(PressDemocrat) - A national conservation group has reached an agreement to buy nearly 20,000 acres of timberland in northwestern Sonoma County, a move that derails the long-disputed, forest-to-vineyards conversion project pushed by CalPERS, the giant state workers pension fund. The $24.5 million purchase of the so-called Preservation Ranch, to be completed by the end of May, is led by The Conservation Fund, based in Virginia. It would contribute up to $6 million toward the purchase.