When it comes to Maine’s interstate and other roadways, what’s growing alongside them is as important to pollinators and plants as the paved portions are to drivers.
Working with the Maine Department of Agriculture, Conservation and Forestry’s natural areas program, the Maine Department of Transportation’s Roadside Invasive Plants and Pollinator Study is defining habitats and how those habitats are used by the pollinators.
“The goal is to learn what we can from the studies about what vegetation we have out there, what type of habitats are along the roads and what habitats are visited and how they are used by pollinators,” Robert Moosmann, statewide vegetation manager with MDOT’s bureau of maintenance and operations, said. “Then we can enhance [roadside] slope environment on the interstate and on other routed roads in the state.”
Such enhancements, Moosmann said, will not only improve conditions for pollinators like bees but also pinpoint areas where that enhancement includes scaling back mowing operations, which will save his department money.
“The importance of pollinators has gained attention in the United States, and the world, in recent years as bees have begun to decline and are continually threatened,” Moosmann said. “The study information will provide a baseline of typical roadside habitats and plant species to improve vegetation management decisions that will benefit these insects.”
Recognizing the sheer volume of pollinating insects in Maine, Moosmann said his department opted to narrow the scope of the study.
“The emphasis is on pollinators,” he said. “But when we look at that group there are quite a few species in Maine, so out of the 250 potential ones, we decided to focus on bumblebees and butterflies.”
Moosmann pointed out enhanced bee and butterfly habitat is also great habitat for various migrating birds.
“They both have similar needs,” he said. “So it’s beneficial to both groups.”
Drivers along Maine’s Interstate 95 and routed roads have likely seen the MDOT pollinator study signs this summer.
“We started last year [with plants] with 20 sites across the state [each] about a mile to 1½ mile long and broken into two-tenth mile long segments,” Moosmann said. “Withing those segments we are listing the dominant plants, habitat description and the top 10 dominant plant species.”
Preliminary results, he said, showed the study areas contained 136 non-native plants and some invasive species. The department added another 20 sites this season expanding the study from Kittery to Houlton and from the western mountains to the coast, Moosmann said.
Of those, he said 11 were tagged to be part of the pollinator study this year. The pollinator portion is a one-year study. Dr. Frank Drummond, professor of insect ecology at the University of Maine, this week said it is too early to draw many conclusions, but a few things have stood out.
“We are focusing on the butterflies and bumblebees,” he said. “Basically we go out and assess the density of flowering plants and assess the density of butterflies and bumblebees and bring samples back to the lab to identify what species [of butterflies and bumblebees] we are seeing.”
That identification process, he said, is just beginning, but he’s noted a strong relation between the density of flowering plants and increased numbers of butterflies.
Drummond is looking at 10 sites in which MDOT decided to reduce mowing this summer, allowing wildflowers to grow. Roadsides are important habitat in Maine, Moosmann said, given that the roads themselves cut through and disconnect habitats through waterways or wetlands.
“DOT made a conscious effort to reduce the intensity of their management in those study sites,” Drummond said. “It’s a cost savings to them, but it also helps enhance native plants and native pollinators.”
In Maine, he said, roadside habitats cover between 10,000 and 12,000 acres.
“There is an amazing amount of acreage in roadside habitat,” Moosmann said. “It’s often considered to be one of the last untouched connectors for certain birds and butterflies.
Fragmented natural landscapes, Drummond said, present problems pollinators and for species that depend on flowering plants for food.
“When habitats become fractured and isolated, fewer individuals are able to find them so the diversity in those spots becomes lower,” he said. “But if you have an uninterrupted large expanse of habitat — even if it’s just narrow strips along the freeway — those can essentially be highways for bees and habitat for mixed, diverse species.”
Nancy Olmstead and her team with the natural area’s program are busy in the field this summer looking at that roadside vegetation.
“We are looking at invasive and non-native plants to be better informed and get a sense of what plants are thriving,” Olmstead said. “We are looking at what plants could be good for habitat and give that information to DOT so they can proceed with some targeted management activities to enhance those habitats.”
Invasive plants, Olmstead explained, are those non-native plants that cause harm to an ecosystem, agriculture or to human health.
“Maine has many plants that are not native,” she said. “But a lot have become ‘naturalized’ to the state and don’t cause the level of harm that rises to invasive.”
Olmstead points to dandelions or orange day lilies as plants that have “come from away” but have not harmed the ecology of Maine. Plants like Japanese knotweed or the bittersweet vine, on the other hand, have tremendous negative impacts on wetlands and other vegetation, she said.
“With this study we have a unique opportunity for active management along the roadsides,” Olmstead said. “There is so much potential to promote the good plants and suppress the bad ones.”