060116 sentinel weevils1 ov

Bryce Christiaens collects weevils off of Dalmatian toadflax on Mount Sentinel in this 2016 file photo. These weevils are used as a natural deterrent on any overgrowth of knapweeds.

Weeds resemble fire and wildlife in at least one way. Leafy spurge and spotted knapweed don't respect boundaries, so one land manager alone can't deal with their spread.

This spring, Nature Plants published a study examining the weed problem through a social lens with a University of Montana faculty member among the 15 authors. The report addresses the global nature of the threat, but the matter also is one UM assistant professor Alex Metcalf has worked on at the local level with Missoula County Weed District and Extension.

Metcalf said people who manage weeds typically tend to think about economic reasons for doing so and consider constraints such as "time and money and know-how." The extension community will develop a program to try to help, he said, but they've generally been frustrated with results.

"It doesn't move the needle as much as they want it to," Metcalf said.

So the community reached out to Metcalf, and the local work runs parallel to the study in Nature Plants. Basically, his research is shedding light on one reason society's traditional approach to weeds might be limiting.

"We tend to throw out solutions that ignore the collective nature of the problem," Metcalf said.

Here's how weeds really work. Generally, one neighbor's actions to control weeds affect another neighbor's property, and where many landowners control for weeds, Metcalf said they create social expectations that others do so as well.

"Where that doesn't exist, people aren't getting the social cues that indicate control is important," he said.

So public communication through social networks that controlling weeds is critical is inspiring better weed management than traditional messages. Metcalf said that type of influence cuts across cultures, although it plays out differently.

"There's a social dynamic here that is exacerbated by the fact that weeds cross boundaries very easily," Metcalf said.

He said the other finding from the study is that weeds "tend to be a weakest link" problem. For example, Metcalf said with a quarantine, participation needs to be complete or the quarantine doesn't work.

"Weeds aren't quite that bad, but they're that type of problem," Metcalf said.

In other words, if just one property owner has land that becomes a seed source, everyone else can be working hard, but the problem stays. Metcalf said he's particularly interested in how private land conservation and natural resource management are influenced by social interactions among landowners.

"There's some profound implications for our policy and how we build incentive programs at the state level, and I think we're just starting to scratch the surface on that," Metcalf said.

Bryce Christiaens, Missoula County Weed District manager, said weeds traditionally have been seen as an agricultural issue. Weed districts were set up to manage things like county rights of way, and weed managers also played a regulatory role.

But he said weeds have a wider impact, affecting native plant communities, wildlife, and riparian ecosystems. So weed managers have needed to shift their approach.

"How do we engage a public to assist in the management of this as a natural resource issue?" Christiaens said.

Just sending the government in to tell landowners what to do isn't the right approach and neither is hitting people with a barrage of facts, he said. Rather, he said the challenge needs an appropriate message through the right messenger.

"How do we address this social values aspect?" Christiaens said.

To help answer the question, weed managers reached out to people with expertise such as Metcalf along with those who manage fire and human-wildlife conflict. He said the solution is identifying people's shared values and the things they're engaged in, and figuring out how invasive weeds fit.

For example, Christiaens said in the terrestrial world, that solution means working with groups such as the Blackfoot Challenge, which already has identified a set of values around managing land that's sustaining their families.

In Missoula, he said species like spotted knapweed and leafy spurge are established and may not ever be eradicated, but a lot of new "invader threats" could be eliminated. He said partnerships are key.

"If we can't take them on as a community, we're always going to be a couple steps behind," Christiaens said.

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