Why do leaves change color in autumn?
Leaves produce nutrients for trees through a process called photosynthesis. Trees absorb sunlight,
water, and carbon dioxide and turn them into energy. Leaves are essential for trees.
What factors cause leaves to change color?
The low temperature
Low temperatures destroy chlorophyll in the leaves. When chlorophyll is destroyed, the
green leaves turn yellow. Further lower temperatures increase anthocyanin production, and
the leaves turn red (Keating, 2020).
The dry weather
Dry weather causes leaves to accumulate more sugar. As a result, anthocyanin production
increases, and leaves become redder (Keating, 2020).
Bright and clear weather
Clear autumn weather allows leaves to continue photosynthesis using chlorophyll. Increased sugar concentrations in the leaves produce more Anthocyanins. As a result, the leaves turn red (Keating, 2020).
The reason why leaves change color
In addition to changing weather, there are reasons why leaves change color. The main reason for the
color change is not the chilly weather, but the lack of sunlight. In autumn, the length of day and night
is almost the same. But after that, the nights get longer and the days get shorter. When the amount of
sunlight decreases, trees stop collecting energy and enter a period of dormancy (Lohmiller, 2022).
When sunlight and moisture decrease, trees break down chlorophyll and the green color of the leaves
becomes blurred. Chlorophyll’s green color covers other pigments. Therefore, when chlorophyll
breaks down, people can see yellow or red. However, not all trees turn into autumn colors. Only some
deciduous trees, such as maple, birch, and oak, change color (Lohmiller, 2022).
Can climate change affect color change times?
Climate change will slow the start of autumn leaves. The warm weather keeps the green leaves longer. Some scientists argue that warm temperatures in autumn can reduce anthocyanin production, causing leaves to become less vivid red or purple. If climate warming continues, the aging of trees will begin earlier than now. When autumn gets warmer due to climate change, the color of autumn leaves is difficult to clear (Ogliore, 2022).
Why do leaves change color differently?
Chlorophyll makes the leaves green. Chlorophyll helps plants absorb energy from sunlight to produce nutrients. Leaves also contain a pigment called carotenoids. It can change from yellow to orange to brown. However, most leaves look green because chlorophyll blocks this pigment (Tyrrell, 2017). Trees produce a lot of chlorophyll in spring and summer because they are rich in sunlight and water. In autumn, when sunlight decreases and the temperature decreases, trees enter the process of reducing and decomposing chlorophyll production. As chlorophyll decreases, the leaves are yellow, orange, and brown in carotenoids (Tyrrell, 2017). Some trees produce a pigment called anthocyanin. This pigment can turn dark red and purple. According to some studies, anthocyanins can protect leaves from intense sunlight (Tyrrell, 2017).
Conclusion
Due to global warming, the time of autumn leaves is being delayed more than in the past. It is because the temperature of autumn is increasing. Some scientists argue that if global warming gets worse, it may be hard to see autumn leaves. When the temperature of autumn rises, trees are active in photosynthesis. As a result, chlorophyll increases, and sugar in the leaves decreases. As a result,
the leaves are difficult to show the colors of autumn, such as red and yellow. Everyone should try to prevent global warming in order to spend autumn enjoying beautiful autumn leaves.
References
Keating, H. (2020). Why autumn leaves change colour. [online] Woodland Trust. Available at:
https://www.woodlandtrust.org.uk/blog/2020/10/why-autumn-leaves-change-colour/ [Accessed 19 October 2022].
Lohmiller, B. (2022). Why Do Fall Leaves Change Color? [online] Almanac.com. Available at:
https://www.almanac.com/why-do-leaves-change-color-fall [Accessed 19 October 2022].
Ogliore, T. (2022). No, autumn leaves are not changing color later because of climate change – The
Source – Washington University in St. Louis. [online] The Source. Available at:
https://source.wustl.edu/2022/09/no-autumn-leaves-are-not-changing-color-later-because-of-climate-
change/#:~:text=The%20general%20thinking%20is%20that [Accessed 19 October 2022].
Tyrrell, K. (2017). Why do leaves change color in the fall? [online] UWMadScience. Available at:
https://uwmadscience.news.wisc.edu/botany/why-do-leaves-change-color-in-the-fall/ [Accessed 19
October 2022].
