Understanding Fire History to Foster Fire Resilience on the Mount Hood Wildfire Crisis Strategy Priority Landscape

Photo Credit

USDA Forest Service

Andrew Merschel leads a field tour with the Wasco County and Hood River Forest Collaboratives and discusses the fire history of a relatively dry Douglas-fir forest.

Forest Service researchers are working with land managers to address questions about fire resilience and examine how wildfire has shaped forest dynamics on the Mount Hood priority landscape to ensure the success of the agency’s 2022 10-year Wildfire Crisis Strategy.

Land managers working on the Mount Hood priority landscape are tasked with implementing the Wildfire Crisis Strategy goals of safeguarding communities, increasing fuels treatments, and supporting postfire restoration. To achieve these goals, they need more information about the effects of wildfire and its historical severity patterns in the mixed Douglas-fir and western hemlock forests that make up this landscape. A common assumption about these forests has been that wildfire generally occurs infrequently and only during severe drought and fire weather.

However, recent research suggests that, based on historical fire return intervals, forests in the western Cascades have missed multiple fire cycles. Pacific Northwest Research Station scientists Andrew Merschel, David Bell, and Matthew Reilly are using a fine-grained sampling approach to refine our understanding of the role that fire plays in forest dynamics on the Mount Hood priority landscape. The approach includes sampling cross sections of old stumps and logs and examining their annual growth rings. Fire scars found in the cross sections provide direct evidence of when and where historical fires occurred. By creating annually precise records of historical fires, researchers can better understand how the tempo of fire and its effects on forest conditions varies in different forest types across the diverse Mount Hood priority landscape.

“One of our goals is a better understanding of historical fire regimes in temperate rainforests of the Pacific Northwest. There’s a lot of debate in the region about where non-stand-replacing fires occurred and how often,” said Merschel. “By creating annually precise records of historical fires and pairing them with datasets on forest development and conditions, which has not been done before, we can add critical information about how historical fires helped shape forested landscapes.”

This approach has the potential to reduce existing uncertainty about the influence of low- to moderate-severity fires on tree establishment and the development of old-growth characteristics, which will help inform ecologically appropriate strategies for promoting fire resilience for the different forest types on this landscape.

The scientists are collaborating with the Mount Hood National Forest and their partners, including forest collaboratives, the Confederated Tribes of Grand Ronde, watershed councils, and environmental organizations. This shared learning approach among partners will increase consensus surrounding appropriate management actions and the quality and pace of their implementation.

“We have questions as scientists, but we are also building in the key questions of land managers,” said Bell. “We are working with these partners to figure out what is a priority for them. We are trying to answer the question of what fire looked like historically in these landscapes, and what work it was doing to create the forests we see today.”

Objectives

• Identify priority forest types and project areas within the Mount Hood Wildfire Crisis Strategy priority landscape for tree-ring reconstructions.
• Refine our understanding of the attributes of historical fire regimes including fire frequency, extent, and severity. 
• Characterize how historical fire regimes influenced successional dynamics and forest conditions. 
• Describe how historical fire regimes, successional dynamics, and forest conditions are related to biophysical setting.

Expected Products

• Workshops and field tours to study sites to describe research methodology and guide interpretation of study results. 
• Translation of research findings through presentations, field trips, and reports to support development of ecologically appropriate strategies (e.g. prescribed fire, thinning and fuels treatments, and no action) that collectively increase fire resilience and restore ecological functions of forest ecosystems on the Mount Hood Wildfire Crisis Strategy priority landscape.

Expected Outcomes

• Improved understanding of fire histories and the effects of excluding fires in sampled forest types. 
• Identification of ecologically appropriate treatments for departed forests. 
• Development of treatment strategies to restore active fire regimes. 
• Increased extent and effectiveness of treated areas. 
• Identification of needed followup treatments by type and interval. 
• Increased partner consensus on restoration needs. 
• Increased support for proposed management on the Mount Hood Wildfire Crisis Strategy priority landscape.

Metrics of Success

Aligning the implementation of the Wildfire Crisis Strategy on the Mount Hood priority landscape with clear documentation of a complex and variable historical fire regime and its variability across a gradient of warm-dry to cool-wet forest ecosystems will provide a scientific basis for building public consensus around strategies to foster landscape resilience to future wildfires.

Keywords: Coproduction, fire regime, forest resilience, low-severity fire, mixed-conifer forest.