Fire Regimes

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Historical range of variability (HRV): Uses and various approaches

Webinar recording.

Description: Range of Variability (ROV) concepts – including Natural (NRV), Historic (HRV), Current (CRV), and Future (FRV) – are frequently used by the US Forest Service to help define land management goals. This webinar provides an introduction to ROV terminology and examples of how the Malheur, Umatilla, and Wallowa-Whitman National Forests in the Blue Mountains have applied ROV concepts during project planning when addressing key requirements of the Eastside Screens. The discussion includes overviews of tools commonly used to conduct ROV analyses.

Presenter: Nathan Poage, Forest Service Ecologist,

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Wildfire trends across the western US: Forest fires have increased in size, severity, and frequency across western forests

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Wildfire across the western US has increased in size, frequency, and severity since the 1950s. These changes are closely linked with increases in temperature and an increased frequency and intensity of drought. Historically, frequent low to moderate-severity fires dominated the fire regime in many western forests, maintaining low-density forests with larger trees. A history of fire exclusion, logging activity, grazing, and invasive species has led to an uncharacteristic build-up of forest fuels in many areas, increasing the susceptibility to large-scale, high-severity wildfire. The US has a history of fire suppression efforts that has exacerbated the problem by increasing the density of trees and fuel availability, and reduced the overall area burned by wildfires to levels that are below those that occurred before the beginning of the 20th century.

The western US is also experiencing larger, more severe fires that are often near communities. In recent decades, the build-up of forest fuels, a warmer and drier climate, and expansion of the wildland-urban interface (WUI) into forested areas has changed western landscapes and increased wildfire hazard. Federal policy and management have primarily focused on fire suppression and more recently on fuels reduction on some federal lands. Forest restoration and fuels reduction projects have had positive ecological impacts; however, the pace and scale of forest treatments is not keeping up with heightened wildfire activity across the West.

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Science supporting dry forest and rangeland planning

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The Northeastern California Plateaus Bioregion Science Synthesis reviews literature relevant to the ecology and management of the Great Basin ecosystems and dry pine forests of the Lassen and Modoc National Forests. Critical factors on these national forests are reduced water availability—expected to become more challenging as levels and patterns of precipitation and temperature change under climate variability—coupled with a high proportion of rangeland and open woodland whose vegetation community is influenced by grazing of livestock and wild animal populations. Conifer encroachment of rangelands and the densification of woodlands, a result of fire suppression, impact wildlife communities that rely on open woodlands and other habitats characterized by having overstories of low density. Sagebrush habitat, in particular, is threatened by fragmentation and conversion. Socioeconomic changes in the region include a transition in the economic base from extraction to that of consumption of amenity values, and the resulting fragmentation of landownership. The local human population is expected to continue its trend of decline, but increased pressure by recreationists from nearby expanding urban areas is forcing land managers to consider increasingly complex situations or actions integrating social, ecological, and economic factors. Indigenous peoples are assuming a greater role in the management of their lands. Finally, disturbance patterns, such as nonhistorical fire frequency and intensity levels, novel combinations of climate patterns, and the pervasive pressure of nonnative invasive species could result in future ecosystems different than those today, presenting additional managerial challenges. This synthesis is intended to serve as a science-based foundation that supports management of Northeastern California forests, woodlands, and rangelands.

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Forecasting fire regime changes by mapping driver changes across California

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This California Fire Regime Ecoregion classification map (i.e., using clustered driver variability layers) aims to devise a fire regime classification that better aligns with ecosystem types.

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Why is sagebrush country on fire?

Webinar recording.

Overview: Invasive annual grasses are quickly expanding across the West, dramatically changing sagebrush country. Today we are experiencing more frequent and hotter wildfires that are harmful to communities, western lands, and wildlife. This webinar discusses the wildfire trends, identify the culprits, the impacts, and break down the challenges/opportunities.

Presenter: Michele Crist, leading landscape ecologist with the National Interagency Fire Center.

Resources and information referenced in the webinar available on the SageWest website.

Sea of cheatgrass

The Cheatgrass Challenge: Resources, Efforts, and Partnerships

Cheatgrass Challenge webpage.

The Bureau of Land Management (BLM) and Natural Resources Conservation Service (NRCS) in Idaho and Wyoming have teamed up with each other along with partners in their respective states to address cheatgrass proliferation in the West. The Cheatgrass Challenge is a call to arms for agricultural producers, federal and state agencies, educational institutions and non-profit organizations.

As the Challenge develops, the webpage will be updated with additional information and resources, so check back regularly for updates.

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2020 Natural Areas Virtual Conference: Sierra to Sagebrush

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The 2020 Natural Areas Virtual Conference- Sierra to sagebrush: Integrating management and stewardship across landscapes was an engaging virtual format providing as much research, technique and practical application of science as you have come to expect at a Natural Areas Conference.

The 47th Natural Areas Conference is focused on the unique ecological and management dynamics that distinguish the Nevada-California borderlands, the Great Basin and Sierra mountains.  This conference is designed to bring together land and resource managers, scientists, and policy makers to share and discuss creative ideas that cross disciplines, ecosystems, and jurisdictional boundaries. These interactions are critical to solving landscape scale issues in the region.


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12 Years of Wildland fire science at the USGS: Publications, 2006–17

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In this report, we identify and characterize scientific literature produced by USGS scientists during 2006–17 that addresses topics associated with wildland fire science. Our goals were to (1) make the most complete list possible of product citations readily available in an organized format, and (2) use bibliometric analysis approaches to highlight the productivity of USGS scientists and the impact of contributions that the Bureau has provided to the scientific, land management, and fire management communities.

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Human altered disturbance patterns and forest succession: Impacts of competition and ungulate herbivory

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Using a region-wide exclosure network across a broad gradient of aspen–conifer overstory abundance, we empirically tested the effects of ungulate herbivory and conifer competition (that increases with fire suppression), on the regeneration and recruitment of aspen forests over a 4-year period. The study results indicate that ungulate herbivory and increasing abundance of overstory conifers dramatically reduced aspen regeneration and recruitment success. The average height of aspen suckers exposed to ungulate herbivory was 72% shorter than aspen suckers in fenced plots and resulted in 24% less recruitment. There was a 9% decrease in aspen recruitment and 12% decrease in average aspen height with every 20% increase in overstory conifer density. Aspen suckers were most vulnerable to herbivory at 70 cm height, with the probability of herbivory decreasing under 50 cm or above 90 cm. Steep slope angles and higher winter precipitation increased aspen regeneration and recruitment success. Reduction in aspen recruitment in response to ungulate herbivory and competition by conifers may result in loss of biodiversity, altered forest function and loss of key ecosystem services because of the important role that aspen plays in facilitating forest succession and biodiversity.

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Burn severity effects on plant diversity and composition in mixed conifer

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This study found that the understory plant community was not fundamentally altered by these fires and fire contributed to increased species diversity both locally and regionally, suggesting that low to moderate burn severity fire is a treatment that contributes to long-term maintenance of a diverse and productive understory. Individual species traits were significant drivers of understory species assemblages and, as future change in climate and fire regimes leads to shifts in species composition, anticipation of consequences will be important. Although invasive species occurred at low cover levels, noxious weeds and invasive annual grasses will continue to be management challenges, particularly in dry regions of mixed conifer forests.

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