I’ve noticed that quite a few of the old trees dotting our sidewalks have been cut in half

Dear Urban Decoder: I’ve noticed that quite a few of the old trees dotting our sidewalks have been cut in half. Why remove only the top and not the whole thing?—Simon Leung, King West Village

Short of a crater on the moon, you’d have a hard time finding a worse place for a tree than a hole in a city sidewalk. To say nothing of choking urban pollution, the concrete acts like an oven, soaking up deadly levels of heat while crushing the oxygen out of the soil below. Add to this five summers of droughtlike conditions and it’s no surprise that local wood chippers have been busy of late. As for the beheaded trunks, they’re simply easier for the city’s cranes—which pluck them out of the ground, roots and all—to grasp. Incidentally, there has been some good news for our beleaguered woody friends: Toronto has not only beefed up its fleet of water trucks (displaying the motto “Life support system for trees”) but is introducing a new generation of sidewalks equipped with roomy underground soil trenches and air pockets that funnel precious oxygen to gasping roots.