Why do leaves change color in the fall? We know that leaves mostly appear to be green due to chlorophyll. There are also other pigments contained in a leaf, but chlorophyll prevails; because of that, we believe that leaves are green. Chlorophyll is produced thanks to day light. In the fall, days get shorter and there is less light, so chlorophyll is not produced in great measures. That is why green color stops being the main color. Chlorophyll is needed for the photosynthesis process.
On the other hand, anthocyanin production increases. This is the red pigment contained in a leaf. Another pigment found in a leaf is carotenoid. Cartenoids produce orange, yellow and brown; they can be found in the leaf chloroplasts (so as chlorophyll).These pigments do not require day light, so leaves get orange, red and yellow. A leaf can be more yellow or orange, while some of them are redder. That depends on which pigment is prevailing.
Colors also depend on species. Some plants are brown, yellow and red, like oaks for example. Maple species are different among themselves and there are many beautiful colors of maple species. There are some species that fall out almost instantly, like elms, for example.
Weather also affects colors of leaves. Moisture is an important factor, so as temperature. If days are sunny and warm, and then suddenly become cold, there are chances that leaves will be very colorful. The moisture amount in the air and the soil is one of the most important factors affecting the leaves colors. This tends to change every year, so fall is different every year and leaves have different colors every season. If the autumn is warm and very sunny, leaves will remain green for some time. However, if the nights are cold, there are considerable chances for the autumn colors to show up.
When the autumn starts, days get shorter and light intervals decrease. Leaves change their colors due to less chlorophyll. However, this is not the only change. Leaves also start to fall off during the autumn. This is one of the ways that trees use to prepare themselves for the winter. Trees need to keep their water supplies needed for the winter. Leaves are not much helpful in this process, so the tree takes all the moisture from the leaves, making them fall off. When the entire cycle is finished, the new leaves will start to grow – as soon as the winter is over.