The department of real estate assessments is hereby established. The office of county assessor is hereby created and shall be filled by a full-time real estate appraiser or assessor certified by the tax commissioner and appointed by the board. He shall carry out all duties relating to biennial assessment of real property for taxation. He shall be directly responsible to the county administrator and serve at the pleasure of the board. The board of supervisors may by resolution fix the amount of his compensation and determine the number and compensation of his assistants and staff.