Skip to main content

Susan Prichard

Followers

19

Following

6

Public Views

Interests

Uploads

Papers by Susan Prichard

Appendix B. Spur area sequential autoregression (SAR) regression models of categorical predictor variables including: (a) treatment type, (b) mountasin pine beetle (MPB) classification, and (c) cover type

Spur area sequential autoregression (SAR) regression models of categorical predictor variables in... more

An overview of the fuel characteristic classification system—quantifying, classifying, and creating fuelbeds for resource planners

Abstract: We present an overview of the Fuel Characteristic Classification System (FCCS), a tool ... more Abstract: We present an overview of the Fuel Characteristic Classification System (FCCS), a tool that enables land man-agers, regulators, and scientists to create and catalogue fuelbeds and to classify those fuelbeds for their capacity to support fire and consume fuels. The fuelbed characteristics and fire classification from this tool will provide inputs for current and future sophisticated models for the quantification of fire behavior, fire effects, and carbon accounting and enable assess-ment of fuel treatment effectiveness. The system was designed from requirements provided by land managers, scientists, and policy makers gathered through six regional workshops. The FCCS contains a set of fuelbeds representing the United States, which were compiled from scientific literature, fuels photo series, fuels data sets, and expert opinion. The system enables modification and enhancement of these fuelbeds to represent a particular scale of interest. The FCCS then reports assigned and cal...

The Fuel Characteristic Classification System (FCCS) is in the public domain and the recipient ma... more The Fuel Characteristic Classification System (FCCS) is in the public domain and the recipient may not assert any proprietary rights thereto or represent them to anyone as other than government-produced programs. The FCCS software is provided “as is ” without warranty of any kind, including but not limited to the implied warranties of merchantability and fitness for a particular purpose. The user assumes all responsibility for the accuracy and suitability of these programs for a specific application. The use of trade or firm names in this publication is for reader information and does not imply endorsement by the U.S. Department of Agriculture of any product or service. The views and opinions of authors expressed herein do not necessarily state or reflect those of the U.S. government or any agency thereof. 1 2 3 4 5 6 Cover photographs:

Contents lists available at ScienceOirect

We reconstructed a 10,500-yr fire and vegetation history of a montane site in the North Cascade R... more We reconstructed a 10,500-yr fire and vegetation history of a montane site in the North Cascade Range, Washington State based on lake sediment charcoal, macrofossil and pollen records. High-resolution sampling and abundant macrofossils made it possible to analyze relationships between fire and vegetation. During the early Holocene (> 10,500 to ca. 8000 cal yr BP) forests were subalpine woodlands dominated by Pinus contorto. Around 8000 cal yr BP,P.contorta sharply declined in the macrofossil record. Shade tolerant, mesic species first appeared ca. 4500 cal yr BP. Cupressus nootkatensis appeared most recently at 2000 cal yr BP.Fire frequency varies throughout the record, with significantly shorrer mean fire return intervals in the early Holocene than the mid and late Holocene. Charcoal peaks are significantly correlated with an initial increase in macrofossil accumulation rates followed by a decrease, likely corresponding to tree mortality following fire. Climate appears to be a key driver in vegetation and fire regimes over millennial time scales. Fire and other disturbances altered forest vegetation at shorter time scales. and vegetation may have mediated local fire regimes. For example, dominance of P. contorta in the early Holocene forests may have been reinforced by its susceptibility to frequent. stand-replacing fire events.

State of Fire Behavior Models and their Application to Ecosystem and Smoke Management Issues: Special Session Summary Report

: With over 30 million acres of land throughout the United States, the DoD manages a wide diversi... more : With over 30 million acres of land throughout the United States, the DoD manages a wide diversity of ecosystems and important habitat for many threatened and endangered species. Of the 5 million acres of DoD forestland, over half are southern pine forests that are generally maintained by frequent prescribed burns. In fire-adapted ecosystems such as southern pine and western pine forests, the DoD uses fire as an important ecological restoration and forest management tool and conducts prescribed burns on an average of 400,000 acres annually. To support DoD's continued use of fire in ecosystem-based management, SERDP and its sister demonstration program ESTCP have funded efforts to characterize wildland fire emissions to meet air quality requirements, understand how fire interacts with invasive non-native species such as cheatgrass (Bromus techtorum) in the western United States, and demonstrate and validate fire behavior models. To provide direction to its future research and de...

crisscrossing Science Episode 06: Fire Adapted Ecosystems

Since 2005 I have been working with mobile communities in the cities of Berlin, Germany and Johan... more Since 2005 I have been working with mobile communities in the cities of Berlin, Germany and Johannesburg, South Africa. The two cities differ in many aspects but also share similarities. They both have histories of division but also great diversity, which while challenging can also provide the opportunity for the evolution of truly pluralist spaces and communities of citizens and non-citizens. It is in this context that the present project emerged, to encourage points of contact between non/citizens and to imagine future spaces, that host a multiplicity of voices and interests.

A tale of two fires: The relative effectiveness of past wildfires in mitigating wildfire behavior and effects

The incidence of large, costly landscape-scale fires in western North America is increasing. To c... more The incidence of large, costly landscape-scale fires in western North America is increasing. To combat these fires, researchers and managers have expressed increased interest in investigating the effectiveness of past, stand-replacing wildfires as bottom-up controls on fire spread and severity. Specifically, how effective are past wildfires in mitigating the behavior and effect of future fires, and for how long? Our research focused on two recent fires that encountered past wildfires but with significantly different outcomes. The 2006 Tripod Complex fires in Washington State flanked around, but did not reburn, the 1970 Forks Fire, while the 2012 Octopus Mountain Fire in Kootenay National Park in British Columbia reburned much of the 1991 Spar Mountain Fire area. In 2013 we sampled fuels and vegetation in unburned portions of the Tripod/Forks and the Octopus/Spar Mountain fire areas in order to quantify canopy and surface fuel characteristics and elucidate why fire behavior and effec...

Landscape analysis of fuel treatment longevity and effectiveness in the 2006 Tripod Complex Fires Final

In this study, we evaluated relationships between fire severity and fuel treatment type, age and ... more In this study, we evaluated relationships between fire severity and fuel treatment type, age and size in the 2006 Tripod Complex fires. The 2006 Tripod Complex fires, which burned over 70,000 ha and involved over 380 past harvest and fuel treatment units, offer a relatively unique opportunity to assess fuel treatment efficacy under extreme fire weather conditions. A secondary objective was to evaluate other drivers of fire severity including landform, weather, vegetation, and past disturbances including wildfires and a recent mountain pine beetle outbreak. We evaluated drivers of burn severity in two study areas that are centered on early progressions of the wildfire complex.

Evaluating the influence of prior burn mosaics on subsequent wildfire behavior , severity , and fire management options

Wildfire and climate change adaptation of western North American forests: a case for intentional management

Ecological Applications

Forest landscapes across western North America (wNA) have experienced extensive changes over the ... more Forest landscapes across western North America (wNA) have experienced extensive changes over the last two centuries, while climatic warming has become a global reality over the last 4 decades. Resulting interactions between historical increases in forested area and density and recent rapid warming, increasing insect mortality, and wildfire burned areas, are now leading to substantial abrupt landscape alterations. These outcomes are forcing forest planners and managers to identify strategies that can modify future outcomes that are ecologically and/or socially undesirable. Past forest management, including widespread harvest of fire- and climate-tolerant large old trees and old forests, fire exclusion (both Indigenous and lightning ignitions), and highly effective wildfire suppression have contributed to the current state of wNA forests. These practices were successful at meeting short-term demands, but they match poorly to modern realities. Hagmann et al. (in press) review a century of observations and multi-scale, multi-proxy research evidence that details widespread changes in forested landscapes and wildfire regimes since the influx of European colonists. Over the preceding 10 millennia, large areas of wNA were already settled and proactively managed with intentional burning by Indigenous tribes. Prichard et al. (in press) then review the research on management practices historically applied by Indigenous tribes and currently applied by some managers to intentionally manage forests for resilient conditions. They address ten questions surrounding the application and relevance of these management practices. Here, we highlight the main findings of both papers and offer recommendations for management. We discuss progress paralysis that often occurs with strict adherence to the precautionary principle; offer insights for dealing with the common problem of irreducible uncertainty and suggestions for reframing management and policy direction; and identify key knowledge gaps and research needs.

Evidence for widespread changes in the structure, composition, and fire regimes of western North American forests

Ecological Applications

Implementation of wildfire-and climate-adaptation strategies in seasonally dry forests of western... more Implementation of wildfire-and climate-adaptation strategies in seasonally dry forests of western North America is impeded by numerous constraints and uncertainties. After more than a century of resource and land use change, some question the need for proactive management, particularly given novel social, ecological, and climatic conditions. To address this question, we first provide a framework for assessing changes in landscape conditions and fire regimes. Using this framework, we then evaluate evidence of change in contemporary conditions relative to those maintained by active fire regimes, i.e., those uninterrupted by a century or more of human-induced fire exclusion. The cumulative results of more than a century of research document a persistent and substantial fire deficit and widespread alterations to Manuscript

The Fire and Tree Mortality Database, for empirical modeling of individual tree mortality after fire

Scientific Data

Wildland fires have a multitude of ecological effects in forests, woodlands, and savannas across ... more Wildland fires have a multitude of ecological effects in forests, woodlands, and savannas across the globe. A major focus of past research has been on tree mortality from fire, as trees provide a vast range of biological services. We assembled a database of individual-tree records from prescribed fires and wildfires in the United States. The Fire and Tree Mortality (FTM) database includes records from 164,293 individual trees with records of fire injury (crown scorch, bole char, etc.), tree diameter, and either mortality or top-kill up to ten years post-fire. Data span 142 species and 62 genera, from 409 fires occurring from 1981-2016. Additional variables such as insect attack are included when available. The FTM database can be used to evaluate individual fire-caused mortality models for pre-fire planning and post-fire decision support, to develop improved models, and to explore general patterns of individual fire-induced tree death. The database can also be used to identify knowl...

Wildfire-Driven Forest Conversion in Western North American Landscapes

BioScience

Changing disturbance regimes and climate can overcome forest ecosystem resilience. Following high... more 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. In the present article, we synthesize a growing body of evidence of fire-driven conversion and our understanding of its causes across western North America. We assess our capacity to predict conversion and highlight important uncertainties. 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 wh...

Towards Spatially Explicit Quantification of Pre- and Postfire Fuels and Fuel Consumption from Traditional and Point Cloud Measurements

Forest Science

Methods to accurately estimate spatially explicit fuel consumption are needed because consumption... more Methods to accurately estimate spatially explicit fuel consumption are needed because consumption relates directly to fire behavior, effects, and smoke emissions. Our objective was to quantify sparkleberry (Vaccinium arboretum Marshall) shrub fuels before and after six experimental prescribed fires at Fort Jackson in South Carolina. We used a novel approach to characterize shrubs non-destructively from three-dimensional (3D) point cloud data collected with a terrestrial laser scanner. The point cloud data were reduced to 0.001 m–3 voxels that were either occupied to indicate fuel presence or empty to indicate fuel absence. The density of occupied voxels was related significantly by a logarithmic function to 3D fuel bulk density samples that were destructively harvested (adjusted R2 = .32, P < .0001). Based on our findings, a survey-grade Global Navigation Satellite System may be necessary to accurately associate 3D point cloud data to 3D fuel bulk density measurements destructive...

Fuel treatment effectiveness in the context of landform, vegetation and large, wind-driven wildfires

Forest Service Research Data Archive

Large wildfires (>50,000 ha) are becoming increasingly common in semiarid landscapes of the weste... more Large wildfires (>50,000 ha) are becoming increasingly common in semiarid landscapes of the western United States. Although fuel reduction treatments are used to mitigate potential wildfire effects, they can be overwhelmed in wind-driven wildfire events with extreme fire behavior. We evaluated drivers of fire severity and fuel treatment effectiveness in the 2014 Carlton Complex, a record-setting complex of wildfires in north-central Washington State. Across varied topography, vegetation, and distinct fire progressions, we used a combination of simultaneous autoregression (SAR) and random forest (RF) approaches to model drivers of fire severity and evaluated how fuel treatments mitigated fire severity. Predictor variables included fuel treatment type, time since treatment, topographic indices, vegetation and fuels, and weather summarized by progression interval. We found that the two spatial regression methods are generally complementary and are instructive as a combined approach for landscape analyses of fire severity. Simultaneous autoregression improves upon traditional linear models by incorporating information about neighboring pixel burn severity, which avoids type I errors in coefficient estimates and incorrect inferences. Random forest modeling provides a flexible modeling environment capable of capturing complex interactions and nonlinearities while still accounting for spatial autocorrelation through the use of spatially explicit predictor variables. All treatment areas burned with higher proportions of moderate and highseverity fire during early fire progressions, but thin and underburn, underburn only, and past wildfires were more effective than thin-only and thin and pile burn treatments. Treatment units had much greater percentages of unburned and low severity area in later progressions that burned under milder fire weather conditions, and differences between treatments were less pronounced. Our results provide evidence that strategic placement of fuels reduction treatments can effectively reduce localized fire spread and severity even under severe fire weather. During wind-driven fire spread progressions, fuel treatments that were located on leeward slopes tended to have lower fire severity than treatments located on windward slopes. As fire and fuels managers evaluate options for increasing landscape resilience to future climate change and wildfires, strategic placement of fuel treatments may be guided by retrospective studies of past large wildfire events.

Wildland fire emission factors in North America: synthesis of existing data, measurement needs and management applications

International Journal of Wildland Fire

Field and laboratory emission factors (EFs) of wildland fire emissions for 276 known air pollutan... more Field and laboratory emission factors (EFs) of wildland fire emissions for 276 known air pollutants sampled across Canada and the US were compiled. An online database, the Smoke Emissions Repository Application (SERA), was created to enable analysis and summaries of existing EFs to be used in smoke management and emissions inventories. We evaluated how EFs of select pollutants (CO, CO2, CH4, NOx, total particulate matter (PM), PM2.5 and SO2) are influenced by combustion phase, burn type and fuel type. Of the 12533 records in the database, over a third (n=5637) are represented by 23 air pollutants, most designated as US Environmental Protection Agency criteria air pollutants, greenhouse gases, hazardous air pollutants or known air toxins. Among all pollutants in the database, including the most common pollutants PM, CO, CO2 and CH4, records are unevenly distributed with a bias towards flaming combustion, prescribed burning and laboratory measurements. Across all EFs, records are most...

Next‐Generation Biomass Mapping for Regional Emissions and Carbon Inventories: Incorporating Uncertainty in Wildland Fuel Characterization

Journal of Geophysical Research: Biogeosciences

Biomass mapping is used in variety of applications including carbon assessments, emission invento... more Biomass mapping is used in variety of applications including carbon assessments, emission inventories, and wildland fire and fuel planning. Single values are often applied to individual pixels to represent biomass of classified vegetation, but each biomass estimate has associated uncertainty that is generally not acknowledged nor quantified. In this study, we developed a geospatial database of wildland fuel biomass values to characterize the inherent variability within and across major vegetation types of the United States and Canada. For vegetation types that had sufficient quantification of biomass by fuel type (e.g., canopy, shrub, herbaceous, fine downed wood, coarse downed wood, and organic soil layers), we developed empirical distribution estimates. Based on available data, fitted distributions will be useful for informing the first-generation biomass mapping that incorporates variability in loading by vegetation and fuel type and to evaluate potential errors in point estimates given in current map products. Because combustible biomass is a common input in fire and smoke models, variability estimated for fitted distributions can be used to inform data input uncertainty in predictions of wildland fuel consumption and emissions and to provide stochastic inputs of biomass to ensemble simulation models. Plain Language Summary The mass of live and dead vegetation, termed biomass, is used in variety of applications including carbon mapping, wildland smoke emission modeling, and fire management. In many mapping projects, single biomass values are often used to represent classified vegetation types. However, in reality, the biomass of grasslands, shrublands, and forests is extremely variable, and mapped values are associated with a high degree of uncertainty. In this study, we developed a database of wildland fuel biomass by major vegetation type in the United States and Canada. For wellstudied vegetation types we developed mathematical models that statistically represent the distribution of biomass observations. Based on available data, fitted distributions will be useful for informing the firstgeneration biomass mapping that incorporates uncertainty estimates by major vegetation type to evaluate potential errors in current map products. Because biomass is a common input in fire and smoke models, fitted distributions can be used to evaluate the uncertainty in predicted wildfire emissions.

Fire and tree mortality database

Forest Service Research Data Archive

Climate, Environment, and Disturbance History Govern Resilience of Western North American Forests

Frontiers in Ecology and Evolution

Before the advent of intensive forest management and fire suppression, western North American for... more Before the advent of intensive forest management and fire suppression, western North American forests exhibited a naturally occurring resistance and resilience to wildfires and other disturbances. Resilience, which encompasses resistance, reflects the amount of disruption an ecosystem can withstand before its structure or organization qualitatively shift to a different basin of attraction. In fire-maintained forests, resilience to disturbance events arose primarily from vegetation pattern-disturbance process interactions at several levels of organization. Using evidence from 15 ecoregions, spanning forests from Canada to Mexico, we review the properties of forests that reinforced qualities of resilience and resistance. We show examples of multi-level landscape resilience, of feedbacks within and among levels, and how conditions have changed under climatic and management influences. We highlight geographic similarities and important differences in the structure and organization of historical landscapes, their forest types, and in the conditions that have changed resilience and resistance to abrupt or large-scale Hessburg et al. Resilience in North American Forests disruptions. We discuss the role of the regional climate in episodically or abruptly reorganizing plant and animal biogeography and forest resilience and resistance to disturbances. We give clear examples of these changes and suggest that managing for resilient forests is a construct that strongly depends on scale and human social values. It involves human communities actively working with the ecosystems they depend on, and the processes that shape them, to adapt landscapes, species, and human communities to climate change while maintaining core ecosystem processes and services. Finally, it compels us to embrace management approaches that incorporate ongoing disturbances and anticipated effects of climatic changes, and to support dynamically shifting patchworks of forest and non-forest. Doing so could make these shifting forest conditions and wildfire regimes less disruptive to individuals and society.

Fire behaviour and smoke modelling: model improvement and measurement needs for next-generation smoke research and forecasting systems

International Journal of Wildland Fire

There is an urgent need for next-generation smoke research and forecasting (SRF) systems to meet ... more There is an urgent need for next-generation smoke research and forecasting (SRF) systems to meet the challenges of the growing air quality, health and safety concerns associated with wildland fire emissions. This review paper presents simulations and experiments of hypothetical prescribed burns with a suite of selected fire behaviour and smoke models and identifies major issues for model improvement and the most critical observational needs. The results are used to understand the new and improved capability required for the next-generation SRF systems and to support the design of the Fire and Smoke Model Evaluation Experiment (FASMEE) and other field campaigns. The next-generation SRF systems should have more coupling of fire, smoke and atmospheric processes. The development of the coupling capability requires comprehensive and spatially and temporally integrated measurements across the various disciplines to characterise flame and energy structure (e.g. individual cells, vertical h...