Any such agency may sell or otherwise dispose of timber or other forest products grown in any such forest in such manner as the governing authority of such agency may determine, subject to the approval of the commissioner of natural resources. The proceeds of such sales shall be paid into the treasury of the agency, and may be used for maintenance or improvement of the forest, for acquisition of additional land for such forests, or for any other purpose within the lawful powers of the agency, as its governing authority may determine.