To satisfy this demand for natural areas requires supplying costly resources. The extent of recovery or improvement that could be achieved would depend in part on how high the costs were for improvement per acre, and the rise in costs as efforts continued. Data collected from a number of sites and sources yielded a wide range of estimates that varied according to the objectives of the managers and the initial conditions of the site. Wetlands are more expensive to restore or create than prairies. Spending per acre declines appreciably as the size of the wilderness site increases.
Costs also decline appreciably as the site reaches stability and only maintenance is needed.
Balancing preferences and costs shows, first, that an expansion and improvement of the region's wilderness space over present efforts in this direction is supportable in strictly economic terms. Second, and more concretely, about 5,000 additional acres in the initial year could be added to existing native areas. As maintenance spending to assure vigorous and continuing growth is essential, the annual addition of new acres would decline as the proportion of the annual revenue stream spent on maintenance increases. The end result of this decline is that 25,000 acres eventually could be added to the region's existing stock, or an increase of a litte over ten percent. These new natural spaces would be an increase over presently planned efforts of this nature, and would represent an addition to the present stock of indigenous biodiversity.