Summer homes on federal land occupied under lease. Notwithstanding ORS 307.060, there shall be exempt from property taxation real property of the United States used and occupied for summer homes under a lease issued pursuant to the Act of June 1, 1938 (52 Stat. 609; 43 U.S.C. 682a), as amended, or Public Law 94-579, Title III, section 302, October 21, 1976, 90 Stat. 2762 (43 U.S.C. 1732), but improvements thereon are subject to taxation. [1979 c.422 §1]