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Southern Des Plaines River Preserve - Phase II Woodland Restoration and Oak Regeneration Project
by Matthew Ueltzen, Lake County Forest Preserves
November 15, 2014

Some information in this article is out of date. For the most current information go to the Lake County Forest Preserve District website at

photo by Tim Burke

The DesPlaines River Valley was formed by glacial melt about 14,000 years ago. Fossil profiles show variations in floral composition over time from 11,070 to 10,800 BP. During this time, the region was populated by spruce, fir, larch, pines and herbs. From 10,950 to 10,300, the spruce woodland was being replaced by aspen, birch and ash. The birch forests were replaced by elm, oak, hickory and walnut from about 10,300 to 7,800 BP. A warmer and drier climate favored the emergence of oak and hickory forest woodlands to the present day.

At a glance, the oak woodlands of the Southern DesPlaines Preserves appear healthy. However, scientists have observed that oak trees and other desirable trees are aging with few young oaks germinating in the understory to take their place. Fire suppression and increases in shade-tolerant species, have caused ecological shifts and reduced regeneration of oaks.

In the past, oak forests supported a diverse array of native plants and wildlife. These species are declining or absent in today's degraded woodlands.

photo by Tim Burke

In order to reverse this decline and the impacts of ecological shifts, woodland restoration and oak regeneration projects are being introduced into the hardwood forests of Northeastern Illinois.

In Lake County

Beautiful oak woodlands define the unique natural and historic landscape of Lake County. Oak trees create an environment which sustains critical ecosystem processes and species of diversity.

The Woodland Restoration and Oak Regeneration Project is supported by Chicago Wilderness, Illinois Nature Preserves Commission, the Illinois Department of Natural Resources, Morton Arboretum, U.S. Forest Service as well as the Chicago Botanic Garden, Illinois Natural History Survey and Lincoln Park Zoo.

Goals of the Restoration Project
1. Restore light transmission in woodlands to 30-50 percent
2. Increase oak regeneration and the diversity of tree species and sizes
3. Restore the abundance and diversity of native shrubs and ground-layer plants
4. Create a mosaic of habitats, improving conditions for plants and wildlife.

Oak woodlands are in decline across the eastern United States and particularly in the northeastern Illinois area because the amount of light reaching the ground is inadequate for the survival and reproduction of oaks and native woodland understory plants. Without enough light reaching the forest floor, young oak seedlings and saplings cannot grow past a few years of age.

It takes mature oaks decades to hundreds of years of age to establish a healthy woodland ecosystem and food source for the survival of native plants and animals. A ratio of 30-50% light is necessary to favor non-shade tolerant plants like oaks and hickories. To achieve this light ratio, the canopy must be dramatically opened to allow adequate light penetration to reach the woodland floor. To complement opening the canopy, the systemic removal of invasive brush and weeds and the introduction of prescribed burns is necessary. Otherwise, shade tolerant species such as maples and elm will dominate the woodland and encourage buckthorn and weeds to take over the understory.

Without restoration, oak woodlands will not survive. They will be replaced by denser, darker forests which do not provide habitat for a rich array of songbirds, butterflies, wildflowers, shrubs and other oak woodland native species. This will result in the loss of biodiversity and the potential extinction of native species.

Restoration Project Selective Clearing Areas - Winter 2014-15
1. 22 acres of northern flatwoods - 29.9 acres of moderately moist and moderately dry forest in MacArthur Woods
2. 128 acres of northern flatwoods and fern communities and 44.6 acres of moderately moist and moderately dry forest in Ryerson Woods
3. 43.4 acres of northern flatwoods and 20.6 acres of moderately moist forest in Wright Woods (Lloyd's Woods section)

These woodlands represent some of the highest quality natural areas in Lake County. Some are also dedicated Illinois Nature Preserves. 85% of salamanders and frogs, 75% of turtles and snakes and 138 species of birds are known to these preserves and depend upon healthy oak ecosystems for survival. These preserves are located where historic vegetation communities transitioned from prairie to forests and savannas within the DesPlaines River Valley region.

Why Restore Oaks

Oaks are the keystone species providing food and habitat for natīve wildlife.

The scope of the large scale restoration project is to restore the health of oak woodlands which have declined exponentially since European settlement. In 1830, 88% of oak dominated communities were known in Lake County, comprising about l87,000 acres. In 2010, only 23,000 acres of oak dominated communities remained.

The situation continues to be especially critical since remaining oak communities are degraded and under pressure from development, invasive species, habitat fragmentation, fire suppression and loss of sunlight reaching the woodland floor, thereby preventing the germination, growth and survival of young oak seedlings and saplings and resulting in habitat and hydrological degradation. If these remaining woodlands are not restored as ecological priority projects now, we could be facing a future with no oak trees and companion species and wildlife in our world.

Woodland restoration and oak regeneration projects provide the only viable solution to reverse this decline and rebuild sustainable forest ecosystems.

A restored woodland sustains healthy and integrated ecosystems, ensures the survival of native plants, provides habitat for birds, butterflies, amphibians and a myriad of wildlife. An understory of native herbaceous plants within a restored woodland helps control erosion. Native herbaceous grasses and sedges populate what might otherwise remain barren and exposed soil, filter and hold rainfall and encourage the formation of rain pools and isolated wetlands. These ecosystem types are essential to provide habitat for aquatic species, wildflowers, ferns, fungi and a diversity of native trees, shrubs and sedges.

The Restoration Project is funded in part by a Lake County Forest Preserve District referendum approved by Lake County voters. A contactor will remove invasive woody species and shade tolerant understory trees from identified project sites. Canopy and understory trees will also be selectively removed from sections of identified habitats to improve light transmission to the ground. Prescribed burns will be introduced.

The project will encourage the regeneration of shade intolerant trees and shrub species such as white oak, red oak, walnut, viburnums and hazelnut These native trees and shrubs provide important cover and food for wildlife.

Project volunteers gather thousands upon thousands of acorns each fall. Acorns are germinated in nurseries and oak seedlings are grown and remain in nurseries until, as young saplings about three or fours years old, they are mature enough to be transplanted into woodland restoration areas in the preserves.

Volunteers also monitor and track the survival rate and growth of the young transplanted oaks. These saplings and young oaks carry the gene pool of thousands of years of natural history within them and represent the hope of saving our oak woodlands for the future.

For more information about the Woodland Restoration and Oak Regeneration Project go to:

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