I can't read all the replies now to see if this has been brought up...but why not hybridize? You may never be able to create a real genuine prairie again, but you can have pastures full of native (think used to droughts) grasses and wildflowers, substitute bison for domestic cattle on rotation, and still have areas (like zone 1 or 2) that are heavy on trees. This would still help the native flora and fauna much more than what they have now, you'd have drought resistant pastures, and you'd have tons of edge habitats that way...all while creating a sustainable food system for yourself, your family, your community, or whatever your goal there is.
