Fuels & Fuel Treatments
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Two of the principal functional groups of the understory vegetation (grasses and forbs) respond positively to tree removal by any means, with grasses—both annual and perennial—showing the greatest increases to both burning and cutting over the ten-year time period. This was an expected result, because it was assumed that understory species were significantly suppressed prior to treatment by pinyon and juniper trees on the landscape as a result of competition for resources, principally water (but possibly also light). If the hypothesis of competition for water were true, then we would expect to also see an increase in water resources in the soil after trees were removed, mirroring the response in the understory vegetation.
Prescribed fire and mow treatments maintained fire behavior below this threshold for extreme fire behavior, and in early years even kept it within the 4 ft control mark. Control and tebuthiuron treatments can be expected to have fire behavior that is more difficult to control.
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This study applied a remote sensing change detection approach to map reductions in pinyon-juniper cover across the sage-grouse range and developed a method for rapidly updating maps of canopy cover. We found total conifer reduction over the past several years (2011−2013 to 2015−2017) amounted to 1.6% of the area supporting tree cover within our study area, which is likely just keeping pace with estimates of expansion. Two-thirds of conifer reduction was attributed to active management (1.04% of the treed area) while wildfire accounted for one-third of all estimated conifer reduction in the region (0.56% of the treed area). Results also illustrate the breadth of this management effort—crossing ownership, agency, and state boundaries.
Description: Recent advances in wildland fire behavior models (e.g. FIRETEC) utilizing high spatial and temporal resolution fluid dynamics calculations have facilitated complex modeling of fire-atmospheric feedbacks. Unfortunately this fire modeling approach requires exceptional computational resources that are unlikely to be available to most wildland fire managers. QUIC-Fire is a new physics-based cellular automata fire spread tool that that offers advanced fire modeling capabilities without the demand for extraordinary computational resources. QUIC-Fire is a new step towards expanding next generation fire model access to a wider audience of practitioners and users.
Presenters: Rodd Linn, Los Alamos National Lab, Scott Goodrick, USFS Southern Research Station, Kevin Hiers, Tall Timbers Research Station.
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This study looked at sites with high cover of biocrusts prior to treatments, it demonstrates positive effects of the herbicide, tebuthiuron on lichens with an increase in cover of 10% and trending towards slightly negative effects on moss cover. Across plots, imazapic trended towards a decrease in lichen and moss cover without being statistically significant. Mowing and prescribed fire reduced cover of mosses, with the latter leading to greater declines across sites (declines of 18% vs. 32%). Reductions in moss cover mirrored gains in cover of bare soil, which is associated with increased risk of invasion by grasses responsible for increasing fire risk. The study demonstrates that the use of herbicides simultaneously reduces fuels and maintains greater cover of lichens and mosses compared with other fuel‐reduction treatments, possibly reducing risk of invasion by annual grasses that are responsible for increasing fire risk.
Description: Oregon State University’s Forestry & Natural Resources Extension Fire Program and its partners present a webinar series on Wildfire Preparedness and Prevention in Oregon. The first of three webinars focuses on wildfire awareness. What is the wildfire problem? What are the current conditions? How could the COVID-19 pandemic affect wildfire response? How can we prevent wildfires from starting? These are questions that will be addressed by a panel of speakers.
Presenters:
Mike Totey, Oregon Department of Forestry
Daniel Leavell, Oregon State University
Kristin Babbs, Keep Oregon Green
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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.
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Fuel treatments are widely used to alter fuels in forested ecosystems to mitigate wildfire behavior and effects. However, few studies have examined long-term ecological effects of interacting fuel treatments (commercial harvests, pre-commercial thinnings, pile and burning, and prescribed fire) and wildfire. Using annually fitted Landsat satellite-derived Normalized Burn Ratio (NBR) curves and paired pre-fire treated and untreated field sites, we tested changes in the differenced NBR (dNBR) and years since treatment as predictors of biophysical attributes one and nine years after the 2007 Egley Fire Complex in Oregon, USA. We also assessed short- and long-term fuel treatment impacts on field-measured attributes one and nine years post fire.
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We argue that prescribed fire science requires a fundamentally different approach to connecting related disciplines of physical, natural, and social sciences. We also posit that research aimed at questions relevant to prescribed fire will improve overall wildland fire science and stimulate the development of useful knowledge about managed wildfires. Because prescribed fires are increasingly promoted and applied for wildfire management and are intentionally ignited to meet policy and land manager objectives, a broader research agenda incorporating the unique features of prescribed fire is needed. We highlight the primary differences between prescribed fire science and wildfire science in the study of fuels, fire behavior, fire weather, fire effects, and fire social science. Wildfires managed for resource benefits (“managed wildfires”) offer a bridge for linking these science frameworks. A recognition of the unique science needs related to prescribed fire will be key to addressing the global challenge of managing wildland fire for long-term sustainability of natural resources.
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This study evaluated drivers of fire severity and fuel treatment effectiveness in the 2014 Carlton Complex, a record‐setting complex of wildfires in north‐central Washington State. All treatment areas burned with higher proportions of moderate and high severity fire during early fire progressions, but thin and underburn, underburn only, and past wildfires were more effective than thin‐only and thin and pile burn treatments. Treatment units had much greater percentages of unburned and low severity area in later progressions that burned under milder fire weather conditions, and differences between treatments were less pronounced. Our results provide evidence that strategic placement of fuels reduction treatments can effectively reduce localized fire spread and severity even under severe fire weather. During wind‐driven fire spread progressions, fuel treatments that were located on leeward slopes tended to have lower fire severity than treatments located on windward slopes. As fire and fuels managers evaluate options for increasing landscape resilience to future climate change and wildfires, strategic placement of fuel treatments may be guided by retrospective studies of past large wildfire events.
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The primary objective of this study was to explore the application of a dynamic global vegetation model (DGVM), the Ecosystem Demography (EDv2.2), to understand vegetation dynamics and ecosystem productivity in varying climate and fire scenarios. Most vegetation models do not represent sagebrush’s physical and physiological functions. Thus, we developed a sagebrush plant functional type (PFT) to use in modeling. Associated with this, the researchers performed a series of analyses and evaluations of the sagebrush and in the context of scenarios under natural (undisturbed) and disturbed (fire) environments.
- Results indicate that a number of sagebrush parameters are most sensitive to how productive the plant is (in our model). These include specific leaf area (SLA), stomatal slope, fine root turnover rate, cuticular conductance, and maximum carboxylation rate. These findings allow future sagebrush modeling efforts to further refine these parameters in different environments.
- The researchers comparisons between model runs and field data from Reynold Creek Experimental Watershed (RCEW), show good agreement. Improvements are needed to refine the model with additional PFTs representative of a range of elevations in the Great Basin.
- The researchers fire scenario modeling suggested that fire substantially reduced shrub gross primary production (GPP) and it took several decades before it was restored to pre-fire conditions. Grass GPP, however, responded more quickly in post-fire conditions. While these processes are representative of field observations and other studies, additional PFTs and improvement in fire routines in the model will provide for a better prognosis of future ecosystem dynamics of the sagebrush-steppe.