Restoration and Hazardous Fuel Reduction

Background In California’s mixed-conifer forests, fuel reduction treatments can successfully reduce fire severity, bolster forest resilience, and make lasting changes in forest structure. However, current understanding of the duration of treatment effectiveness is lacking robust empirical evidence.

The synergistic effects of widespread high-severity wildfire and anthropogenic climate change are driving large-scale vegetation conversion. In the southwestern United States, areas that were once dominated by conifer forests are now shrub- or grasslands after high-severity wildfire, an ecosystem conversion that could be permanent without human intervention.

As 21st-century climate and disturbance dynamics depart from historic baselines, ecosystem resilience is uncertain. Multiple drivers are changing simultaneously, and interactions among drivers could amplify ecosystem vulnerability to change. Subalpine forests in Greater Yellowstone (Northern Rocky Mountains, USA) were historically resilient to infrequent (100–300 year), severe fire.

As contemporary wildfire activity intensifies across the western United States, there is increasing recognition that a variety of forest management activities are necessary to restore ecosystem function and reduce wildfire hazard in dry forests. However, the pace and scale of current, active forest management is insufficient to address restoration needs.

Background: The risk of destructive wildfire on fire-prone landscapes with excessive fuel buildup has prompted the use of fuel reduction treatments to protect valued resources from wildfire damage. The question of how to maximize the effectiveness of fuel reduction treatments at landscape scales is important because treating an entire landscape may be undesirable or unfeasible.

Context Addressing ecosystem degradation in the Anthropocene will require ecological restoration across large spatial extents. Identifying areas where natural regeneration will occur without direct resource investment will improve scalability of restoration actions.

Because of past land use changes and changing climate, forests are moving outside of their historical range of variation. As fires become more severe, forest managers are searching for strategies that can restore forest health and reduce fire risk. However, management activities are only one part of a suite of disturbance vectors that shape forest conditions.

Knowledge of how ecocultural landscapes co-evolved, how they were shaped and maintained by local people, and what processes disturbed the landscape should inform the planning, execution, and significance of restoration projects. Indigenous stewardship has resulted in legacies of diverse and productive ecocultural environments.

Mechanical forest thinning treatments are implemented across the western United States (US) to improve forest health and reduce hazardous fuels. However, the main challenge in thinning operations is low financial feasibility.

In the western US, wildfires are modifying the structure, composition, and patterns of forested landscapes at ratesthat far exceed mechanical thinning and prescribed fire treatments. There are conflicting narratives as to whetherthese wildfires are restoring landscape resilience to future climate and wildfires.