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At least 577 records · Page 32Linked to original sources

USGS2015

Timing of susceptibility to post-fire debris flows in the western USA

Watersheds recently burned by wildfires can have an increased susceptibility to debris flow, although little is known about how long this susceptibility persists, and how it changes over time. We here use a compilation of 75 debris-flow response and fire-ignition dates, vegetation and bedrock class, rainfall regime, and initiation process from throughout the western U.S. to address these issues. The great majority (85 percent) of debris flows occurred within the first 12 months following wildfire, with 71 percent within the first six months. Seven percent of the debris flows occurred between 1 and 1.5 years after a fire, or during the second rainy season to impact an area. Within the first 1.5 years following fires, all but one of the debris flows initiated through runoff-dominated processes, and debris flows occurred in similar proportions in forested and non-forested landscapes. Geologic materials affected how long debris-flow activity persisted, and the timing of debris flows varied within different rainfall regimes. A second, later period of increased debris flow susceptibility between 2.2 and 10 years after fires is indicated by the remaining 8 percent of events, which occurred primarily in forested terrains and initiated largely through landslide processes. The short time period between fire and debris-flow response within the first 1.5 years after ignition, and the longer-term response between 2.2 and 10 years after fire, demonstrate the necessity of both rapid and long-term reactions by land managers and emergency-response agencies to mitigate hazards from debris flows from recently burned areas in the western U.S.

Environmental & Engineering Geoscience↗

USGS1978

Reproduction of chaparral shrubs after fire: A comparison of sprouting and seeding strategies

The relative ability of sprouting and nonsprouting chaparral shrubs to recover from fire was studied by examining population of congeneric pairs of species in burned and adjacent unburned areas. The pairs of species selected, with the nonsprouting species named first, were Arctostaphylos glauca - A. glandulosa and Ceanothus greggii - C. leucodermis . Data were also obtained on certain associated species, particularly Adenostoma fasciculatum . The numbers, sizes and condition of the component species at each of the sites were measured. Both sprouting and nonsprouting species showed vigorous recovery from fire. It seemed likely that the burned stands would eventually reach a state of development comparable to that shown in the preburn stand without any significant shifts in composition Mortality of shrubs resulting from the fire was complete for nonsprouters but varied in sprouting species. In some there was essentially no mortality, while in others, especially Adenostoma , it was rather high. Seedling establishment in the shrub species varied markedly and seemed to be correlated with the degree of fire-caused mortality. A profound difference was observed in the life histories of the two nonsprouting shrubs. Whereas Ceanothus greggii produced a very high number of seedlings after fire, Arctostaphylos glauca produced substantially fewer. A comparison of the density-size distribution of live and dead stems indicated that C. greggii suffers high mortality early in succession, but A. glauca loses very few individuals even after 90 years without fire. In light of these results a model is proposed which we believe explains the adaptive significance of the obligate-seeding strategy in the southern California chaparral.

American Midland Naturalist↗

USGS2011

Geospatial Multi-Agency Coordination (GeoMAC) wildland fire perimeters, 2008

The Geospatial Multi-Agency Coordination (GeoMAC) has been collecting and storing data on wildland fire perimeters since August 2000. The dataset presented via this U.S. Geological Survey Data Series product contains the GeoMAC wildland fire perimeter data for the calendar year 2008, which are based upon input from incident intelligence sources, Global Positioning System (GPS) data, and infrared (IR) imagery. Wildland fire perimeter data are obtained from the incidents, evaluated for completeness and accuracy, and processed to reflect consistent field names and attributes. After a quality check, the perimeters are loaded to GeoMAC databases, which support the GeoMAC Web application for access by wildland fire managers and the public. The wildland fire perimeters are viewed through the Web application. The data are subsequently archived according to year and state and are made available for downloading through the Internet in shapefile and Keyhole Markup Language (KML) format. These wildland fire perimeter data are also retained for historical, planning, and research purposes. The datasets that pertain to this report can be found on the Rocky Mountain Geographic Science Center HTTP site at http://rmgsc.cr.usgs.gov/outgoing/GeoMAC/historic_fire_data/. The links are also provided on the sidebar.

Arizona;California;Colorado;Idaho;Nevada;New Mexic↗

USGS2003

Rapid-deployment data-collection networks for wildland fire applications

Rapid-deployment data-collection networks were developed for wildland fire applications like the Missionary Ridge Fire. The Missionary Ridge Fire began June 9, 2002, near Durango, Colorado. An Interagency Burned Area Emergency Rehabilitation (BAER) Team arrived in Durango, Colorado, to assess the fire. At that time, the fire had burned over 70,000 acres and was still actively burning. The fire was contained on July 14, after consuming 73,400 acres. The team was charged with assessing the potential postfire effects on health and safety, and risks to property and natural resources. From this assessment, the team would prescribe treatments on Federal lands to reduce damage to the values at risk from the burned watersheds. The team found that human life was at risk early in their assessment.

Colorado, South Dakota↗

USGS2011

Vegetation recovery after fire in the Klamath-Siskiyou region, southern Oregon

In July 2002, lightning strikes started five forest fires that merged into one massive wildfire in the Klamath-Siskiyou Ecoregion of southern Oregon. Aided by drought, severe weather conditions, dry fuels, and steep topography, the fire grew to more than 200,000 hectares of mostly public forest land. Known as the Biscuit Fire, it was Oregon's largest forest fire in more than 130 years and one of the largest wildfires on record in the United States. Discussions centered around why such a massive fire was happening, how large would it become, who was keeping communities and homes safe, and what would be the final economic and ecological outcome. Weeks later when the fire was out, conversations turned to other questions, including what, if anything, should happen for forest recovery.

Oregon↗

USGS2005

Effects of prescribed fire in the coastal prairies of Texas

Prescribed fire is widely applied for habitat management in coastal ecosystems. Fire management plans typically list a variety of objectives for prescribed burning, including succession management, promotion of native flora and fauna, providing habitat for species of importance, wildfire risk reduction (fuels management), as well as reduction and/or prevention of invasive species. In most cases, the information needed to determine the degree to which management objectives are met is not available. This study sought to provide an assessment of key objectives of fire management at the U.S. Fish and Wildlife Service (USFWS) Texas Mid-coast National Wildlife Refuge Complex. The main purpose of this work was to provide information and recommendations that will support Region 2 of the USFWS in the conduct of their fire and habitat management activities in the Western Gulf coast region. There were four main components of this project: (1) a historical analysis of the role of fire in this ecosystem, (2) the development of standard methodology for assessing and monitoring fire effects in this system, (3) an evaluation of the effects of prescribed burning on the habitat being managed, and (4) an evaluation of the effects of burning on select fauna of special concern. A team of researchers, including some from the U.S. Geological Survey (USGS), Southeast Missouri State University, and Louisiana State University were involved in the various components of this project. Extensive support by USFWS personnel, both at the Texas Mid-coast National Wildlife Refuge Complex and in the Regional Office (Region 2, USFWS), was a key component in this work. Data from the three years of this study were combined with the results of previous USGS studies performed at the site to strengthen our conclusions.

Open-File Report↗

USGS2010

Emergency assessments of postfire debris-flow hazards for the 2009 La Brea, Jesusita, Guiberson, Morris, Sheep, Oak Glen, Pendleton, and Cottonwood fires in southern California

This report presents an emergency assessment of potential debris-flow hazards from basins burned by the 2009 La Brea and Jesusita fires in Santa Barbara County, the Guiberson fire in Ventura County, the Morris fire in Los Angeles County, the Sheep, Oak Glen, and Pendleton fires in San Bernardino County, and the Cottonwood fire in Riverside County, southern California. Statistical-empirical models developed to analyze postfire debris flows are used to estimate the probability and volume of debris-flows produced from drainage basins within each of the burned areas. Debris-flow probabilities and volumes are estimated as functions of different measures of basin burned extent, gradient, and material properties in response to both a 3-hour-duration, 2-year-recurrence thunderstorm and to a widespread, 12-hour-duration, 2-year-recurrence winter storm. This assessment provides critical information for issuing warnings, locating and designing mitigation measures, and planning evacuation timing and routes within the first two winters following the fire.

Open-File Report↗

USGS2024

RE-ARMing salt marshes: A resilience-experimentalist approach to prescribed fire and bird conservation in high marshes of the Gulf of Mexico

Uncertainty, complexity, and dynamic changes present challenges for conservation and natural resource management. Evidence-based approaches grounded in reliable information and rigorous analysis can enhance the navigation of the uncertainties and trade-offs inherent in conservation problems. This study highlights the importance of collaborative efforts and evidence-based decision-making, specifically implementing the Resilience-Experimentalist school of adaptive management (RE-ARM), which emphasizes stakeholder involvement, shared understanding, and experimentation. Our goal was to develop an adaptive management framework to reduce the uncertainty around the use of prescribed fire to manage the habitat for eastern black rails ( Laterallus jamaicensis jamaicensis ) and mottled ducks ( Anas fulvigula ) in saltmarshes of the Gulf of Mexico. Supported by discussions at a series of workshops, we used a value of information analysis to select a fire management hypothesis to test, developed an influence diagram to represent the system under fire management, used the influence diagram to develop a Bayesian decision network (BDN), and conducted a power analysis to guide management experiments and monitoring. Value of information analysis identified fire return interval as the critical uncertainty. Our BDN provided valuable insight into how managers believe prescribed fire influences vegetation characteristics and how vegetation influences both eastern black rail occupancy and mottled duck abundance. The results of the power analysis indicated that a standard occupancy modeling framework was more useful to compare 2- and 5-year fire return intervals for black rails than two alternative designs (removal and conditional). Our BDN can be used to predict the probability of achieving the desirable vegetative response to increase the occupancy probability of black rails and abundance of mottled ducks, and monitoring data can be used to update the BDN (learn) and improve best management practices for prescribed burns (adapt). Linking the value of information, BDNs, and power analysis enhances our understanding of the system, improves management decision-making, and builds trust among scientists, interested parties, and decision-makers. This approach lays the groundwork for knowledge co-production and adaptive management.

Frontiers in Conservation Science↗

USGS2021

Forest resistance to extended drought enhanced by prescribed fire in low elevation forests of the Sierra Nevada

Prescribed fire reduces fire hazards by removing dead and live fuels (small trees and shrubs). Reductions in forest density following prescribed fire treatments (often in concert with mechanical treatments) may also lessen competition so that residual trees might be more likely to survive when confronted with additional stressors, such as drought. The current evidence for these effects is mixed and additional study is needed. Previous work found increased tree survivorship in low elevation forests with a recent history of fire during the early years of an intense drought (2012 to 2014) in national parks in the southern Sierra Nevada. We extend these observations through additional years of intense drought and continuing elevated tree mortality through 2017 at Sequoia and Kings Canyon National Parks. Relative to unburned sites, we found that burned sites had lower stem density and had lower proportions of recently dead trees (for stems ≤47.5 cm dbh) that presumably died during the drought. Differences in recent tree mortality among burned and unburned sites held for both fir (white fir and red fir) and pine (sugar pine and ponderosa pine) species. Unlike earlier results, models of individual tree mortality probability supported an interaction between plot burn status and tree size, suggesting the effect of prescribed fire was limited to small trees. We consider differences with other recent results and discuss potential management implications including trade-offs between large tree mortality following prescribed fire and increased drought resistance.

California↗

USGS2021

Climatic aridity shapes post-fire interactions between Ceanothus spp. and Douglas-fir (Pseudotsuga menziesii) across the Klamath Mountains

Climate change is leading to increased drought intensity and fire frequency, creating early-successional landscapes with novel disturbance–recovery dynamics. In the Klamath Mountains of northwestern California and southwestern Oregon, early-successional interactions between nitrogen (N)-fixing shrubs ( Ceanothus spp.) and long-lived conifers (Douglas-fir) are especially important determinants of forest development. We sampled post-fire vegetation and soil biogeochemistry in 57 plots along gradients of time since fire (7–28 years) and climatic water deficit (aridity). We found that Ceanothus biomass increased, and Douglas-fir biomass decreased with increasing aridity. High aridity and Ceanothus biomass interacted with lower soil C:N more than either factor alone. Ceanothus biomass was initially high after fire and declined with time, suggesting a large initial pulse of N-fixation that could enhance N availability for establishing Douglas-fir. We conclude that future increases in aridity and wildfire frequency will likely limit post-fire Douglas-fir establishment, though Ceanothus may ameliorate some of these impacts through benefits to microclimate and soils. Results from this study contribute to our understanding of the effects of climate change and wildfires on interspecific interactions and forest dynamics. Management seeking to accelerate forest recovery after high-severity fire should emphasize early-successional conifer establishment while maintaining N-fixing shrubs to enhance soil fertility.

California, Oregon↗

USGS2016

Continuous 1985-2012 Landsat monitoring to assess fire effects on meadows in Yosemite National Park, California

To assess how montane meadow vegetation recovered after a wildfire that occurred in Yosemite National Park, CA in 1996, Google Earth Engine image processing was applied to leverage the entire Landsat Thematic Mapper archive from 1985 to 2012. Vegetation greenness (normalized difference vegetation index [NDVI]) was summarized every 16 days across the 28-year Landsat time series for 26 meadows. Disturbance event detection was hindered by the subtle influence of low-severity fire on meadow vegetation. A hard break (August 1996) was identified corresponding to the Ackerson Fire, and monthly composites were used to compare NDVI values and NDVI trends within burned and unburned meadows before, immediately after, and continuously for more than a decade following the fire date. Results indicate that NDVI values were significantly lower at 95% confidence level for burned meadows following the fire date, yet not significantly lower at 95% confidence level in the unburned meadows. Burned meadows continued to exhibit lower monthly NDVI in the dormant season through 2012. Over the entire monitoring period, the negative-trending, dormant season NDVI slopes in the burned meadows were also significantly lower than unburned meadows at 90% confidence level. Lower than average NDVI values and slopes in the dormant season compared to unburned meadows, coupled with photographic evidence, strongly suggest that evergreen vegetation was removed from the periphery of some meadows after the fire. These analyses provide insight into how satellite imagery can be used to monitor low-severity fire effects on meadow vegetation.

California↗

USGS2024

Characteristics of debris-flow-prone watersheds and debris-flow-triggering rainstorms following the Tadpole Fire, New Mexico, USA

Moderate- or high-severity fires promote increases in runoff and erosion, leading to a greater likelihood of extreme geomorphic responses, including debris flows. In the first several years following fire, the majority of debris flows initiate when runoff rapidly entrains sediment on steep slopes. From a hazard perspective, it is important to be able to anticipate when and where watershed responses will be dominated by debris flows rather than flood flows. Rainfall intensity averaged over a 15 min duration, I 15 , in particular, has been identified as a key predictor of debris flow likelihood. Developing effective warning systems and predictive models for post-fire debris flow hazards therefore relies on high-temporal resolution rainfall data at the time debris flows initiate. In this study, we documented the geomorphic response of a series of watersheds following a wildfire in western New Mexico, USA, with an emphasis on constraining debris flow timing within rainstorms to better characterize debris-flow-triggering rainfall intensities. We estimated temporal changes in soil hydraulic properties and ground cover in areas burned at different severities over >2 years to offer explanations for observed differences in spatial and temporal patterns in debris flow activity. We observed 16 debris flows, all of which initiated during the first several months following the fire. The average recurrence interval of the debris-flow-triggering I 15 is 1.3 years, which highlights the susceptibility of recently burned watersheds to runoff-generated debris flows in this region. All but one of the debris flows initiated in watersheds burned primarily at moderate or high soil burn severity. Since soil hydraulic properties appeared to be relatively resilient to burning, we attribute reduced debris flow activity at later times to decreases in the fraction of bare ground. Results provide additional constraints on the rainfall characteristics that promote post-fire debris flow initiation in a region where fire size and severity have been increasing.

New Mexico↗

USGS2017

Influence of repeated prescribed fire on tree growth and mortality in Pinus resinosa forests, northern Minnesota

Prescribed fire is widely used for ecological restoration and fuel reduction in fire-dependent ecosystems, most of which are also prone to drought. Despite the importance of drought in fire-adapted forests, little is known about cumulative effects of repeated prescribed burning on tree growth and related response to drought. Using dendrochronological data in red pine ( Pinus resinosa Ait.)-dominated forests in northern Minnesota, USA, we examined growth responses before and after understory prescribed fires between 1960 and 1970, to assess whether repeated burning influences growth responses of overstory trees and vulnerability of overstory tree growth to drought. We found no difference in tree-level growth vulnerability to drought, expressed as growth resistance, resilience, and recovery, between areas receiving prescribed fire treatments and untreated forests. Annual mortality rates during the period of active burning were also low (less than 2%) in all treatments. These findings indicate that prescribed fire can be effectively integrated into management plans and climate change adaptation strategies for red pine forest ecosystems without significant short- or long-term negative consequences for growth or mortality rates of overstory trees.

Minnesota↗

USGS1998

Effects of wet- and dry-season fires on Jacquemontia curtisii, a south Florida pine forest endemic

South Florida pine forests have a diverse endemic flora that has evolved under the influence of recurrent fire. We studied the response of Jacquemontia curtisii Peter ex Hallier f. (pineland clustervine), a perennial herbaceous member of that flora, to experimental fires during wet and dry seasons. In each of three populations, three treatments were applied: wet-season (June) prescribed fire, dry-season (January) prescribed fire, and an unburned control. Flowering, fruiting, and seedling establishment were followed for up to one year. Mortality of adult plants was twice as great after wet-season burns than after dry-season burns even though fire temperatures were higher in the dry-season burns. Within a season of burning, mortality was greater for the more severely burned plants or the smaller plants. Wet-season burns produced over three times more flowers than not burning, in spite of mortality of more than half the plants. Burning stimulated germination from the soil seed bank. Dry-season burns resulted in five times more seedlings than wet-season burns and more of these seedlings were alive one year after the burn. It is likely that the long-term viability of Jacquemontia curtisii populations is favored by diversity in fire season and severity.

Florida↗

USGS1996

Toxicity of fire retardant chemicals to aquatic organisms: Progress report

Fire retardants and suppressants used extensively in North America are often applied in environmentally sensitive areas that may contain endangered, threatened, or economically important plant and animal species. We conducted laboratory acute toxicity tests in both hard and soft waters with five commonly used fire control chemicals (Fire Trol LCG-R, Fire-Trol GTS-R, Phos-Chek D-75-F, Phos-Chek WD-881, and Silv-Ex). Organisms used in the tests included two fish (rainbow trout and fathead minnow), two aquatic invertebrates ( Daphnia magna and Hyalella azteca ), and a green algae ( Selenastrum capricornutum ). In general, the green algae was substantially more sensitive to the three non-foam fire chemicals than the animals, the Daphnia were the most sensitive test organism in exposures with foams. The two foams (Silv-Ex and Phos-Chek WD-881) had similar toxicity and were more toxic than the three non-foams. Water quality did not seem to modify the toxicity of the five fire chemicals in a consistent manner.

Conference Paper↗

USGS2002

Lots of lightning and plenty of people: An ecological history of fire in the upland southwest

Was the pre-European Southwest a region of wild landscapes, shaped primarily by natural processes like lightning-ignited fire, or did people substantially mold these lands into regional-scale artifacts through their use of fire and other means? Perspectives on this question have varied markedly through time and between scholars, as evident from the quotes interspersed through this chapter (see Box 5.1.). As the American frontier closed around the turn of the nineteenth century, lightning was rarely considered a primary cause of fire, with most fires in western forests assumed to be human-ignited. Native Americans were thought to have been the primary source of burning in the Southwest until EuroAmericans usurped that role after ca. 1850. Today, lightning-ignited fire is widely acknowledged to be an ancient and essential ecological process in the American Southwest (Pyne 1995a:282-283; Swetnam and Baisan 1996a; Bogan et al. 1998), for millennia structuring landscapes from low-elevation desert grasslands to montane forests. However, because the Southwest has been home to people for more than 12,000 years, with large human populations for over 1,000 years (Plog et al. 1988), some scholars continue to assert the dominance of aboriginal burning in the fire regimes of this region (Dobyns 1981; Pyne 1995a, 1996, 1997). This essay focuses on the roles of

Book chapter↗

USGS2006

Heterogeneity in fire severity within early season and late season prescribed burns in a mixed-conifer forest

Structural heterogeneity in forests of the Sierra Nevada was historically produced through variation in fire regimes and local environmental factors. The amount of heterogeneity that prescription burning can achieve might now be more limited owing to high fuel loads and increased fuel continuity. Topography, woody fuel loading, and vegetative composition were quantified in plots within replicated early and late season burn units. Two indices of fire severity were evaluated in the same plots after the burns. Scorch height ranged from 2.8 to 25.4 m in early season plots and 3.1 to 38.5 m in late season plots, whereas percentage of ground surface burned ranged from 24 to 96% in early season plots and from 47 to 100% in late season plots. Scorch height was greatest in areas with steeper slopes, higher basal area of live trees, high percentage of basal area composed of pine, and more small woody fuel. Percentage of area burned was greatest in areas with less bare ground and rock cover (more fuel continuity), steeper slopes, and units burned in the fall (lower fuel moisture). Thus topographic and biotic factors still contribute to the abundant heterogeneity in fire severity with prescribed burning, even under the current high fuel loading conditions. Burning areas with high fuel loads in early season when fuels are moister may lead to patterns of heterogeneity in fire effects that more closely approximate the expected patchiness of historical fires.

California, Nevada↗

USGS2009

Synthesis of sediment yields after wildland fire in different rainfall regimes in the western United States

Measurements of post-fire sediment erosion, transport, and deposition collected within 2 years of a wildfire were compiled from the published literature (19272007) for sites across the western United States. Annual post-fire sediment yields were computed and grouped into four measurement methods (hillslope point and plot measurements, channel measurements of suspended-sediment and sediment erosion or deposition volumes). Post-fire sediment yields for each method were then grouped into eight different rainfall regimes. Mean sediment yield from channels (240 t ha-1) was significantly greater than from hillslopes (82 t ha-1). This indicated that on the time scale of wildfire (10100 years) channels were the primary sources of available sediment. A lack of correlation of sediment yield with topographic slope and soil erodibility further suggested that sediment availability may be more important than slope or soil erodibility in predicting post-fire sediment yields. The maximum post-fire sediment yields were comparable to long-term sediment yields from major rivers of the world. Based on 80 years of data from the literature, wildfires have been an important geomorphic agent of landscape change when linked with sufficient rainfall. These effects are limited in spatial scale to the immediate burned area and to downstream channel corridors.

International Journal of Wildland Fire↗