** Forestry products firms slip as U.S. is poised to double duties on softwood lumber

** U.S. Dept of Commerce has made preliminary decision to more than double countervailing duties on imports of Canadian softwood lumber from 6.74% to 14.38%

** Combined with dept's preliminary decision earlier this year to increase anti-dumping duties to 20.07%. This could bring total duty rate to 34.45% this fall

** Timber REITS Potlatchdeltic Corp PCH.O, Weyerhaeuser WY.N, and Rayonier RYN.N down 3% to 4.6%

** Canadian forestry firms Conifex CFF.TO, Canfor Corp CFP.TO, Interfor IFP.TO and West Fraser WFG.TO slide 6.6% to 3.9%

** BC Lumber Trade Council called the duties " unjustified and harmful", adding that if implemented, these rates will hurt workers and communities on both sides of the border and drive-up lumber prices for American consumers

(Reporting by Mrinalika Roy)