IMPORTANT RANGE PLANTS. 3 
1. A Transition zone or yellow-pine association occupying the 
country between 3,000 and 4,500 feet elevation. 
2. A Canadian zone or lodgepole-pine association between 4,500 
and 6,800 feet elevation. 
3. A Hudsonian zone or white-bark pine association between 
6,500 and 8,500 feet elevation. 
4. An Arctic-alpine zone or alpine-meadow association from 
8,000 feet elevation up. 
Owing to the wide difference in the physical conditions in these 
zones, numerous rather distinct range types occur. The time 
during which each is grazed varies according to the location. 
The Transition zone (yellow-pine association), owing to the open 
character of the tree stand, supports a rather dense grass cover. 
Big bunchgrass (Agropyron spicatum) occurs in pure stands on the 
less elevated lands, and pine grass (Calamagrostis suJcsdorfii), blue 
bunchgrass {Festuca idahoensis), little bluegrass (Poa sandbergii), and 
mountain June grass (Koeleria cristata), named in the order of their 
importance, are the most valuable species at somewhat higher 
elevations. The majority of the important species are herbaceous. 
This zone is among the first to be grazed in the spring, the lower 
lands usually supporting stock early in March. By June 1 the forage 
in the higher adjoining lands is preferred because of its greater 
succulence. 
The Canadian zone (lodgepole-pine association) is more densely 
forested than the others. Also the forage, instead of being herbace- 
ous, is mainly shrubby or of the "chaparral" type. The most im- 
portant browse plants in this zone are fire willow (Salix nuttaMii), 
black elder (Sambucus melanocarpa), high huckleberry (Vaccinium 
membranaceum), and wax currant (Ribes cereum). Since the physical 
conditions in the Canadian zone are intermediate between those of 
the Transition zone below and the Hudsonian zone above, few plants 
are wholly confined to this region, and many of the species of the 
transition zone are encountered here. The grazing period in the 
Canadian zone comes approximately between May 15 and July 15. 
The Hudsonian zone (white-bark pine association) is characterized 
by scattered small clumps of woodland and a preponderance of 
grassland. The most important forage species are mountain bunch- 
grass (Festuca viridula), onion grass (Melica bella), porcupine grass 
(Stipa occidentalis), wild celery (Ligusticum oreganum), and butter- 
weed (Senecio triangularis). 
While this region is not suited for early grazing, because of the 
lateness of the growing season, it has as great an area and carries 
about as many stock as both of the lower zones together. It includes 
all the high summer sheep lands, except the few crests that are 
grazed above timber line. The grazing period begins approximately 
July 15 and continues through August and September, 
