Interfor Corp. says the company has markedly increased lumber shipments from Canada to China as a result of tariffs imposed on its U.S. production.  Barton Bender, vice-president of sales, told a conference call with financial analysts, that Interfor has tried to keep overall lumber shipments to the country constant after China retaliated to U.S. tariffs with its own import tax of up to 25 per cent on some goods.  Bender says it has increased exports from Canada to China despite shipping costs that are roughly 50 per cent higher than from the Southern ...