Where the required buffer is not superseded by that identified in Subsection 16-4.14, the buffer shall be landscaped by the planting of grass and/or ground cover, shrubs and trees. Two shrubs and one tree shall be provided for each 500 square feet of area, or fraction thereof, of the buffer strip. If located within a planned shopping center, the landscaping of the use shall be consistent with the overall landscape plan of the center. If not part of the center, the buffer strip requirement identified above in Subsection 16-19B.20c, shall also contain screening of dense hedges (not less than three feet in height at the time of planting) and/or decorative fencing (six feet in height).