Balsam-Pappel
Lodgepole pine is the most common associate of white spruce in the SBPS. White spruce also occurs with trembling aspen in seral stands, and mixtures of black and white spruces occupy cold low-lying sites. Floodplain stands of black cottonwood ("Populus balsamifera" ssp. "trichocarpa") and white spruce occur uncommonly.