Thursday, December 12, 2013

Accommodating Dynamic Tree Growth in a Static Urban Landscape

Street trees are spared the competition they'd face from other trees if growing in a woodland. Instead, they must contend with manmade constraints above and below. The urban landscape is a struggle between the dynamic nature of trees and the static nature of human infrastructure. What this street, Birch Avenue, needs is trees--though likely not birch trees--to provide cooling shade for the street, the parked cars and the houses in the summer. But any tree plant planted on the left side of the street has to deal with the overhead wires.

This pin oak is on the other side of the street, with no wires above, but faces considerable constriction at ground level, with sidewalk on one side and curb on the other.

It appears to be thriving nonetheless, but partly at the expense of the confining pavement. It has actually pushed up the pavement of the road, just enough to cause a potential hazard for snowplows whose blades could be damaged by any bumps in the road.

And the unevenness of the sidewalk presents a potential tripping hazard, particularly for elderly pedestrians. The tree's roots also caused some damage to a residential waterline. Should this improbably thriving tree come out, or is there some way to accommodate the needs of people, machines and tree? One big step forward was the recent decision by town council to take responsibility for care of sidewalks. The unevenness of the sidewalk can be smoothed out by grinding down the raised section of concrete.

This isn't an isolated issue. Here's another tree starting to push the curb out. Birch Ave. is providing a good test case for how to integrate trees into a very constricted landscape, so that all their benefits of shade, air conditioning, carbon sequestration and beauty can be enjoyed.


SFB said...

The wires should be underground and the tree should be in a bulb-out. What we see here at the minute is just a mess.

Stephen Hiltner said...

It would be great to bury the lines and install bulb-outs if the street width and parking accommodate it, but multiply the expense of such remedies by the number of other streets with similar problems, and one has to see how the initial cost of the remedies balances out with trying to deal with the existing imperfect situation. Does one take out a tree that's doing a lot of good and a little harm, or try to minimize the harm? Maybe a community would be better off with making big changes rather than managing ongoing problems indefinitely, but my aim at this point is to illustrate the problem.