In all cases where a board of forest preserve commissioners of any forest preserve district having a population of 500,000 or more inhabitants has heretofore, during the fiscal years, 1965, 1966, 1967, 1968, 1969, 1970, 1971, 1972, 1973, 1974, 1975, 1976, 1977, 1978, 1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, and 1991 within the time required by law adopted annual appropriation ordinances for said years, and thereafter same were published in a newspaper as provided by law, and subsequently in such fiscal years, within the time required by law the board of forest preserve district commissioners had adopted tax levy ordinances based upon the appropriation ordinances for said fiscal years, for corporate, zoological, botanical, construction of improvements and development of forests and lands and employees annuity and benefit fund purposes, and a certified copy of such tax levy ordinances was duly filed with the county clerk of the county in which said districts are located, then such appropriation ordinances and tax levy ordinances and the taxes assessed, levied and extended thereon, are hereby validated, notwithstanding that the several amounts and purposes for which such appropriations were made and taxes levied, for such corporate, zoological, botanical, construction of improvements and development of forests and lands and employees annuity and benefit fund purposes, were not specifically itemized in detail, as required by statute, and notwithstanding that in said appropriation or levy ordinances stated amounts of money are appropriated and levied for named public purposes, and general language is used which renders the amounts for such purposes uncertain and illegal, or the purposes for which the amounts are appropriated and levied uncertain and illegal. Nothing herein contained shall be construed as validating any tax levy in excess of the statutory rate of taxation authorized for any such fiscal year or for any purpose not permitted by the constitution.