LSU students work to keep invasive species in check in Bluebonnet Swamp

A few yards off the walking paths at the BREC Bluebonnet Swamp Nature Center, an LSU biology class does battle with invaders. The students are definitely outnumbered.

The invaders are elephant ear plants, popular in gardens and landscaping in Baton Rouge, but less so to BREC, which sees the broad-leafed plants taking over the lowest-lying parts of the urban swamp. So, Barry Aronhime’s class is combining learning with an effort to stop the invasion.

Aronhime isn’t positive how the elephant ear got into the swamp. Its presence is heaviest on the upstream end of the creek that goes through the area, and is prevalent along the edges of the creek. Most of the project is directed at the downstream end in hopes of stopping the spread.

Elephant ear quickly crowds out native small plants, perhaps because its large leaves prevent other small plants from getting enough sunlight to flourish.

“It’s a swamp. It’s not a terribly diverse area in terms of little plants,” said Aronhime, who is in his third year of a project that predates his arrival. “There are at least six or so species out there, but in patches dense with elephant ear, elephant ear is all you have. It changes it to a monoculture.”

And it doesn’t give up easily. Even when winter freezes cause the leaves and above-ground stalks to die back, the tubers below ground do just fine, Aronhime said, and the plants grow back quickly when warmer weather returns. Simply digging them up has had little effect.

So far, the class has attacked the problem four ways. Some areas are left untouched to serve as control areas for comparison. Elephant ear is removed in other patches, native plants are added in yet other areas, and removal and replanting is done in others.

In addition to using native plants already growing in Bluebonnet Swamp, the class is adding other plants like iris and pickerel weed that are native to the area but aren’t found in this swamp. In addition to growing taller so they won’t be shaded out by the invaders, Aronhime also hopes to see if there is strength in a greater variety of plant competition.

“We’re trying a whole bunch of different native plants in there in sort of a hope that the community is greater than the sum of its parts,” he said. “I don’t think there’s a native out there in the swamp that can compete one-on-one with elephant ear. If it were, elephant ear wouldn’t be doing what it’s doing. We’re sort of hoping if we have a real high diversity, that will prevent the elephant ear from coming back in.”

If there is a glamorous aspect to being a biology major — as most of the students are — this is not it. Students in rubber hip boots sink six inches into the muck as they get to the target areas, which are marked by small PVC pipes sunk vertically into the ground. The act of plotting the areas on a map was difficult; the tree canopy made inexpensive GPS devices unusable.

“That was chaos,” Aronhime said.

As well, the poles are set low enough that they aren’t eyesores for people walking the trails, which only makes it more challenging for the students trying to find these reference points.

“I just lost the pole yet again,” said Cassie Graziano, a senior from New Orleans, who was counting elephant ears and native plants in one plot with Hilarie Nixon, of Lake Charles, and Nonna Nissen, of Zachary.

Groups of about a dozen students have been attacking the elephant ear in morning and afternoon shifts starting in early October.

“At this point, we’re just trying to keep it from going further,” Aronhime said. “Optimistically, we could look for a complete eradication, but for right now I think it’s pretty ambitious just to hope to stop it.”