This article, and others in the series "Parks in Science History", was written by a graduate student at the University of Maryland. The articles highlight the roles that national parks have played in the history of science and, therefore, the world's intellectual heritage. More articles and videos will be produced in the future.
The fires had burned for months across large sections of the park. In fact, they were collectively the largest wildland fire ever known within the park boundary. Based on the scale of the burns, Dr. Turner had expected to see large swaths of uniformly burned forest, but instead the burned land below her looked like a mosaic, an intricate mixture of severely burned, lightly burned, and unburned areas.
These are just a few of the questions Monica asked in the months that followed. Asking ecological questions on such a large landscape scale was new at the time. Only two years earlier, Monica had helped organize the first landscape ecology meeting in the U.S., during an era when traditional ecologists were still wary of studying patterns and processes across thousands of square kilometers. Though she had no idea at the time, she would become a leader in the field of landscape ecology, spending more than a quarter century studying burn patterns in Yellowstone and paving the way for future landscape ecologists.
Before 1988, Yellowstone - a 9,000 km2 expanse of forests that is 80% lodgepole pine - was no stranger to fire. As in many parts of the Rocky Mountains, fires burn every year in the park and are a big influence on the landscape’s animals and plants. Until the early 1970’s, Yellowstone’s park managers extinguished all fires in the park because fire suppression was believed to protect both humans and wildlife. But they began to realize that these fires are a natural part of the landscape and shouldn’t be suppressed. Managers launched a natural fire program in 1972, and so fires caused by lightning were no longer put out. For more than a decade, fires were small, went out by themselves, and mostly just burned old trees.
You might wonder, then, why everyone was shocked by the 1988 fires. At first, 1988 seemed like any other dry year. But then weather conditions became very unusual, with unprecedented drought and wind. As the summer went on, the fires got bigger and bigger. By the end of September, they had burned more than 3,212 km2 of forest containing trees of all ages. The 1988 fires in Yellowstone burned more square kilometers than anyone had ever seen.
- The most severe burn classification was “Crown Fire,” and was given to places where the tree canopies were consumed by fire, meaning that all or most of the seeds stored in the canopies were destroyed.
- Places with fires that killed the trees but did not destroy the tree canopies were called “Severe Surface Burns”.
- “Light Surface Burn” was the classification given to places where the trees survived but stems were scorched.
- “Unburned” was given to places that were hardly burned at all.
Why did the landscape become a mosaic? The reason has to do with the most common type of fire that burned in Yellowstone in 1988. Of the three burn categories, crown fires were responsible for most of the area burned. Unlike other fires, very large crown fires are unaffected by landscape features (roads, rivers, mountains, and valleys) or tree age. Only wind can control these large crown fires. As wind speed and direction change, crown fires sweeping across the landscape burn certain places more severely while they skip over nearby areas. After a big crown fire, you will find places that were hardly touched by fire right next to areas that were highly affected. Looking down at Yellowstone from an airplane in the years following the 1988 fires, the mixture of severely burned, medium burned, and lightly burned places looked like a mosaic.
Yellowstone’s forests were very resilient, and so in the years following the 1988 fires burned areas filled up once more with young lodgepole pine trees. But will Yellowstone’s forests recover from large fires in the future? Monica worries that the answer might be “No”. Extreme weather events -- think of the drought and high winds that fed the 1988 fires -- are increasingly common. As the western U.S. becomes hotter and drier, there have been more and more big fires. Will young forests have enough time to recover between increasingly frequent burns? Or will the landscape look different in the future than it has in the past? Time, along with more large-scale studies and models, will tell.
For further reading, check out her 1994 article.
Frequently Asked Questions: 1988 Fires - Yellowstone National Park (U.S. National Park Service). https://www.nps.gov/yell/learn/nature/1988firefaqs.htm. Accessed 13 Aug 2018b
Monica G. Turner – The Ecological Society of America’s History and Records. https://esa.org/history/turner-m-g/. Accessed 13 Aug 2018a
Photo Galleries - Yellowstone National Park (U.S. National Park Service). https://www.nps.gov/yell/learn/photosmultimedia/photogallery.htm. Accessed 6 Jun 2018
Turner MG, Hargrove WW, Gardner RH, Romme WH (1994) Effects of fire on landscape heterogeneity in Yellowstone National Park, Wyoming. J Veg Sci 5:731–742 . doi: 10.2307/3235886
Wildland Fire: Fire Interpretation: History of National Park Service Fire Policy | U.S. National Park Service. https://www.nps.gov/fire/wildland-fire/learning-center/history/history-of-NPS-fire-policy.cfm. Accessed 12 Aug 2018
Zagorski N (2007) Profile of Monica G. Turner. Proc Natl Acad Sci U S A 104:4779–81 . doi: 10.1073/pnas.0701264104