AROUND THE GARDEN

A plaintive comment the other day in the Eye really gave me pause:

“Will the future bring us 30-50 feet of tree clearance along power lines? Personally that would make me sad, but I fear this will be the public's angry response to this disaster.”

This commenter, whose name is Linda, posed an excellent question. Many of us read reports elsewhere that CL&P plans to re-evaluate their tree-pruning strategy.

So far, Tree Fanatic hasn’t received any requests from CL&P for advice, but here’s what I would say should they get around to making the call (I know their phone lines have been awfully busy of late):

"STOP BUTCHERING OUR TREES!”

I know that sounds simplistic. There is scientific backing for it, though.

The truth is, trees don’t respond well to hacking. If you turn a tree into an exaggerated question mark, a capitol letter “C”, or carve out a huge “V” from the center of the tree, that tree has been weakened terribly. If you take a tree such as the sugar maple next door to me and limb it up so the very first branch is 50 feet above grade and the tree looks like a feather duster, that tree’s center of gravity has shifted much higher than its root structure can support.

That tree is now horizontal, having fallen precisely parallel to the utility lines that it formerly “threatened.”

As you too may have done, I spent a lot of time this past week looking at trees, both the tragically wrecked and the miraculously spared.

Not every instance was clear-cut – an unfortunate turn of phrase, admittedly.

But what I saw convinced me that pruning trees, and pruning them properly, made a big difference. Planting trees in groves helped, too – here in the Eastern Deciduous Forest, which is how our landscape began, trees evolved to grow in clusters, even forests. A group of trees has a stronger root system than a single “focal point” tree.

But back to pruning. On a macro level, you might want to look at Camp Street, a short residential street that runs from Washington Street north to Westfield Street. A utility crew of contract tree workers had been there for over a week in mid-August, severely pruning trees that overhung the wires.

By Sunday evening, Camp Street was a scene of devastation. Several trees came completely out of the ground, while others snapped in half. A leafy canopy that shaded the roadway is gone, probably never to be replaced.

A huge red maple on my street was turned into one of the famous question mark shapes not long ago. This tree, its balance distorted by asymmetrical limb removal, fell on a neighbor’s dogwood, demolishing both trees.

Urban forestry, although not well-known to the general public, is a much-studied discipline. As with the science of nutrition, theories about urban forestry have changed over the decades. An exceptionally creative researcher at the University of Florida has experimented with the effects of high winds on trees that have been pruned in multiple ways and trees that have not been pruned at all.

When I met my first arborist, I was advised to thin the interior of my sugar maples so that wind could penetrate their canopies. Twenty years later, I have seen the results of Dr. Ed Gilman’s research at U. Fla., and understand that the “lion’s tailing” of the 1980s is bad practice. The most effective kind of pruning for survival in high winds is a thinning of the outer canopy, which still reduces the “wind sail” factor, but doesn’t leave the tree out of balance.

Sadly, many of the trees that blew over during Irene were trees with full, dense canopies. These appeared to be healthy trees, but the combination of high winds and saturated soil toppled them.

Next week: Much more on how to – and how not to – prune a tree.