Potlatch Corp. plans to sell its poplar tree farm in Boardman, Ore., and reinvest the money in Wisconsin forestlands. A group of private investors will purchase the tree farm for $65 million, company officials announced Friday. The sale is expected to close later this spring. At the request of the investors, they are not being identified at this time, said Mark Benson, Potlatch's vice president of public affairs.The poplars are a silvery-green landmark to motorists driving a dusty stretch of Interstate 84. When Potlatch established the 17,000-acre plantation in 1992, the company planned to produce wood chips for its pulp and paperboard operations in Lewiston.