Leaves start turning all sorts of beautiful colors this time of year. It seems like they are green one day and yellow, red, orange, or gold the next. Have you ever wondered why leaves change color in the autumn? I did some digging, and this is what I found. Enjoy!
A Look at the Changes Inside a Tree’s Leaves
There are many cells inside a single leaf. These cells contain chlorophyll and food (glucose) for the tree. It’s the chlorophyll that gives a leaf its green color. In the spring and summer seasons, a lot of food is being made inside the leaves of trees. But as the days get shorter and temperatures begin to drop in the autumn, food production inside a leaf slows down. This is how a tree prepares for dormancy in the cold weather months. As a result, the chlorophyll starts to disappear, leaving behind the yellows, oranges, purples, reds, and golds we see in our fall foliage.
The Effect of Temperature and Light on Leaf Color
Temperature and sunlight have an influence on the colors of leaves. For instance, red maple trees are known for their brilliant red leaves. A combination of lots of sunlight and temperatures that don’t fall below freezing in the fall boosts the development of anthocyanin in maple leaves. It’s the anthocyanin that turns this tree’s leaves bright red. However, if there’s an early frost, the colder temperatures will lessen the production of anthocyanin, reducing the brightness of the red maple’s leaves.
Why Do Some Leaves Change Color Sooner Than Others?
Sometimes, a tree’s leaves change color early due to stress. The tree may be experiencing the stress of an infestation of pests eating its leaves. It changes its leaf color as a defense mechanism against the pests. Also, a nitrogen deficiency can cause a tree’s leaves to change color early.
Why Do Some Leaves Change Color Later Than Others?
A mild autumn can cause a slowdown in leaf color changes. The mild weather prompts the continued production of chlorophyll, causing the leaves to stay green. A rainy autumn can also cause a slowdown in leaf color changes. Moisture makes leaves hardier, so they keep their green color longer. I guess that’s the upside of having a rainy autumn!
Interesting Autumn Facts
- Leaves aren’t actually turning gold, orange, red, purple, and yellow. These colors appear when the chlorophyll fades from a leaf; they were there all along, but the chlorophyll hides these bright colors during the warmer months.
- A dry summer that is not too hot usually produces vibrant leaf colors in the fall.
- A windy autumn can blow lots of leaves off of the trees without allowing them the opportunity to change color.
- Fallen leaves serve the purpose of protecting tree seeds as they germinate over the colder months.
Now that you know why leaves change in the autumn, why not take a drive and look at some of the beautiful leaves throughout our country? Whether you take a drive or look out your window, don’t miss the opportunity to admire the beauty of the season. Thanks for reading. – Alan