We used to think we could draw boundaries around our woodlands, set them aside, and they would be OK. But as we have discovered, passively managed woodlands degrade over time. Many factors conspire against woodlands, including:
Invasive species, such as plants, insects, and other wildlife
Overpopulation of browsing deer
Suppression of fire
Now we have a new model for woodland conservation: Ecological restoration. Ecological restoration is:
A way to jump-start natural processes in order to revive a failing ecosystem
An intentional, human-induced activity that initiates the recovery of an ecosystem's health, integrity, and sustainability
A young methodology based on the emerging science of restoration ecology
In our 60-acre Woodland Restoration Project, The Morton Arboretum is demonstrating ecological restoration practices and testing some new techniques we hope will bring favorable results. We are also training volunteer woodland stewards to help us acheive our goal, which is to restore and sustain a healthy, diverse oak woodland where native trees and other plants and wildlife can flourish.
Our woodlands are much different than they were in the early 1800s. At that time surveyors documented a woodland with oaks of different sizes, hickory, and an understory of oak sprouts, hickory, and hazelnut. Fire suppression during the last 170 years, as well as other human-created disturbances, have caused many changes in these woodlands. Today, even-aged oaks primarily occur in the canopy of the woodland with no younger, immature trees at the ground level. In fact, many more trees exist today than were present during the pre-settlement era, blocking essential sunlight in the woodlands.
Since our restoration project began in October 2007, the demonstration woodland has undergone dramatic changes, including
A more open tree canopy, allowing sunlight to filter in.
A new wetland area that is home to native wetland plants and animals.
A new oak savanna being created out of meadows long ago cleared for farming and livestock grazing.
Newly planted and volunteering native trees, shrubs, grasses, and wildflowers that are beginning to flourish.
These results were accomplished through countless hours of hard work by Arboretum staff and volunteers. We used a comprehensive approach to woodland restoration.
This is the story, season by season, of how we did it…
With support from an Institute of Museum and Library Services conservation grant, the Arboretum launched a comprehensive environmental survey of its wooded natural areas and adjacent leased property.
Based on records at the Sterling Morton Library, municipal libraries, and research by Plant Conservation Biologist Marlin Bowles, we learned the land's history and relationship to the rest of the region. We used this information to develop a plan for restoration and management to set objectives and direct our restoration activities.
When the land at the Arboretum was settled in the 1830s and 40s, it was primarily used for logging and farming. At that time, settlers heavily logged and grazed the woodlands and installed drain tiles to drain water from their property, making it more "productive" for them. Much of the water was redirected to Lacey Creek, which feeds into the East Branch of the DuPage River.
One of the first goals of the project was to restore the site's hydrology. Working with an outside contractor, the Arboretum conducted a hydrological investigation of the site, mapping locations of drain tiles within the 60-acre project area.
After the drain tiles were removed, the water immediately began pooling in low spots, creating new wetlands. Now when rain falls, the wetlands act like a sponge, absorbing the water and making it available to plant and wildlife species, which increases the biological diversity in this area. Native species are emerging from the seed bank within the wetland, such as common bur reed, hard-stemmed bulrush, sedges, and others.
Using stakes and ribbons, work crews selectively identified and marked trees, mostly shade-adapted species such as sugar maple, American basswood, ash, and cherry, for removal in a 30-acre research area. In January and February 2008, selected trees were removed to open the canopy, allowing sunlight to filter into the woodland.
Some of the cut trees were chipped for use on Arboretum trails. Others were milled to make lumber or structures such as benches.
With increased light levels and more space created by controlling invasive species, native plant seeds that were latent in the soil can now emerge.
Controlling invasive species is the most labor-intensive and long-range activity of the project. We are using a range of control methods, including hand pulling, cutting, digging, and herbicides. Crew members are continually, systematically walking through the woodlands, removing invasive woody and herbaceous plants, such as
reed canary grass, a wetland plant that is colonizing other area woodlands
Seasonal ground crew aids and volunteers planted more than 1,000 trees and shrubs throughout the woodland demonstration area. Additional planting will continue as budget allows, with constant evaluation and monitoring of growth. The structural diversity offered by the trees and shrubs offer wildlife habitat for birds, mammals, and amphibians.
One key area is "Barney's Meadow" (named after the first documented landowner in the 1840s), a 30-acre meadow that was forested in pre-settlement times. There we planted woody plants in a density equal to oak savannas, leaving large open, unplanted areas for continued nesting habitat for grassland birds.
Native plant species were chosen based on current species in existence here and historical records. They included: New Jersey-tea, blue-fruited dogwood, American hazelnut, wafer-ash, early wild rose, pasture rose, elderberry, bladdernut, nannyberry, black-haw, and prickly-ash.
In addition to planting trees and shrubs, select native seeds were sown in the restored wetland. Their germination and growth will be assessed and monitored for long-term results.
To allow newly planted oak trees and hazelnut shrubs to get established, we did not burn in 2008. However, controlled burns will be implemented within this woodland in the future. Burning is an essential process in the development and management of this region's oak woodlands, as well as prairies. Our native species within these natural communities are adapted to fire. Slow-moving ground fires help to control competitive growth.
We are monitoring the health of the woodlands, by measuring the long-term success of planted trees and shrubs, as well as their growth patterns, and natural recruitment of trees in the woodland. We're also monitoring birds, butterflies, and amphibians. Lessons learned will impact how the Arboretum will approach future woodland management and restoration.
Management and control of invasive species in the newly formed wetlands and forested areas, where the tree canopy was thinned, has presented a greater challenge than originally anticipated. This is due to the emergence of different invasive species in the wetlands and woodlands.
Meet the Arboretum's Manager of Natural Resources, Kurt Dreisilker, who is steering the woodland demonstration project.