In our efforts to predict fire danger, we coupled CAL FIRE (California Department of Forestry and Fire Protection) FRAP (Fire and Resource Assessment Program) fire data with hourly climate data from four stations, and with regional indices of SAW wind speed, and with seasonal drought data from the Palmer Drought Severity Index. We found that different tools work better for SAW fires versus non-SAW fires.

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In our efforts to predict fire danger, we coupled CAL FIRE (California Department of Forestry and Fire Protection) FRAP (Fire and Resource Assessment Program) fire data with hourly climate data from four stations, and with regional indices of SAW wind speed, and with seasonal drought data from the Palmer Drought Severity Index. We found that different tools work better for SAW fires versus non-SAW fires.

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Fire is strongly linked to outdoor recreation in the United States. Recreational uses of fires, whether in designated campgrounds or the backcountry, include warmth, cooking, and fostering a comfortable atmosphere. However, through inattention, negligence, or bad luck, recreational fires sometimes ignite wildfires. This paper evaluates whether the density of wildfire ignited by recreation or ceremony on U.S. Forest Service lands, and the size of such wildfires, is influenced by proximity to designated campgrounds, visitor density, previous and current drought conditions, and the type of vegetation surrounding the ignition point.

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Although fuels treatments are generally shown to be effective at reducing fire severity, there is widespread interest in monitoring that efficacy as the climate continues to warm and the incidence of extreme fire weather increases. This paper compared basal area mortality across adjacent treated and untreated sites in the 2021 Dixie Fire of California’s Sierra Nevada.

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Although vegetation types other than conifer forests make up the majority of burned area in California wildfires, relatively few studies quantify the drivers and patterns of vegetation change in these ecosystems. The impacts of fire exclusion on non-conifer systems remain poorly understood, and the relative influence of fuels compared to factors like climate change or type conversion on fire behavior is largely unknown. To address this knowledge gap, the authors investigated large-scale vegetation change as a possible driver of current trends in fire behavior within mixed-hardwood and shrub-dominated ecosystems in central and coastal Northern California.

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Giant sequoia (Sequoiadendron giganteum) regeneration is reliant on local surface fires, where episodic pulses of heat desiccate and open their cones, releasing seed onto bare mineral soil. Historically, these fires were characterized as ‘mixed severity’, composed of a large matrix that burned at low or moderate severity interspersed with small forest gaps created by local high severity fire. While sequoia regeneration can flourish within these small, high severity gaps,recent ‘megafires’ have produced unprecedentedly large patches of high severity, where the majority of sequoias as killed. This research aims to help resource managers determine whether and where to replant giant sequoia after high severity wildfire.

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Identification and conservation of mature and old-growth forests has become a federal government priority.  In California’s Sierra Nevada’s most of the remaining large trees are concentrated on Forest Service and National Park Service lands. We used airborne lidar data to census large (≥30” diameter at breast height (DBH)) and very large (≥40”) trees across three large Sierra landscapes. We found that large trees are either locally absent to rare or are aggregated in stands with 8-20 large trees per acre.

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Quantification of competition levels in forest stands benefits assessments of stand health, vulnerability to stressors, and prediction of future stand dynamics. Because different forests have different carrying capacities that can be maintained given differences in site productivities, it is important to consider stocking in terms that are relative to these maximum levels. Stand Density Index (SDI) is a common metric of competition in temperate forests of Western North America, originating in 1933 and gaining widespread use within the field of forestry throughout the 20th century. The authors of this study synthesized the large body of published literature on SDI since its introduction in 1933.

Decades of fire suppression have increased fuel loads and fire severity, leading to the “fire suppression paradox”—by suppressing fires we make fires harder to put out in the future. However, in this study, the authors show a separate impact of fire suppression that may cause even greater increases in average fire severity than climate change or fuel accumulation.

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In this study, the authors used observed weather and climate data, as well as climate model simulations, to project shifts in the frequency and seasonality of burn windows in the Western United States. Real-world burn plans were used to calculate median upper and lower prescription values for weather, climate, and vegetation parameters. These upper and lower median values determined days that were suitable for prescribed fire (RxDay) at a given location, in both the past and in a warmer climate future.

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This study explores the effects of historical logging on tree regeneration and successive effects on stand development under a history of fire exclusion. The authors leveraged a silvicultural experiment from the 1920s in the Sierra Nevada mixed-conifer forest of the Stanislaus-Tuolumne Experimental Forest to test if silvicultural objectives of increasing pine stocking rates were met. Combining historical (pre- and post-logging in 1928-1929) and contemporary tree regeneration data along with overstory and microsite conditions, they assessed the impact of logging on pine decline.

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This study analyzed a 2-km hourly gridded weather dataset over a 23-year period to investigate the influence of climatological trends on prescribed fire weather windows. The authors explored how prescribed fire windows changed over this period for two California counties: Sonoma County near the coast and Plumas County in the Sierra Nevada, which contrast in land ownership types, vegetation, and climate. These counties represent diverse prescribed fire considerations in regions where recent catastrophic wildfire has drawn interest from land managers. Using burn prescriptions written by experienced local fire practitioners, the authors identified the degree of weather-driven change in prescribed fire opportunities for these two distinct areas within California.

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This study summarizes Indigenous oral traditions, assesses current and historical forest structure, and measures fire effects of the 2021 Dixie Fire to understand the state of forests in the northern Sierra Nevada with cultural significance to the Mountain Maidu. Oral traditions of the Mountain Maidu cultural burning practices were passed down through generations and were incorporated into this work by one of the authors. The focal site of the study was the Plumas National Forest expanded on University of California, and data included Berkeley forest inventory plots, a California black oak census, and dendroecological fire history records. Regional forest conditions were assessed historically via a 1924 forest inventory, while current conditions were quantified through data from the Forest Inventory Analysis program.

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This paper examines a 20-year forest restoration study in the northern Sierra Nevada looking at changes in forest structure and composition, fuel accumulation, modeled fire behavior, intertree competition, and economics resulting from four treatment regimes: multiple applications of prescribed fire (Fire), multiple mechanical restoration thinnings (Mech), multiple mechanical restoration thinnings followed by prescribed fire (Mech + Fire), and untreated controls

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Biogeomorphic Responses to Wildfire in Fluvial Ecosystems draws together interdisciplinary studies and reviews that highlight key insights important to support heterogeneity, biodiversity, and resilience in fluvial ecosystems (Florsheim et al., 2024).

This study analyzes tree death in Yosemite National Park and Sequoia/Kings Canyon National Park following the 2012-2016 drought.

This study analyzes data from a mixed-severity fire in the northern range of coast redwood to create a model for predicting postfire response of four redwood community plants.Mastication, thinning, and prescribed fire can help shift fire-prone forests to a structure more resilient to fire and other disturbances. However, the ability to evaluate treatment effectiveness requires long-term monitoring of forest responses to disturbances and assessing changes in fuel loadings and structure. Researchers from Michigan State University and the USFS Fire Behavior Assessment Team remeasured a ponderosa pine forest 13 years after a combination of treatments were implemented: no treatment/control (C), mastication (M), mastication + burn (MB), and mastication + pull back of surface fuels + burn (MPB).

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This study analyzes data from a mixed-severity fire in the northern range of coast redwood to create a model for predicting postfire response of four redwood community plants.

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This study investigates Bishop pine's unique fire ecology, seed bank dynamics, and the impacts pine pitch canker infection has on stands.

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This study investigates whether wildfire enables the upslope migration of upper montane conifers into the current range of subalpine conifers in the Sierra Nevada, California.

Researchers from Michigan State University and the USFS Fire Behavior Assessment Team used 15 years of immediate pre- and post-fire fuel and wildfire behavior data to identify the role of fire advancement mode and pre-fire environmental drivers (e.g., topography, fire weather, and fuel loadings) on fuel consumption and fire effects in California mixed-conifer forests.

This study finds that the usefulness of several fire severity metrics (Composite Burn Index, RdNBR) depends on whether the land had burned recently and how severely.

This report compiles research on fuel conditions, fire history, and fire effects data from contemporary wildfires to provide context for the future management of old growth coast redwood stands and restoration of old growth attributes in second growth forests. The report also investigates fire hazards present in redwood forests and their fire management implications.

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In California’s dry mixed conifer forests, increasingly large high severity wildfires threaten to convert significant areas of forested land into shrub dominated landscapes in the absence of active reforestation, including control of competing vegetation. Previous studies have found that salvage logging and other methods used to prepare a site for reforestation may reduce shrub cover after wildfire. This study investigated the effect of masticated fuel depth on shrub growth where salvage logging and mastication followed high severity wildfire.

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In Southern California, native bunchgrass communities dominated by Stipa pulchra are widely distributed in the state but often share dominance with non-native annual grasses. Restoration of these grasslands is focused on altering the balance of native to non-native grasses to favor the native perennial grasses. This study investigated the impact of burning on vegetation recovery.

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Supported by the Clark County (Nevada) Desert Conservation Program and the California Fire Science Consortium, we completed a status of knowledge synthesis of restoration practices aimed at enhancing recovery of damaged habitats in the Mojave and western Sonoran Desert, some of the driest locations in North America.

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It is not well understood whether desert plantings can facilitate recruitment of other natives (or mainly just non-natives), or whether facilitation changes through time as a restoration site matures. To address these uncertainties, we partnered with the National Park Service to study plant community change below planted perennials and in interspaces (areas between perennials) during 12 years (2009-2020) in Joshua Tree National Park, California, in the southern Mojave Desert.

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This study uses tree cores gathered at three 4-hectare plots to make inferences about temporal aspects of tree recruitment in pine-dominated ecosystems of the California Sierra Nevada and the Sierra San Petro Martir in northwestern Mexico.

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In this paper, the authors quantify change in the extent of mature conifer forests in the southern Sierra Nevada of California during 2011-2020, a decade and ecoregion characterized by compounding severe wildfires and drought follow prolonged fire exclusion.

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