The city shall have the right to plant, prune, maintain and remove trees, plants and shrubs within the lines of all streets, alleys, avenues, lanes, squares and public grounds as may be necessary to ensure safety when servicing city utilities or to preserve the symmetry and beauty of public grounds. The city may remove or cause or order to be removed, any tree or part thereof that is in an unsafe condition or, by reason of its nature, is injurious to sewers, electric power lines, gas lines, water lines or other public improvements, or is affected with any injurious fungus, insect or other pest.