The board, or the city council, shall include in the annual budget of the board the amount of money necessary to meet the expenses of doing the work during the following fiscal year, including the compensation of the city forester and other employees, but excepting so much of the expense of doing the work as is assessable to abutting property, in accordance with the provisions of this part. The taxes levied for such purposes shall be in addition to any other taxes for park or street improvement purposes. If these expenditures are already provided for by law or by ordinance, then the law or the ordinance shall govern and control.