 In cool , moist areas ranging from 4 @,@ 800 feet ( 1 @,@ 500 m ) to 6 @,@ 800 feet ( 2 @,@ 100 m ) , Douglas fir is predominant . Lodgepole pine and quaking aspen may be found alongside Douglas fir in cooler areas , both moist and dry , but particularly where frost pockets form . Understories in this forest type are dominated by mountain maple , mountain ash , and blue huckleberry in moister areas and white spirea , common snowberry , elk sedge , and pinegrass in drier areas . Between 3 @,@ 400 feet ( 1 @,@ 000 m ) and 6 @,@ 500 feet ( 2 @,@ 000 m ) in the moist northern parts of the forest , grand fir is predominant and western larch is one of the first trees to become established during ecological succession following disturbances , whereas understories consist of mountain maple , mountain ash , blue huckleberry , and mallow ninebark . Subalpine fir dominates from 4 @,@ 800 feet ( 1 @,@ 500 m ) to 7 @,@ 500 feet ( 2 @,@ 300 m ) along with mountain maple , serviceberry , Scouler 's willow , Sitka alder , menziesia , Utah honeysuckle , and mountain ash . 
