Riparian Landscapes - Mountains and Plains: The Ecology of Wyoming Landscapes - page 65

cottonwood and willows, saltcedar is a phreatophyte.
However, it generally transpires more water than the
native species do, most likely because it often produces
stands with more square feet of leaf area per square foot
of ground area (the leaf area index). 49
controlling the spread of both Russian olive and
saltcedar, and many other invasive herbaceous plants
in the riparian zone, has been difficult. Herbicides
typically kill some native species as well as the
invasives, and the chemicals are not recommended for
use in close proximity to waterways. cutting the shrubs
or trees followed by the application of herbicide to
the root crown has been effective, though costly, and
there has been some success with biological control. 50
A fundamental approach is to manage the river so
that cottonwood, boxelder, and other native trees are
favored. As the native trees grow taller, the saltcedar dies
because of insufficient light. 51 of course, this approach
may require allowing floods and reducing the beaver
population, especially if cottonwood establishment and
growth is desired.

and dikes have been constructed to prevent flooding.52 52
Along with such developments, the ecosystem services
provided by riparian ecosystems have been diminished,
creating costs that often are not considered—costs
related to water quality, sustained streamflow, and wild-
life habitat. 53
And now an added concern is warming of the
climate. Higher temperatures could lead to continued
decline in cottonwood abundance if floodplains become
drier, floods are insufficient to enable new seedling
establishment, or fires occur more frequently. one
effect of a warmer climate already has been observed:
earlier snowmelt, which increases the probability of
drought-caused mortality of riparian plants during a
longer, warmer summer. 54 Some rivers and streams that
formerly flowed all year may become ephemeral, causing
dramatic changes to the riparian flora and fauna—not
to mention municipalities, industry, and interstate
compacts. 55 With a warmer climate, frost-sensitive
invasive plants—such as saltcedar—probably will
expand their ranges, and Russian olive could become
more common, because it tolerates drought better
than cottonwood can. 56 Water shortages will promote
controversial initiatives, such as cloud seeding and
additional trans-basin diversions, and also will reduce
the availability of water for ecologically beneficial
instream flows or floods. Sweeping generalizations for
all riparian ecosystems are not possible, but it's clear
that benefiting from riparian resources in the future
will require a coordinated effort by policymakers,
riparian scientists, fisheries biologists, engineers, and
land managers.

there is one clear conclusion for riparian landscapes:
streamflow regulation, agriculture, irrigation, livestock
grazing, invasive plants, fire suppression, and other
human activities have created riparian habitats that
are quite different from those of the 1800s. to varying
degrees, alterations are occurring in both the lowlands
and mountains, especially where roads and summer
homes have been constructed in valley bottoms, large
herds of livestock or big game congregate, land is culti-
vated, dams have created reservoirs and regulated flows,