Leaves change color in fall because the tree has to hibernate for the winter. but it's leaves can't stay on the tree while it's hibernating so the tree has a decision: to keep it's leaves and freeze to death or to drop these leaves and hibernate. the colors are:
color BROWN GREEN RED PURPLE ORANGE YELLOW | chemical result of water trapped inside the leaf chlorophyll anthocyanin anthocyanin xanthophyll carotene |