Fire Ecology & Effects
Webinar recording.
Area burned by wildland fire has been increasing since the mid-1980s across much of the US. But the effects of fire on vegetation and soil – what we call burn severity or fire severity – is maybe the more important measure, ecologically speaking. Stand-replacing, or high-severity fire, for example, is more likely than low-severity fire to negatively impact ecosystems by increasing post-fire erosion potential, catalyzing conversions from forest to non-forest, and reducing carbon stocks. While high-severity fire has its place in the natural cycles of some ecosystems, it also can pose societal problems by jeopardizing human safety and infrastructure. In this webinar, we will briefly describe new approaches to mapping the severity of past fires using satellite imagery and cloud-based computing. The main focus of this webinar, however, will highlight recent advancements in modeling and predictive mapping of near-future burn severity; the mapped products predict the probability of high-severity fire, if a fire were to occur. Maps characterizing fire severity, whether they characterize past fires or represent predictions of the near-future, provide important information for managers and scientists who are tasked with managing fuel and wildland fire.
National and regional preparedness level (PL) designations support decisions about wildfire risk management. Such decisions occur across the fire season and influence pre-positioning of resources in areas of greatest fire potential, recall of personnel from off-duty status, requests for back-up resources from other areas, responses to requests to share resources with other regions during fire events, and decisions about fuel treatment and risk reduction, such as prescribed burning. In this paper, we assess the association between PLs assigned at national and regional (Northwest) scales and a set of predictors including meteorological and climate variables, wildfire activity and the mobilisation and allocation levels of fire suppression resources. To better understand the implicit weighting applied to these factors in setting PLs, we discern the qualitative and quantitative factors associated with PL designations by statistical analysis of the historical record of PLs across a range of conditions. Our analysis constitutes an important step towards efforts to forecast PLs and to support the future projection and anticipation of firefighting resource demand, thereby aiding wildfire risk management, planning and preparedness.
Managed wildfire is an increasingly relevant management option to restore variability in vegetation structure within fire-suppressed montane forests in western North America. Managed wildfire often reduces tree cover and density, potentially leading to increases in soil moisture availability, water storage in soils and groundwater, and streamflow. However, the potential hydrologic impacts of managed wildfire in montane watersheds remain uncertain and are likely context dependent. Here, we characterize the response of vegetation and soil moisture to 47 years (1971–2018) of managed wildfire in Sugarloaf Creek Basin (SCB) in Sequoia-Kings Canyon National Park in the Sierra Nevada, California, USA, using repeat plot measurements, remote sensing of vegetation, and a combination of continuous in situ and episodic spatially distributed soil moisture measurements. We find that, by comparison to a nearby watershed with higher vegetation productivity and greater fire frequency, the managed wildfire regime at SCB caused relatively little change in dominant vegetation over the 47 year period and relatively little response of soil moisture. Fire occurrence was limited to drier mixed-conifer sites; fire-caused overstory tree mortality patches were generally less than 10 ha, and fires had little effect on removing mid- and lower strata trees. Few dense meadow areas were created by fire, with most forest conversion leading to sparse meadow and shrub areas, which had similar soil moisture profiles to nearby mixed-conifer vegetation. Future fires in SCB could be managed to encourage greater tree mortality adjacent to wetlands to increase soil moisture, although the potential hydrologic benefits of the program in drier basins such as this one may be limited.
Webinar recording.
Description: Burn severity is the ecological change resulting from wildland fires. Areas burned with high severity are of concern to land managers and others because postfire vegetation, soil, and other important ecosystem components can be highly altered. Using satellite-derived maps of burn severity for almost 12,000 fires, researchers at the US Forest Service, Rocky Mountain Research Station developed statistical models to describe the spatial distribution of high-severity fire and produce a predictive map of severe fire potential for the contiguous United States. In this webinar, hear about methods used in this study and how the results and data products can be useful to scientists and land managers.
Presenter: Greg Dillon, Spatial Fire Analyst, U.S. Forest Service
View article.
Approximately 75% of models tested had acceptable, excellent, or outstanding predictive ability. The models that performed poorly were primarily models predicting stem mortality of angiosperms or tree mortality of thin-barked conifers. This suggests that different approaches—such as different model forms, better estimates of bark thickness, and additional predictors—may be warranted for these taxa. Future data collection and research should target the geographical and taxonomic data gaps and poorly performing models identified in this study. Our evaluation of post-fire tree mortality models is the most comprehensive effort to date and allows users to have a clear understanding of the expected accuracy in predicting tree death from fire for 44 species.
Pygmy rabbits, greater sage grouse, songbirds, and Umtanum desert buckwheat…oh my! Learn how fire and land management can impact key threatened and endangered species and the top three things to take into consideration before taking action where these species call sage brush their home.
Alison Dean, Central Oregon Fire Management Service and U.S. Bureau of Land Management, and Marth Brabec, City of Boise, will provide an overview of historic and modern fire behavior in different communities of the sagebrush biome, shrub steppe ecology, and post-fire restoration considerations.
Webinar recording.
Description: Changing disturbance regimes and climate can overcome forest ecosystem resilience. Following high-severity fire, forest recovery may be compromised by lack of tree seed sources, warmer and drier postfire climate, or short-interval reburning. A potential outcome of the loss of resilience is the conversion of the prefire forest to a different forest type or nonforest vegetation. Conversion implies major, extensive, and enduring changes in dominant species, life forms, or functions, with impacts on ecosystem services. The webinar will synthesize a growing body of evidence of fire-driven conversion and our understanding of its causes across western North America. Increasing forest vulnerability to changing fire activity and climate compels shifts in management approaches, and we propose key themes for applied research coproduced by scientists and managers to support decision-making in an era when the prefire forest may not return.
Presenters: Jonathan Coop, Western Colorado University; Sean Parks, US Forest Service; Camille Stevens-Rumann, Colorado State University
This open access book synthesizes leading-edge science and management information about forest and rangeland soils of the United States. It offers ways to better understand changing conditions and their impacts on soils, and explores directions that positively affect the future of forest and rangeland soil health. This book outlines soil processes and identifies the research needed to manage forest and rangeland soils in the United States. Chapters give an overview of the state of forest and rangeland soils research in the Nation, including multi-decadal programs (chapter 1), then summarizes various human-caused and natural impacts and their effects on soil carbon, hydrology, biogeochemistry, and biological diversity (chapters 2-5). Other chapters look at the effects of changing conditions on forest soils in wetland and urban settings (chapters 6-7). Impacts include: climate change, severe wildfires, invasive species, pests and diseases, pollution, and land use change. Chapter 8 considers approaches to maintaining or regaining forest and rangeland soil health in the face of these varied impacts. Mapping, monitoring, and data sharing are discussed in chapter 9 as ways to leverage scientific and human resources to address soil health at scales from the landscape to the individual parcel (monitoring networks, data sharing Web sites, and educational soils-centered programs are tabulated in appendix B). Chapter 10 highlights opportunities for deepening our understanding of soils and for sustaining long-term ecosystem health and appendix C summarizes research needs. Nine regional summaries (appendix A) offer a more detailed look at forest and rangeland soils in the United States and its Affiliates.
View literature review.
To inform future restoration efforts, we reviewed the known effects of fire and habitat management and restoration on hummingbirds in four key habitat types in North America. We examined seven species that most commonly occur west of the Rocky Mountains: Rufous (Selasphorus rufus), Calliope (S. calliope), Broad-tailed (S. platycercus), Costa’s (Calypte costae), Black-chinned (Archilochus alexandri), Anna’s
(Calypte anna), and Allen’s (S. sasin). Our review found that most western hummingbird species respond positively to wild or prescribed fire in forested and chaparral habitats of the western United States, although some hummingbird occurrence declines following fire, possibly due to the loss of preferred nesting habitat in mature forests. Restoration practices that eradicate exotic plants, encourage the regeneration of native shrubs
and flowering plants (especially understory vegetation), and promote early and midsuccessional habitats connected with native stand trees will benefit hummingbirds by providing foraging habitat in migration and on breeding grounds. Restoration practices that encourage the regeneration of native shrubs, understory vegetation, and native epiphytes, while maintaining forest canopy, can also benefit hummingbirds. We also identify many critical
research questions and needs which, if addressed, would improve the quantification of pre- and postfire and habitat management impacts on hummingbirds, especially Allen’s and Rufous populations, which are experiencing steep population declines.