Rick Holmes: In defense of the invader trees

Rick Holmes

The people of Marlborough stood by their trees three years ago, and the maples on West Main Street are thriving. The maples on Hopkinton Common might not be so lucky.

In Marlborough, the road commissioner had the trees in his sights because the majestic maples, whose leaves almost formed a tunnel on the city's main thoroughfare west of downtown, were in the path of his plans to upgrade the road.

The construction would so damage the trees that they would die, he explained, so we might as well kill them now. But the friends of the maples didn't buy that line. The politicians heard their protests and agreed to treat the trees with tenderness both during and after construction.

Their efforts paid off. The 21 trees on West Main Street saved from the chainsaw three years ago are thriving today.

The maples of Hopkinton are pretty healthy, too. Their enemy isn't a road supervisor with a backhoe, but a tree warden with his own chainsaw. It's not that the maples on the town common are getting in the way of new pavement. They are getting in the way of - if I've got this right - sunlight.

The trees, he explained to a reporter, have a dense crown that blocks sunlight and prevents other vegetation from growing under them.

The good citizens of Hopkinton had a different word for this quality when they planted the maples decades ago: shade. Sit in the sun on Hopkinton common on a summer's day and you'll understand their point.

But it's not just the shade of the trees that bothers Tree Warden Paul Gleason. It's that these trees are, well, Norwegian.

They don't speak with a funny accent or smell like herring, but Norway maples just don't belong here. They are invaders who put down roots where they aren't wanted. They multiply. Using a technical tree warden term, Gleason said "they produce a gazillion seeds."

The maples in Marlborough are Norway maples as well. But Marlborough is apparently more welcoming to aliens, at least of the arboreal variety.

Norwegian maples aren't the only invaders we're supposed to be worrying about. Brazilians - waterweed and milfoil, that is - are on the state's list of prohibited plants. So are Japanese knotweed, European buckthorn, African couchgrass and Chinese waterspinach.

That lovely purple flower now blooming in wet areas along the highway and at the edge of the pond? Purple loosestrife, an import considered a threat to the native ecosystem. Burning bush, which turns a lovely red in the fall? An invader from the wrong side of the border. Bittersweet vines, which produce yellow and red berries perfect for decorating the estate in October? Prohibited.

They are invasive species, the self-appointed guardians of nature have declared, and you aren't allowed to import or propagate them in Massachusetts anymore.

Purple loosestrife, they'll explain, grows a dense thicket that native birds find impenetrable. Milfoil, cabomba weed and other invasives clog our ponds. Invasive water meal is blamed for the deaths of hundreds of sunfish in Framingham's Norton Pond this month.

Nature's guardians are doing what they can. Town meetings cough up thousands of dollars every year to evict the invaders from lakes and ponds. I have friends spending their weekend days pulling garlic mustard and multiflora rose out of conservation lands. My mother-in-law is dedicated to cleansing her section of the Maine coast of invasive barberry.

All are well-intentioned, but I have resisted their entreaties to join the crusade. I'm afraid my sympathies lie with the immigrants, whether plant or human.

The invasives, it seems to me, are doing what nature tells them to do. They expand their territory when conditions allow it. They find a niche and exploit it. They reproduce. Like human immigrants, they are opportunistic, entrepreneurial and unstoppable.

I must confess that I have harbored some of these invaders. That burning bush in my backyard - legal when we bought it, I swear - is on the banned plants list. That bittersweet that so nicely decorates our mailbox? My mother-in-law, for one, would love to uproot it for us.

We may pull it out one of these days, and my wife - the real landscaper in the family - will replace it with something else we like. But I won't pretend there's anything especially virtuous in that act, or that we are restoring our yard to its natural state.

The natural state is a state of change. Plants and animal species come and go, constantly adapting to the species around them. Global warming is mostly a product of human intervention, but the reaction of plants - pine trees retreating to the north, kudzu expanding from the south - is natural.

Nature wants that pond to become a swamp. It is humans who build the dams that make the ponds and harvest the milfoil to stop nature's work. The idea that some plants "belong" here while others don't, is a human construct. A plant "belongs" wherever it can find the water, sun and nutrients it needs to thrive.

Hopkinton's residents have tended their Town Common since soon after its founding in 1715. Like all but a few acres of the state, the land hasn't been in its natural state for centuries.

We are gardeners of this region, and to garden is to intervene in nature, to pick winners and losers. We like the birds displaced by purple loosestrife better than whatever creatures would find the loosestrife more hospitable. If we choose sugar maples instead of Norway maples, there's nothing natural about our selection.

Yes, we should be responsible stewards and careful gardeners, but let's not fool ourselves: Our pleasures and our prejudices infect the decisions humans make in managing our environment. And on a hot summer day, there's nothing like the cool shade of a dense green crown to add pleasure to a walk down Main Street or a picnic on the town common. Even if its forefathers came from Norway.

Rick Holmes is opinion editor for the MetroWest Daily News (Framingham, Mass.) He can be reached at rholmes@cnc.com.