Rare restoration: A unique ecosystem

A former sand-and-gravel pit is recognized with a prestigious award for its scarce ecosystem.

The site where a sand-and-gravel pit once operated in St. Marys, Ontario, Canada, now serves as a public recreation area that features a rare tallgrass prairie plantation, a fen and a pond that supports native plant species, amphibians and reptiles.

The pit – the Wildwood Pit – is now about 40 years gone, but the unique environmental restoration work done there over several decades caught the attention of the Ontario Stone, Sand & Gravel Association (OSSGA). The association recently recognized the Wildwood Pit within the Wildwood Conservation Area with its highest honor, the Bronze Plaque, because of the unique ecosystem created there over time. The pit is the 20th site in Ontario to earn the award since it was established in 1975, and the public can see the restoration work for itself by taking the Wildwood Lake Trail.

“This represents the best of the best among the thousands of rehabilitated former aggregate extraction sites in the province,” says Ted Wigdor, CEO of OSSGA. “The diverse ecosystem created here with rare plant species and habitat for snakes and turtles is why this site is so exceptional.”

Before the Wildwood Pit was restored, it provided construction materials used to build infrastructure that protects local residents from Thames River floods to this day. Significant floods were reported in the area dating back to the late 18th century, and the area sustained its worst flood in 1937.

The 1937 flood reportedly damaged properties and resulted in several casualties. It also led to the development of the Upper Thames River Conservation Authority (UTRCA), which recommended the construction of the Wildwood Dam. According to UTRCA, the nearby Wildwood Pit provided the materials used to build the dam and concrete baffle walls over a three-year period.

The operational pit reached the end of its life in 1971, and the UTRCA and the Ministry of Resources began restoration work on it in 1996.

“We saw that it was starting to naturalize on its own,” says Cathy Quinlan, a terrestrial biologist who started at UTRCA a year or two after the Wildwood Pit restoration began. “We wanted to build on it and create communities that were best suited to it.”

The project

According to Quinlan, UTRCA typically tries to return an aggregate site to the form it had before production took place. The Wildwood Pit was previously farmland, she says, but because little soil remained in the pit the odds of returning the land to farming purposes were unlikely.

So the conservation authority explored alternatives. A tallgrass prairie was a viable option, Quinlan says, as awareness of their loss was spreading in the mid-1990s. Tallgrass prairies can tolerate poor soil conditions, she adds, so an experiment with species native to tallgrass prairies seemed worthwhile.

“The staff here used a variety of species – four grass species and 12 flower species,” she says. “We experimented with a few common species of prairie flowers and grasses.”

Only a couple of grasses took off on the site, according to Quinlan. Indian grass, which she describes as a rusty-colored grass with a great spread, is one. Big Bluestem is another strong performer at the former Wildwood Pit, although it’s performing well in areas that contain more soil.

“We don’t really know why something grows and why something doesn’t,” she says. “Maybe the conditions are just right for one species.”

A number of prescribed burns were also performed on site to help plant species establish themselves.

“There are a couple of theories of what fire does for native prairies,” Quinlan says. “It burns off any woody stuff. A lot of times, if you do a fire in the early spring and some weedy things are starting to grow but the prairie species are not, you can knock back those weed species.”

Another theory is that a prescribed burn blackens the surface, warms the ground and helps spur on prairie grasses, she adds.

“It also uses up some nutrients, and prairie plants don’t need the nutrients,” Quinlan says.

The last time UTRCA treated the site was in the late-1990s – just a few years after restoration work began. The project was largely a forgotten one, though, because UTRCA is continuously taking on projects throughout the region. But the award OSSGA gave was a welcome reminder of the work done at the Wildwood Pit.

“Several people on the staff here are in the area and they’re constantly walking by it and letting us know how things have changed there,” Quinlan says. “We’ve put up some interpretive signs so people can read what we’ve done to the pit in terms of what we planted and how it started. It also helps us because every 10 years there’s some staff change, and people forget what we did. But it was a pretty big deal in its day.”