Mountain ecosystems consist of elevational dines in climatic and soil conditions, which can influence tree growth morphology and adaptation. This study characterizes influences of seed, mycorrhizas, and soil from three altitudes on seedling growth of lodgepole pine ('Pinus contorta' Dougl. var. 'latifolia' Engelm.) and interior spruce (' Picea glauca' (Moench) Voss * 'Picea engelmannii' Parry ex Engelm.). Soil fertility and seedling growth declined with elevation. Growth differed among seed sources in interior spruce, suggesting genetic differences, but not lodgepole pine. The presence of soil microflora improved growth in the high elevation soil and reduced growth in the lower elevational soil. Ectomycorrhizal (EM) composition and influence on growth also varied among soils, and soil-specific EMs in high elevation soil greatly improved growth suggesting their importance to seedling development. Lodgepole pine from high elevation appears to depend on EM associations for growth. Interior spruce, however, appeared to have a slower growth in higher elevation populations, but this does not appear to be adaptive to its native soil environment. Further research is required to demonstrate the extent to which these strategies benefit seedling growth and survival under field conditions.