How Mountain Biking Might Lead to the Spread of Some Invasive Species

Arborists, trail organizations, and resource managers in Michigan are concerned about the potential for mountain bikers to spread invasive plant species.
Volunteers pull Spotted Knapweed, an invasive species, Saturday June 24th at Island Lake Recreaton Area in Brighton, Mi. Photo courtesy of MDNR.

Trail advocacy and stewardship is something many mountain bikers support. We try not to ride when the trails are too wet and encourage others to stay off, clear branches or fallen trees after a storm, or volunteer at trail maintenance days.

Trails take a long time to build, so ensuring trails are built and managed sustainably is a top priority. Trail organizations work with land managers on proposed trail networks, flagging areas, and ensuring proper processes happen during development. 

Biologists usually review proposed trails that may threaten wildlife or plant life and hydrologists or geologists may get involved during the NEPA process too.

Despite all of this, we may still be damaging the trails and surrounding areas in a way we are completely unaware of—spreading invasive plant species.

Photo: Jeff Barber

Before the holiday break, we received an email from Julie Stachecki, an avid cyclist and arborist from Michigan. While it might sound a little crazy at first, she said they’re seeing cases of invasive species in Michigan, and that others are finding the plant in neighboring states.

She also shared a campaign with a Michigan trail organization and the Michigan Department of Natural Resources (MDNR) to reduce the spread of invasive plant species.

We got in touch with Stachecki, and the MDNR to learn more about the problems they are seeing, how invasive plant species are spreading, and ways we can prevent the spread. 

What exactly are we spreading?

Oak wilt in Michigan. Photo: Joseph O’Brien, U.S. Forest Service

For Stachecki, it all started when she was consulting for a colleague in Arkansas whose property suffered from oak wilt. As they walked her property, they found the same invasive plant species Stachecki was concerned about: Japanese stiltgrass.

“We found some Japanese stiltgrass, and my friend commented that stiltgrass is like a ground cover in Arkansas. My alarm bells and red flags just went crazy,” Stachecki told us. Being an arborist, Stachecki is familiar with plant species that harm surrounding native vegetation, like stiltgrass. But she hadn’t just read or studied about stiltgrass. She would see it in the forests back home in Michigan.

Knowing that Arkansas is a major mountain bike destination, Stachecki saw how this invasive species could easily spread nationwide. “[Japanese stiltgrass] is an annual. It germinates, grows, sets flower and seed, and dies in one season,” Stachecki said. “Each plant can set between a hundred and a thousand seeds.” 

These seeds can be on mud on our tires, drivetrain, suspension linkage, etc. After a wonderful visit to Bentonville, you pack up your bike and board a plane home. Unbeknownst to you, you may unintentionally spread the Japanese stiltgrass seeds in your local forest on your next ride.

But Stachecki isn’t the first to bring awareness to the mountain bikers spreading invasive plant species like Japanese stiltgrass. As she connected the dots of this invasive species issue, she remembered an article on the West Michigan Mountain Biking Alliance’s website reminding riders to “ride, clean, repeat.

Ride, Clean, Repeat is a campaign developed by Michigan’s North County Cooperative Invasive Species Management Area and amplified by MDNR. Ride, clean, repeat raises awareness among trail users, both motorized and non-motorized, in the prevention of the spreading of invasive plant species.

Japanese Stiltgrass along a trail in Brown County, Indiana. Photo courtesy of MDNR

Japanese stiltgrass

Katie Grzesiak, MDNR’s Terrestrial Invasive Species Coordinator, realizes that mountain biking isn’t the only culprit spreading invasive species. 

“We know that hikers are a part of it, we know bikers are a part of it, and sometimes pets,” Grzesiak said. “We know that on multi-use trails, invasive species are being spread.”

And, while it is an “everybody” problem, there are trails in Michigan predominantly used by mountain bikers covered in invasive plant species like stiltgrass. Typically, the greatest challenge in preventing the spread is the lack of information and education to groups like mountain bikers.

“You’ll see boot brush stations at the trailheads and think that’s only for hikers,” Grzesiak said. “You can’t put your bike tires or chain in there. So you’re not going to use that decontamination, and you might not even think it’s for you.”

Japanese stiltgrass. Photo:, Chuck Bargeron, University of Georgia

Japanese stiltgrass isn’t all the MDNR is hunting. They have also been battling oriental bittersweet and oak wilt, amongst other invasive plant species. The MDNR is primarily concerned with the spread of Japanese stiltgrass, as it is a relatively new invasive species in the state.

And it does spread easily. “It’s a very floppy grass, very flexible,” Grzesiak said. “And so it’s very easy to get caught in a chain and have a little seed get stuck in cleats on your shoes.” And once stiltgrass is on the ground, it spreads rapidly, covering large areas, choking out other plants and ground cover competing for resources.

Grzesiak shared a story about a friend who sent her pictures from a mountain bike trail in Ohio where Japanese stiltgrass covered the surrounding land. Thus, the MDNR and others are pushing to educate trail users, including mountain bikers, on the nuisance they see literally pop up.

How can we fight the spread of invasive plant species?

Also on our call was Emily Leslie, a Natural Resource Steward for MDNR. Leslie works in the DNR Parks and Recreation division, supervising eight parks where she is literally “boots on the ground,” as she put it.

For the MDNR, fighting invasive species starts with educating the trail users. Leslie feels this begins with the Ride, Clean, Repeat campaign but sees a way to help spread the message about invasive species by connecting it to a habit many mountain bikers already have. And it isn’t tough.

“Just cleaning off your bike,” Leslie said. “Many of you guys already clean up your bike every time.

Cleaning the dirt and grime off our bikes seriously prolongs their life. Leslie hopes we can further that connection by realizing it can extend the life land around our trails, too. 

Oriental bittersweet. Photo: James R. Allison, Georgia DNR

Making sure our bikes are clean after each ride is the first step. Leslie also suggested that riders get involved with their local trail organizations. Leslie shared about a volunteer helping with invasive species removal: “I had a volunteer who’s really involved with the mountain biking association. It’s become a really good partnership because he’s seen techniques I’m using that he can apply to the mountain bike association and raise awareness about invasive species for them.”

Before working with Leslie and MDNR, this volunteer battled invasive species, removing them from trails several times throughout the season. After showing him proper techniques and a pesticide to use, he was fighting the plants only once a year, and he could share with his trail organization how to eradicate the plants they battled properly.

It is essential to emphasize that the trail organization needs to connect with land managers for education on the proper removal of invasive species, or we can end up doing more damage.

Stachecki was riding near the end of last spring and saw trail workers clearing low-hanging oak branches. This corresponds with the high-risk period for oak wilt infection.

“Oak wilt is a pathogen. If it gets into a fresh wound down in a red oak tree, that red oak tree will die within six to eight weeks,” Stachecki told us. “It doesn’t matter the tree’s size. It will die, and then this pathogen moves through the trunk and into the root system, and it continues to kill red oaks that it is root-crafted with.”

Leslie realizes that joining her and the MDNR for a Saturday volunteer day may be difficult for some. Many mountain bikers already give up a handful of Saturdays during the year and join their trail organization to help with maintenance. But, if more trail organizations could partner with agencies like DNR and have a member properly trained on invasive plant species identification and removal, there is a much better chance of preventing the spread.

“Having more eyes out there is going to benefit all of us,” Leslie said.