Why Leaves Change Color

Why Leaves Change Color

By Bob Ryan

Depending on where you live, you are probably enjoying the first taste of autumn… shorter days, cool crisp nights and leaves showing their fall colors. Oranges, reds, golds and browns are quickly replacing green in the forest as the trees prepare for winter. Just how do leaves change color, and how can we take advantage of what fall has to offer us?

As the days grow shorter in the fall, the leaves begin their process of changing color and falling off the trees. Rainfall, temperature and food supply all play a part.

Remember studying photosynthesis in science class? Trees use sunlight to convert water and carbon dioxide to sugar, which is food for the tree. The leaves are filled with hidden color pigments that produce the leaves’ true colors. The pigments in leaves and the colors that they produce are:

Carotenoid - yellow, orange and brown
Anthocyanin - red
Chlorophyll - the leaves’ basic green color

Chlorophyll, the most important, gives green coloration to leaves and is necessary for photosynthesis. Why do we only see green most of the year? The light from the sun has all the colors of the spectrum (red, orange, yellow, green, blue, indigo and violet) but during the summer the chlorophyll absorbs all the colors except green. The green is reflected and that is the color perceived by the eye. Simply, when the production of chlorophyll ceases in the autumn, the leaves show their true colors.

Why do colors seem more vibrant in certain years? Yellows and golds are fairly constant each year, but the reds can vary. Weather conditions such as moisture and temperature play a part. If you favor the intense reds, purples and crimson leaf displays, you should hope for warm sunny days and cool crisp night in early fall. On sunny days the leaves busily produce sugars, which are trapped in the leaf during the cooler, not freezing, nights. This results in vibrant shades of reds when the leaves begin changing color.

Rainfall plays a part in autumn color. A late spring or summer drought may delay the beginning of leaf color change by a few weeks. A warm, wet fall will dull the leaf colors also. While no two years are ever alike, the best conditions are a wet, warm spring, a normal summer, and a fall with cool, not freezing, nights and warm sunny days.

When nature’s spectacular color show is drawing to a close, why do leaves fall to the ground? The tree, branches and roots are capable of enduring nearly all kinds of weather, but the leaves are more fragile. Veins that carry the sugars out of the leaf and into the tree began closing in the shorter days of fall. When they have closed completely, a layer of cells forms at the base of the leaf, called the separation layer, and the leaf falls to the ground. The leaves’ decomposition adds nutrients to the soil… becoming nature’s ultimate recycling machine.

With a little advance planning, you can enjoy nature’s color show at its peak. Based on averages from previous years, the highest elevations of Western North Carolina hit peak color from late September to early October. The rest of Western North Carolina peaks from early to mid October. In the foothills, the peak can be between mid to late October. Fall foliage web sites, such as www.fallfoliageprimer.com have the latest reports. You’ll find current color updates, fall photo tips and the most scenic drives in the area.

A good tree guide makes it easy to identify trees by their fall colors. One handy pocket sized guide is “Fall Color Finder, A Pocket Guide to the More Colorful Trees of Eastern North America”. It contains color photos, maps and a leaf shape index. This valuable guide is only $5.95 and is available at all locations of Mast General Store.

Nature’s beautiful fashion show won’t last long, so get out and enjoy it. Stop by your Mast General Store for the latest guides, clothes and advice for your Take It Outside fall adventure.

For Fall Color Updates Be Sure To Visit Mast Store's