by Carolyn Bernhardt
November 11, 2024
In Minnesota, a surprising discovery about reed canarygrass (RCG) begs the question: how should land managers handle native species with invasive tendencies? A recent study funded by the Minnesota Invasive Terrestrial Plants and Pests Center (MITPPC) analyzed RCG populations across the state. They found that, contrary to common assumptions, the grass is predominantly native rather than introduced.
Reed canarygrass (Phalaris arundinacea), a dominant native species in Minnesota’s wetlands, is well-known for its aggressive spread. It forms dense, single-species areas that outcompetes other plants, and threatens local biodiversity.
Neil Anderson, PhD, a professor in the Department of Horticultural Science in the College of Food, Agricultural and Natural Resource Sciences, led the research. Anderson used genetic testing to compare DNA from statewide samples with known European and native strains. The findings encourage a shift in management strategies to balance ecological goals with practical conservation efforts.
“We never found any non-native RCG in all of our collections so far—none,” Anderson says. “As we point out in our papers, it’s a misunderstanding between ecologists, early genetic work, and assumptions that it’s non-native because people saw it taking over. We make the case in our papers that native plants can be invasive [in their behavior].” (See papers on RCG funded by MITPPC.)
With funding from the Environmental Natural Resources Trust Fund, which supports MITPPC’s competitive grant program, Minnesota has become a leader in this research. “If we didn’t have that huge investment, we couldn’t do this research,” Anderson notes. This study underscores the importance of understanding a species’ origins to inform management practices, adapting strategies based on site conditions, land use, and available resources.
Unpacking a complex character
While native to Minnesota, RCG has dominated many landscapes across the state for several reasons. Its expansion across the Midwest over the last century was largely influenced by settler-driven uses, including as forage, ornamental, biofuel, and restoration crops. During the Dust Bowl, RCG hay shipments from a large stand in Roseau, MN, were widely transported as cattle feed, possibly fueling its spread along trade routes. “And maybe there were elite types that evolved to be even more aggressive than older ones,” says Anderson.
As a geneticist, Anderson notes that no “silver bullet” gene is responsible for invasiveness. “There is no specific one trait that makes something invasive; it’s a whole suite of them,” he explains, adding that these traits vary widely among species. RCG, for instance, cannot grow in water deeper than 30 cm, but thrives in ditches, dry uplands, and even some industrial areas. “Something that is widely adapted, that flowers a lot, and can get seeds into the seed bank is pretty good at taking over,” he says.
While RCG aggressively competes with other plants, Anderson notes its potential uses: “A lot of Tribal nations have historically used reed canarygrass, and it’s something of interest to keep around.” It’s also valuable for biofuel in places like Europe, and can assist in bioremediation.
However, RCG can overtake areas without consistent management and suppress rare native species. “Land managers seem like saints because they have a really hard job. You have to continue that vigilance every year; otherwise, it comes right back,” Anderson says.
A call for science-based decisions
Anderson and his team are pioneering new ways to approach reed canary grass (RCG) management with a broader perspective on invasive species policy. In a 2021 paper, they outlined philosophical and policy-based approaches to RCG and called for clear strategies and collective efforts. Yet Anderson points out that “no major, collective effort is underway” to establish formal management policies, largely due to challenges in distinguishing native RCG from its non-native counterpart. “It’s an expensive molecular test,” he says. “There’s no handheld tool for this yet. If you can’t identify it, how do you know what you’re managing?”
Anderson hopes their work provides a template for future policies. Meanwhile, he advises land managers to focus on their specific goals for managing RCG rather than automatically prioritizing its removal. At the Minnesota Arboretum, for instance, managers plan to remove RCG from a restored wetland because their goal is to maintain native biodiversity. In cases like these, where managers are committed to restoration, removal may align well with their objectives. However, when new funding is needed solely for RCG removal, Anderson encourages considering whether it’s worth the investment, given that RCG seeds persist in the soil and ongoing management is expected. “What is the goal of this particular management? If you just want native species, it’s a native species!” he says.
Anderson’s work on RCG highlights a broader challenge facing invasive species management. “The suite of invasive species keeps growing, whether plants, insects, or animals, and that will continue as climate change forces species to move,” he explains. “Yet, funding tends to focus on the latest, most visible invasives, while many others get overlooked.”
The current definition of invasiveness in policy dates back to President Clinton’s 1999 Executive Order 13112, which presumes that non-native species are inherently harmful while native species are not. Anderson says this is oversimplified. “We still have a regulatory definition that’s not based on science. It makes invasive species management like a religion, instead of asking, ‘What does the science say?’”
Anderson challenges the notion that RCG’s spread is unnatural, arguing that human influence is part of the ecosystem’s evolution. “We’re natural beings on this planet,” he says. “Granted, we may be one of the most impactful, but we’re still part of the ecosystem.”
Testing for the broader scope
Anderson emphasizes the importance of molecular testing in managing reed canarygrass (RCG). He believes that establishing a dedicated lab for this testing could be a significant advancement. “But right now it’s just [our lab] because we have the SNP library that helps us distinguish between European and Native North American types,” he says. Currently, land managers must apply for grants to test their RCG populations, collect samples, and send them for analysis.
A comprehensive national survey of RCG is also crucial. Minnesota has robust sampling, but data from other regions lags behind.
Anderson stresses the need for land managers to develop policies for evaluating and assessing the risks of native and invasive species. “We are basically guiding evolution, right? So, it better not be fear-based,” he asserts. “We need to discuss these things and come up with solutions. That’s the only way we can solve problems on a global basis. Invasive species evolution by itself is a force that is moving globally everywhere you look. Likewise, climate adaptation is lighting the fire to help it go faster, and that concerns everybody, so it’s a global issue everyone needs to look at.”
More information
- Tools to distinguish native from exotic reed canarygrass, research project
- Management and control issues for native, invasive species (reed canarygrass): Evaluating philosophical, management, and legislative issues, American Society for Horticultural Science, 2021
- Reed canarygrass management, Minnesota Department of Natural Resources
- Identification tips: Reed canarygrass (video), U of M AIS Detectors
Research from the Minnesota Invasive Terrestrial Plants and Pests Center is supported by the Environment and Natural Resources Trust Fund, as recommended by the Legislative-Citizen Commission on Minnesota Resources.
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