Though the landscape looks barren, new prairie and savanna plants are quietly waiting to spring to life at Hickory Hollow once the weather warms. With a major seeding effort and other first steps, the Wetlands Initiative has kicked off restoring rare habitats on the 283-acre parcel that TWI acquired to expand our Dixon Waterfowl Refuge at Hennepin & Hopper Lakes in late 2014.
The tract, nicknamed Hickory Hollow for the wooded ravine and intermittent stream that runs through the property, is located in the Refuge’s southeastern corner, upslope from the high-quality Dore Seep Nature Preserve. It contains woodland areas, including some that will be restored to sand oak savanna, and former soybean fields that will be transformed back to mesic prairie and sand prairie.
Intensive restoration work at Hickory Hollow officially began in September 2015. The main work items this past fall and winter have been removal of aggressive or non-native trees and shrubs in the savanna restoration zones and seeding of native species to begin restoring the farm fields to high-quality prairies. In January, TWI spread more than 2,200 pounds of seed made up of 165 native species across the bare, snowy fields. This technique is known as frost seeding; natural freezing and thawing cycles over winter and early spring help the seed mix with the soil and are needed for many species to germinate.
The plants installed included common prairie species like leadplant and cream wild indigo, rare sand prairie-adapted plants such as sand milkweed and clustered poppy-mallow, and savanna shrubs like American hazelnut.
“The goal is to establish a diverse mix of species that are characteristic of high-quality prairies and savannas in Illinois, including rare sand prairie and sand savanna habitat,” said Gary Sullivan, TWI’s senior ecologist and the Hickory Hollow project manager. “We surveyed undisturbed habitats in Illinois and cross-referenced them with both the literature and the collective wisdom of other restoration ecologists to build a robust assemblage of plant species, and we’ll be planting more species from the list over the next two years.”
Savannas are park-like grasslands with scattered oak and hickory trees that allow sunlight to reach most of the ground. Because savannas have a lower tree density than other wooded areas, TWI worked with a contractor to thin trees across about 22 acres that have been targeted for savanna restoration, preserving the more valuable and larger trees. Refuge site managers are also removing smaller trees and shrubs like honey locust and honeysuckle from the edges of woodland areas that would otherwise quickly invade the savanna and prairie.
Restoring Hickory Hollow represents a singular opportunity to bring back some of Illinois’ rarest habitats. “Sand prairie and sand oak savanna are now extremely rare in Illinois, and most of what is left is found in small, isolated remnants,” said Sullivan. “It will take years for the new prairies and savannas to fully develop, but the Hickory Hollow project ultimately will bring back some of the largest examples of these unique habitats anywhere in the state.”
The restoration is expected to benefit a number of imperiled or declining bird species, particularly Neotropical migrants (bird species that nest in North America during the summer and then spend the winter in the tropics). The project will add breeding habitat at the Refuge for migratory birds of conservation concern that rely on grassland, savanna, and woodland like the Black-billed Cuckoo, Great Crested Flycatcher, Summer Tanager, and Grasshopper Sparrow. TWI has received a two-year, $100,000 grant for the Hickory Hollow effort from the federal Neotropical Migratory Bird Conservation Act (NMBCA) program, and TWI staff are conducting bird surveys to monitor their response to the restoration.
The next steps in 2016 will be to plant more species as plugs (seedlings) to help dense plant communities establish, to continue removing plants and trees that don’t belong in the habitats, and to plant young trees in the savanna restoration areas. TWI plans to hold a volunteer plug planting day in May or June 2016, which will be one of the first opportunities to view the new parcel.
At least two more years of restoration will be needed to transform the Hickory Hollow tract, including another round of seeding and more rounds of invasive removal. Once intensive restoration work is completed, Hickory Hollow will be open for the public to explore with a trail system, interpretive signs, and other amenities. But for now, the first seeds of the future habitats await their chance.
In addition to the NMBCA award from the U.S. Fish and Wildlife Service, the Hickory Hollow Savanna and Prairie Restoration is being funded by Grand Victoria Foundation, Oberweiler Foundation, and individual donors to the Wetlands Initiative.