Biogeography of the Megazoo: Biogeographic studies suggest organizing principles for a future system of wild lands.

A system of primary wildland reserves may be required to ensure a diversity of plant and animal species in the future. A strategy for locating such reserves involves considerations of their location, number, size, and linkage. The equilibrium theory of island biogeography is a useful analytical tool for predicting future biogeographies according to the dynamics of present plant and animal distributions. Existing reserves in the United States are inadequate in size and number and are clumped in one geographic region. In a planned network there might be several levels of reserves, starting with first- and second-order watersheds of large enough size to support a stable population of large carnivores. Reserves should be distributed so that they include a maximum of the world's biological diversity. Lower-order reserves might serve as stepping-stones among which a supply of species might move as a kind of distributed storage and reintroduce themsleves when local instabilities occur. This would maintain a high immigration rate to balance an extinction rate which can only increase as human settlements expand.