“Prairies are sometimes called ‘upside-down forests,’ because so much life is below the ground,” says narrator Penny Preston in the new documentary “The Last Prairie,” about the Jennings Prairie in Slippery Rock.

It’s a beautiful image that implies there’s often more than meets the eye in the natural world. At 20 acres, the Jennings Prairie is just a tiny sliver of land. It seems like a picturesque meadow tucked inside the Jennings Environmental Education Center — but it’s actually a small but complete prairie ecosystem. It is the only public and protected prairie in Pennsylvania.

From “The Last Prairie” by Wild Excellence Films.

The short documentary is devoid of people, focusing instead on the wild profusion of color found in the prairie’s wildflowers. If there’s a star, it’s the Eastern Massasauga Rattlesnake, who likes to hide in the prairie’s grasses. The snake is extremely shy and difficult to find. For this film, the Mid-Atlantic Center for Herpetology and Conservation provided a GPS-tagged massasauga.

Filmmakers David and Melissa Rohm, a married couple based in Pittsburgh, make nature documentaries all over the U.S. Starting in May, they’ll begin a project called “Golden Eagles: Witnesses to a Changing West” for PBS.

No, they weren’t worried about shooting the elusive, venomous rattlesnake on its home turf.

“We use a very long lens!” says David Rohm. “We get too excited to be scared, and we are always respectful. That makes all the difference with conservation photography … respecting the animals’ boundaries. And massasaugas are very shy by nature anyway. We let the animal tell us what’s appropriate.”

Eastern Massasauga Rattlesnake. From “The Last Prairie” by Wild Excellence Films.

More than 225 native plant species have been identified in the prairie, including a dozen that are threatened or endangered.

Spoiler alert: there is some shocking, unexpected footage in the film of the prairie burning that is jarring, given the wildfires we saw last year out West. Park rangers with flamethrowers started the blaze.

“The burning can look destructive but, in fact, it’s quite the opposite,” says Melissa Rohm. “The burns help get rid of woody vegetation that would take over the prairie, and help rejuvenate the grasses and wildflowers. They also add nutrients back into the soil. The park takes great care and caution to only burn at the right time of year, in the right weather conditions, to protect the wildlife. The controlled burns mimic what a lightning strike would do in a larger prairie.”

A controlled burn at Jennings Prairie. Photo courtesy of Wild Excellence Films.

The Jennings Prairie only exists because of the foresight of botanist Dr. Otto Emery Jennings, after whom it’s named. He first discovered this prairie in 1905 and initiated the purchase and protection of it by the Western Pennsylvania Conservancy.

The Rohms chose the prairie as a subject because they have been coming here for years, and many people are not aware of it.

“We started filming there a few years ago,” says Melissa. “It was too pretty not to film! Then we added segments about the massasauga and the prescribed burn to tell the story more completely. We felt that more people needed to know the importance of the ecosystem, and we also wanted to encourage awareness around prairie conservation in general.”

From “The Last Prairie” by Wild Excellence Films.

The couple’s production company, Wild Excellence Films, has made documentaries for the Allegheny Land Trust, Glade Run Lake Conservancy, Butler County Tourism and Convention Bureau and Cook Forest State Park. One project, in particular, has really stood out.

“We love them all, but it was really special producing the DVD for the Flight 93 National Memorial,” says Melissa.

“We’re happy that the DVD is helping to raise money for the memorial. A lot of people still think that the site is ‘just a field,’ but it is incredibly well-designed and poignant. The DVD helps visitors know what to look for in the landscape and architecture so that they can have a more meaningful and memorable visit.”

Filming this summer, the golden eagle documentary is also a big deal for them. Birds feature prominently in all of their work, including “The Last Prairie.”

“It will be broadcast on Wyoming PBS, and we hope it will get national distribution,” says Melissa. “It tells the story of the threats to Wyoming’s golden eagles and the people who are working to conserve them. The birds have to deal with a lot of challenges: poaching, lead poisoning, habitat loss, being hit by cars, prey decline.”

For the Rohms, working together has become second nature, so to speak.

“Working together, you develop a synergy after awhile and a kind of a mental shorthand,” says David. “For example, I will pass up a shot on a landscape because I know Melissa already captured it while I was filming another area, stuff like that. We each have our own styles of filming as well. That’s the power of nature; each landscape, animal or situation means something to each individual — and everyone sees different aspects of inspiration and beauty in nature in their own special way.”