Somme Prairie Grove 6-17-12 147


A woodland, or wooded community, is an ecosystem dominated by trees. In our region, various types of woodlands took hold in areas shielded at least to some degree from fire.


A large woodland known as the Big Woods once covered northeastern Cook County. Harms Woods in Glenview and Perkins Woods in Evanston were once part of the Big Woods. Another prominent woodland exists today in the Palos Preserves, in Willow Springs. Early settlers gave this highland the name “Mount Forest Island” because it resembled a wooded island rising out of a waving sea of prairie.


Wooded communities are often described by their dominant trees (oak-hickory woodland or maple-elm-basswood forest) and tree canopy density. Here are some notable woodland types in the Forest Preserves of Cook County:


Open woodlands. The trees in an open woodland, often oaks and hickories, are spread out enough to let a significant amount of light through to grasses, sedges and forbs. In Cook County, open woodlands are often found in high rolling hills or uplands protected by small creeks. They’re also found along the outer fringes of forests along major rivers.

>>>See it at Theodore Stone Forest Preserve in Hodgkins; Harms Woods in Glenview; Deer Grove in Palatine; Swallow Cliff and Cap Sauers in Palos Hills; Tinley Creek Woods along Tinley Creek.

You Know You’re in a Woodland When:

  • You can see trees around you. (You’re probably also standing in shade.)
  • Your surroundings feel sheltered, with less wind even on a windy day.
  • You see plants that do well in shade, such as wild geranium, bottlebrush grass and trillium.
  • You see birds such as woodpeckers (which find food in tree bark) and Cooper’s hawks (agile flyers that can chase other birds between trees).

Forests. With a nearly closed canopy, forests are even more sheltered from fire than open woodlands. You’ll often find them in river valleys and other wet areas, as well as around hills and ravines. They’re especially prevalent on the east side of these firebreaks, historically protected from the large prairie fires that were driven by prevailing winds blowing from the west. Shade-tolerant species such as sugar maple and red oak dominate our forests.

>>>See it at Black Partridge Woods in Lemont; River Trail Nature Center in Northbrook, Linne Woods in Morton Grove, Henry De Tonty and Paw Paw Nature Preserves in Willow Springs; the ravines of Swallow Cliff and McClaughry Springs in Palos Hills; Tinley Creek in Palos Heights.


Floodplain forests. Often dominated by elm, ash, hackberry, basswood and silver maple, this forest type is found everywhere along our creeks and rivers. The plants and trees here must be able to withstand periodic flooding.

>>>See it at Thatcher Woods in River Forest; River Trail Nature Center in Northbrook; Zoo Woods in Brookfield; Bemis Woods and Salt Creek Bike Trail in Western Springs; Thorn Creek in Lynwood; Deer Grove in Palatine.

Did You Know?

  • The oldest trees in the forest preserves are probably bur and white oaks. Some are more than 400 years old.
  • Our largest trees are cottonwoods and oaks. One cottonwood measured in at more than 100 feet tall, with a trunk that takes four adults to reach around.
  • Many local woodlands also depend on fire. A fire in an oak woodland, for instance, helps maintain an open habitat that will allow enough light for oak seedlings and wildflowers.

Flatwoods. A flatwoods is, as the name suggests, flat. Underlain by a layer of clay that keeps water from draining well, a flatwoods is often quite wet and supports many unique species such as swamp white oak, black ash, many wetland sedges and buttonbush.

>>>See it at Harms Flatwoods in Glenview; Sidney Yates Flatwoods in the Clayton Smith Preserves in northwest Chicago; Kloempken Forest Preserve in Des Plaines.

Read more about the ecosystems of the Forest Preserves of Cook County:

Visit two of the treasures of the Forest Preserves of Cook County