After Phragmites Kill, Native Plants Prove Complicated to Cultivate: NPR

Keith Hambrecht vividly remembers his first experience with the bane of American wetlands, a tall, dense reed called Phragmites.

“I didn’t know what it was at the time,” he says, recalling working with a small conservation group in Utah about a decade ago. They were instructed to go to a pond and pull out these invasive weeds by hand, a plan he now describes as “weird.”

“We spent maybe five minutes pulling a few phragmite logs out of the ground,” says Hambrecht. “It’s basically impossible.”

Now he has a much better idea of ​​the extreme measures required to combat this plant.

The problem is that once the reeds are poisoned and cut down, all that’s left is an empty patch of mud – the perfect environment for the phragmites to return.

That’s why ecologists in Utah are trying to figure out how to get native plants there to grow quickly to prevent phragmites from re-establishing themselves.

“In many wetland systems, this is a fairly new endeavor and the methods are untested,” he says Karin KettenringWetland ecologist at Utah State University.

But there is one place on the Great Salt Lake that gives her hope. There, her research team has experimental plots that have shown how mixtures of native seeds can restore a wetland after phragmites have been eradicated.

“For the first time, we saw a much greater diversity of native species re-establishing themselves,” she says. “We had literally never achieved this before.”

A risky packaging material

Puffy-Topped Phragmites have been around in North America for more than a century. It was likely introduced to the East Coast as a type of packaging material, with the fluffy seed heads used like Styrofoam in shipping, Kettenring says.

“It didn’t get to Utah until the early 1990s, or at least it didn’t explode there,” she says.

Tens of thousands of acres are now covered by this reed in this state. Its huge stems can grow over twelve feet tall, forming dense, impenetrable clumps that crowd out everything else. And its dense root systems reach deep into moist soil.

“The way water flows over the land is significantly changed by this plant. This is just completely different than anything that has been here before,” says Hambrecht, pointing out that it can clog canals and block river flow. “It has pretty far-reaching implications.”

Utah is just a story. This plant has become a major problem in wetlands across the United States, where it dominates areas that should be filled with a variety of native plants that meet the needs of insects and animals such as migratory birds.

An area of ​​the Farmington Bay Waterfowl Management Area where phragmites have been managed and some native plants are growing again.

Karin Kettenring

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Karin Kettenring

To get rid of phragmites, land managers like Hambrechtwho works for the Utah Division of Forestry, Fire, & State Lands must spray thousands of acres with herbicides. The huge amount of dead plant material must then be shredded or burned.

However, once areas are treated, native wetland plants do not simply grow back naturally. Considering how much labor and time it would take to grow mature native plants, sowing seeds seems to be the only possible option, says Hambrecht.

It is difficult to hold onto the seeds, partly due to the fluctuating water levels.

“If you have a wetland and water is the defining feature, you might think that you can plan for a consistent water supply,” he says Hailey Machnikowskia graduate student in Kettenring’s lab. “We don’t think that’s the case.”

Graduate student Montana Horchler distributes different seeds between posts to find out what can be helpful in wetland restoration. Organza is wrapped around some plots – the material allows water to flow through the mesh while keeping the plants separated.

Karin Kettenring

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Karin Kettenring

Mix seeds

Machnikowski stands in what looks like a wet meadow in the Howard Slough Waterfowl Management Area. In this vast swamp area there are water channels crossed by dikes and on which roads lie.

To get to their experimental areas, the researchers have to put on waders, cross a water channel and then dig through the mud.

Here they have scattered seeds from a carefully selected mix of nearly two dozen different native species. They included everything from drought-tolerant plants to those that like to have their feet wet, “basically hoping that something in that mix would suit the conditions,” Machnikowski explains.

“Every two weeks we come here and do visual estimates of cover by species,” says the doctoral student Montana Horchlerwho tested the effect of sowing several times a year and not just once in the spring.

Some seeds they tried were a failure. Others are doing surprisingly well, like a native plant called pickleweed and a beggar species with bright yellow flowers.

“We are making an effort and are slowly but surely learning little by little,” he says Sam Kurkowskithe head of Kettenring’s laboratory.

But if the lessons learned are to be applied on a larger scale, they’ll need to somehow obtain a lot of seeds that aren’t typically found in a store.

For their test plots, they collected seeds from wild plants – a laborious process. Ideally, they could contract with domestic plant seed companies to supply the seeds, but that still needs to be clarified.

“We just had a large joint meeting this fall with native plant vendors and wetland managers to share our experiences and facilitate collaboration,” Hambrecht says.

Many of the domestic seed suppliers are “smaller companies and don’t have a big profit margin,” says Kettenring. This means they may not be able to take the financial risk of producing lots of rarely sought-after seeds unless they know for sure they have a buyer.

In considering all of these challenges, Hambrecht says collaboration between land managers and researchers has been invaluable.

“I hope it can serve as an example for other issues of this kind,” he says. “I think people look at the problems of large invasive species and feel like they are completely pointless. But really we just need to find solutions to many of the challenges and then work together on a strategic long-term plan to restore these ecosystems.”