PRESENT TYPES OF VEGETATION IN THE PARK 5 
2. Sagebrush deserts .—The great central plateau of the park varies 
in elevation between 7,000 and 8,500 feet, but some of the northern 
end extends somewhat below 6,000 feet. The sagebrush deserts are 
typical of the lower portions, 6,000 to 7,500 feet. Between Mam¬ 
moth and the North Entrance two other typical desert plants, Grease- 
wood (Sarcobatus vermieulatus) and Pricklypear (Opuntia polya - 
cant ha ), are found with the sagebrush. The climate of the park, 
however, is not a desert climate and these deserts are very slowly 
and gradually being replaced by forests. 
3. Alpine and subalpine meadows .—Characterized by grasses, 
sedges, and many kinds of flowers. Timberline in the park is at 
approximately 10,000 feet. The alpine meadows are those above 
timberline, while the subalpine meadows are those below timberline. 
The chief difference in appearance of the two is due to the dwarf 
condition of all alpine plants. Both display a riot of color through¬ 
out most of the park season. The only place in the park where 
most visitors ever get above timberline, however, is on Mount 
Washburn. 
4. Douglas-fir forest .—This type of forest occurs below 7,000 feet 
and is very limited in the park. It is best seen at Tower Falls. 
5. Lodgepole pine forest .—This is the most extensive type of plant 
community in the park covering nearly three-fourths of its area, 
mostly between 7,000 and 8,500 feet altitude. Lodgepole pine trees 
often grow in very dense stands, but they are adapted to a shallow 
soil. Their roots are very superficial, so that they are not well 
anchored, and the forest floor is usually covered with fallen trees. 
For this reason the fire hazard in this type of forest is very great 
during a dry season. Although this is the most extensive type of 
vegetation in the park, it is a temporary one so far as the develop¬ 
ment of the vegetation is concerned and will normally be replaced, 
sooner or later, by spruce and fir. 
6. Aspen forest —The aspen is the only common broad-leaved tree 
in the park. Aspen forests are not extensive in area, but because of 
the white bark and bright green foliage which becomes brilliantly 
yellow in autumn they are conspicuous. This type of vegetation 
often succeeds a forest fire and may also develop in moist depres¬ 
sions or ravines. 
7. Spruce-fir forest .—Engelmann spruce and alpine fir have al¬ 
ready replaced the lodgepole pine in the more favorable situations, 
especially in the higher elevations, since this forest extends to timber- 
line. A convenient place to observe at close range an example of 
this type of forest is along the Savage Trail from Canyon Lodge to 
the Upper Fall of the Yellowstone. Here the constant spray from 
the Upper Fall has made the water relation sufficiently favorable 
to enable the spruce and fir to replace the pine forest. 
