The Greater Yellowstone Ecosystem - Mountains and Plains: The Ecology of Wyoming Landscapes - page 253

Fig. 15.8. elevational distribution of
major forest types near Grand teton
national Park. the solid vertical lines
show the range of elevations over which
each tree species is important as a forest
dominant; the vertical dotted lines indi-
cate the range over which the species can
be found. Adapted from Baker (1986) and
Whitlock (1993).

Elevation
(feet)

tundra

Whitebark p.

9000

Spruce-fir-pine

8000

Lodgepole pine

7000

Douglas-fir

6000

Limber pine

sagebrush steppe

5000

spruce-subalpine fir forest, 4 percent Douglas-fir wood-
land, and 1 percent aspen groves. 31 in general, plant dis-
tribution is determined by elevation, topography, and
geologic substrate (fig. 15.8).
Douglas-fir and lodgepole pine are the most common
trees at low elevations in the Jackson Hole area, typically
occurring together on Blacktail Butte and in the Gros
Ventre Mountains to the east, where soils are deep and
fertile enough to support tree growth. Five Douglas-fir
habitat types have been identified, with the distinguish-
ing understory species being ninebark and Rocky Moun-
tain maple on comparatively moist sites, and mountain
snowberry, pine reedgrass, and spiraea on the drier sites. 32
Lodgepole pine is common on some mountain slopes,
such as Signal Mountain, as well as the west slopes of
the tetons and the mountains to the north and east of
Jackson Hole, but it is infrequent on the east face of the
tetons. At higher elevations on the tetons, Douglas-fir
forests are replaced by subalpine forests dominated by
engelmann spruce and subalpine fir. Whitebark pine is
common above 8,000 feet, especially on dry windy sites,
and extends to upper treeline. Avalanche tracks on the
steep-walled canyons of the tetons are obvious to hikers,
extending from above treeline into the forested valleys
and across streambeds, sometimes reaching a short dis-
tance up on the opposite slope (see chapter 14).
in some areas Douglas-fir extends to higher eleva-
tions than does lodgepole pine, such as around Jackson
Lake. Lodgepole usually occurs above Douglas-fir in
the Rocky Mountains, but in Jackson Hole the pine is

common on the valley floor, especially on the glacial
moraines where soil moisture is available late in sum-
mer (fig. 15.9). 33 Also, temperature inversions caused by
cold-air drainage may cause the valley bottoms to be
cool enough for lodgepole pine.
Aspen groves are found in upland areas that are rel-
atively moist, such as at lower elevations where snow
accumulates or where there is groundwater seepage
to the surface. Frequently the groves are interspersed
in sagebrush-dominated shrublands. Douglas-fir is
a common associate. 34 Mixed foothill shrublands or
Douglas-fir grow on drier sites (see chapter 10). Sage-
brush-dominated shrublands occupy the floor of Jack-
son Hole, except on glacial moraines, where conifer
forests are common (see fig. 15.9). Rivers and streams
are fringed by riparian woodlands or shrublands (see
chapter 4). When overlooking the Snake River from
Antelope Flats, ancient river terraces are conspicuous
(see fig. 15.3), with coniferous woodlands on the steep
slopes of cut banks and willow-dominated point bars
on the opposite shore. extensive willow shrublands also
occur near Jackson Lake, such as the Willow Flats area
southwest of Jackson Lake Lodge.
Much of the teton range rises above treeline. the
steeper slopes appear barren, supporting only lichens
and herbaceous plants in crevices. Alpine meadows and
fellfields are found where soil has developed, such as
around Solitude and Amphitheater lakes. in parts of
the Gros Ventre Mountains to the east of Jackson Hole,
sparse plant growth is seen at lower elevations, appar-