Subalpine fir is very shade tolerant and easily establishes under a closed canopy. Subalpine fir is able to establish in duff because of its rapid root growth. Subalpine fir seedlings grow very slowly. Near timberline subalpine fir frequently reproduces by layering, probably as a result of heavy snow, wind, and cold temperatures which restrict growth away from the ground. Under closed forest canopy, reproduction by layering is negligible.
Subalpine fir is a middle to upper elevation mountain conifer.
It generally occupies sites with a short growing season caused by cold winters, cool summers, frequent summer frosts, and heavy snowpack. At its lower elevational limits, subalpine fir is often restricted to streambottoms, ravines, frosty basins, or north exposures. Throughout its range, subalpine fir is most commonly associated with Engelmann spruce. These two species frequently occur as codominants forming widespread subalpine forests. Understory vegetation is extremely variable, changing with elevation, exposure, and soil moisture.