Dry conifer forests of the Colorado Front Range have experienced a dramatic increase in wildfire activity in recent decades. Many of these recent wildfires burned severely across a considerable portion of their footprint, and created vast stand-replacing patches that are devoid of surviving trees. While historical wildfires in the Front Range sometimes included a stand-replacing component, uncertainty remains regarding how the amount and spatial extent of stand-replacing burning compares between recent wildfires and historical ones. In 2002, the Hayman Fire burned across the unlogged Cheesman Lake landscape, a 3,400 hectare dry-conifer forest landscape in Colorado that had been the subject of previous fire history and forest structure research. We opportunistically leveraged pre-existing fire history and forest structure to provide insight into whether the Hayman Fire burned more severely than historical ones.
1. Living old trees were abundant and widespread across the landscape before the Hayman Fire, despite the fact that some stand-replacing burning had been a component of the landscape’s historical “mixed-severity” fire regime. Of 106 stand polygons that had been sampled for tree ages prior to the fire, 70 percent contained at least one tree more than 200 years old, and 29 percent contained at least one tree greater than 400 years old; these polygons were well-distributed across the landscape.
2. The 2002 Hayman Fire resulted in the nearly complete loss of old trees across the landscape. Following the Hayman Fire, only 4 percent of the polygons contained one or more trees more than 200 years old post-fire, and only 3 percent contained one or more trees more than 400 years old.
The researchers conclude that the amount and spatial extent of stand-replacing burning within the Hayman Fire was unprecedented at this landscape over at least the last four centuries.