Why Do Leaves Change In The Fall?

by Staff Writer

The first sign of autumn is the changing of the leaves. That glorius time of the year in the south when the tempertures dip, indicating that school is about to start, football games are about to be played and the state fair is on its way.

The fall down south is a beautiful time when nature is at its glorious. We transition from shorts and fllipflops to boots and sweaters and prepare for family get-togethers. But why do the leaves change at all?

It’s actually just a bit of science that results in all of that beautiful explosion of color. Tree leaves that change color in autumn are called deciduous. Most of the year, these leaves are green because of the chlorophyll used to absorb energy from sunlight during photosynthesis. The leaves convert the energy into sugars to feed the tree.

As the season changes, temperatures drop and days get shorter. Trees get less direct sunlight, and the chlorophyll in the leaves breaks down.

The lack of chlorophyll reveals yellow and orange pigments that were already in the leaves but hidden during spring and summer.

Isn’t it interesting to think that leaves aren’t really green. They are a multitude of colors (much like people) but only express one color.

Darker red leaves are the result of a chemical reaction. Sugars that trapped in the leaves produce new pigments called anthocyanins that did not exist in the leaf during the growing season. Some trees, like oaks and dogwoods, produce red leaves.

We have a chemical reaction and decreased sunlight to thank for the gorgeous display of colors we watch in autumn.

Then… the leaves fall.

Trees build a protective seal between leaves and their branches as the temperature decrease. They take in as many nutrients as possible from the leaves, but leaves simply can’t survive the cold conditions of winter, and would make trees vulnerable to damage if they remained. When the leaves are cut off from the fluid in the branches, they… fall. Creating that lovely time of the year when red, yellow and orange leaves fall to the ground giving the name of the season. Fall of the leaf, as it was historically known.