Ecologists have known for many years that wildfire is essential to the evolution of a natural setting. Records kept in Yellowstone since 1931 show that lightning starts an average of 22 fires each year. Large-scale fires burn through the conifer forests of the Yellowstone plateau every 250 to 400 years and take place in the low-elevation grass-lands on average every 25 to 60 years. When fires are, suppressed the habitat gradually becomes less diverse. This, in turn, affects the variety of animals able to successfully inhabit a particular area.

In the first few decades after Yellowstone was established as the world’s first national park in 1872, no effective fire fighting was done. Then, during the Army administration of Yellowstone (1886-1918), fire suppression occurred most frequently on the grass lands of the northern range. Throughout the rest of the park, which is largely covered by a lodgepole pine forest, reliable and consistent fire suppression began with the era of modern airborne firefighting techniques of the past 30 to 40 years.

In natural areas such as Yellowstone National Park, preserving a state of wildness is a primary goal of management. In 1972, Yellowstone was one of several national parks that initiated programs to allow some naturally caused fires to burn. By 1988, scientists had learned much about the occurrence and behavior of fire. Tens of thousands of lightning strikes simply fizzled out with no acreage burned. While 140 lightning strikes produced fires, most burned only a small area. Eighty percent of the lightning starts in this period went out by themselves.

The Historic Fires of 1988
The summer of 1988 was the driest on record in Yellowstone. Though substantial precipitation fell during April and May, practically no rain fell in June, July, or August—an event previously unrecorded in the park’s 112-year written record of weather conditions. In early summer, about 20 lightning-caused fires had been allowed to burn, and eleven of these fires burned themselves out.

But fires that continued to burn into the extremely dry weeks of late June and July met dramatically changed conditions. By late July, moisture content of grasses and small branches had dropped as low as 2 or 3 percent, and downed trees measured at 7 percent (kiln-dried lumber is 12 percent). After July 15, no new natural fires were allowed to burn and after July 21, all fires were fought.

The extreme weather conditions and heavy, dry accumulations of “fuel’ (vegetation of various types) presented even the most skilled professional fire fighters with conditions rarely observed. Typical firefighting techniques were frequently ineffective because fires spread long distances by “spotting,” a phenomenon in which wind carries embers from the tops of 200-foot flames far across unburned forest to start spot fires well ahead of the main fire. Fires routinely jumped barriers that normally stopped them such as rivers, roads, and major topographic features such as the Grand Canyon of the Yellowstone River. Fires advanced rapidly, making frontal attacks dangerous and impossible.

By the last week of September, about 50 lightning-caused fires had occurred in the park, 8 of which were still burning. More than $120,000,000 had been spent on fire control efforts in the greater Yellowstone area, and most major park developments—and a few surrounding communities—had been evacuated at least once as fire approached within a few miles of them. At the operation’s peak, 9,000 firefighters (including Army and Marine units), more than 100 fire engines, and dozens of helicopters participated in the complex effort to control the fires and protect developments. It was the largest such cooperative effort ever undertaken in the United States.

Changes Since 1988
Changes in both the natural landscape of Yellowstone and the management of naturally-caused fires have taken place since the historic fires of 1988. Scientists knew that the vegetative cover of Yellowstone was, in large part, the product of fires that had burned for millennia before the arrival of European humans. The growth of new plants and entire plant communities began immediately. In most places, plant growth is unusually lush because minerals and other nutrients are released by fire into the soil and because increased light stimulates growth in what was previously shaded forest floor.

These fires did not annihilate all life in their paths. Burning at a variety of temperatures, sometimes as ground fires, sometimes as crown fires (burning through treetops), fires killed many lodgepole pines and other trees but did not kill most other plants. Instead, they burned off the tops, leaving roots to regenerate. The fires created a mosaic of burns, partial burns, and unburned areas that provide new habitats for plants and animals.

Yellowstone National Park is one of the greatest living laboratories on the planet. Here, we can observe the effects of fire and other natural forces and processes, and learn from them. And what we learn is that change is constant in the natural world, flowing from the past into the present—continuing into the future to outcomes both predictable and mysterious,

Facts About the Fires of 1988
Why They Occurred
Conditions occurred that were never before seen in the history of Yellowstone: extended drought & high winds.

Statistics

• 9 fires caused by humans
• 42 fires caused by lightning
• 36% of the park burned (793,880 acres)
• Fires begun outside of the park burned more than half of the total acreage
• About 400 large mammals, primarily elk, perished
• $120 million spent fighting the fires
• 25,000 people employed in these efforts

Fighting the Fires

• Until July 21, naturally-caused fires allowed to burn.
• After that, all fires fought, regardless of their cause.
• Largest fire-fighting effort in the history of the U.S.
• Effort saved human life and property, but probably had little impact on the fires themselves.
• Rain and snow finally stopped the advance of the fires.

After the Fires

• Enormous public controversy occurred.
• Several high-level task forces formed to review NPS fire policies.
• Their recommendations reaffirmed the importance of natural fire in an ecosystem.
• They recommended additional guidelines be established to manage natural fire in Yellowstone.