Grasslands - Mountains and Plains: The Ecology of Wyoming Landscapes - page 106

irrigating or fertilizing the native plants would be good,
to increase their vigor, but Blumenthal and his associ-
ates found that maintaining water and nutrients at low
levels reduced the invasibility of the grassland they
studied in northern colorado. 87 careful manipulation
of the time and nature of livestock grazing also would
restore some level of herbivory, assuming the invasive
species were eaten.
Where weeds are already well established and the
goal is to restore native species, Blumenthal and his
associates found that adding carbon to the soil, in the
form of sawdust, reduced the availability of nitrogen.
this causes a decline in soil fertility, which the native
plants can tolerate better than the invasive species. in
their experiment, adding nitrogen favored the intro-
duced species. thus, disturbances that make nutrients
more available should be minimized while this kind
of restoration work is in progress. Where feasible, her-
bicides were integrated with this work in a way that
favored the native species, helping them become estab-
lished. this research was motivated by the observation
that the primary expense of controlling invasives, by
whatever means, results from the fact that it has to
be done time and time again. if native species can be
restored and managed properly, they persist year after
year, preventing or slowing plant invasion well into the
future—an ecosystem service powered by solar energy.
native plant growth and biomass may be less than that
of the invasive plants, but the expense of maintain-
ing the grassland is greatly diminished. Moreover, the
adverse effects of the invading species are reduced.

tion until a small population was found near Meeteetse
in 1981. now, through captive breeding, there are sev-
eral thousand ferrets, and some are breeding success-
fully in the wild. 88
the most conspicuous grazing in the twenty-first
century is by cattle. But, of the large herbivores, only
the pronghorn now completes its life cycle on the
grasslands—each animal very likely dying in or near the
same county where it was born. in the early 1700s, native
American hunters would have seen a greater diversity of
large mammals, and very likely they would have heard
the barking of prairie dogs almost every day during the
summer. Raptors and other predators would have been
more common with such a large prey base. there would
have been many large animal carcasses, providing food
for numerous kinds of scavengers. nathaniel Wyeth
wrote in 1832 about an abundance of buffalo along the
Sweetwater River valley, and in 1857—long before the
introduction of sheep and cattle—William A. carter
wrote about seeing thousands of dead animals. 89 Ravens,
vultures, coyotes, and other scavengers would have fed
on the carcasses. now and then a grizzly bear or pack
of wolves would have chased them away. Seeing a bad-
ger would be common. the clickity-clack of grasshopper
wings would have been frequent in the summer, but with
no spotlights, the nocturnal swift fox and black-footed
ferret would have gone unnoticed most of the time.
today, a grassland ecosystem like the one first
encountered by euroAmericans in the early 1800s, and
the first human immigrants some 15,000 years earlier,
does not exist. Most of the native plants are there, and
some of the small native animals can be found if one
looks long enough. Grasshoppers still exist, some years
more than others, and occasionally a prairie dog town
can be found. coyotes will be heard. With luck, a swift
fox will be visible as it darts across the road at night.
However, off in the distance, the large animals are most
likely cattle rather than bison, deer, elk, pronghorn, or
large predators—or the camels, mammoths, saber-tooth
tigers, and other extinct species of earlier times.
considering the relatively depauperate nature of
grasslands now—at least aboveground—there is reason
to promote the establishment of a grassland national
park in an area large enough to restore the diversity that
once existed there. neighbors would justifiably object
to the re-establishment of wolves and grizzly bears on

Challenges for the Future

traveling across north America, it's rare to find native
grasslands that extend to the horizon as they once did.
Most have been plowed for cropland or converted to
pastures of introduced plants. Prairie dog towns can
be seen along the highways in the western states, but
the population of these animals is probably less than
10 percent of what it was in the 1800s. Many think that
the black-tailed prairie dog should be listed federally
as an endangered species, especially now that sylvatic
plague has been introduced to America and frequently
kills entire colonies. Because of the decline in prairie
dogs, the black-footed ferret was on the brink of extinc-