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In-Depth Information
Missouri River Basin
Great Divide Basin
Great Basin
1
Yellowstone
2
Clark's Fork
3
Big Horn
4
Little Big Horn
5
Tongue
6
Powder
7
Little Missouri
8
Belle Fourche
9
Cheyenne
10
Niobrara
11
North Platte
12
South Platte
13
Great Divide
16
Bear
Colorado River Basin
Snake River Basin
14
Little Snake
15
Green
17
Snake
Fig. 4.1. A network of creeks and rivers connects the land-
scapes of the region. Many smaller creeks are ephemeral,
lacking water during the driest part of the summer. the loca-
tions of Yellowstone Lake and the larger reservoirs are shown.
Drainages 14-17 lie west of the continental divide. Drainage
13 is the Great Divide Basin (see fig. 1.2), which is formed by
a split in the continental divide and has no outlet. About 72
percent of Wyoming contributes to the Missouri River drain-
age. Drawing by Linda Marston.
From Rivulet to River
aspen, and balsam poplar). Associated shrubs include
red osier dogwood, silver buffaloberry, thinleaf alder,
water birch, and several species of willow—often in
dense thickets (table 4.1). At still lower elevations, such
as in the Green River, Wind River, and Bighorn basins,
and on the Great Plains, plains cottonwood becomes
the most conspicuous tree (fig. 4.4).
Several studies have examined streamside vegetation
the patchy riparian mosaic is affected by various envi-
ronmental factors, primarily duration of soil saturation,
soil depth and texture, frequency of flooding, depth to
the water table, oxygen availability for roots, duration
of snow cover, growing season length and temperature,
As rivulets merge, a first-order stream develops with
the adjacent vegetation dominated by several species
of sedges, grasses, and willows (table 4.1). Meadows and
short willow shrublands (see fig. 2.5) become more con-
spicuous as two first-order streams come together, form-
ing a second-order stream, and as two second-order
streams merge to form a third-order stream. Lower on
the mountain, such shrubs as thinleaf alder, water birch,
and tall willows become more conspicuous (figs. 4.2 and
4.3). in the foothills, trees are more common, primar-
ily narrowleaf cottonwood, but also engelmann spruce
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