Why do leaves change color and fall? Learn the science behind fall foliage

By spring, the leaves on trees grow and assume the color green, and by autumn, they change to sometimes brilliantly warm colors and fall. But why do they do that?

Every fall season, nature lovers look forward to scenic fall foliage . But do we know the science behind why leaves do this once the temperatures start dropping?

Here's how nature creates art during the fall.

Leaves changed color earlier than usual because of Ohio's drought

Before we get to the science, we have to mention how Ohio's late summer weather might impact the timing of fall colors.

Ohio's prolonged summer drought caused weeks without adequate precipitation. The U.S. Drought Monitor had listed portions of 16 Southeast Ohio counties as being under a D4 Exceptional Drought, the most severe designation possible. Many of Ohio's corn and soybeans have been harvested early due to the lack of rainfall.

The drought brought stress to the trees, causing them to change colors weeks ahead of schedule. The worse the drought, the earlier fall colors appear more widespread.

Areas that have had a lot of rain may be experiencing a more typical fall timeline. Akron and Northeast Ohio are prime spots to see fall colors.

What makes leaves change color?

The warm colors of autumn depend on three factors, according to the United States Forest Service :

• The leaf pigments
• The duration of nights
• The weather .

The color of leaves is regulated based on the length of nights as the months go by. The duration of autumn nights is the primary reason for the pigment change, and less from other factors like temperature, rainfall, and food supply.

As the sun sets earlier and earlier during fall, the nights grow longer and cooler, starting the process of the leaves changing to autumn colors.

How do the leaves change their pigment?

The pigment that gives leaves its usual green color is a chemical called chlorophyll—and it thrives in the sun, especially during summers when we get more daylight.

As the nights grow longer and cooler in fall, it is a signal for the leaf to stop making chlorophyll in order to prepare for winter, according to SciJinks .

As green colors fade, the leaves turn to reds, yellows, and oranges. Like chlorophyll is to green, each fall color has a chemical that gives its hue.

• Xanthophylls - Yellows
• Carotenoids - Oranges
• Anthocyanins - Reds

Each chemical is dependent on the species of the tree.

After the leaves change color, how do they fall?

So, we know why leaves change color. The next step is for them to fall.

As the temperatures drop and the nights grow longer, the trees decrease the production of auxin , which is a hormone in trees that regulates growth.

While the auxin reduces, a layer of cells called the abscission layer is broken down, straining the bond between the leaf and the tree branch, according to Forestry and Land Scotland . As time goes by, the bond gets weaker and weaker, and the leaf eventually gets knocked down by the wind.

Why do leaves fall?

Trees lose their leaves to prepare for winter. Without the leaves, the tree will spend less energy through harsh winters.

Additionally, not having leaves allows for wind to blow through a tree's branches without straining it, and helps conserve moisture in its trunk.

Where and when leaves are predicted to change

Here's a county-by-county breakdown of how the 2024 foliage is predicted to change across the U.S.:

This article originally appeared on The Columbus Dispatch: Why do leaves change color and fall? Learn the science behind fall foliage