Fire Regimes

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Disturbance and sustainability in forests of the western US

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This report assesses recent forest disturbance in the Western United States and discusses implications for sustainability. Individual chapters focus on fire, drought, insects, disease, invasive plants, and socioeconomic impacts. Disturbance data came from a variety of sources, including the Forest Inventory and Analysis program, Forest Health Protection, and the National Interagency Fire Center. Disturbance trends with the potential to affect forest sustainability include alterations in fire regimes, periods of drought in some parts of the region, and increases in invasive plants, insects, and disease. Climate affects most disturbance processes, particularly drought, fire, and biotic disturbances, and climate change is expected to continue to affect disturbance processes in various ways and degrees.

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Great Basin pinyon and juniper: Ecology, history, and restoration website

Visit the PJ website, authored by Rick Miller

Pinyon (Pinus spp.) and juniper (Juniperus spp.) woodlands occupy over 78,000 square miles of the Great Basin and northern Colorado Plateau. These woodlands have persisted for tens of thousands of years and provide important biodiversity and habitat for many species across the region. Yet, relatively recent infill of new trees into old-growth woodlands and expansion of trees into adjacent sagebrush-steppe, riparian, and aspen communities have created a considerable mix of concerns around wildfire, drought-mortality, invasive species, watershed function, tree removal, and loss of habitat, biodiversity, and resilience.

This website provides background information on the ecology and management of PJ woodlands useful to the interested public and emerging information important to resource managers.
1) PJ 101 provides a brief introduction to and description of PJ woodlands with links to more in-depth information.
2) FAQ (Frequently Asked Questions) briefly addresses questions related to the ecology and management of PJ woodlands.
3) Tools provides information and concepts for evaluating landscapes, which are specifically useful for predicting disturbance or vegetation management responses in PJ woodlands.
4) Literature provides brief summaries and links to recently published PJ woodlands studies. Study findings are highlighted and discussed in terms of our current understanding.

This website will be continually updated with new articles, questions, and tools.

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How climate change and fire exclusion drive wildfire regimes at actionable scales

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Extreme wildfires are increasing in frequency globally, prompting new efforts to mitigate risk. The ecological appropriateness of risk mitigation strategies, however, depends on what factors are driving these increases. While regional syntheses attribute increases in fire activity to both climate change and fuel accumulation through fire exclusion, they have not disaggregated causal drivers at scales where land management is implemented. Recent advances in fire regime modeling can help us understand which drivers dominate at management-relevant scales. We conducted fire regime simulations using historical climate and fire exclusion scenarios across two watersheds in the Inland Northwestern U.S., which occur at different positions along an aridity continuum. In one watershed, climate change was the key driver increasing burn probability and the frequency of large fires; in the other, fire exclusion dominated in some locations. We also demonstrate that some areas become more fuel-limited as fire-season aridity increases due to climate change. Thus, even within watersheds, fuel management must be spatially and temporally explicit to optimize effectiveness. To guide management, we show that spatial estimates of soil aridity (or temporally averaged soil moisture) can provide a relatively simple, first-order indicator of where in a watershed fire regime is climate vs. fuel-limited and where fire regimes are most vulnerable to change.

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Weekly CA fire science seminar series

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This online seminar series will cover the breadth of wildland fire research relevant to California and introduce researchers to new topics and research groups across the state. Topics will include fire weather, wildfire risk, fire ecology, remote sensing, emissions, fire dynamics, fire modeling and public health. Featuring many early-career researchers, this series is aimed at a highly interdisciplinary academic audience but is open to anyone interested in these topics.

View an up-to-date schedule here: https://frg.berkeley.edu/california-fire-science-seminar-series/

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The effects of prescribed fire on wildfire regimes and impacts

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Prescribed fire can result in significant benefits to ecosystems and society. Examples include improved wildlife habitat, enhanced biodiversity, reduced threat of destructive wildfire, and enhanced ecosystem resilience. Prescribed fire can also come with costs, such as reduced air quality and impacts to fire sensitive species. To plan for appropriate use of prescribed fire, managers need information on the tradeoffs between prescribed fire and wildfire regimes. In this study, we argue that information on tradeoffs should be presented at spatial and temporal scales commensurate with the scales at which these processes occur and that simulation modeling exercises should include some realistic measure of wildfire probability. To that end, we synthesized available scientific literature on relationships between prescribed fire and wildfire regimes, and their associated ecological and societal effects, focusing specifically on simulation modeling studies that consider wildfire probability and empirical and modeling studies that consider prescribed fire and wildfire regimes at spatial and temporal scales beyond individual events.

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Patterns and trends in wildfire activity in the US from 1984-2015

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This study shows that simultaneous wildfire is at least as correlated with preparedness levels as other burned area measures and identify changes in simultaneous wildfire occurrence within the western and southern United States. Seasonal variation and spatial autocorrelation in simultaneous wildfire occurrence provide evidence of coupling of wildfire activity in portions of the western United States. Best-approximating models of simultaneity suggest that high levels of simultaneous wildfire often coincided with low fuel moisture and high levels of lightning occurrence. Model uncertainty was high in some contexts but, with only a few exceptions, there was strong evidence that the best model should include both a dryness and lightning indicator.

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Invasive Annual Grass Workshop

Workshop information.

Invasive annual grasses threaten millions of acres of sagebrush rangelands across the west. This two day workshop hosted by the Harney County Wildfire Collaborative and Oregon SageCon Partnership will explore the barriers and opportunities for addressing invasive annual grasses in Oregon and beyond the state. In this workshop some of the most pressing issues related to invasive annual grass management will be discussed, including the connection between invasive annual grasses and wildfire and what can be done to better address this threat.

VIRTUAL Workshop Dates & Agenda
Monday, December 14, 12:30-4:30pm: Defend the Core—Keeping the Good, Good

  • Hard truths of invasive annual grasses
  • Stopping the Spread
  • Supersizing Suppression Success
  • Reducing Wildfire Risk
  • Ratcheting Up Resiliency

Tuesday, December 15, 8:30am-12:30pm: Grow the Core—Restoring At-Risk and Converted Lands

  • Managing Invasive Annual Grasses
  • Innovative Restoration
  • Prioritizing Limited Resources & Sustaining Long-term Investment
  • Where Do We Go From Here
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Restoration in a fire forest: The benefits of burning

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Wildfire has historically played an important role in the health and structure of Oregon’s dry forests. Prescribed fire is a valuable tool used to restore forest health, increase firefighter safety, and better protect nearby human resources in these fire-adapted landscapes.

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Misconceptions and benefits of fire

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The most common misconception of wildfire is that all fire is bad. But there are important benefits that smaller and more frequent fires offer to the environment. Matt Jolly, an ecologist at the U.S. Forest Service Rocky Mountain Research Station, talks about the natural and important role of fire in maintaining a healthy ecosystem.

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Re-introducing fire in sagebrush steppe experiencing decreased fire frequency: Does burning promote spatial and temporal heterogeneity?

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Fire frequency has decreased in many shrub-steppe communities. Re-introducing fire may be needed to increase spatial and temporal variability in vegetation, but is often hindered by concerns of undesired vegetation shifts. These concerns arise, in part, because long-term effects of fire re-introduction in these communities after prolonged fire exclusion and other departures from historical conditions are unknown. To better understand the effects of re-introducing fire, we evaluated plant community response to re-introducing fire for 12 years post fire in six mountain big sagebrush communities. Herbaceous biomass production was 1.7-fold greater in burned compared with unburned areas at the conclusion of the study. Exotic annual grasses appeared to be problematic in the first 8 years post fire, but became inconsequential (~1% cover) by the end of the study. Re-introducing fire promoted other shrubs (excluding sagebrush) that were probably inhibited by competition from sagebrush. Sagebrush cover and density remained low in burned areas for the duration of the study, because of limited recruitment in the years immediately post fire and competition from herbaceous vegetation. Re-introducing fire appears to increase temporal and spatial heterogeneity in shrub-steppe communities experiencing prolonged fire exclusion and, therefore, may be needed to maintain a diversity of plant communities.

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