The tall man I was chatting with along Lockridge Drive was part of a crew sent by Montgomery County to mow the grass on either side of the stream. I had asked him if they couldn’t also cut down the invasive vines that are climbing up and covering the native trees along the stream.
He said they couldn’t cut the vines that day, but that he would speak to his supervisor about it.
“Should I call 311 (the number we call to request County services)?” I asked.
“Don’t call 311,” he joked. “Call 911!”
He was kidding, of course, but he had a point. Invasive vines pose a life-and-death threat to our native trees.
Invasive plants are those that have escaped cultivation and damage our natural ecosystems, according to Carole Barth, an ecologist who lives on Lockridge and manages the Tree Conservation Program for the Prince George’s County Department of the Environment.
Some, like porcelain berry, a vine with attractive blue berries, and oriental bittersweet, with red-orange berries, were originally brought here from other countries for their ornamental value, she said. Other invasive plants were not brought intentionally. Japanese stiltgrass, for example, was used for packing china shipped from Asia. Now our neighborhoods and parks are blanketed with stiltgrass.
The invasive vines that cover our trees do not encounter their natural predators or natural diseases in this foreign (to them) environment. “That means if you’re a plant with no predators where you are, you can put 100 percent of your energy into growth,” Barth pointed out.
And grow they do. In the process, they damage and can eventually kill the trees they climb on. They “grab all the sunlight,” Barth said, preventing the tree’s leaves from producing food for the tree. They also weigh the tree down. “As the vines get bigger and bigger, the weight puts stress on branches and can weaken the tree,” she said.
In addition, some invasive vines, like English ivy, “hold on by exuding a chemical and working their tendrils into the cracks, actually under the bark, eventually opening the tree up to invasion by bugs and diseases,” Barth added.
The trees are defenseless against this onslaught of vines, she said, since the trees did not evolve with these vines and, therefore, never developed a means to defend against them. The vines pose a mortal threat to the native trees that live along the stream — including willow oaks, black walnut trees, persimmon, native azalea, and American basswood — many of which were planted by the civic association over 20 years ago, Barth said.
She said a solution could be achieved if the County sent a crew to cut each vine as close to the root near the ground as possible, and also to cut it as high as they could reach, as if to make a window. “The top will die off,” she said. She said no one should pull the vine off the trees, however, although “it feels satisfying to do it.” For one thing, “if the vine has weakened the tree, you could bring a limb down on yourself.” And ripping down the vine can also damage the tree further by pulling off the leaves and the bark.
If a group of neighbors followed up after the County crew a couple of times a year by recutting the vines at the bottom, “it may take three years to get to the point that the vines pose an extremely minor problem,” Barth said.
Since I placed my 311 call several weeks ago, no action has been taken by the County to cut the vines and help save our trees on Lockridge Drive. If readers are concerned about this threat, you, too, may want to call 311 to plead for action.
[Loube, a retired Prince George’s County ESOL and Reading Recovery teacher who has lived on Cavalier Drive for 31 years, is an avid gardener.] ■
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