Skip to main content

Archive - March 2021

What is a Forest?
A forest is an area of land containing at least 10 percent forest trees. The trees may be of any size. The minimum area for forest classification is one acre.

What are Some Types of Forests in Illinois?
The major forest types in Illinois are oak-hickory, elm-ash-cottonwood, maple-beech-birch, oak-gum-cypress, oak-pine, loblolly-shortleaf pine and white-red-jack pine forest.

What makes Up a Forest?
Forests are composed of living and nonliving things. The living things are adapted to the characteristics of a forest by their form, function and behavior. Forest organisms include a great variety of species, from viruses to mammals. Plants are the producers of food energy in the forest ecosystem. Animals known as herbivores get food energy by eating plant parts. Other animals, the omnivores, get food energy by eating plant parts and other animals. Still other animals obtain food energy by eating only animals. Those predator animals are carnivores. Decomposers feed on dead organisms and return chemicals from them to the forest to be used again.

The forest has different layers of within it. The forest floor has dead leaves, fallen logs, rocks, stumps, vines and forest debris. Many organisms live in and under the forest floor. This is a busy place where dead organisms are recycled into nutrients that can be used again in the forest. The herb layer is composed mainly of green plants with soft, nonwoody tissues. Most of the herbs in the forest are wildflowers. The shrub and understory layer is taller than the herb layer but not as tall as the canopy. A shrub is a small woody plant that has several stems rising from the ground at the same spot. Some shrubs are small trees that eventually may grow into large trees. Trees that are smaller than the largest trees in the forest are called the understory trees. The canopy includes the tallest trees in the forest. Their leaves and branches form a protective umbrella over the lower layers of the forest.

What are the Values of Forests?
Forests are very important to the environment. They are also important to people.

Oxygen Production and Release of Water: Forests not only have many trees, but they also contain many other types of plants. Plants convert water, sunlight, carbon dioxide and minerals into food for themselves. Another product of this chemical process is oxygen. Although plants need some oxygen, they produce more than they can use and release the extra into the environment where it is used by many living things and in chemical reactions by nonliving things. Through transpiration and evaporation, plants return moisture to the air, too.

Storing Carbon: Forests take in more carbon dioxide from the atmosphere than any other ecosystem. This transformation of carbon dioxide to wood is very important because it helps reduce the buildup of carbon dioxide in the atmosphere. Such a buildup is a real problem as we continue to burn large amounts of coal, oil and natural gas (fossil fuels that release large amounts of carbon dioxide into the atmosphere).

Erosion Control: Rainfall on unprotected soil can lead to the removal of soil particles in water runoff, causing erosion and moving those soil particles to places where they are not wanted. The erosive effect of rainfall in a forest is lessened by trees. The forest canopy slows the speed at which raindrops hit the forest floor. The network of plant roots in the forest holds the soil and allows rainfall to be slowly absorbed.

Wildlife Habitat: Forests support the greatest number of individuals and the greatest diversity of wildlife species of all Illinois’ habitats. More than 420 vertebrate species are dependent on Illinois’ forests. More than 260 species of native trees and 285 species of native shrubs are found in Illinois’ forests.

Economics: Forests provide many recreational opportunities that also bring money to the community. Hunting, camping, picnicking, bird watching, mushroom hunting and hiking are a few forest-related recreational activities. Hundreds of food products are made or obtained from trees or tree products, including nuts and fruits. Many forest plants have medicinal value, such as the pain reliever found in the bark of willow, antiseptic in the bark of white oak, fungicide in the butternut and oil and expectorant from white pine tar. Wood from Illinois’ forests is used to make many products, and there are thousands of jobs related to forestry in Illinois.

Where are the Forests in Illinois?
Forests can be found in every county in Illinois. Private individuals own 82 percent of Illinois forest land, followed by private corporations (7 percent), national forest (6 percent), state government (2 percent), other federal (2 percent) and county and municipal governments (1 percent). Gardner Woods (Adams County), Beall Woods (Wabash County), Forest Park Nature Preserve (Peoria County), Funk’s Grove (McLean County), Little Black Slough (Johnson County), Norris Woods Nature Preserve (Jefferson County), Redman’s Forest (Clark County) and Sonneman Woods (Fayette County) are some examples of large forest tracts remaining in the state. The Shawnee National Forest of the U.S. Forest Service grows in southern Illinois.

What are Some Threats to Forests?
Habitat Loss - In Illinois it is estimated that in 1820, the time when many European settlers were beginning to enter the state, 14.8 million acres were wooded. A little over one century later, only 3.02 million acres of forest remained. By 1980 the amount of forested land had increased to 4.26 million acres in Illinois. Most of the original loss was due to clearing for agricultural use and for timber harvest. Today, forests continue to be removed for agricultural processes, construction, road-building and other projects.

Fragmentation and Small Patch Size - In addition to the loss of the original forest to agriculture and timber harvest, most of the forests that remain were fragmented. In fragmentation, many small patches of forest replaced large expanses of timber. Large, continuous blocks of timber are rare throughout most of the Midwest, commonly occurring only in areas of very rough topography, along waterways and in depressions in swampy areas where agriculture is not possible. This fragmentation has resulted in isolation of these forest plots from each other by separating them with other habitats. It has caused changes for the wildlife species living there, too.

Reduction in Fire – The reduction in fire frequency in the Midwest has changed the structure and composition of many forests and related habitats. Fires occur much less often than they once did. Fires are necessary for the growth of some plant species. Overall, the reduction in fires has resulted in an increase in shade-tolerant, fire-sensitive tree species and a decrease in oaks and hickories, tree species that provide much food and shelter for wildlife in the forest. The structure of the understory and other levels of the forest has changed, too.

Exotic Species Introductions - Nearly one-third of the vascular plant species in Illinois are exotics. While some of these species are agricultural and roadside weeds only, some species are major pests in forests. Exotic plant species commonly reduce diversity by decreasing the habitat available and the habitat quality for the native fauna. Exotic insects and pathogens have also become a major problem in forests, sometimes attacking entire communities, in other instances decimating a one species. By the middle of the 1900s the introduced Dutch elm disease fungus and the virus disease, phloem necrosis, had eliminated the American elm as a common ornamental throughout most of North America and had greatly reduced its importance in most forest stands. Gypsy moths, which were imported from Europe in the late 1800s, can cause enormous devastation over large areas. The larvae of this species feed on the leaves of most of our native forest trees and shrubs. The emerald ash borer (Agrilus planipennis) is another exotic insect species that is causing devastation in Illinois’ forests.

These are just a few examples of some of the many issues that forests face.

Good forestry management practices can help save our forests and their inhabitants for many years to come.

Podcast and Resources