After a more than a century of fighting to keep fire out of forests, reintroducing it is now an important management goal. Yet changes over the past century have left prescribed burning with a big job to do. Development, wildfire suppression, rising global temperatures, extended droughts, exotic species invasions, and longer fire seasons add complexity to using this practice.
Managers must consider how often, how intensely, and what time of year to burn; for insights they often look to how and when fires burned historically. However, attempting to mimic historical wildfires that burned in hot, dry conditions is risky. Burning in fall or spring when temperature and humidity are low reduces the risk of prescribed fires becoming uncontrollable, but does it have the intended effects? How do forest ecosystems that historically were adapted to fire respond when fire is reintroduced after so much time without it?
Forest Service researchers Becky Kerns and Michelle Day conducted a long-term experiment in the Malheur National Forest, Oregon, to assess how season and time between prescribed burns affect understory plant communities in ponderosa pine forests. They found that some native plants persisted and recovered from fire but didn’t respond vigorously, while invasive species tended to spread. These findings may help forest managers design more effective prescribed-fire treatments and avoid unintended consequences.
Fuel reduction treatments are designed to meet multiple management objectives, resulting in unique vegetation structures that do not conform to standard classifications and vary considerably over space and time. We evaluated how different post-treatment vegetation structures relate to patterns in wildfire severity. To reconstruct both untreated and treated pre-fire forest structure, we used post-fire stand data measured at three different fuel treatment units burned by the 2011 Wallow Fire (Arizona). We describe (1) how forest structure differs among the treatment units, both in the untreated forest and within the treated area; and (2) how those differences in forest structure explain variability in burn severity. We show that the retention of smaller trees (ladder fuels) for wildlife cover relates significantly to higher severity within one treatment unit. Further variability in within-treatment severity is explained by the severity of the wildfire in the untreated forest as the fire approached the treated area. The untreated forest structure and species composition constrain post-treatment structure and composition, which was related to within-treatment structure and post-fire composition and structure. The study design presented in this paper suggests that evaluations of fuel treatment effectiveness can move beyond simple classifications of treatment type and fire behaviour.
The increasing amount of high-severity wildfire in historical low and mixed-severity fire regimes in western US forests has created a need to better understand the ecological effects of different post fire management approaches. For three different salvage prescriptions, we quantified change in stand structural metrics (snag densities and snag basal areas), dead woody fuel loadings, tree regeneration survival, and percentage change in vegetation cover before and after post-fire logging 1 year after the 2015 Stickpin Wildfire on the Colville National Forest in northeastern Washington State, USA. In a generalized randomized block design three salvage logging prescriptions were randomly assigned within each block: no treatment control (C); standard salvage retention (SSR; thin to 3.4 m2/ha basal area); and mimic green tree thinning (GTR; thin to 10.3 m2/ha basal area). SSR reduced average snag basal area 73–83% to 4.1–8.8 m2/ha (68–674 trees ha−1). GTR reduced average snag (standing dead trees) basal area 41–71% to 6.5–15.9 m2/ha (90–794 trees ha−1). There were mixed results for the change in dead woody fuel loadings depending on fuel size class. In general, fine (FWD) and coarse woody (CWD) debris tended to increase immediately post-treatment in logged areas relative to the controls but did not exceed management loading threshold for providing acceptable risk of fire hazard. Treated stands had a significant increase in FWD relative to controls, including the individual 1-, 10-, and 100-hr fuel size classes. The treatment effect differed by experimental block. The 1000-hr sound class did not have a significant treatment effect. Changes in surface fuel loading were inconsequential to modeled wildfire behavior metrics (rate-of-spread, flame lengths). The Fire and Fuels Extension to Forest Vegetation Simulator (FFE-FVS) modeling projected CWD accumulation in the controls exceeded total accumulation in both treatments. Future fuel loadings may affect reburn severity as our simulated wildfire 20 years after harvesting caused significant mortality (89%) to regenerating forest. Almost all blocks showed a decrease in seedling counts pre and post-logging, including the control plots. This study provides empirical data on the effects of different postfire management strategies that can inform environmental analyses for future post-fire management decision and address social concerns associated with this oftencontroversial practice (Roccaforte et al., 2012).
The Nature Conservancy and the Forest Service, Department of Agriculture have long-term goals to reintroduce fire into U.S. ecosystems at ecologically relevant spatial and temporal scales. Building on decades of collaborative work, a Master Participating Agreement was signed in March 2017 to increase overall fire management capacity through training and education. In October 2017, The Nature Conservancy hosted a cross-boundary fire training, education, research, and restoration-related event for 2 weeks at Sycan Marsh Preserve in Oregon. Eighty people from 15 organizations applied prescribed fire on over 1,200 acres (490 ha). Managers and scientists participated in the applied learning and training exercise. The exercise was a success; operational and research objectives were met, as indicated by multiagency, multidisciplinary fire research, and effectiveness monitoring. This paper describes a paradigm shift of fire-adapted, cross-boundary, multiagency landscape-scale restoration. Participants integrated adaptive management and translational ecology so that applied controlled burning incorporated the most up-to-date scientifically informed management decisions. Scientists worked with practitioners to advance their understanding of the challenges being addressed by managers. The model program has stimulated an exponential increase in landscape-scale and ecologically relevant dry forest restoration in eastern Oregon. Collaboration between managers and scientists is foundational in the long-term success of fire-adapted restoration. Examples of effects of prescribed fire on ecosystem services in the project area, such as increased resilience of trees in drought years, are also provided.
Across the American West, forests have diverse owners and are managed for different goals. But when wildfire ignites on one parcel—whether managed by the USDA Forest Service, a corporation, a tribe, or a family forest land owner—all neighbors are at risk. Fire doesn’t respect property boundaries.
For the past decade, the Forest Service has been promoting an “all-lands” approach that advocates cross-boundary cooperation to reduce fire danger across landscapes with multiple owners. In 2014, the Joint Chiefs’ Landscape Restoration Partnership—a cooperative venture between the Forest Service and the USDA Natural Resources Conservation Service—formed to fund all-lands projects that involve forest and rangeland restoration, including fuels reduction.
Susan Charnley, a research social scientist with the Forest Service’s Pacific Northwest Research Station, and colleagues recently looked at six of these projects in Oregon and California to identify the social factors that lead to success. They found that cross-boundary cooperation can make wildfire mitigation more effective. Other factors that help include funding, trust, reciprocity, technical support, workforce capacity, communication, and an understanding that the benefits of working together outweigh the costs.
As wildfire becomes a more persistent threat across much of the Western United States, information about successful cooperative wildfire management is crucial.
Fine particulate matter, PM2.5, has been documented to have adverse health effects, and wildland fires are a major contributor to PM2.5 air pollution in the USA. Forecasters use numerical models to predict PM2.5 concentrations to warn the public of impending health risk. Statistical methods are needed to calibrate the numerical model forecast using monitor data to reduce bias and quantify uncertainty. Typical model calibration techniques do not allow for errors due to misalignment of geographic locations. We propose a spatiotemporal downscaling methodology that uses image registration techniques to identify the spatial misalignment and accounts for and corrects the bias produced by such warping. Our model is fitted in a Bayesian framework to provide uncertainty quantification of the misalignment and other sources of error. We apply this method to different simulated data sets and show enhanced performance of the method in presence of spatial misalignment. Finally, we apply the method to a large fire in Washington state and show that the proposed method provides more realistic uncertainty quantification than standard methods.
Insects are essential components of forest ecosystems, representing most of the biological diversity and affecting virtually all ecological processes (Schowalter 1994). Most species are beneficial (Coulson and Witter 1984, Haack and Byler 1993), yet others periodically become so abundant that they threaten ecological, economic, social or aesthetic values at local to regional scales (tables 6.1 through 6.3). Insects influence forest ecosystem structure and function in complex and dynamic ways, for example, by regulating certain aspects of primary production; nutrient cycling; ecological succession; and the size, distribution and abundance of plants and other animals (Mattson 1977, Mattson and Addy 1975). Effects on forest vegetation range from being undetectable, to short-term reductions in crown cover, to modest increases in background levels of tree mortality, to extensive amounts of tree mortality observed at regional scales.