This is in a county that is bigger than the state of Delaware- and has 8,000 people... And pretty remote from the only incorporated town, which has a population of about 3500-- so I don't think subdivision was a major problem for quite some time in the future...Most new folks are looking for acreage 5 miles from town....
It appears to me that while the current owner gets a substantial payment for entering into the easement--one thing these conservation easements do do is lower the future value of the land because of development restrictions and having someone overseeing your land forever--so that it lowers the value if it is ever allowed to be transferred to another rancher/producer-- but because of the wildlife, and nondevelopment requirements makes the land worth that much more to the Greeny Weeny and Save the Buffalo groups like Horseless said...
Don't get me wrong- I think in some of the more heavy populated areas the conservation easements probably helped to save some ranch lands from being developed- but I'm not sure it isn't working in reverse in some other areas- altho also like Horseless said- its keeping some operations from going under for the present time anyway....