Any such forest preserve district has the power to acquire by purchase, gift, condemnation or otherwise, property necessary or appropriate for the purpose of exercising the powers granted by Sections 18.1 through 18.10 of this Act. Any land so acquired under such sections shall not be included as a part of the total acreage of such forest preserve district for the purpose of determining the number of acres of land for which indebtedness can be incurred for the acquisition of land without first submitting the matter to the voters of such district as provided in Section 13 of this Act.