First to fall: Why do some trees change color earlier than others?

MILWAUKEE - Have you noticed that some trees seem to put on their fall colors weeks before their neighbors? There’s actually a reason! 

Why do some trees turn color before the rest?

Dig deeper:

Different tree species have their own genetic clocks and respond differently to changes in daylight, temperature and water availability. Below are the types of trees that are among the first to change color during the fall.

Black Gum: Black gum trees are naturally early to change. Their genetics play a role, and the tree also tends to self-prune branches and leaves that are no longer as beneficial to maintain as conditions change.

Dogwood: Dogwoods can turn early because of their genetics and shorter growing season. They are also particularly sensitive to changes in light and temperature. 

Their leaves on the outer portions of the tree may mature and begin changing before leaves deeper inside the canopy.

Tulip Poplar: Tulip poplars have large, thin leaves that lose water quickly. Combined with their high water demands and relatively shallow root systems, this can make them more sensitive to dry conditions. 

Early yellowing and leaf drop can be a natural survival strategy—the tree reduces water loss rather than indicating that it is dying.

Red Maple: Red maples are genetically programmed to begin their fall transition earlier than many other species, including some oaks. They can even show subtle color changes by late summer.

As nights cool, sugar becomes trapped in the leaves, allowing the tree to produce red and purple anthocyanin pigments.

White Ash: Trees don't all interpret the seasonal signals of shorter days and cooler nights at the same pace. White ash is naturally programmed to begin its autumn shutdown relatively early. 

As chlorophyll breaks down, the green fades and underlying yellow and sometimes reddish-purple pigments become visible.

Yellow Birch: Yellow birches are also early changers, partly because of their pigment makeup and preference for cooler conditions. 

Their chlorophyll can begin breaking down earlier, revealing the yellow pigments that were already present in the leaves.

The science behind fall foliage

Dig deeper:

As days get shorter and temperatures cool in the fall, trees begin preparing for winter. One of the first things that happens is that trees stop producing chlorophyll, the pigment responsible for their green color. 

As chlorophyll breaks down, the yellow and orange pigments that were already present in the leaves—called carotenoids—become visible. 

Some trees, such as maples, also produce anthocyanins, which create vibrant red and purple colors. These pigments can form when sugars become trapped in the leaves as temperatures cool.

Eventually, the tree forms a protective layer at the base of each leaf, cutting off its connection to the branch. The leaf dries out and falls, allowing the tree to conserve water and energy through the winter.

Ideal weather for vibrant fall foliage

Big picture view:

The best fall color usually happens when we have sunny, mild days and cool nights, with temperatures dropping into the 40s but staying above freezing. 

Adequate moisture throughout the growing season helps keep leaves healthy, while a lack of early freezes, strong winds, or heavy rain allows the colors to develop and stick around longer.

Drought conditions can cause leaves to turn brown and fall, shortening the fall foliage season, which parts of northern Wisconsin are dealing with right now.Infor

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