On narrow streets and Broadway, street trees with a minimum caliper of four inches shall be provided for the entire length of the street frontage of the zoning lot, except adjacent to the Midblock Open Areas and the Grove. Such trees shall be planted at maximum intervals of 25 feet on center. The location and/or spacing of trees may be waived by the Commissioner of Parks and Recreation to the extent that these requirements are determined to be infeasible. All trees shall be planted flush to grade and in accordance with the applicable standards of the Department of Parks and Recreations, and shall be located within a soft surface, landscaped strip at least five feet wide adjacent to the curb, which landscaped strips need not be continuous. Other planted landscape treatment and amenities may be permitted within such landscaped strip. Such trees shall be maintained by the owner of the adjacent development or enlargement.