(1) General. Existing features which would add value to the type of intended development or to the county as a whole, such as trees, watercourses falls, beaches, historic spots and similar irreplaceable assets, shall be preserved in the design of the subdivision. No trees shall be removed from any subdivision nor any change of grade of the land affected until primary approval of the preliminary plat has been granted. All trees on the plat which are required to be retained shall be preserved and all trees, where needed, shall be welled and protected against change of grade. The sketch plan shall show the number and location of existing trees, as required by these regulations and shall further indicate all those marked for retention and the location of all proposed shade trees required along the street side(s) of each lot as required by these regulations.