Section 448.54 shall not divest or deprive the council of the city of any jurisdiction or power now existing by virtue of any statute or charter, to levy assessments for the grading, protecting, improving, and ornamenting of any public park, square, or grounds now or hereafter laid out, and for planting and protecting shade and ornamental trees and for constructing or reconstructing sewers, sidewalks, retaining walls, gutters, curbing, and for boulevards, macadamizing, and paving in or upon any streets set apart for park and parkway purposes.