Happy Wednesday Fireshed community!
We hope you’re enjoying the first glimpses of spring and have been taking some time to prepare your home and property for fire season (you can visit our resident resources page to learn what steps you can take now). Forestry and fire science are constantly evolving fields as new research provides insight into best practices and climate change projections. We wanted to share with you some new scientific research that will inform forest management and restoration decisions made in our region.
This week’s Wildfire Wednesday features information on:
Overview of fuel treatment effectiveness
Updates on new fuels-reduction research
Upcoming webinar series of interest: Science You Can Use
Best,
Liz
Overview of fuel treatment effectiveness
What are fuel reduction treatments?
Photo credit: Deschutes National Forest
A fuel reduction treatment is a carefully selected treatment to “help reduce and rearrange the amount and continuity of fuel within a forest stand and across the landscape”. These treatments can include “thinning, prescribed burning, pruning, and mechanical understory treatments, such as mastication or mowing” and often include a combination of these treatments. These treatments reduce and rearrange surface fuels, increase the vertical and horizontal distance between tree crowns, retain large-trees, and promote fire-adapted forests while retaining wildlife habitat (OSU extension).
What do we know about fuel reduction treatments?
Through both on-the-ground wildfire and modeling, there is a scientific consensus that fuel reduction treatments have the ability to change fire behavior. Certain treatments, such as thinning and leaving behind slash, can actually create more extreme fire behavior, whereas other treatments, like thinning and surface fuels reduction, can moderate fire behavior. A 2016 meta-analysis of 56 studies concluded that thinning followed by burning treatments had positive effects in terms of reducing fire severity, tree mortality, and crown scorch. Fuel reduction treatments are an important component in protecting the wildland urban interface (WUI). Thinning and fuel breaks can modify fire behavior and protect homes and values at risk and also provide a safer environment for firefighters to protect resources. Fuel reduction treatments, and particularly prescribed fires, are critical to combat the increased frequency, size and severity of wildfires that we’ve experienced in recent decades.
This summary was based off the “Fuel treatment effectiveness” memo from the Forest Stewards Guild written by Dr. Zander Evans.
New fuel-reduction literature
Landscape-scale forest restoration decreases vulnerability to drought mortality under climate change in southwest USA ponderosa forest
“Drought-induced tree mortality is predicted to increase in dry forests across the globe as future projections show hotter, drier climates. This could potentially result in large-scale tree die-offs, changes in species composition, and loss of forest ecosystem services, including carbon storage. While some studies have found that forest stands with greater basal areas (BA) have higher drought mortality, many have not evaluated the extent to which forests restored to lower densities via restoration activities affect drought mortality. The southwestern USA is particularly susceptible to tree mortality due to the predicted increases in temperature, drier soils, and forests with high density.” This paper examined the modeled effect of ponderosa pine mortality in response to a landscape-scale forest restoration project in northern Arizona (Four Forests Restoration Initiative). The results from this paper indicate that forest restoration projects have the potential to mitigate the effects of climate change and subsequent tree mortality.
Highlights:
• Dry western US forests are at risk of large-scale tree die-offs due to hot-drought.
• We modeled forest restoration effects on future ponderosa pine drought mortality.
• Without thinning, mortality will increase 45–57% over current rates by mid-century.
• With thinning, mid-century mortality rates remain near or below contemporary rates.
• Lower tree density can mitigate the effects of climate change on drought mortality.
Effectiveness of fuel treatments at the landscape scale: State of understanding and key research gaps
This literature review synthesized 127 studies related to landscape-scale fueld treatment effectiveness in North American ecosystems. This summary “generally provided evidence that fuel treatments reduced negative outcomes of wildfire and in some cases promoted beneficial wildfire outcomes, although these effects diminished over time following treatment and were influenced by factors such as weather conditions at the time of fire. The simulation studies showed that fuel treatment extent, size, placement, timing, and prescription influenced the degree of effectiveness. Empirical studies, though limited in scope, provided evidence that fuel treatments were effective at reducing the rate of spread, progression, extent, or severity of actual wildfires both within and outside of treated areas. Case studies documented outcomes of specific wildfire events and contained managers’ evaluations of fuel treatment effectiveness. Across the three study types, the importance of treating multiple strata to reduce fuels contributing to fire spread and severity was emphasized. Fuel treatments contributed to fire suppression efforts by reducing costs and facilitating suppression activities such as fireline construction.”
Objectives:
Evaluate the extent to which landscape fuel treatments:
Mitigate adverse effects of wildfire.
Provide opportunities to manage fire for beneficial effects of wildfire.
Provide opportunities for cost efficient fire suppression strategies and maximize firefighter safety.
Provide results to inform future fuel treatment planning.
Identify research gaps.
Science You Can Use Spring 2022 Webinar Series
“Join us for the Spring 2022 Science You Can Use webinar series featuring seven land-manager focused webinars presented by Rocky Mountain Research Station scientists and collaborators. These one-hour sessions will begin with concise presentations followed by Q&A and discussion. Webinars will be hosted on Zoom. Recordings will be posted on this page as soon as they are available.”
Upcoming webinars:
March 30, 10:00 - 11:00 MT
Recent Megafires Provide a Tipping Point for Desertification of Conifer Ecosystems
April 6, 10:00 - 11:00 MT
Accounting for the Benefits of Public Lands
April 13, 10:00 - 11:00 MT
Effects of Forest Management and Climate Scenarios on Biodiversity in the Sierra Nevada Mountains
April 20, 10:00 - 11:00 MT
Effective Communication about Wildfire Management: Observations from 20 years of fire social science research