South of the Grand Concourse the green arrives in pieces — a strip beside a stoop, a corner lot, a churchyard about the size of a parking space. GM Trash Removal & Lawn Care Co. treats every one of those pieces like a full property: mowed, edged, trimmed at the fence line, cleared out at each turn of the season. In a place this dense a tidy patch of grass reads from half a block away, and people do notice. Summer afternoons the mower works its way around bike racks and hydrants; come October it is leaves, bagged and gone before the wind can move them along. Small squares of green, kept sharp, block after block.