Large swaths of open space along highways across the state have gone from green to brown recently, and, State Highway Administration officials say, it's all to help out the environment.

After years of unchecked vegetative growth under a tight transportation budget, the state is now in an all-out war on several invasive species that have overtaken the edges of the state's asphalt corridors and interchanges.


From the Eastern Shore to Western Maryland, nine counties in all, state highway crews are ripping out the foreign plants — even though some are "pretty" and lush — to give species native to Maryland some breathing room, said Kevin Wilsey, a team leader in landscape operations in the SHA's office of environmental design.

"The real goal is trying to re-establish some of our native vegetation," Wilsey said.

The $10.4 million effort, covered by multiple contracts, will clear about 650 miles of roadway by 2015, officials said. It follows other state efforts to battle invasive species, including along the Jones Falls Expressway in Baltimore in 2011, and the introduction of certain insects, including the "Mile-a-Minute Weevil," that eat the foreign plants.

In the Baltimore region, work is being completed in Anne Arundel, Baltimore, Carroll and Howard counties. Officials have said the pre-emptive maintenance of the roadside areas is worth the major investment, in part because they are critical to drainage and because reactive maintenance is more expensive.

Through this fall, and again in the spring, crews will plant additional native species in the areas that have been or will be cleared, to help make up for the loss, Wilsey said.

The new plants likely will remain smaller than the invasives, which may make roadsides seem less lush, officials said, but will improve drivers' sight lines and better support native wildlife.

In future years, the SHA will maintain the areas and keep them free from invasive species such as Callery pear, thistle and ailanthus, which by nature are hearty survivors that can rebound, Wilsey said.

"What we're looking at now is trying to have a more long-term plan," he said.

That's good news for the broader state ecosystem, said Jonathan McKnight, a biologist with the Maryland Department of Natural Resources who has served on national and state advisory boards dealing with the issue of invasive species.

"We know from a lot of science that invasive species are a major cause of the loss of biological diversity and the degradation of natural areas and wilderness, so we've long been deeply concerned about the amount of invasive species and animals — both the number of species out there and the volume we're seeing," McKnight said.

Invasive species spread in part by thriving in areas where native species have been disturbed or hedged back, which makes highways and other roadways a perfect environment for them, McKnight said.

"Any disturbance will act as a foothold for an invasive species, and a road can actually act as an artery that can allow a species to spread," he said.

McKnight said he is encouraged by the SHA's current efforts — even if the result isn't aesthetically pleasing at first.

"There's a tendency to think that green is good," he said, "but some green is good, and some green is bad."