Managed wildfires, naturally ignited wildfires that are managed for resource benefit, have the potential to reduce fuel loads and minimize the effects of future wildfires, but have been utilized mainly in remote settings. A new policy federal guidance in 2009 provided greater flexibility for using this tool with the effects of the 2009 changes still not fully understood. In summary, we found that managed wildfires are significantly different and a preferable ecological option to full suppression wildfires mainly due to the reduced high severity proportion and smaller high severity patches. The reduced negative affects associated with managed wildfires are related to the docile weather conditions in which these wildfires burn, mainly after the peak wildfire season. Despite the benefits of managed wildfires, our Western U.S. analysis found that although the number of managed wildfires has increased since 2009 the overall area burned has not significantly changed prior to and following the 2009 policy guidance, particularly in California. However, these managed wildfire patterns vary within the western U.S. Similarly, the majority of managed wildfires are still burning in or close to wilderness areas and away from the wildland urban interface (WUI). Therefore, although the 2009 Guidance has promoted greater use of this fuel reduction tool, the total area burned and location of these treatments have not significantly changed. This suggests that the 2009 policy guidance alone did not alter the overall problem of high fuel loads and homogeneous landscape conditions that continue to facilitate large destructive wildfires across the western US. A review of existing research and preliminary analysis of interviews from 2021 fires indicates that barriers to decisions to authorize a managed wildfire include both environmental and social factors. Environmental factors include burning conditions including weather and fuel conditions. Social factors include internal factors such as agency support and resources and external factors such as perceived public pressure to suppress.

Key Findings The 2009 Policy Guidance led to an estimated 53‐73% increase in the number manage wildfires, with the most notable increases in the Inland Empire, Rocky Mountains and Southwest regions, however, this not necessarily translate to greater area burned.

Managed wildfires tend to burn longer (52 to 11 days for suppression fires), later in the year and during more docile weather conditions, which results in lower percent high severity. In contrast, high severity burn patches in full suppression fires had greater area, reach, aggregation, total core area, were simpler in shape, and decayed slower than patches in managed fires.

Managed and full suppression wildfires are also distinctly different in terms of where they burn. Strategies to manage wildfires for resource benefits are used in remote wilderness areas further from WUI, usually involve a single agency. Moreover, although these geographic characteristics also vary by region they have not changed before and after 2009.

Barriers to managed wildfire are dominated by environmental (burning conditions) as well as social factors including both internal (institutional) and external (public pressure).