In reworking ArborWiki's page on the Ann Arbor Greenbelt, I came across an item from Concentrate that noted,

When Ann Arbor initially proposed its Greenbelt Program, local developers worried that it would create competition, scarcity and drive up the cost of building sprawl in Washtenaw County. Now developers are starting to sell land to the Greenbelt.

The Ann Arbor City Council approved spending $626,000 in city money to buy 139 acres of rural land in Superior Township from Biltmore, a residential development company. ... The land is in two parcels along either side of Prospect Road near Vreeland Road.