pounds, and the fields blossomed, none of it would be possible without a corps of volunteers, like jay stacy. >> so what are you cutting today? >> this particular forb is called prairie coreopsis, scientific name corpeopsis palmata. >> how long have you been doing this? >> i've been doing this, this is my 21st year. >> i'm a prairie barber! >> all the tall grass planting was a little too successful. >> we just needed something to level the playing field. >> what they needed was something to thin out the grass, like an enormous vacuum. the solution? not a dyson, but a herd of bison. a posse of 800-pound grazing machines. >> we've just arrived at the nachusa grasslands and i am seeing these bison for the first time and i feel like i have been transported back 150-200 years. its pretty remarkable to see these enormous animals that were almost wiped out from north america. oh there's a baby, there's a little one. oh, a couple of them. bison have been part of the vision of the project since the very beginning, but it has taken us close to 30 years to be able to put together enough of a landscape