500
Explain why leave on a deciduous tree change colors and fall off in the autumn.
Reduced sunlight in autumn causes reduced production of chlorophyll in the leaves. As the chlorophyll (green pigment) fades, other pigments show through (red, orange, yellow). The sugar and nutrients in the leaves go into the stem and roots for storage. An abscission layer forms at the base of the petiole to sever the leaf from the branch. The leaf falls from the tree leaving a leaf scar behind.