Many gardeners are aware leaves are responsible for making food for plants through
the process of photosynthesis. Chlorophyll in the leaves captures energy from the sun resulting in their green pigment. Chlorophyll production slows down this time of year because the amount of daylight decreases. With this change in chlorophyll, the green leaf color of trees begins to fade allowing other pigments to be visible.
If tree leaves are turning orange/yellow, that indicates the presence of xanthophylls and
carotenes. Tannins produce brown colors and anthocyanins create red/purple colors.
These pigments are present year-round but are only noticed when the green from the
chlorophyll fades. This is the reason for fall color in trees.
Fall color varies by tree species as well as environmental conditions. Certain oaks and
maples put on a brilliant display with a variety of colors, but some species only show
one color before leaf drop. The level of pigmentation is different among each species.
Fall leaf color can be cut short by frost and freezes, but even the summer weather has a
role with the fall display. If you notice the same trees looking different this fall than last,
it is likely an environmental factor that is at work.
