By May the lawns below the Kensico Dam are green again and the tulip poplars along the Bronx River are throwing their first real shade over Valhalla. Roque Tree Services works those Mount Pleasant blocks — Thornwood, Hawthorne, the hill streets — where mature trees stand close to one another and closer still to the houses. Pruning lifts a crown off a roof and opens the middle so wind moves through it; trimming keeps the sidewalk and the driveway clear without wrecking the shape. Removals are rigged over patios, pools and fences, let down on rope, and finished with the ground raked. When a storm leaves a mess, the cleanup is done by the time the neighbors get home.