The Science Behind Colorful Fall Leaves
Every year in large parts of the earth, people get to witness a change to nature. Slowly but surely over the course of a mere couple of months, all the leaves shift from green to vibrant yellows, reds and oranges. But why?
According to an Arborist in San Jose, there are three basic pigments each foliage tree and bush produces. The most common and well known is Chlorophyll, the green pigment involved in photosynthesis that is a continuous and vital part of the growth process and thus causes the leaves to keep their green shade for large parts of the year.
Next we have Carotenoids which are orange and yellow pigments. You will also be able to find these in leaves for a majority of the year but Chlorophyll’s vibrancy largely overshadows it. Both Carotenoids and Chlorophyll are produced in chloroplasts. These are small structures found within the leaf.And finally, there is Anthocyanins, a red pigment which generally doesn’t make an appearance until fall. Unlike the other two pigments, Anthocyanins can be found in the watery substance within the cells of the leaf.
Unlike your typical pine tree, foliage trees switch into a dormant mode throughout the cold seasons which heightens their need to photosynthesize but also requires them to drop their leaves. By doing this, they reduce the chances of water evaporating from the leaves which allows them to live on despite the scarceness of water they can draw in through their roots throughout the cold seasons.
As the sun rises later and sets sooner, the trees stop their Chlorophyll production which allows the Carotenoids and Anthocyanins to shine through and change the leaves’ colors. Following this, winter comes and the abscission zone is formed at the bottom of the leaf stalk which blocks all resources from traveling through and, over time, kills off the leaf.
When Fall Looks Particularly Beautiful
Depending on how closely you pay attention to nature’s ways, you may have noticed that the red shades of the leaves vary from year to year. As we have already learned, the red pigment is produced by the Anthocyanins. However, it is also only produced throughout a specific time period each year and at varying quantities.
Now, why is that? Well, it turns out that the weather is largely to blame for this. What we need for a particularly gorgeous and colorful display in fall is a sunny day with a cool night and generally dry weather. These conditions help the leaves retain their sugar household which in turn increases the levels of Anthocyanins.There can also be other factors at play, such as summer droughts and warm or wet autumns which can also reduce Anthocyanin production.