Land of this size never transfers via Zillow or Redfin. And most agents don't know how land use works so finding any old real estate agent won't cut it either.
There are "green space" banks that exist where a developer is making a subdivision in one part of the county but they are required to do a tree-save in other parts. That would potentially be one option, that it becomes preserved via a green space bank.
You really need to start with a land use attorney. I recommend Vince Keegan. He's in Tyson's. Start with him and see what he can do for you.