Why do the leaves change colors and why do they change the colors they change??

Answer 1

Trees in temperate zones have to protect themselves from freezing winter temperatures. Ice expands when frozen and would burst the leaf cells if they continued growing all winter. Trees begin preparing for dormancy when the temperatures cool and day light shortens. They shut down all growth and store food for the spring start up. This also tells them to stop replacing chlorophyll.
Yellow & Orange: The caratenoids are not as cold sensitive so remain functioning longer producing the lovely yellow and orange colors.

Red & Purple: The red, magenta & burgundy colors are due to anthocyanins. The leaf begins producing them in the fall for a short time for several reasons. One reason, in the reddest of trees, is for a signal. As chlorophyll shuts down in the leaf the appearance of bright red signals "Do NOT eat me!!" Just as caterpillars and butterflys use bright color to warn predators off so do plants that produce high levels of toxins. Aphids and other insects often reappear in high numbers with the return of wetter weather in fall and some trees fight back.
Trees in tropical climates never go through a seasonal leaf drop nor do they have a winter dormancy because they never experience freezing temperatures.

Answer 2

The colors you see in leaves are actually the real color of the leaves. During the summer, the chlorophyll in the leaves overpower the other pigments since the green is what the plant needs to do photosynthesis. When the days start getting shorter, the tree stops allowing water to flow down the petiole (stem) of the leaf. This stops the process of photosynthesis and destroys the cholophyll. THis allows the other pigments to show through. The vividness or brightness of the leaf colors are affected by the temperature. Chilly nights with mild days will cause the leaves to be more striking in thier colors. The very mild temperatures we have been having (New England) makes the leaves not so bright this year.

Answer 3

they change because of the decrease in daylight.