Two family tree farms in Pierce County are in the forefront of a relatively new way to preserve open space – one we should all hope proves successful.

They’re test projects for a program that could help address one of the main reasons the county is losing an average of 1,900 acres of agricultural land a year: landowners selling their property for development.

The program is called the transfer of development rights (TDR). It could be an important tool in local governments’ efforts to channel density where they want it to go while giving property owners alternatives to selling their land to developers who would turn it into warehouses or tract housing.

Under the TDR program, the landowner sells the development rights – essentially getting compensated for keeping it in agricultural use instead of selling it for development. A developer can buy those rights in the form of transfer credits and use them to exceed density and height limits in other areas of the unincorporated county. If incorporated cities join Pierce County in the TDR program, the credits could be used there, too.

In the case of the tree farms – which are located near South Prairie and Eatonville – the nonprofit Cascade Land Conservancy purchased the development rights using $987,000 in state grant money. Instead of selling the farms to developers – who could build up to 37 homes on them – the families that own them will be able to keep working the property and profiting from timber sales.

To make the program work, though, someone has to be willing to buy those development rights from the conservancy. With the construction industry in the tank due to the recession, that might take a while to happen.

But if it does, it would be a win-win-win-win situation. Property owners get to continue using their land, developers gain more options for their projects, local governments gain a growth-management tool and Pierce County residents get to hold on to pieces of fast-disappearing open space.

If there’s a down side to this program, it’s not readily apparent. Pierce County, the conservancy and the participating property owners deserve credit for helping get the TDR program off the ground.