The Greater Yellowstone Ecosystem - Mountains and Plains: The Ecology of Wyoming Landscapes - page 259

Northern Yellowstone Elk Herd

25

20

15

1988
Fires

1995
Wolf
reintroduction

10

5

1970 1975 1980 1985 1990 1995 2000 2005 2010

YEAR

Fig. 15.13. Population trends in the northern Yellowstone
elk herd from 1971 to 2010. Beginning in 1968, the park
ended its program of artificially controlling elk numbers.
For that reason—and because of a series of moderate winters
and low levels of predation—the population grew. Large fires
burned approximately a third of the park in 1988, including
much of the northern winter range, and wolves were reintro-
duced to the park in 1995 after nearly a century of absence.

the recent decline in elk numbers is due to several factors, as
discussed in the text. three sets of data are shown (black and
red points): Schullery and Whittlesey (1992) for 1971-1992
(black); Vucetich et al. (2005) for 1985-2004 (red), and the
Yellowstone center for Resources (unpublished) for 2005-
2010 (red). the data overlap in the period 1986-1992 and
differ slightly, reflecting the difficulty in censusing wildlife
populations.

but they were generally ineffective in remote forested
areas. By the time a fire was reported and a crew found
it, often days later, the fire commonly had either gone
out or had become so intense that it could not be extin-
guished with hand tools. only with the availability of
new fire-fighting equipment after World War ii, notably
aircraft and smokejumpers, were managers able to sup-
press most ignitions.
in the wake of the 1963 Leopold report, researchers
began reporting that fire was an important ecological
process in most western forests and rangelands and
that fire exclusion was leading to undesirable ecologi-
cal changes. therefore in 1972—in the spirit of natural
regulation—park managers initiated a cautious pro-
gram of allowing lightning-caused fires to burn with-
out interference in a remote portion of the park during
moderate weather conditions, when the risk of human
injury or serious resource damage was minimal. in 1976
this natural fire program was expanded to encompass
most of the park's backcountry area. During a period of
15 years, from 1972 through 1987, a total of 235 light-
ning-ignited fires were allowed to burn, of which only
27 burned more than an acre; the largest burned 7,400
acre s. 63 YnP's natural fire program seemed to be suc-
cessful, and similar natural fire programs were imple-

mented in surrounding wilderness areas and in Grand
teton national Park. However, in 1988 researchers and
managers learned that 15 years was not long enough to
fully understand the ecology of fire in the GYe.
the summer of 1988 turned out to be one of the
driest and windiest on record. Some 248 fires were
ignited in the GYe by lightning or humans and burned
approximately 1.4 million acres (fig. 15.14). A massive
fire-fighting effort—25,000 fire-fighters and $120 mil-
lion—succeeded in minimizing loss of life and property
but could not stop the spread of fires across the land-
scape until significant precipitation finally arrived in
mid-September. 64
Park managers convened a panel of experts to eval-
uate the ecological impacts of the fires and to predict
likely ecosystem responses and management implica-
tions. 65 t he panel concluded that the size and severity
of the fires were influenced more by drought and wind
than by fuels or previous management practices. they
noted that large and severe fires also had occurred in
the early 1700s (fig. 15.15) . 66 Subsequent research has
shown that large fires have recurred in Yellowstone at
intervals of decades or centuries throughout most of
the Holocene . 67 the 1988 fires were not confined to the
park but burned substantial portions of surrounding