Darker red leaves are the result of a chemical change. During Summer and Spring leaves serve as foods necessary for the trees growth. Why Do Leaves Change Color In The Autumn From Science Bob S Blog Fall Science Plant Science Preschool Science Chlorophyll is constantly breaking down and being replaced through summer but this process slows down in autumn. . Why leaves are green in color short. The rainbow of autumn colors. These include yellow flavonols orange carotenoids and red to purple anthocyanins. Light regulates chlorophyll production so as autumn days grow shorter less chlorophyll is produced. The green pigment in leaves is chlorophyll. When leaves appear green it is because they contain an abundance of chlorophyll. This chemical absorbs the energy from sunlight and assists in food production during photosynthesis. In the fall because of changes in length of daylight and change in temperature leaves...