Wisconsin State Farmer

MADISON

A warm and wet summer has set the stage for a spectacular fall color change, Wisconsin Department of Natural Resources forestry experts say.

The beauty of Wisconsin's forests attracts many visitors, especially during the next two months as the showy fall colors begin in the Northwoods and move through the state to southern Wisconsin.

"People often ask us where to go to see the best colors," said Kirsten Held, DNR outreach specialist with the Division of Forestry. "The answer is anywhere in the state. It's all a matter of keeping track where the color is traveling."

Peak fall color varies slightly from year to year depending on the weather conditions, but the shortened day length is the primary trigger for trees to begin changing color. Peak fall color usually occurs in far northern Wisconsin during the last week of September and first week of October. However, the first hints of color typically appear in isolated, lower lying areas by mid-September. Peak color generally occurs in central Wisconsin during mid-October and in southern Wisconsin during the latter half of October.

With state, county and federal forests as well as state parks and natural areas accessible to the public throughout the state, it's possible to follow the progression of fall colors from hundreds of locations. In addition to viewing colors from your car or along walking trails, many of the public forest lands offer the opportunity to enjoy the colors while paddling down a river or on a lake.

Wisconsin's State Forests - Black River, Brule River, Flambeau River, Governor Knowles, Northern Highland-American Legion, Peshtigo River, Point Beach, and Kettle Moraine's six units -- are great for fall color viewing. Find other state forests, parks, trails and recreation areas for viewing options on the DNR website, dnr.wi.gov.

Weather during the growing season is critical for the abundant quantity of leaves needed to provide the potential for an excellent fall color display, Held said. In many areas of the state, 2016 has produced a healthy crop of leaves. Already, a few red maples have started to turn in northern Wisconsin, signaling the start of the annual show within the next couple of weeks.

"The intensity of the fall color season is dependent on the weather that Wisconsin receives during September and October," Held said. "To have the most brilliant and vibrant fall color display, a series of fall days filled with bright sunshine and cool, but frost free, evenings are required."

The duration of the fall color season is related to the intensity of wind and rain during late-September and October. High winds and driving rains cause significant numbers of the leaves to fall from the trees, which can prematurely shorten the display.

While the annual fall color show is a huge attraction for the thousands who flock to Wisconsin, and contribute to the state's strong tourism industry, the economic impact of the forests themselves is even more significant.

"While the fall color show, orchestrated by Mother Nature using the state's 17.1 million acres of forests, is an important contributor to the state's economy, wood products from the state's forests contribute $24.7 billion to the Wisconsin economy each year," Held said.

For current information on the current best fall color viewing areas in Wisconsin contact the Department of Tourism's Fall Color Hotline at 1-800-432-TRIP or online at the Fall Color Report (exit DNR) on the Travel Wisconsin website.

What causes trees to turn color?

The timing of fall color in Wisconsin's forests is determined more by the shortening daylight hours than it is by temperature, but temperature and other weather conditions play a big role in the intensity and duration of fall colors, said Held.

There are three types of pigments that are directly involved in producing colorful leaf displays: chlorophyll, carotenoids and anthocyanins. Here's how they work:

Chlorophyll is present in the leaves during thegrowing season and gives the leaves their green color. In the processcalled photosynthesis, chlorophyll utilizes the sun's energy to producesimple sugars - the tree's food - from water and carbon dioxide.

Carotenoids are present in the leaf chloroplastsalso, but because the green coloration of the chlorophylls predominate,they aren't seen through the growing season. The carotenoid pigments areresponsible for the yellow colorations of fall leaves.

Anthocyanins produce the brilliant reds and purplesthat everyone associates with a spectacular fall color season. This colorpigment develops in the early autumn within the leaf cells to protect theleaves from bright light as biological processes transition from foodproduction to storage. During this period, called senescence, the leaves'photosynthetic components are broken down and the nutrients, mainlynitrogen and phosphorus, are moved within the tree for storage and use thefollowing year.

Certain tree and shrub species are commonly associated with differing colors during the fall: green ash, white birch and aspen turn golden yellow; red maple a brilliant red; oak and hickory become a reddish-brown color; white ash a deep purple; and sumac a scarlet red. Even tamarack turns a beautiful deep golden yellow and loses its needles in the fall, the only conifer (evergreen) tree in Wisconsin to shed its needles.

Learn more about why state forests change colors throughout the year by searching the DNR website, dnr.wi.gov, for "science of fall leaf colors."