While lupines are celebrated as one of Maine’s most iconic blooming flowers — showcased on Acadia National Park souvenirs and the centerpiece of the beloved children’s book “Miss Rumphius” — the park has spent years balancing their popularity with the ecological threat they pose as one of many invasive species in Acadia.
Lupines are just one of dozens of invasive plants in Acadia, where a changing climate has shifted temperatures and growing seasons, stressing native habitats and accelerating the proliferation of invasive plants.
But, unlike many invasives targeted by the park’s invasive management team, lupines are only managed when they encroach on at-risk species or significant natural habitats like wetlands or summits, according to the park service.
Lupines can be found throughout some of the park’s most popular attractions, including its largest wetland, the Great Meadow, according to Chris Nadeau, a climate change adaptation scientist who has researched invasives in Acadia.
The park manages lupine more selectively than other invasives like glossy buckthorn, one of the more ecologically damaging non-native plants in Acadia and the focus of an ongoing restoration project at the Great Meadow.
“The big problem is that the park spends over 1,000 hours a year trying to remove invasive plants like glossy buckthorn, and you go back a few years later and they’re just back,” Nadeau said.
Acadia has been managing invasives since 1989, after officials determined purple loosestrife was threatening local wetlands. The invasive plant management team focuses on 29 high-priority non-native species, which make up nearly a third of the park’s total plant population, according to the park service.
Management strategies have been largely successful: invasive plants cover less than one percent of park forests and wetlands, according to local nonprofit and research-oriented Schoodic Institute. But those that remain pose a sustained threat to native habitats.
Currently, the park and its partners at the Schoodic Institute and local nonprofit Friends of Acadia are spearheading Acadia’s largest restoration project yet at the Great Meadow, which is one of 150 field sites the invasive management team oversees annually.
Part of that restoration project involves finding the best way to remove glossy buckthorn. The shrub last year consumed 60 percent of the invasive team’s time, according to Nadeau, who is working on the restoration effort.
Although lupine may not occupy as much of the park’s time as glossy buckthorn, it’s among the most controversial plants Acadia’s team oversees. Given the plant’s cultural importance, the park’s work on lupine has looked a bit different from its management of other invasive plants.
A species of lupine that was once native to Maine — sundial lupine — has mostly disappeared in the state, including at Acadia. Now, Bigleaf lupine, a prolific non-native, invasive species that originated in the western U.S. and was introduced in Maine as a landscaping plant, has replaced it, dotting the park’s fields and roadsides with its purple and blue leaflets.
The plant was immortalized in Damariscotta resident Barbara Cooney’s 1982 classic children’s book “Miss Rumphius,” in which the protagonist, inspired by English native Hilda Edwards Hamlin, scatters lupine seeds along Maine’s coast, according to the New England Historical Society.
Despite its picturesque qualities, lupine can threaten native habitats at Acadia and produce seeds that are toxic to wildlife in large quantities. In previous years, the park removed lupines that were encroaching on a milkweed habitat, a host plant for migratory monarch butterflies who can’t eat lupines.
But, like many plants, the invasive species also contributes to the park’s ecosystem: it provides nectar for pollinating insects, attracts hummingbirds and helps prevent erosion with its deep, soil-enriching roots.
A park spokesperson previously said the park had removed lupine on Bar Island, Fernald Point and near Great Meadow Drive, according to local blog Acadia on My Mind.
Acadia no longer has a dedicated spokesperson. An inquiry sent Monday to a general park communications email did not receive a response.
The park’s approach to glossy buckthorn is strikingly different from its selective management of lupine, in part because of the shrub’s ecological impact.
Glossy buckthorn, unlike many invasive species, doesn’t require disturbed soil and can survive most environments. It grows particularly rapidly and produces an abundant supply of diuretic berries that birds eat and disperse, spreading, Nadeau said, like wildfire.
Buckthorn was introduced to the United States as an ornamental and, “back in the day when we didn’t know any better,” for wildlife habitat, Nadeau previously said.
Scientists at the Great Meadow are now trying to determine if they can replace the buckthorn rather than just removing it, which the park’s invasive management team has been doing for over a decade, according to Nadeau, a lead researcher on the project.
The Great Meadow, sitting in a valley between Dorr, Kebo and Champlain Mountains, is a hotspot for glossy buckthorn: it’s one of two locations where scientists have set up monitoring stations to evaluate the best way to address the invasive shrub’s spread.
Scientists installed 21 fenced plots between the Great Meadow and Bass Harbor Marsh, another glossy buckthorn hotspot on the southern end of Mount Desert Island where the park started removal efforts in the summer of 2020. Each plot is divided into four subplots, where scientists are experimenting with different kinds of species and planting techniques to see which best competes with glossy buckthorn.
“So how can we slow what we call reinvasion? What we found so far is that if we plant native shrubs after we’ve removed buckthorn, that reduces the natural regeneration of buckthorn by 43%,” Nadeau said. “Also, if we plant native shrubs, that reduces seed germination by 41%. So if a seed does get in there, it’s much less likely to germinate and produce buckthorns.”