Fall 2002

Extensive restoration, still underway, enhances the fen's unique biodiversity

McHenry County, Illinois

Over the last 150 years, the rolling, wooded terrain known as Sterne's Woods and Fen has supported activities as varied as hunting, fishing, tree farming, gravel quarrying, and thoroughbred horse racing. At times, a pond, lake, and artesian well could be found here too.

The Crystal Lake Park District purchased 185-acre Sterne's Woods in 1986, and the preserve has been undergoing restoration ever since, beginning with extensive controlled burns led by Steve Byers of the Illinois Nature Preserves Commission. In 1994, a portion of the woods was designated as an Illinois Nature Preserve to recognize and further protect its unique biodiversity. Restoration work is now in the capable hands of volunteers and the Park District.

Fens are few in the Chicago area, but the preserve's 40 acres of wetlands include a fen, a marsh, and a sedge meadow. Combined with 140 acres of woods and a profusion of plant and forb species, Sterne's harbors an array of riches.

Fens require flowing water laden with calcium and other minerals such as magnesium. These conditions often occur in morainal areas such as Sterne's, where water percolates through calcium-rich sand and gravel dragged here by glaciers thousands of years ago. The water pools atop impermeable glacial drift and then bubbles back to the surface from below, creating the alkaline conditions favorable to fens.

Early in the summer, the fen boasts the state-endangered grass-pink orchid, our upside-down orchid with the showiest petal on top. From mid June to early August, the female Baltimore checkerspot butterfly lays her eggs on the underside of the turtlehead plant, an uncommon member of the snapdragon family with creamy-white, pink-fringed flowers. In early autumn, liatris also blooms in the fen.

The sedge meadow and marsh lie east of the fen. "In the fall, there are fringed gentians everywhere," said site steward Larry Smith. "They have delicate petals like blue eyelashes." Visitors may also see lady's slipper orchids, grass-of-parnassus, great blue lobelia, cup plants, and shrubby cinquefoil.

Together with renowned McHenry County naturalist Bill Wingate, who over the years taught the values of restoration to countless volunteers, Smith plotted the path for the Prairie Trail, which runs east of the woods, just over the border ridge of pines once planted by doctor Ted Sterne, the previous landowner.

The trail leads to upland woods, a quilt of trees, plants, and forbs and passes through basswood, ironwood, black walnut, tulip, and white and black oak trees. Volunteers are gradually thinning the walnut trees to open up the area for oaks, which were once predominant here.

Swallowtail butterflies lay their eggs on prickly ash here, and blue cohosh, nodding onion, columbine, bottlebrush grass, wild cucumber, vervain, and American bellflower abound. The woods also hold jack-in-the-pulpit, lady fern, sensitive fern, royal fern and ebony spleenwort. Wingate Prairie and Veteran Acres to the south provide a buffer for the fen, as do these drier upland woods.

There are hayrides in the fall through Sterne's Woods, as well as biking and cross-country skiing trails that avoid the fens. The 26-mile Prairie Trail, open all year for bikers and walkers, is due east of the nature preserve on Hillside Road. It winds north to the Wisconsin border and south to Algonquin, where it joins the longer Illinois Prairie Trail. Penny Lake borders Sterne's Woods on the west.

If groups of five to ten are interested in touring Sterne's Woods and Fen, call Crystal Lake Park District Natural Resources Manager Rita Hickman at (815) 455-1763. To help with restoration efforts, join Operation Buckthorn — underway four Saturdays in February.

— Gail Goldberger