causes the leaves to display their striking autumn colors. In the summer , most trees have green leaves because they contain the pigment chlorophyll. This pigment is also used to convert sunlight into energy for the tree.

In summer, chlorophyll is constantly replaced in the leaves. When it gets cold, the plants stop making chlorophyll and it breaks down into smaller pieces. The trees can reuse the nitrogen that is in the chlorophyll molecule.

This is why leaves change colors before they fall off of the tree; the important nutrients that can be reused are taken out of the leaf. The time when leaves start changing color is more dependent on light than on temperature so leaves start changing color at about the same time each year.

When deciduous trees reach this light threshold , carbohydrates are transferred from the leaf to the branch and no new minerals are brought in. Trees and shrubs glow school bus-yellow, pumpkin-orange, and stoplight-red as they retrieve nutrients made in their leaves that summer.

But it's the same fall color that drives me nuts. Every year at Southern Living , we zoom all over the South, trying to capture beautiful images of fall foliage at its peak. The image above isn't one of them. I just took it this morning as the full moon was setting behind some Bradford pears.

Pretty artsy, huh? And no one -- and I mean no one -- can tell you if the fall color will be good this year and when the peak will happen. There's no more sinking feeling than flying somewhere to photograph fall foliage, come in for the landing, look out the window, and see nothing but green, green, green.

Ok, Ok, being told you bear a striking resemblance to Susan Boyle is pretty devastating too, but all I had to do fix this was pluck my eyebrows and change my hair. It's not the same when hunting flowers. I once did a story on a whole neighborhood in Chevy Chase, MD where every street was lined on both sides with 'Yoshino' flowering cherries.

This is the same cherry planted around the Tidal Basin. Getting the story meant getting to Chevy Chase at peak bloom. But this wasn't that hard because there's a National Park Service website you can go to where an expert on cherry trees examines the flowers every day and tells you with great accuracy what percentage of flowers will be in full bloom on a given day.

There's no such site for fall color. Oh sure, some tourism sites will give you a week when they think fall color will be nice, but they really don't know.