ISU Extension News

Extension Communications
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915

9/21/98

Contacts:
Mark Vitosh, Extension Forestry, (515) 294-6739
Elaine Edwards, Extension Communication Systems, (515) 294-5168

Yard and Garden Column for the Week Beginning Sept. 25.

FALL COLOR IN IOWA'S FORESTS

By Mark Vitosh
Extension forester
Iowa State University Extension

Forests! What forests? I thought Iowa consisted only of agricultural fields, farms, small towns and open prairie. Well, Iowa has a significant forest resource that provides many benefits such as improved water and air quality, wildlife habitat, reduced soil erosion, wood products, employment and outdoor recreational opportunities. The most recent (1990) U.S.D.A. Forest Service forestland inventory indicated that 6 percent (approximately 2 million acres) of Iowa's land area is forested, and 92 percent of this forestland is owned by private landowners.

There is also an important forest resource in our towns and communities called the community forest. The community forest is made up of trees along our streets, in parks, in your yard, at the school, along the creek or river and downtown in the business district. These trees work together to create a forest ecosystem, which can have a major impact on the community. The trees in these forests help beautify the community, save energy by providing shade and winter protection, increase property values, reduce noise pollution and provide many similar benefits of a traditional forest. Now that we know there are trees and forests in Iowa, let's talk about the beauty of the changing fall colors that can be found throughout the state in all forested areas.

The color in the leaves comes from cells called pigments. The green color we see every spring comes from the pigment called chlorophyll. Throughout the summer the pigments that give us fall colors such as orange, yellow and brown are produced in the leaves, but they are hidden by the green chlorophyll. In fall, as the days become shorter and cooler, the production of chlorophyll slows down and eventually stops. As the green color disappears, the hidden pigments are unmasked and their beauty is released. Not all pigments are present in the leaves throughout the summer. For example, the pigments that provide the eye-catching red and purple colors are actually not produced in the leaf until the fall.

The timing, intensity and quality of fall color varies each year throughout the state and even on the trees scattered in your yard or neighborhood. In general, fall color change occurs between the middle of September and the end of October. There are many things such as temperature, moisture, rain, wind and the availability of sunlight that impact the quality of fall color. Clear sunny days, cool nights and dry conditions promote high quality fall color. These colorful displays are often cut short by heavy winds, rainfall and freezing temperatures that can kill leaf tissue and cause the leaves to fall early.

The types of trees and color schemes vary with the location in the state and the location within the landscape. For example, the mixture of tree species commonly found on upland sites will differ from those found on bottomland sites along rivers and streams. Also, tree species commonly found on north and east facing slopes will be different than those on south and west facing slopes. This type of tree species diversity often creates a beautiful array of different colors throughout the landscape.

One of the earliest indicators of the changing seasons is the red and crimson colors shown by the sumacs along the roadsides. These plants can develop into small trees or large shrubs. As you cross through the bottoms of valleys along rivers or streams there are often many shades of yellow. These assorted yellows are provided by trees like willow, cottonwood, black walnut, green ash, boxelder, elm, hackberry and river birch. Silver maple in these areas provides a mixture of yellow and orange colors.

As you make your way out of the valleys, onto the slopes and the hilltops you may find a wide variety of colors. You could find the red vibrant colors of red oak, the vibrant yellows, reds, and oranges of hard maples, the purples of white ash and white oak, and the yellows of basswood, quaking and bigtooth aspen, hickory and bur oak. As fall comes to a close, some of these yellows often fade to a brownish color.

In Iowa when people talk fall color displays, the northeast section of the state is often mentioned. This is a tremendous area to visit, but the beauty of fall color can be found throughout the entire state. There are many state parks, forests, wildlife areas, county parks, lakes, rivers and communities that provide an opportunity to enjoy Iowa's fall magic.

The biggest challenge to a successful fall color expedition is venturing out when there is a good array of color. The best way to catch good colors is to call ahead before you decide to depart on your trip. Local chambers of commerce, travel bureaus, county conservation offices, county nature centers and Iowa State University County Extension offices can often provide updates on local color displays, lists of local fall festivals and recreational activities that are occurring. Another good source of leaf color information is the Iowa Department of Natural Resources (DNR) Leaf-Line at 515-233-4110. The message on this line is updated every Monday from the middle of September to the middle of October. This information is collected from the twelve DNR foresters that cover the state.

As you go out on your leaf color hunt in the next few weeks, remember to call ahead, dress for cool weather, put film in the camera, drive safely and stop once in awhile to really enjoy Iowa's beauty.

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ml: isugarden


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