Fire suppression in Jasper National Park has changed the way forests burn, making them more similar in structure. By studying tree rings, researchers found that most sites had a mix of low and high-severity fires in the past, but now many areas only have evidence of high-severity fires. Different tree species like lodgepole pine and spruce grow together after fires, but the forests have aged together since the last big fire over a century ago. Without more fires, the forests have become more uniform and are at risk of severe fires. To help the forests stay healthy, it's important to bring back controlled fires to restore the natural balance.