The environmental health of Greater Yellowstone's public land is tied to the fate of the surrounding lands in private ownership. The links are many, and they are reciprocal. Agriculture needs the high quality water and the protection from flooding given by undamaged watersheds.
Wildlife needs the habitat found on private lands.
To wildlife, and from the perspective of science, public and private lands are bound together, part and parcel of the same natural system. Thus, any realistic attempt to manage ecosystems must consider both the environmental function of lands, regardless of ownership, and the lines we draw in law and practice between the public and private domains. Compared to the nation as a whole, Greater Yellowstone has a relatively small proportion of private land, but its ecological importance is great. For instance, the riparian cottonwood forest on the South Fork of the Snake River, of which more than half is in private ownership, is one of the most biologically diverse parts of the region. Consequently, rural private lands are vital as functional parts of the Greater Yellowstone Ecosystem.