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Arborist Scott Johnston partners with The EDGE

Scott Johnston partners with The EDGE’s Facilities Manager, Dan Nellis, to ensure the safety of our clients and our trees.  Since 2009, Scott has logged 144 hands on volunteer and consultant hours.

An arborist muses on a 35-year career high in the branches

(Adrian Higgins/The Washington Post)

By Adrian Higgins Gardening columnist

Scott Johnston has his feet on the ground but his heart in the air. Day in and out, he trusts his life to a harness, coils of half-inch rope and 35 years of knowledge gained by working in trees.

“Do you want me to rig up and climb a tree?” he asked. That’s all right, I said, clinging to my notebook. I’m not sure my nerves could take it, even as a spectator. Johnston, who is 58 and looks like a maturing matinee idol, thinks nothing of getting high into an 80-foot oak or tulip tree. As an independent certified arborist, he has devoted his working life to trees, is passionate about them and, if you scratch below the cambium, is vexed by the way we treat them.

His firm, Johnston Tree Care (motto: A cut above), is based in Marshall, Va. I caught up with him at the State Arboretum of Virginia, just east of Winchester, where he was giving a class on pruning. The students were gathered under the canopy of a yellowwood, a beautiful native tree that can be finicky: The same smooth, gray bark that gives the tree character is also easily damaged, and this one had three large inner branches with significant elongated wounds from winter sun scald.

If the students were looking at the damage, Johnston was seeing the healing, the way the tree was beginning to wrap the exposed heartwood with enclosing sapwood. Other branches that I might have taken out, he’d leave. Every leaf you take away, he said, reduces the tree’s ability to feed itself. The various parts of trees speak to one another, hormonally. If you remove a lot of the canopy, the roots respond by dying back — not a good thing.

Johnston points out branches to remove from a mature fringe tree at the State Arboretum of Virginia. (Adrian Higgins/The Washington Post)

So he is conservative when it comes to pruning, and subordinates our aesthetics to the tree’s biology. “I see trees made poorer by overpruning; it makes me cautious,” he said.

Washington is called the City of Trees, but as close as we all live to the urban forest, it’s amazing how many people don’t really see the big plants that give us shade, beauty, color and even, when leaves rustle, a little music. Or maybe we just shrink from them because of their sheer scale and mass. (The General Sherman sequoia in California, Johnston has calculated, weighs as much as 20,000 people.) “Trees are beyond me,” said one homeowner in the class. “I just put them in God’s hands.”

Just don’t put them in the hands of the tree man who comes knocking on your door looking for work, especially if he arrives bearing photos of trees that have fallen on houses. This is a scare tactic to elicit work that isn’t necessary and will probably harm your trees, Johnston said. These days, the practice of simply reducing the size of a tree by arbitrarily cutting branches back — “topping” — is universally understood to be harmful (except for crape myrtles, inexplicably). But a common alternative practice of thinning the canopy by stripping branches of foliage and leaving “lion’s tails” can be just as bad, Johnston said. Apart from the loss of foliage, the technique weakens branches, causes them to flail in a gale and break apart.

Even within the mainstream tree-care industry, Johnston says, a lot of risks are overstated and work is oversold, with the idea that any tree with some decayed heartwood is ready to collapse. “People get excited because there’s a little cavity,” he said. Carpenter ants don’t cause trees to fall — they nest in already decayed wood — and a big limb above a house doesn’t necessarily need removing. In fact, he said, to do so may cause more damage should the tree topple because the bough will brace the rest of the tree. “I have seen a lot of trees ruined,” he said, by the removal of a large overhanging branch.

Formative pruning is important. This is the practice of taking out undesirable branches when first planted to leave a proper scaffold of branching. Moreover, when you buy a young tree, pick an individual “that isn’t full of problems,” he said.

During his career, he has seen more sophisticated climbing gear and a greater reliance on rope systems developed for other enterprises, including rock climbing and caving. What hasn’t changed is the chance to live and work in a world that most people don’t experience.

It can be a place unsuited to the fainthearted. He has been known to come face to face with blacksnakes and hornets. And yes, cats really do get stuck in trees and need someone to rescue them. They are not necessarily grateful. Tip: Carry a pillowcase as a sack.

The more he is around trees, the more he is in awe of them. In his own years in their world, so much more has become known about how they live with soil organisms, how they repair damage and how they can communicate with other trees. “We know if a woodland is attacked by gypsy moths, trees miles away start producing far more defensive chemicals,” he said. It seems unlikely that Johnston will ever find a tree to be anything less than a living miracle.

“I can’t imagine working this hard if I didn’t care about it,” he said.

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