Most people visit Yellowstone National Park to enjoy its beautiful scenery and natural wonders – geysers, lakes, waterfalls, mountains and, of course, the wildlife. The world’s first national park never disappoints.
But my students and I are not vacationing when we head to Yellowstone. Instead, we venture into the wilderness to understand how Yellowstone’s forests work and how natural disturbances, such as wildfires and insect outbreaks, affect the landscape.
My Yellowstone research began nearly 30 years ago, after the notorious 1988 fires. Throughout the summer, those fires burned about one-third of the park, an area the size of Rhode Island.
Forests were blackened for miles. Headlines shouted that Yellowstone was destroyed. But our long-term studies have shown that those pronouncements were dead wrong.
Big fires are not necessarily bad, and severe wildfires have been business as usual in Yellowstone for 10,000 years. The 1988 fires were driven by climate conditions – extreme drought and high winds – not by past fire suppression or an unnatural buildup of fuels.
The fires did not produce a barren wasteland. Rather, they created a patchwork of burned and unburned forests. Such mosaics help the native plants and animals rebound from disturbance.
Forest recovery was surprisingly fast after the 1988 fires. Soils were not deeply burned because the fires carried quickly from tree to tree. Wildflowers and grasses sprouted from surviving roots, creating splashes of color amidst blackened trees.
Tiny seedlings of lodgepole pine, the most common tree in Yellowstone, carpeted the burned areas within one year. Today, visitors might not even realize that the vistas of young healthy forests are a legacy of the 1988 fires.
Yellowstone’s forests also face periodic disturbance by native bark beetles and we studied the outbreak that peaked about 10 years ago. Reddish needles of beetle-killed trees are conspicuous during an outbreak and may suggest that the forest is dying.
However, bark beetles prefer to attack large trees, leaving small trees unscathed. The survivors benefit from extra sunlight, water and nutrients, and they respond with a burst of growth. There is no ecological catastrophe. Bark beetles kill trees, but they do not destroy the forest.
Our research has shown that Yellowstone’s forests are well adapted to their historical cycles of disturbance and recovery.
The rules of the game are changing, however, as temperatures warm and fires increase in size and frequency. Yellowstone is invaluable as a natural laboratory for studying the effects of environmental change.
Our current research asks whether the forests’ ability to rebound naturally from disturbances will be sustained in Yellowstone in coming decades.
We return to Yellowstone in July to collect data in recently burned forests and seek clues about how forests may change in the future. I will again have the privilege of sharing my enthusiasm for science – and Yellowstone – with UW-Madison undergraduate and graduate students.
So, if you see a UW-Madison vehicle while vacationing in Yellowstone, stop and talk. We would enjoy sharing the lessons we continue to learn from this crown jewel of our national parks.