The pin oaks along Cathedral Avenue hang on to their leaves well past the first cold snaps, rust-colored and rattling in the dark, and then they let the whole business go at once. Francisco's Diaz Landscaping & Tree Service handles both ends of that — the lawns underneath and the crowns above. Through the growing months it is mowing, trimming and beds kept clear; in the cooler ones it is leaves hauled off and limbs taken down with a rope instead of a prayer, thinned for light or cut back off a roofline. Old trees in a village this built-up need a hand to stay good neighbors, and a lawn buried under oak leaves will not come back green in April. Clear ground, sound trees, a yard that can breathe again by Thanksgiving.