During the sultry summer months in the D.C. region, it's easy to spot invasive vines, climbing high into the tree canopy along roadways, smothering native plants and trees, and giving the mid-Atlantic's temperate deciduous forests a tropical jungle vibe.

A new report makes the case that freeing trees from these vine invaders is an essential tool to fight climate change.

Jesse Buff, with the Chesapeake Climate Action Network, authored the study, after cataloging the vines present on every single city block in Takoma Park, Md. He did it on foot, walking the city's 36 miles of roadway.

"I walked probably quite a bit more than that," says Buff. "I had to keep going back and forth, in many cases, surveying the front and backs of houses."

In all, Buff counted nearly 5,000 trees affected by invasive vines. That's not counting trees with just a few tendrils creeping up the trunk: the trees he counted as "affected" are so threatened, they're likely to be killed by vines within the next 5-7 years.

The in-depth study of Takoma Park's vines provides a fine-grain snapshot of a stubborn regional problem. The mid-Atlantic's climate, with a lengthy warm season, provides perfect conditions for a number of fast-growing, sun-loving vines native to Asia. These include porcelainberry, Chinese wisteria, Japanese wisteria, Japanese honeysuckle, winter creeper, mile-a-minute, and oriental bittersweet. One of the most common and destructive, English ivy, is native to Europe.

Most invasive vines now common to the mid-Atlantic were first brought here in the 18th and 19th centuries as ornamental plants, and many are still sold at garden shops. From suburban yards, the vines can quickly spread to any open space with adequate light, climbing toward the sun.

On a wooded path in a residential neighborhood in Takoma Park, Buff points out one tree whose trunk is wrapped with thick intertwining vines, all the way up into the canopy.

"You can see how eventually the weight of this thing would really pull on a tree," Buff says.

A tree burdened with all that extra weight can easily topple in a storm. That's just one way invasive vines can kill a tree — even a towering, century-old one. Some vines can literally strangle a tree, girdling it so tightly it cuts off nutrients to the tree. Other vines block sunlight from reaching the tree's leaves, interrupting photosynthesis and dooming it. Other vines change the microenvironment against the trunk of a tree, allowing moisture to gather, and letting in pathogens and insects.

"The climate perspective is that trees are one of our best tools for capturing carbon," says Buff. "Standing trees are already taking in carbon, and they do a much better job of that than young trees. So it stands to reason that you want to save these old trees, instead of trying to plant new trees, as a first order of business."

On top of fighting climate change by sequestering carbon, mature trees can also help us adapt to a warmer planet. For example, areas with lots of tree cover can be 10 or 15 degrees cooler than areas without. Big trees also help reduce flooding, by slowing down stormwater runoff.

Buff's report includes a number of recommendations to combat invasive vines. Top among them is to grow the volunteer corps to attack the invaders. Volunteers like Jourdan Garnier.

"I remember my first big tree that I really just had to just work around the entire thing. It took to two weeks, like, two separate trips to attack," Garnier says. It was a giant, old cherry tree, covered with multiple species of invasive vines and surrounded by thorny brambles.

It was a great feeling, Garnier says, to see the vines wilting when he was finally done freeing the tree. "What the vines actually do to the trees is so violent, so just being able to see that you had that impact on a tree, it's really satisfying."

Garnier recently graduated from high school. A couple months ago, he started volunteering on Saturdays working on vines in Takoma Park. He says it was eye-opening — and now he sees invasive vines wherever he goes.

"You have a moment where you're like, oh, dang, I recognize the vine species. And then you're like, oh, God, why is it everywhere? This is not isolated. This is not a weekend thing. This is an everywhere, all-the-time, does-not-stop thing."

The report documents invasive vines all across Takoma Park. On single-family properties, more than one in five houses had trees under attack. Vines could even be found in many well-maintained yards.

Marty Frye, the city's urban forest manager, says the situation can sneak up on residents.

"It is kind of like a frog boiling in water. If the heat slowly rises, you don't really notice that it's a problem," says Frye. "People look at their backyard and they just see green sometimes, and don't really notice that part of that green is slowly encroaching on the canopy of their tree."

Cutting vines from a tree is not rocket science, but it does require some basic knowledge to be able to differentiate invasive vines from native vines, which sometimes look similar. Native vines, including grapevines, Virginia creeper, and poison ivy, coevolved with the region's native trees, and can coexist in peace. Native vines are also a valuable source of food for local fauna, while invasives are either not eaten or provide low-nutrient food for animals.

In addition to a bit of knowledge, removing invasive vines also requires time and manual labor.

"To be honest, we're a little staff-constrained here," says Frye. "So it unfortunately it has not been an area we've been able to devote a lot of resources to."

And it's never-ending. The goal of eradication is usually not realistic, Frye says. "In a lot of cases we're just doing that temporary mitigation of cutting the vine back from smothering a canopy, but it's still alive on the ground and ready to spring back up."

It is, Frye says, "a frustrating reality that we deal with."

Buff says he hopes other jurisdictions will follow suit, cataloging their invasive vines, as first step to get a handle on the problem. "It is somewhat surprising that we would have this many trees affected in this town," says Buff. "In a place like Takoma, which is relatively environmentally conscious, and where people take great pride in the forest that we have here in town."

This story is from DCist.com, the local news website of WAMU.

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