So this past Saturday was It's My Park! Day in New York City, a day when much tree-planting was going on under the direction of the NYC Parks Department, the Partnership for Parks, and MillionTreesNYC. Unfortunately I wasn't able to attend, since I was with a class, studying the flora of the New Jersey Pine Barrens by canoeing the Batsto River - all in all a good way to spend a Saturday, although it meant I didn't get to witness all the volunteering that went on in the city that day.

But even though I wasn't there, I can claim to have participated. As part of my internship with the city Parks Department, I had helped lay out two tree-planting sites in Brooklyn - including one at Marine Park, where ConEd was evidently helping out on Saturday.

(Planting site at Marine Park, Brooklyn. White X's indicate where trees go.)

At the planting sites, which were grassy and scrubby and had been mown to a short, dry stubble, we laid out plots of 15x15 meters; within each plot, we marked tree-planting spots with X's. The trees were to be arranged in square grids, twelve trees on a side (for a total of 144 trees in each 15x15-meter plot), spaced at four-foot intervals. (Why the combination of metric and English units? Beats me...)

When you think about it, this is a curious system. The trees are far too close together for all of them to survive. No healthy northeastern forest has trees so close together, and competition between the new saplings will certainly lead to the deaths of many of them. (This has not gone unnoticed. Writing for the University of Michigan's Biofuels and Bio-Based Carbon Mitigation site, Jesse Moore provided an appraisal of the MillionTreesNYC program a while ago that included this critique.) Also, the trees in the new "forest" are all arranged in a decidedly unforestlike grid - although, of course, that effect will fade as the weaker trees die.

(Laying out a planting grid at Canarsie Park, Brooklyn.)

But there is some method to the madness. For one thing, these plots are new city forests, certainly, but they're also a science experiment: the Parks Department will be monitoring the growth of the new trees in response to a few variables, like species composition and diversity. Also, the biggest natural threat to the new trees will be strangulation by exotic vines, and competition from invasive trees like tree of heaven (Ailanthus altissima). The Parks Department hopes that, by creating a forest with a canopy that will be closed within just a few years, these invasives will be shaded out before they can become menaces to the new forests.