 An estimated 76 percent of Boise National Forest is forest , which according to the Forest Service is considered land capable of supporting trees on at least 50 percent of its area . The forests are primarily coniferous evergreens , dominated by Douglas fir and ponderosa and lodgepole pines at lower elevations and Engelmann spruce , subalpine fir , and whitebark pine at higher elevations . Grand fir and western larch ( a coniferous deciduous tree ) grow in the northern part of the forest where there are moister conditions . Quaking aspen , a broadleaf deciduous tree , grows both in stands among conifers and in monotypic stands throughout the forest at elevations above 5 @,@ 000 feet ( 1 @,@ 500 m ) . Non @-@ forested areas occupy 23 percent of the forest , primarily on south @-@ facing slopes , lower elevations in the forest 's southern latitudes , or high @-@ elevation areas and are dominated by grasses , forbs , or shrubs . 
 An estimated 76 percent of Boise National Forest <a href='drop_aux' title='1'><mark>is</mark></a>forest , which according to the Forest Service is considered land capable of supporting trees on at least 50 percent of its area . The forests <a href='drop_aux' title='2'><mark>are</mark></a>primarily coniferous evergreens , dominated by Douglas fir and ponderosa and lodgepole pines at lower elevations and Engelmann spruce , subalpine fir , and whitebark pine at higher elevations . Grand fir and western larch ( a coniferous deciduous tree ) grow in the northern part of the forest where <a href='dey_it' title='3'><mark>there</mark></a> are moister conditions . Quaking aspen , a broadleaf deciduous tree , <a href='uninflect' title='4'><mark>grows</mark></a> both in stands among conifers and in monotypic <a href='uninflect' title='5'><mark>stands</mark></a> throughout the forest at elevations above 5 @,@ 000 feet ( 1 @,@ 500 m ) . Non @-@ forested areas occupy 23 percent of the forest , primarily on south @-@ facing slopes , lower elevations in the forest <a href='null_genetive' title='6'><mark>'s</mark></a>southern latitudes , or high @-@ elevation areas and are dominated by grasses , forbs , or shrubs . 
An estimated 76 percent of Boise National Forest forest , which according to da Forest Service is considered land capable of supporting trees on at least 50 percent of its area . Tdaforests primarily coniferous evergreens , dominated by Douglas fir and ponderosa and lodgepole pines at lower elevations and Engelmann spruce , subalpine fir , and whitebark pine at higher elevations . Grand fir and western larch ( a coniferous deciduous tree ) grow in the northern part of the forest where it is moister conditions . Quaking aspen , a broadleaf deciduous tree , grow both in stands among conifers and in monotypic stand throughout thdaorest at elevations above 5 @,@ 000 feet ( 1 @,@ 500 m ) . Non @-@ forested areas occupy 23 percent of the forest , primarily on south @-@ facing slopes , lower elevations in thedarest  southern latitudes , or high @-@ elevation areas and are dominated by grasses , forbs , or shrubs .