The board of supervisors of any county may impose a special tax pursuant to Article 3.5 (commencing with Section 50075) of Chapter 1 of Part 1 of Division 1 of Title 5 and any other procedures as may be applicable. The special taxes shall be applied uniformly to all taxpayers or all real property within the county, or any involved portion thereof, except that unimproved property may be taxed at a lower rate than improved property.