Again this increased temperature change may be sudden. Frost may damage leaves also. Toxic chemicals or a mineral deficiency may account for damage to induce color changes. So damage other than that caused by temperature change can affect fall leaf color. Because magnesium is rare in most soil, plants that require magnesium to grow and which drop their leaves to save water in winter will first extract the magnesium and store it in stems or roots.
Leaves then turn shades of red, yellow, or brown as the magnesium is removed.
Plants that grow with their roots in water, such as alder, can easily retrieve magnesium from the water, so that magnesium in leaves is not transported to stems or roots, and the leaves may stay green until they fall off in winter. The green color is, of course , chlorophyll, which is a porphyrin and when porphyrin is degraded it can turn red, yellow, brown, or a different shade of green.