Riparian Landscapes - Mountains and Plains: The Ecology of Wyoming Landscapes - page 53

Fig. 4.8. Aerial view of riparian
woodlands along the Bighorn River
east of Lovell. Former channel loca-
tions and bands of trees are visible.
Most of the area shown is dominated
by plains cottonwood. the tree-ring
record indicates that, historically, a new
band of trees became established every
10-20 years. the older bands tend to be
farther from the river (see figs. 4.9 and
4.10). Desert shrublands are found on
the adjacent uplands. the red in this
infrared image indicates an abundance
of chlorophyll in the riparian zone
where water is available longer into the
summer, in contrast to the adjacent
desert shrublands. Similar patterns are
found along other meandering rivers,
for example, the Powder River south of
Arvada. image from the U.S. Depart-
ment of Agriculture.

plain, the older trees die if their roots cannot keep up
with the deepening water table. 7 those that survive are
likely to fall into the river when the channel is again at
their base—assuming beavers do not cut them before
that happens.
the riparian zone at lower elevations is often wooded,
dominated by plains cottonwood. other trees include
peachleaf willow, ash, boxelder, lanceleaf cottonwood,
and, rarely, American elm. 8 Along the Wind River near
Riverton, W. F. Raynolds wrote in 1860: “the valley is

a mile or more in width, and the immediate banks of
the stream for 300 or 400 yards are covered with a thick
growth of cottonwood.” Similarly, D. B. Sacket wrote in
1877: “All along the Bighorn River [north of thermopo-
lis] . . . much fine, large cottonwood timber grows.” 9 in
both places, plains cottonwood would have been the
dominant species.
notably, portions of some lowland rivers were histor-
ically devoid of trees (fig. 4.10), such as along the Sweet-
water and Laramie rivers. While camped along crow