Why
Leaves Change Color
If you are in a lucky part of the
world where fall occurs and leaves begin changing it is such a beautiful time
of year. The green summer leaves turn to orange, red, yellow, and brown right
before the leaves fall for the winter time. This happens due to the change in
weather; as days grow shorter and nights grow longer and cooler, biochemical
processes in the leaf begins to change color. There are three types of color
pigments involved with leaves. Chlorophyll; which gives leaves their basic
green color. It is necessary for photosynthesis, the chemical reaction that
enables plants to use sunlight to manufacture sugars for their food. Trees in
the temperate zones store these sugars for their winter dormant period.
Carotenoids; which produce yellow, orange, and brown colors in such things as
corn, carrots, and daffodils, as well as rutabagas, buttercups, and bananas.
Anthocyanin; which give color
to such familiar things as cranberries, red apples, concord grapes,
blueberries, cherries, strawberries, and plums. They are water soluble and
appear in the watery liquid of leaf cells. Both chlorophyll and carotenoids are
present in the chloroplasts of leaf cells throughout the growing season. Most
anthocyanins are produced in the autumn, in response to bright light and excess
plant sugars within leaf cells. During the growing season, chlorophyll is
continually being produced and broken down and leaves appear green. As night
length increases in the autumn, chlorophyll production slows down and then
stops and eventually all the chlorophyll is destroyed. The carotenoids and
anthocyanins that are present in the leaf are then unmasked and show their
colors. Due to weather, cold nights do not let the sugars escape unlike warm
nights. Fallen leaves are good because after they fall they decompose into the
ground and provide the ground with nutrients. Some trees are adapted to the
cold environment and are tough enough to withstand the cold like pine trees. If
these tough trees stay in freezing temperatures too long constantly they will
die due to old age. Tender leaf tissue freezes and fall and start the process
over again in the spring. They are not sure exactly is the forest would survive
without the decomposing of leaves or if you would survive without the falling
of leaves, this questions are still to be solved.
No comments:
Post a Comment