525 ILCS 30/9
A State system of nature preserves is established. The system consists of nature preserves dedicated as provided in this Act.
A natural area which has been found by the Commission to be suitable for inclusion in the system shall become a nature preserve upon its dedication by the owner of the land, or of an interest or a right therein, with the approval of the Commission and the Governor. Dedication may be either donative or for a consideration. The dedication shall be evidenced by an instrument of dedication which shall be in such form as the Commission may approve. So long as consistent with the purposes of this Act, the instrument of dedication may (a) define the respective rights and duties of the owner or custodian and the Commission; (b) contain provisions relating to management, development, use, public access, sale or transfer; (c) provide procedures to be applied in case of violation of its provisions; (d) recognize or create reversionary rights, transfers upon conditions and gifts; (e) contain such other provisions as may be necessary or advisable and (f) vary in provisions from one nature preserve to another in accordance with differences in the characteristics and conditions of the areas involved. No condition of the instrument of dedication shall limit the perpetuity of the dedication except that preexisting encumbrances on the land may be recognized.
The Commission may cause the instrument of dedication and any amendments thereto to be filed for record in the office of the recorder of each county in which the nature preserve is located.
525 ILCS 30/9