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The Northwest Fire Science Consortium works to accelerate the awareness, understanding, and adoption of wildland fire science. We connect managers, practitioners, scientists, and local communities and collaboratives working on fire issues on forest and range lands in Washington and Oregon.

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JFSP Regions


NWFSC is one of
fifteen regional exchanges
sponsored by the Joint Fire Science Program.

Hot Topics

Fuels patterns and a fire following mountain pine beetle mortality in the climax lodgepole pine forests of southern central Oregon

Webinar from Northwest Fire Science Consortium

The last of three webinars focusing on insects and fire, Dr. Dave Shaw and Michelle Agne, Department of Forest Engineering, Resources & Management at Oregon State University, presented on November 23rd - Fuels patterns and a fire following mountain pine beetle mortality in the climax lodgepole pine forests of southern central Oregon

Watch the video on our YouTube Channel

Evaluating crown fire rate of spread predictions from physics-based models

Authored by C.M. Hoffman; Published 2015

Modeling the behavior of crown fires is challenging due to the complex set of coupled processes that drive the characteristics of a spreading wildfire and the large range of spatial and temporal scales over which these processes occur. Detailed physics-based modeling approaches such as FIRETEC and the Wildland Urban Interface Fire Dynamics Simulator (WFDS) simulate fire behavior using computational fluid dynamics based methods to numerically solve the three-dimensional, time dependent, model equations that govern, to some approximation, the component physical processes and their interactions that drive fire behavior. Both of these models have had limited evaluation and have not been assessed for predicting crown fire behavior. In this paper, we utilized a published set of field-scale measured crown fire rate of spread (ROS) data to provide a coarse assessment of crown fire ROS predictions from previously published studies that have utilized WFDS or FIRETEC. Overall, 86% of all simulated ROS values using WFDS or FIRETEC fell within the 95% prediction interval of the empirical data, which was above the goal of 75% for dynamic ecological modeling. However, scarcity of available empirical data is a bottleneck for further assessment of model performance.

Establishing a National Methodology for Operational Mixing Height Determination

Presenters: Matthew Fearon, Desert Research Institute and Robyn Heffernan, National Weather Service

Mixing Height is important for assessing smoke dispersion for prescribed fires and wildfires. This webinar will review and explain the strengths and weaknesses of several tested methods for determining mixing heights. The webinar will include discussion of the innovative Turbulent Kinetic Energy (TKE) method which examines several critical atmospheric variables for predicting Dispersion. TKE represents the most robust method for determining Mixing Height while the Stull Method represents an alternative approach that may be more operationally feasible. The webinar will discuss both approaches for determining Mixing Height. In addition, the National Weather Service will describe their work on a national standard for Mixing Height as a weather element in the NWS Fire Weather Program. Following the presentation there will be ample opportunities for Q/A and discussion

One hour of Category 1 Society of American Foresters Continuing Education credit has been approved.

Forest disturbance across the conterminous United States from 1985-2012: The emerging dominance of forest decline

Authored by W.B. Cohen; Published 2016

Evidence of shifting dominance among major forest disturbance agent classes regionally to globally has been emerging in the literature. For example, climate-related stress and secondary stressors on forests (e.g., insect and disease, fire) have dramatically increased since the turn of the century globally, while harvest rates in the western US and elsewhere have declined. For shifts to be quantified, accurate historical forest disturbance estimates are required as a baseline for examining current trends. We report annual disturbance rates (with uncertainties) in the aggregate and by major change causal agent class for the conterminous US and five geographic subregions between 1985 and 2012. Results are based on human interpretations of Landsat time series from a probability sample of 7200 plots (30 m) distributed throughout the study area. Forest disturbance information was recorded with a Landsat time series visualization and data collection tool that incorporates ancillary high-resolution data. National rates of disturbance varied between 1.5% and 4.5% of forest area per year, with trends being strongly affected by shifting dominance among specific disturbance agent influences at the regional scale. Throughout the time series, national harvest disturbance rates varied between one and two percent, and were largely a function of harvest in the more heavily forested regions of the US (Mountain West, Northeast, and Southeast). During the first part of the time series, national disturbance rates largely reflected trends in harvest disturbance. Beginning in the mid-90s, forest decline-related disturbances associated with diminishing forest health (e.g., physiological stress leading to tree canopy cover loss, increases in tree mortality above background levels), especially in the Mountain West and Lowland West regions of the US, increased dramatically. Consequently, national disturbance rates greatly increased by 2000, and remained high for much of the decade. Decline-related disturbance rates reached as high as 8% per year in the western regions during the early-2000s. Although low compared to harvest and decline, fire disturbance rates also increased in the early- to mid-2000s. We segmented annual decline-related disturbance rates to distinguish between newly impacted areas and areas undergoing gradual but consistent decline over multiple years. We also translated Landsat reflectance change into tree canopy cover change information for greater relevance to ecosystem modelers and forest managers, who can derive better understanding of forest-climate interactions and better adapt management strategies to changing climate regimes. Similar studies could be carried out for other countries where there are sufficient Landsat data and historic temporal snapshots of high-resolution imagery.

Recent Arctic tundra fire initiates widespread thermokarst development

Authored by B.M. Jones; Published 2015

Fire-induced permafrost degradation is well documented in boreal forests, but the role of fires in initiating thermokarst development in Arctic tundra is less well understood. Here we show that Arctic tundra fires may induce widespread thaw subsidence of permafrost terrain in the first seven years following the disturbance. Quantitative analysis of airborne LiDAR data acquired two and seven years post-fire, detected permafrost thaw subsidence across 34% of the burned tundra area studied, compared to less than 1% in similar undisturbed, ice-rich tundra terrain units. The variability in thermokarst development appears to be influenced by the interaction of tundra fire burn severity and near-surface, ground-ice content. Subsidence was greatest in severely burned, ice-rich upland terrain (yedoma), accounting for ~50% of the detected subsidence, despite representing only 30% of the fire disturbed study area. Microtopography increased by 340% in this terrain unit as a result of ice wedge degradation. Increases in the frequency, magnitude, and severity of tundra fires will contribute to future thermokarst development and associated landscape change in Arctic tundra regions.

Archived webinar - Does wildfire likelihood or severity increase following insect outbreaks in conifer forests of the Pacific Northwest?

Webinar from Northwest Fire Science Consortium

The first of three webinars focusing on insects and fire, Dr. Garrett Meigs, Department of Forestry at the University of Vermont, presented on November 4th - Does wildfire likelihood or severity increase following insect outbreaks in conifer forests of the Pacific Northwest?
The video begins at 1:51. Watch the video on our YouTube channel.

Regional likelihood of very large wildfires over the 21st century across the western United States: Motivation to study individual events like the Rim Fire, a unique opportunity with unprecedented remote sensing data

Authored by N. Stavros; Published 2015

Studies project that a warming climate will likely increase wildfire activity in many areas (Westerling and others 2002; Flannigan and others 2005, 2009; Littell and others 2009). These analyses are often of aggregate statistics like annual area burned, which are insufficient for analyzing changes in seasonality of fire events, the temporal resolution useful for fire management and understanding what drives individual events. Stavros and others (in press, a) show that very large wildfires (VLWFs >20,234 ha ~50,000 ac) may account for only the top two percent of all fires burned in the western contiguous United States, but they constitute a substantial fraction (approximately 33 percent) of aggregate area burned from 1984 to 2010, thus providing strong motivation for understanding what drives them. Using composite records of mean and 95% confidence interval of climate indices for individual fires within a region vs. these same indices the weeks leading up to, including, and post ignition, Stavros and others (in press, a) investigate the spatial and temporal variability of the VLWF climate space. The VLWF climate space was used to define explanatory variables for logistic regression models of the probability of VLWF occurrence with high accuracy of area under the curve (AUC) > 0.80. Assessments of this climate space show that relationships between climate and aggregate area burned may be driven by how VLWFs respond to climate, and that climate and weather both before and after ignition determine fire growth to VLWF size.

A Wildfire-relevant climatology of the convective environment of the United States

Authored by B.E. Potter; Published 2015

Convective instability can influence the behaviour of large wildfires. Because wildfires modify the temperature and moisture of air in their plumes, instability calculations using ambient conditions may not accurately represent convective potential for some fire plumes. This study used the North American Regional Reanalysis to develop a climatology of the convective environment specifically tied to large fire events. The climatology is based on the period 1979–2009 and includes ambient convective available potential energy (CAPE) as well as values when surface air is warmed by 0.5, 1.0 or 2.0 K or moistened by 0.5, 1.0 or 2.0 g kg-1. Results for the 2.0 K and 2.0 g kg-1 modifications are presented. The results reveal spatial and seasonal patterns of convective sensitivity to added heat or moisture. The patterns suggest that use of ambient CAPE to estimate the potential plume growth of a large wildfire may underestimate that potential in heat- or moisture-sensitive regions.

The carbon balance of reducing wildfire risk and restoring process: an analysis of 10-year post-treatment carbon dynamics in a mixed-conifer forest

Authored by M.L. Wiechmann; Published 2015

Forests sequester carbon from the atmosphere, helping mitigate climate change. In fire-prone forests, burn events result in direct and indirect emissions of carbon. High fire-induced tree mortality can cause a transition from a carbon sink to source, but thinning and prescribed burning can reduce fire severity and carbon loss when wildfire occurs. However, treatment implementation requires carbon removal and emissions to reduce high-severity fire risk. The carbon removed and emitted during treatment may be resequestered by subsequent tree growth, although there is much uncertainty regarding the length of time required. To assess the long-term carbon dynamics of thinning and burning treatments, we quantified the 10-year post-treatment carbon stocks and 10-year net biome productivity (NBP) from a full-factorial experiment involving three levels of thinning and two levels of burning in a mixed-conifer forest in California’s Sierra Nevada. Our results indicate that (1) the understory thin treatment, that retained large trees, quickly recovered the initial carbon emissions (NBP = 31.4 ± 4.2 Mg C ha−1), (2) the carbon emitted from prescribed fire in the burn-only treatment was resequestered within the historical fire return interval (NBP = 32.8 ± 3.5 Mg C ha−1), and (3) the most effective treatment for reducing fire risk, understory thin and burn, had negative NBP (−6.0 ± 4.5 Mg C ha−1) because of post-fire large tree mortality. Understory thinning and prescribed burning can help stabilize forest carbon and restore ecosystem resilience, but this requires additional emissions beyond only thinning or only burning. Retaining additional mid-sized trees may reduce the carbon impacts of understory thinning and burning.

Wildland fire limits subsequent fire occurrence

Authored by S.A. Parks; Published 2015

Several aspects of wildland fire are moderated by site- and landscape-level vegetation changes caused by previous fire, thereby creating a dynamic where one fire exerts a regulatory control on subsequent fire. For example, wildland fire has been shown to regulate the size and severity of subsequent fire. However, wildland fire has the potential to influence other properties of subsequent fire. One of those properties – the extent to which a previous wildland fire inhibits new fires from igniting and spreading within its perimeter – is the focus of our study. In four large wilderness study areas in the western United States (US), we evaluated whether or not wildland fire regulated the ignition and spread (hereafter occurrence) of subsequent fire. Results clearly indicate that wildland fire indeed regulates subsequent occurrence of fires ≥ 20 ha in all study areas. We also evaluated the longevity of the regulating effect and found that wildland fire limits subsequent fire occurrence for nine years in the warm/dry study area in the south-western US and over 20 years in the cooler/wetter study areas in the northern Rocky Mountains. Our findings expand upon our understanding of the regulating capacity of wildland fire and the importance of wildland fire in creating and maintaining resilience to future fire events.

Wildland Urban Interface 2016

The IAFC's Wildland Urban Interface (WUI) conference is a offers hands-on training and interactive sessions designed to address the challenges of wildland fire. If you are one of the many people responsible for protecting local forests or educating landowners and your community about the importance of land management—then this is the conference for you.

Get email updates. Sign up to receive conference updates and notifications.

Fire severity in southwestern Colorado unaffected by spruce beetle outbreak

Authored by R.A. Andrus; Published 2015
Recent large and severe outbreaks of native bark beetles have raised concern among the general public and land managers about potential for amplified fire activity in western North America. To date, the majority of studies examining bark beetle outbreaks and subsequent fire severity in the U.S. Rocky Mountains have focused on outbreaks of mountain pine beetle (MPB, Dendroctonus ponderosae) in lodgepole pine (Pinus contorta) forests, but few studies, particularly field studies, have addressed the effects of the severity of spruce beetle (Dendroctonus rufipennis Kirby) infestation on subsequent fire severity in subalpine Engelmann spruce (Picea engelmannii) and subalpine fir (Abies lasiocarpa) forests. In Colorado, the annual area infested by spruce beetle outbreaks is rapidly rising, while MPB outbreaks are subsiding; therefore understanding this relationship is of growing importance. We collected extensive field data in subalpine forests in the eastern San Juan Mountains, southwestern Colorado, to investigate whether a gray-stage (<5 years from outbreak to time of fire) spruce beetle infestation affected fire severity. Contrary to the expectation that bark beetle infestation alters subsequent fire severity, correlation and multivariate generalized linear regression analysis revealed no influence of pre-fire spruce beetle severity on nearly all field or remotely sensed measurements of fire severity. Findings were consistent across moderate and extreme burning conditions. In comparison to severity of the pre-fire beetle outbreak, we found that topography, pre-outbreak basal area, and weather conditions exerted a stronger effect on fire severity. Our finding that beetle infestation did not alter fire severity is consistent with previous retrospective studies examining fire activity following other bark beetle outbreaks and reiterates the overriding influence of climate that creates conditions conducive to large, high-severity fires in the subalpine zone of Colorado. Both bark beetle outbreaks and wildfires have increased autonomously due to recent climate variability, but this study does not support the expectation that post-beetle outbreak forests will alter fire severity, a result that has important implications for management and policy decisions.

Archived webinar - Influence of recent bark beetle outbreaks on wildfire

Webinar from Northwest Fire Science Consortium

The second of three webinars focusing on insects and fire, Dr. Sarah Hart, Department of Geography at the University of Colorado Boulder, presented on November 13th - Influence of recent bark beetle outbreaks on wildfire.

Watch the video on our YouTube Channel

Climate stress increases forest fire severity across the western United States

Authored by P.J. van Mantgem; Published 2013

Pervasive warming can lead to chronic stress on forest trees, which may contribute to mortality resulting
from fire-caused injuries. Longitudinal analyses of forest plots from across the western US show that high
pre-fire climatic water deficit was related to increased post-fire tree mortality probabilities. This relationship
between climate and fire was present after accounting for fire defences and injuries, and appeared to influence
the effects of crown and stem injuries. Climate and fire interactions did not vary substantially across
geographical regions, major genera and tree sizes. Our findings support recent physiological evidence showing
that both drought and heating from fire can impair xylem conductivity. Warming trends have been
linked to increasing probabilities of severe fire weather and fire spread; our results suggest that warming
may also increase forest fire severity (the number of trees killed) independent of fire intensity (the amount
of heat released during a fire).

Job Opportunity

Event from Clackamas Community College

Wildland Fire and Forest Management Program Instructor opening at Clackamas Community College in Oregon City, OR.

Fuels and stand structure data for the Summit post-fire logging study: pre-logging, one year post-logging, and 13 years post-logging

Authored by J.D. McIver; Published 2015

The Summit Post-fire Logging Study was conducted on the Malheur National Forest in Oregon from 1997 through 2011. The study was intended to examine the effects of logging after a severe wildfire burned through a set of 12 stands just north of the Middle Fork of the John Day River, Malheur County. The 16,000 hectare (ha) Summit Fire was caused by a lightning storm on August 13, 1996, on the North Fork John Day Ranger District (Umatilla National Forest), burned south onto the Long Creek Ranger District of the Malheur National Forest, and was declared officially controlled on September 16, 1996. Within the Malheur Forest portion of the Summit Fire, an area of 8,103 ha (72%) was judged to have burned at high severity (>80% large trees killed), including much of the area in the lower elevation ponderosa pine forests, which typically experience lower severity fires. The short-term effects of post-fire logging were evaluated by conducting a controlled, replicated experiment between 1997 and 1999. Logging occurred in the summers of 1998 and 1999, and consisted of the application of three treatments (un-logged control, commercial, and fuel reduction), applied to 12 experimental units (stands) in four replicate blocks. Data were taken from within about 258 measurement plots in the 12 units (stands) in 1997 (post-fire, pre-logging) and again in 1999 (post-fire, post-logging). The longer-term effects of post-fire logging on fuels and stand structure were evaluated by re-measuring fuel and stand structure variables in 2011, 15 years after the Summit Fire, and 13 years after post-fire logging. The Summit Post-fire Logging Study database consists of data on fuels and stand structure, taken in 1997, 1999, and 2011. It is important to note that no management activities had occurred within the Summit study area between the initial logging work (1998, 1999), and the intermediate-term measurement year (2011). However, on August 8, 2008, 10 years after post-fire logging at Summit, a small, moderate, surface wildfire (the Sunshine Fire) occurred in the eastern portion of the study area, and burned through most of the easternmost Block 4. This small wildfire was effectively controlled within two days after ignition, by fire personnel of the Malheur National Forest (Roy Walker, Malheur National Forest, pers. comm.) Although this wildfire removed one entire replicate block from the original experiment, it provided us with an opportunity for a controlled test of the logging treatments with an actual moderate severity wildfire. This published dataset therefore, consists of plot-level data on fuels and stand structure taken in 1997, 1999, and 2011, to study both short and longer-term post-fire logging effects as well as the effects of the subsequent reburn that occurred 10 years after post-fire logging. It is also important to note pre-treatment data for block 3 was taken in 1998 rather than 1997 because of a necessary reassignment of treatments prescribed by NEPA. Finally we note that the longer-term plot level data for unit 3F (block 3, management unit 419, fuel reduction treatment) was taken in 2014 due to our failure to find the plots in that unit by 2011.

First Approximations of Prescribed Fire Risks Relative to Other Management Techniques Used on Private Lands

Authored by D. Twidwell; Published 2015

Fire is widely recognized as a critical ecological and evolutionary driver that needs to be at the forefront of land management actions if conservation targets are to be met. However, the prevailing view is that prescribed fire is riskier than other land management techniques. Perceived risks associated with the application of fire limits its use and reduces agency support for prescribed burning in the private sector. As a result, considerably less cost-share support is given for prescribed fire compared to mechanical techniques. This study tests the general perception that fire is a riskier technique relative to other land management options. Due to the lack of data available to directly test this notion, we use a combination of approaches including 1) a comparison of fatalities resulting from different occupations that are proxies for techniques employed in land management, 2) a comparison of fatalities resulting from wildland fire versus prescribed fire, and 3) an exploration of causal factors responsible for wildland fire-related fatalities. This approach establishes a first approximation of the relative risk of fatality to private citizens using prescribed fire compared to other management techniques that are readily used in ecosystem management. Our data do not support using risks of landowner fatalities as justification for the use of alternative land management techniques, such as mechanical (machine-related) equipment, over prescribed fire. Vehicles and heavy machinery are consistently leading reasons for fatalities within occupations selected as proxies for management techniques employed by ranchers and agricultural producers, and also constitute a large proportion of fatalities among firefighters. Our study provides the foundation for agencies to establish data-driven decisions regarding the degree of support they provide for prescribed burning on private lands.

A review of the challenges and opportunities in estimating above ground forest biomass using tree-level models

Authored by H. Temesgen; Published 2015

Accurate biomass measurements and analyses are critical components in quantifying carbon stocks and sequestration rates, assessing potential impacts due to climate change, locating bio-energy processing plants, and mapping and planning fuel treatments. To this end, biomass equations will remain a key component of future carbon measurements and estimation. As researchers in biomass and carbon estimation, we review the present scenario of aboveground biomass estimation, focusing particularly on estimation using tree-level models and identify some cautionary points that we believe will improve the accuracy of biomass and carbon estimates to meet societal needs. In addition, we discuss the critical challenges in developing or calibrating tree biomass models and opportunities for improved biomass. Some of the opportunities to improve biomass estimate include integration of taper and other attributes and combining different data sources. Biomass estimation is a complex process, when possible, we should make use of already available resources such as wood density and forest inventory databases. Combining different data-sets for model development and using independent data-sets for model verification will offer opportunities to improve biomass estimation. Focus should also be made on belowground biomass estimation to accurately estimate the full forest contribution to carbon sequestration. In addition, we suggest developing comprehensive biomass estimation methods that account for differences in site and stand density and improve forest biomass modeling and validation at a range of spatial scales.