Can resource objective wildfire be leveraged to restore old growth forests while stabilizing carbon?
Fire has been removed from many forests in the southwestern U.S. that historically experienced frequent wildfire. In these areas, dense stands of small diameter trees have replaced old growth forest structures, making them vulnerable to uncharacteristically severe wildfires.
These fires can remove large amounts of carbon stored by the forest, impede postfire regeneration, and threaten important wildlife habitat. Treatments like thinning and prescribed burning can be effective at restoring forest structure, but they have not met the vast scale of need. Returning fire to the landscape by managing low- to moderate-severity wildfire when safe to do so could help restore forest health and structure.
Researchers modeled scenarios that incorporated resource objective wildfire and multiple intensities of restoration treatments such as mechanical thinning and prescribed fire to understand how these management practices interact and how they could be used in tandem to achieve desired outcomes over time. They found that the most efficient way to restore old growth ponderosa pine forests was to increase the intensity of restoration treatments and incorporate resource objective wildfire during the spring and fall months.
This approach would also increase the frequency of and area burned by low- to moderate-severity wildfire, ultimately replicating the historic fire regime of ponderosa pine systems. Restoring old growth forests also stabilized how much carbon they emitted versus absorbed, which would help mitigate climate change in the long run by protecting the forest’s carbon sinking capacity.
Like all of the restoration scenarios, expanded use of resource objective wildfire comes with trade-offs. For example, resource objective wildfire during spring and fall more than doubled yearly carbon emission from smoke production, which can also harm human health. Use of resource objective wildfire also poses greater risk of escape and damage to nearby communities. This research can support managers as they weigh trade-offs of various management strategies and their associated long-term outcomes related to old growth restoration, wildfire severity, and carbon dynamics.