Each nature preserve within the system is hereby declared to be held in trust for those uses and purposes expressed in this chapter, which are not prohibited by the articles of dedication, for the benefit of the people of the state of North Dakota, of present and future generations, and declared to be put to its highest, best, and most important use for the public benefit. It must be managed and protected in the manner approved by, and subject to the rules and regulations established by, the department. It may not be taken for any other use except another higher public use after a finding by the department of the existence of an imperative and unavoidable public necessity for such other higher public use and with the approval of the governor. Except as may otherwise be provided in the articles of dedication, the department may grant, for a fair consideration and upon such terms and conditions as it may determine, an estate, interest, or right in, or the department may dispose of, a nature preserve, but only after a finding by the department of the existence of an imperative and unavoidable public necessity of a higher nature for such grant or disposition and such finding must be made subject to the approval of the governor.