At Harlem Meer and adjacent Central Park Conservatory Garden, the farthest northeast corner of the Upper West Side, there are early hints of spring. The buds of the star magnolia are swelling.A pink blush radiates from the newly trimmed spirea bushes. Late afternoon shadows indicate the lengthening day as winter nears its end. A young boy on the lake bank pierces the melting ice with a branch. Spring cannot be far behind.