The Greater Yellowstone Ecosystem - Mountains and Plains: The Ecology of Wyoming Landscapes - page 261

Complete
Suppression
Policy

Natural
Fire
Policy

LP3

40
30
20

% Area
in Each
Cover
Type

LP2

LP1
LP0

10

40
20

% Area
Burned

20 40 60 80 20 40 60 80 20 40 60 80

1700 1800 1900

Fig. 15.15. Percentage area burned per decade from the
1690s through 1980s in a 450-square-mile landscape in cen-
tral Yellowstone national Park, and percentage area covered
by four post-fire stages of forest development during that
time. LP0 is recently burned forest (typically 0-40 years
old), LP1 is young lodgepole pine forest (40-150 years old),

LP2 is mature lodgepole pine forest (150-250 years old),
and LP3 is old-growth lodgepole pine forest, mixed with
spruce and fir on more fertile sites (250 or more years old).
Drafted by Michael turner. Reprinted with permission of
M. G. turner et al. (2001, fig. 7.15) and Springer Science and
Business Media.

tions and fire intensity had changed quickly would not
have been sufficient to deal with more than a few fires
each year, and not every year would have had accept-
able weather conditions. thus, assuming that human-
caused prescribed fires had been used after 1972, when
fire was officially accepted as a necessary process in
YnP, too little of the forest away from human habita-
tions would have been burned to prevent the large-scale
1988 fires.72
even if the 1988 fires cannot be viewed as entirely
“natural” in size or spatial pattern, the ecosystem has
shown great resilience, with surprisingly rapid natural
recovery of almost all components. 70 there were some
exciting ecological surprises as well: a large cohort of
aspen seedlings appeared in burned areas the first year
after the fire (fig. 15.16). Genetic analyses confirmed
that the plants were genuine seedlings, not root sprouts,
as are commonly seen in aspen . 71 Moreover, no aspen
seedlings were observed in unburned areas, suggesting
that successful sexual reproduction of this charismatic
Rocky Mountain tree may occur only in conjunction
with severe fires. Another surprise was that, though the
media sometimes gave the impression that YnP had
been destroyed, visitation increased in the years after
the 1988 ire s. 72

natural fire policies in YnP and other national parks
and national forests across the West were suspended
after the 1988 fires, while another review team evalu-
ated the scientific foundation of fire management.
the team concluded that YnP's natural fire policy was
basically sound but needed more specific criteria for
deciding whether to suppress or to only monitor spe-
cific fire ignitions. Yellowstone managers incorporated
these changes in a new fire management plan in 1992,
and Grand teton national Park and national forest
managers in the GYe developed similar modified poli-
cies. Lightning-ignited fires are again allowed to burn
in the GYe backcountry if they do not threaten life,
property, or significant resources—and if weather and
fire-fighting resources are deemed such that another
1988-like event is highly unlikely.
But the Yellowstone fire story may have only just
begun. the 1988 Yellowstone fires were among the first
of what has proven to be a dramatic increase in large
forest fires across the American West since the mid-
1980s . 73 the increase has been driven primarily by cli-
mate change—in particular, the trend of earlier spring
snowmelt, warmer summers, and a longer period each
year in which wildfires can burn. Anthony Westerling
and colleagues found a statistical correlation between