
Smoky sunset over the Gardner River, August 22, 2016 / NPS
Standing dead trees throughout Yellowstone National Park are a wildfire disaster in the making, according to a new study published in the journal Forest Ecosystems. Each dead tree is a tinderbox. Put them together in groups, and you have the making of a potential firestorm.
The researchers found that as much as 40 percent of the park contains dead, standing trees. “A significant portion of the park is experiencing moderate to high levels of tree mortality,” said the researchers in a release. The causes of mortality range from climate change warming and drying areas of the park, to damage from pests and disease. Many of the densest, most vulnerable concentrations of dead trees pose a threat to important park infrastructure as they're located next to heavily used roads, trails, buildings, and water sources. The researchers also found significant clusters of dead trees near park entrances.
Other sections of dead trees pose less of a threat as they're less dense concentrations in more remote areas of the park, according to the researchers.
To determine the amount of dead trees in Yellowstone, researchers in the study combined data from the National Ecological Observatory Network (NEON), satellite imagery to determine canopy health, height, and coverage distribution. They then fed that data into a powerful machine learning tool called a random forest classification model to map areas of dead trees throughout the park.

Maps showing the ratio of dead trees in the Yellowstone area. Graphic: Di Yang et al.
“Our model showed an accuracy of 76.65%, giving us a clear picture of where standing dead trees are concentrated,” said Di Yang, a geographer at the University of Florida, and co-author of the paper, in a release.
Just for some context into how much data the researchers' model sifted through to determine the amount and location of dead trees in the park, Yellowstone covers more than two million acres and 80 percent of the park is forested. In the summer of 1988, a series of wildfires erupted in Yellowstone, eventually spread far beyond control, and consumed nearly 800,000 acres of the park. The battles to contain the blaze comprised the largest fire fighting effort in the nation's history at the time, according to the National Park Service.
Healthy, naturally occuring fires are crucial to Yellowstone's forest and grassland ecology, but a means to predict where fires may erupt before they spread out of control is a crucial way to protect life and property. The reseachers are hopeful their computer modeling methods can by used by fire managers in Yellowstone and elsehwere to plan out more effective fire management strategies.