Post-fire Environment & Management
Workshop website.
About the Workshop: Since 1975, the Natural Hazards Center has hosted the Annual Natural Hazards Research and Applications Workshop in Colorado. Today the Workshop brings together federal, state, and local mitigation and emergency management officials and planning professionals; representatives of nonprofit, private sector, and humanitarian organizations; hazards and disaster researchers; and others dedicated to alleviating the impacts of disasters. You can read more about the Workshop and its history on the Center’s website.
Workshop Information: Information about this year’s theme and opportunities to contribute can be found under the Workshop Info tab above. You can also browse our past Workshops to see previous programs, speakers, and other materials.
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We evaluated how abiotic stress and biotic interactions determine native bunchgrass abundances across environmental gradients using additive models of cover data from over 500 plots re-measured annually for 5 years as they recovered naturally (untreated) after a megafire (>100,000 ha) in sagebrush steppe threated by the invasive-grass and fire cycle. The species included native bunchgrasses, bluebunch wheatgrass and Sandberg bluegrass, and the exotic and invasive annual cheatgrass. We asked whether associations between native bunchgrasses and cheatgrass were context dependent and if the SGH could help predict interspecific associations between species in a semiarid environment. The association of cover of each native bunchgrass to cheatgrass was not uniform, and instead varied from neutral to negative across environmental gradients in both space and time (i.e., weather), to which the species had nonlinear and sometimes threshold-like responses. Consistent with the SGH, bunchgrasses were generally more negatively related to cheatgrass (i.e., putative competition) in conditions which increased the cover of each bunchgrass – which were higher elevations and temperatures and lower solar heatload, and, for Sandberg bluegrass, drier conditions. There were few indications of positive interactions (i.e., putative facilitation) in stressful conditions, and instead associations were again negative, albeit weaker, in some of the conditions evaluated. Synthesis. These findings demonstrate that the negative association among native bunchgrasses and cheatgrass is context dependent and is determined by the abundances of both interacting species which is driven by environmental stress. This led to a hypothesis that together Sandberg bluegrass and bluebunch wheatgrass provide complementary resistance to cheatgrass at the landscape level, despite their different ecology and contrary to the management preference for bluebunch wheatgrass. Sandberg bluegrass might be critical for providing resistance against cheatgrass where invasion potential is greatest, i.e., at lower elevations, where bluebunch wheatgrass is scarce.
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This StoryMap is an overview of some of the work undertaken by FireEarth scientists, serving as an introduction to the project. FireEarth is not a standalone endeavor, as the work draws on past and concurrent efforts in the field of wildfire science, which are referenced when applicable.
The StoryMap is organized around 13 main sections: 1) About the FireEarth StoryMap, 2) An Introduction to Wildfire, 3) FireEarth’s Goal, 4) Cascading Consequences of Fire, 5) Erosion and Runoff, 6) Cascading Consequence: Fire Intensity Impacts, 7) Regional Hydro-Ecologic Simulation System (RHESSys), 8) Smoke and Air Pollution, 9) Reducing Our Vulnerabilities to Wildfire, 10) Community Adaptation to Fire, 11) Biomimicry: Copying Nature to Coexist with Fire, 12) Conclusion, and 13) All FireEarth-Supported Papers.
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Streamflow often increases after fire, but the persistence of this effect and its importance to present and future regional water resources are unclear. This paper addresses these knowledge gaps for the western United States (WUS), where annual forest fire area increased by more than 1,100% during 1984 to 2020. Among 72 forested basins across the WUS that burned between 1984 and 2019, the multibasin mean streamflow was significantly elevated by 0.19 SDs (P < 0.01) for an average of 6 water years postfire, compared to the range of results expected from climate alone. Significance is assessed by comparing prefire and postfire streamflow responses to climate and also to streamflow among 107 control basins that experienced little to no wildfire during the study period. The streamflow response scales with fire extent: among the 29 basins where >20% of forest area burned in a year, streamflow over the first 6 water years postfire increased by a multibasin average of 0.38 SDs, or 30%. Postfire streamflow increases were significant in all four seasons. Historical fire–climate relationships combined with climate model projections suggest that 2021 to 2050 will see repeated years when climate is more fire-conducive than in 2020, the year currently holding the modern record for WUS forest area burned. These findings center on relatively small, minimally managed basins, but our results suggest that burned areas will grow enough over the next 3 decades to enhance streamflow at regional scales. Wildfire is an emerging driver of runoff change that will increasingly alter climate impacts on water supplies and runoff-related risks.
Webinar recording.
The 2019 Museum Fire burned nearly 2,000 acres of steep forested terrain abutting Flagstaff city limits in northern Arizona. In addition to the immediate fire danger, post-fire flooding posed a significant threat to the downstream community and critical infrastructure, prompting a multi-agency cooperation to evaluate post-fire runoff and geomorphic change during the recovery period (Fall 2019 to present). Uniquely, the burn scar experienced two record-dry monsoons in 2019 and 2020 with minor runoff, followed by a significantly wet monsoon in 2021 resulting in multiple post-fire flow events and damage to areas identified to be at risk. The timing of these flow events proves relatively rare as most burn scars in the Southwest experience their first major runoff events between a few weeks and months following fire, with severity of runoff events generally decreasing with time as the scar recovers. This presentation provides a detailed, multi-year documentation of geomorphic change and recovery in the Museum burn scar throughout its unusual recovery history. Additionally, in response to the 2021 flood events, flood mitigation structures were constructed on the floodplain below the Museum scar; the impact of 2022 monsoonal runoff on these structures is currently being evaluated in context with watershed recovery and will be available for future discussion.
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This study expands on a 2011 tribal research needs assessment with a survey to identify tribal natural resource professionals’ research needs, access to research findings, and interest in participating in research. Information needs identified in our survey includes forest health, water quality, culturally significant species, workforce and tribal youth development, cultural importance of water, and invasive species. Additionally, postfire response and valuation, resilience and long-term forestry, protecting and curating tribal data, and Indigenous burning were more important research needs for tribal members than for nontribal members. This study can inform forestry research planning efforts and establish research priorities and collaborations that are aligned with needs identified by tribal natural resource managers.
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We modeled seasonal habitat use by female greater sage-grouse in the Trout Creek Mountains of Oregon and Nevada, USA, to identify landscape characteristics that influenced sage-grouse habitat selection and to create predictive surfaces of seasonal use 1 and 7 years postfire. We developed three resource selection function models using GPS location data from 2013 to 2019 for three biologically distinct seasons (breeding, n = 149 individuals: 8 March–12 June; summer, n = 140 individuals: 13 June–20 October; and winter, n = 94 individuals: 21 October–7 March). For all seasons, by the fourth or fifth year postfire, sage-grouse selected for unburned patches more than all other burn severity patches and the use of unburned areas in comparison with burned areas increased through time. During the breeding season, sage-grouse selected for low-sagebrush -dominated ecosystems and areas with low biomass (normalized difference vegetation index). During summer, sage-grouse selected for areas with higher annual and perennial grasses and forb cover, and areas that had higher biomass. During winter, sage-grouse selected for areas of intact sagebrush on less rugged terrain. For the winter and breeding season, there was a positive linear relationship between annual grasses and forb cover through time. Seven years postfire (2019), the area predicted to have a high probability of use in each seasonal range decreased (breeding: 16.4%; summer: 12.2%; and winter: 4.2%), while the area predicted to have low or low-medium probability of use increased (breeding: 14.5%; summer: 22.5%; and winter: 22.8%) when compared to the first year following the wildfire (2013). Our results demonstrated a 4- to 5-year time lag before female sage-grouse adapted to a disturbed landscape began avoiding burned areas more than intact, unburned habitats. This mismatch in ecological response may imply declines in habitat availability for sage-grouse and may destabilize population vital rates. Spatially explicit models can aid in identifying priority areas for restoration efforts and conservation actions to mitigate the impacts of future disturbances.
Webinar recordings.
- Monday, November 14 SCIENCE x Forests: Silviculture for the present and future
A compendium of silviculture treatments for forest types in the United States: Silviculture guidance to support modeling, scenario planning, and large-scale simulations, presented by Thomas Schuler
Prescribed burning considerations following mechanical treatments, presented by Sharon Hood
Reforestation in an era of megafires: A wicked problem for the Forest Service in Region 5 and elsewhere, presented by Martin Ritchie - Tuesday, November 15 SCIENCE x Forests: Forests and climate change
Preparing our forests for the future, presented by Mike Battaglia
The Pacific Northwest carbon dynamics research initiative: Co-production to assist land managers and policy makers, presented by Andrew Gray
Sink, swim, or surf: Surging climate change impacts and the role of climate-adaptive silviculture, presented by Alejandro Royo - Wednesday, November 16 SCIENCE x Forests: Innovations in forest research
From the forest to the faucet: Tools and data linking surface water from forested lands to public water systems, presented by Peter Caldwell
Cloud computing advances regional old-growth forest monitoring for the Northwest Forest Plan, presented by David M Bell
What is resilience in frequent-fire forests and how can it be measured?, presented by Malcolm North - Thursday, November 17 SCIENCE x Forests: Urban forestry, community, and wood utilization
The science and practice of urban silviculture, presented by Nancy Sonti and Rich Hallett
Expanding urban wood utilization, presented by Charlie Becker
Not by trees alone: Centering community in urban forestry, presented by Lindsay Campbell - Friday, November 18 SCIENCE x Forests: Invasion and outbreaks in forests
Species home-making in ecosystems: Toward place-based ecological metrics of belonging, presented by Susan Cordell
Invasion and outbreak within an epidemiological model, presented by Rima Lucardi
Mapping Armillaria-killed trees with high-resolution remote sensing, presented by Benjamin Bright
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A slight, gradual decline in total C and N was found with increasing temperature and heat duration, reaching a maximum loss of 14–18% of the total at the highest heat load. Available NH4 increased linearly starting at 150–175 °C and reached a maximum 15-fold increase relative to unburned soil by 450 °C. Nitrification (30-d post-fire) was low regardless of treatment and was essentially eliminated at the highest temperatures. Microbial biomass declined curvilinearly with increased heating, approaching 65% loss compared to unburned soil, and was most rapid in moist soil once temperatures exceeded 60–70 °C. Ultimately, we found no evidence of abrupt heat thresholds for these common soil properties. Instead, property changes followed a slightly declining trajectory (soil C, N, NO3, fungal hyphae) or a steady incremental increase (NH4) or decrease (microbial biomass).