Quaking aspen is also abundant on sunnier exposures and near the forest's lower elevational limit.
The spruce-fir forest is the shadiest, wettest, and densest of the forest types found in the state. The abundance of shade and more annual snowfall leads to lingering snowpacks keeping the forest floor moist much of the year. Much of this falls as snow during the cooler months, but a significant portion falls as heavy rains during the summer monsoon season. Here, the spruce and fir trees must adapt to the strong winds and cold temperatures so common throughout much of the year. The branches of the trees are brittle, so they grow close together to buffer the wind, and both species have narrow, pointed crowns, which help shed snow.