What biological processes cause leaves to change colours in Autumn?

Question

I am curious to learn what are the biological mechanisms that cause leaves of deciduous plants to change colour? What happens to the chlorophyll?What environmental phenomena (temperature/air pressure/length of sunlight) are they responding to?

Answer 1

The colors are produced by secondary pigments found in leaves, but usually not seen because of the high concentration of chlorophyll. The reduced daylight and temperature of Fall trigger the chlorophyll to break down, allowing the colors of these secondary pigments to show through.