Abstract  Thinning and prescribed burning are common management practices for reducing fuel buildup in ponderosa pine forests. However, it is not well understood if their combined use is required to lower wildfire risk and to help restore natural ecological function. We compared 16 treatment combinations of thinning, prescribed fire, and slash retention for two decades across a site quality gradient of second-growth pine stands, measuring changes in forest vegetation growth, structure, and composition. Thinning alone doubled the diameter growth increment of ponderosa pine, moderately stimulated shrub production, and resulted in lower tree mortality compared with unthinned plots. In contrast, repeated fire alone did not substantially alter stand structure or increase tree vigor, herbaceous production, or plant diversity. The combined use of thinning and repeated burning reduced shrub cover, yet produced no changes in herbaceous production, plant diversity, stand structure, or tree vigor compared with thin-only treatments. Additional findings identified (1) inconsequential effects of thinning residues on site productivity, (2) the need for multiple entries of prescribed fire if the abatement of shrubs is required, (3) the ineffectiveness of repeated burning to stimulate plant growth, and (4) that the thinning treatment served as an effective surrogate to fire for managing central Oregon forest vegetation.

Abstract  The effects of fire on vegetation vary based on the properties and amount of existing biomass (or fuel) in a forest stand, weather conditions, and topography. Identifying controls over the spatial patterning of fire-induced vegetation change, or fire severity, is critical in understanding fire as a landscape scale process. We use gridded estimates of fire severity, derived from Landsat ETM+ imagery, to identify the biotic and abiotic factors contributing to the observed spatial patterns of fire severity in two large natural fires. Regression tree analysis indicates the importance of weather, topography, and vegetation variables in explaining fire severity patterns between the two fires. Relative humidity explained the highest proportion of total sum of squares throughout the Hoover fire (Yosemite National Park, 2001). The lowest fire severity corresponded with increased relative humidity. For the Williams fire (Sequoia/Kings Canyon National Parks, 2003) dominant vegetation type explains the highest proportion of sum of squares. Dominant vegetation was also important in determining fire severity throughout the Hoover fire. In both fires, forest stands that were dominated by lodgepole pine (Pinus contorta) burned at highest severity, while red fir (Abies magnifica) stands corresponded with the lowest fire severities. There was evidence in both fires that lower wind speed corresponded with higher fire severity, although the highest fire severity in the Williams fire occurred during increased wind speed. Additionally, in the vegetation types that were associated with lower severity, burn severity was lowest when the time since last fire was fewer than 11 and 17 years for the Williams and Hoover fires, respectively. Based on the factors and patterns identified, managers can anticipate the effects of management ignited and naturally ignited fires at the forest stand and the landscape levels.

Abstract  Forest resilience to climate change is a global concern given the potential effects of increased disturbance activity, warming temperatures and increased moisture stress on plants. We used a multi-regional dataset of 1485 sites across 52 wildfires from the US Rocky Mountains to ask if and how changing climate over the last several decades impacted post-fire tree regeneration, a key indicator of forest resilience. Results highlight significant decreases in tree regeneration in the 21st century. Annual moisture deficits were significantly greater from 2000 to 2015 as compared to 1985-1999, suggesting increasingly unfavourable post-fire growing conditions, corresponding to significantly lower seedling densities and increased regeneration failure. Dry forests that already occur at the edge of their climatic tolerance are most prone to conversion to non-forests after wildfires. Major climate-induced reduction in forest density and extent has important consequences for a myriad of ecosystem services now and in the future.

Abstract  Quantitative metrics of horizontal and vertical structural attributes in eastside old-growth ponderosa pine (Pinus ponderosa P. and C. Lawson var. ponderosa) forests were measured to guide the design of restoration prescriptions. The age. size structure, and the spatial patterns were investigated in old-growth ponderosa pine forests at three protected study areas east of the crest of the Cascade Range: Metolius Research Natural Area and Pringle Butte Research Natural Area in central Oregon and Blacks Mountain Experimental Forest in northern California. The three study areas represented sites characterized by deep accumulations of pumice from Cascade volcanism. All stems greater than or equal to 15 cm in height (minimum height of an established seedling) were mapped and measured on a total of 27 1-ha plots. The distribution of trees within each individual plot was investigated by second-order spatial analysis with Ripley's K(d) function, and then evaluated across each study area with functional data analysis. Coarse woody debris was sampled by using the strip-plot method to determine log density, mean log size, volume, and cover. The oldest trees were 618 years at Metolius, 613 years at Pringle Butte, and 330 years at Blacks Mountain. Stands were multi-aged, with as many as 16 cohorts at Metolius and 22 cohorts at Pringle Butte. Density of live old-growth ponderosa pine in the upper canopy ranged from 34 to 94 trees ha(-1) at Metolius, 35 to 79 trees ha(-1) at Pringle Butte, and 15 to 73 trees ha(-1) at Blacks Mountain; the differences between study areas were not significant, resulting in an overall mean density of 50 +/- 3.5 live old-growth trees ha(-1). Mean diameters of these old-growth trees did not differ among the three study areas; the overall mean was 60.0 +/- 1.55 cm dbh. Large dead ponderosa pines (overall mean diameter 61.7 +/- 4.33 cm) were a common feature at all three study areas; the overall mean density was 9.0 +/- 0.97 trees ha(-1). Ripley's K(d) analysis of spatial point patterns using upper canopy trees revealed significant departure from randomness in 24 of the 27 plots. Functional data analysis of the spatial relationship of all sample plots by study area revealed two strong patterns. At scales of 1.2 less than or equal to d less than or equal to 2.6 m at Metolius and 1.6 less than or equal to d less than or equal to 8.4 m at Blacks Mountain, the deviation from random was not significant, suggesting the distribution of old-growth trees was random. More important. significant positive deviation from complete spatial randomness at larger scales at Metolius and Blacks Mountain suggested a clumped distribution. Maximum radii of the clumps were about 22.5 m in diameter at Metolius and about 24 m in diameter at Blacks Mountain. In contrast, old-growth trees at Pringle Butte were randomly distributed. Density of logs at Metolius and Pringle Butte was 47.0 +/- 5.28 logs ha(-1), their mean large-end diameter was 37.6 +/- 2.41 cm. the mean length of each log was 4.2 +/- 0.09 m, the cumulative length of all logs averaged 512.9 +/- 78.12 m, the total volume averaged 62.3 +/- 6.30 m(3) ha(-1), and the cover averaged 1.7 +/- 0.08%. A majority of the logs were in an advanced stage of decomposition, suggesting that they were in place for considerable time. These results are discussed in the context of reference conditions for restoration of ecosystem health and ecological integrity in eastside ponderosa pine forests.

Abstract  Air pollution sensors are quickly proliferating for use in a wide variety of applications, with a low price point that supports use in high-density networks, citizen science, and individual consumer use. This emerging technology motivates the assessment under real-world conditions, including varying pollution levels and environmental conditions. A seven-month, systematic field evaluation of low-cost air pollution sensors was performed in Denver, Colorado, over 2015-2016; the location was chosen to evaluate the sensors in a high-altitude, cool, and dry climate. A suite of particulate matter (PM), ozone (O3), and nitrogen dioxide (NO2) sensors were deployed in triplicate and were collocated with federal equivalent method (FEM) monitors at an urban regulatory site. Sensors were evaluated for their data completeness, correlation with reference monitors, and ability to reproduce trends in pollution data, such as daily concentration values and wind-direction patterns. Most sensors showed high data completeness when data loggers were functioning properly. The sensors displayed a range of correlations with reference instruments, from poor to very high (e.g., hourly-average PM Pearson correlations with reference measurements varied from 0.01 to 0.86). Some sensors showed a change in response to laboratory audits/testing from before the sampling campaign to afterwards, such as Aeroqual, where the O3 response slope changed from about 1.2 to 0.6. Some PM sensors measured wind-direction and time-of-day trends similar to those measured by reference monitors, while others did not. This study showed different results for sensor performance than previous studies performed by the U.S. EPA and others, which could be due to different geographic location, meteorology, and aerosol properties. These results imply that continued field testing is necessary to understand emerging air sensing technology.

Abstract  Increased forest fire activity across the western continental United States (US) in recent decades has likely been enabled by a number of factors, including the legacy of fire suppression and human settlement, natural climate variability, and human-caused climate change. We use modeled climate projections to estimate the contribution of anthropogenic climate change to observed increases in eight fuel aridity metrics and forest fire area across the western United States. Anthropogenic increases in temperature and vapor pressure deficit significantly enhanced fuel aridity across western US forests over the past several decades and, during 2000–2015, contributed to 75% more forested area experiencing high (>1 σ) fire-season fuel aridity and an average of nine additional days per year of high fire potential. Anthropogenic climate change accounted for ∼55% of observed increases in fuel aridity from 1979 to 2015 across western US forests, highlighting both anthropogenic climate change and natural climate variability as important contributors to increased wildfire potential in recent decades. We estimate that human-caused climate change contributed to an additional 4.2 million ha of forest fire area during 1984–2015, nearly doubling the forest fire area expected in its absence. Natural climate variability will continue to alternate between modulating and compounding anthropogenic increases in fuel aridity, but anthropogenic climate change has emerged as a driver of increased forest fire activity and should continue to do so while fuels are not limiting.

Abstract  This report enumerates all possible costs of wildfire management and wildfire-related losses. It, further, compiles estimates or proposes methods for estimating the costs and losses identified. These estimates can be used for C+NVC modeling, and can also be used to produce an estimate of the ‘economic burden’ of wildfire for the United States. The economic burden represents the impact wildfire has on the U.S. economy. Tracking the economic burden of wildfire could be used to assess return-on-investment into wildfire interventions. The economic burden is decomposed into: 1. intervention costs; 2. prevention/preparedness, mitigation, suppression, and cross-cutting; 2. and into direct and indirect wildfire related (net) losses. The annualized economic burden from wildfire is estimated to be between $71.1 billion to $347.8 billion ($2016 US). Annualized costs are estimated to range from $7.6 billion to $62.8 billion. Annualized losses are estimated to range from $63.5 billion to $285.0 billion.

Abstract  In the 15 western states there are at least 28 million acres of forest that could benefit from some type of mechanical treatment to reduce hazardous fuel loading. It is estimated that about 60 percent of this area could be operationally accessible for treatment with a total biomass treatment volume of 345 million bone dry tons (bdt). Two-thirds of this forest area is on public lands. Most of the volume is in trees 6 inches diameter and greater that have conventional utilization opportunities. Transportation cost and distance to markets, however, may preclude actual recovery. Treatment costs are increased by the need to treat large numbers of low-volume stems less than 4 inches in diameter. Gross costs can range from $35 to over $1000 per acre depending on type of operation, terrain, and number of trees to be treated. Some areas will likely be prohibitively expensive to treat, although cost estimates presented here may be high because they are based on the use of conventional timber harvesting systems applied to small diameter treatments. Implementation of any significant fuel reduction effort will generate large volumes of biomass and require the development of additional workforce and operations capacity in western forests.

Abstract  A series of small-scale laboratory fires were conducted to study the relationship between fuel type, moisture content, energy released and emissions during the combustion process of live wildland fuels. The experimental design sought to understand the effects that varying moisture content of different fire-promoting plant species had on the release of total energy, gaseous emissions (CO, CO2), particulate matter less than 2.5 mu m in diameter (PM2.5) and fire radiative energy (FRE). Instantaneous FRE, or fire radiative power (FRP), is an important parameter used in remote sensing to relate the emitted energy to the biomass fuel consumption. Currently, remote sensing techniques rely on empirically based linear relationships between emitted FRE and biomass consumed. However, this relationship is based on the assumption that all fuels emit the same amount of energy per unit mass, regardless of fuel conditions (type, moisture, packing, orientation, etc.). In this study, we revisited these assumptions under the influence of moisture content for species that are adapted to fire, containing volatile oils. Results show that, in terms of the total energy released, this assumption holds fairly well regardless of fuel type and moisture content. However, FRE was found to be slightly dependent on the fuel type and very dependent on the moisture content of the fuel. Most of this variation was attributed to changes in the behaviour of the combustion process for different fuels, similarly observed in emissions measurements. These results highlight a need to further examine the role of fuel moisture and combustion state when determining emissions from remotely sensed measurements.

Abstract  The Northwest Community Forest Coalition invited EPA-WED Research Scientist Bob McKane to present the Keynote Address for the 2018 Northwest Community Forest Forum on May 9‐11 in Astoria, OR. His address will describe "How Visualizing Ecosystem Land Management Assessments (VELMA) modeling quantifies co‐benefits and tradeoffs in Community Forest management". He will also participate in the Forum's opening panel discussion and in breakout sessions during Forum. The Northwest Community Forest Coalition is a network of practitioners supporting the emergence, development, and management of community forests. This 4th biennial Community Forest Forum and Field Tour will bring together over 100 community‐based organizations, land trusts, private landowners, local government officials, and others to learn and network. Community‐owned forests are an innovative governance model that enables forestland to be managed for both conservation and economic development values. Members of the Coalition have a shared vision that community forests can play an important role in establishing sustainable rural working lands that supply an array of ecosystem services – clean drinking water, fuel, fiber, jobs, and recreation – for surrounding rural communities and more distant urban centers. VELMA is an eco‐hydrology model designed to help users assess green infrastructure options for controlling the fate and transport of water, nutrients, and toxics across multiple spatial and temporal scales for different ecoregions and present and future climates. It’s part of SHC Project 2.61, Community–based Ecosystem Goods and Services. Dr. McKane has worked previously with the Nisqually Community Forest team on developing salmon‐friendly timber management plans with VELMA.

Abstract  Our goal was to move toward full economic valuation of fuels-reduction treatments applied to ponderosa pine (Pinus ponderosa) forests. For each of five fuels-reduction projects in northern Arizona, we calculated the economic value of carbon storage and carbon releases over one century produced by two fuels-reduction treatments of thinning following by prescribed burning every one (Rx10) or two (Rx20) decades and for no treatment followed by intense wildfire once in the first 50 years (HF50) or once in the first 100 years (HF100). Our estimates include two uses of harvested wood, the current use as pallets, and multiproduct use as paper, pallets, and construction materials. Additionally, we included the economic value of damage and loss from wildfire. Results indicate that treatments increase carbon stock in live trees over time; however, the inclusion of carbon emissions from treatments reduces net carbon storage and thereby carbon credits and revenue. The economic valuation shows that the highest net benefit of $5029.74 ha(-1) occurs for the Rx20 treatment with the HF50 baseline and the high estimated treatment benefits of avoided losses, regional economic benefits, and community value of fire risk reduction. The lowest net benefit of -$3458.02 ha(-1) occurs for the Rx10 treatment with the HF100 baseline and the low estimated treatment benefits. We conclude that current nonmarket values such as avoided wildfire damage should be included with values of traditional wood products and emerging values of carbon storage to more appropriately estimate long-term benefits and costs of forest fuels-reduction treatments.

Abstract  Where a legacy of aggressive wildland fire suppression has left forests in need of fuel reduction, allowing wildland fire to burn may provide fuel treatment benefits, thereby reducing suppression costs from subsequent fires. The least-cost-plus-net-value-change model of wildland fire economics includes benefits of wildfire in a framework for evaluating suppression options. In this study, we estimated one component of that benefit – the expected present value of the reduction in suppression costs for subsequent fires arising from the fuel treatment effect of a current fire. To that end, we employed Monte Carlo methods to generate a set of scenarios for subsequent fire ignition and weather events, which are referred to as sample paths, for a study area in central Oregon. We simulated fire on the landscape over a 100-year time horizon using existing models of fire behaviour, vegetation and fuels development, and suppression effectiveness, and we estimated suppression costs using an existing suppression cost model. Our estimates suggest that the potential cost savings may be substantial. Further research is needed to estimate the full least-cost-plus-net-value-change model. This line of research will extend the set of tools available for developing wildfire management plans for forested landscapes.

Abstract  In the fire-prone Western U.S., the scale of surrounding forest density can be realized by homebuyers as an amenity for aesthetics and cooling effects, or as a disamenity in terms of wildfire risk. There has been a lack of academic attention to understanding this duality of forest density preferences for homebuyers in at-risk Wildland Urban Interfaces (WUIs). To fill this gap, we investigated the influence of forest density on WUI house sales in four high fire-risk zones in dry, mixed conifer forests of the Western U.S with a spatial hedonic pricing model. Explanatory attributes related to house structure, neighborhood, and environmental amenities were assessed, along with a set of WUI variables that included forest density ranges at two buffer levels— a 100 m radius level and a 500 m radius level. Results indicate a strong preference for lower forest density at the 100 m level, but a countering preference for higher forest density at the larger 500 m buffer. These findings suggest the need to reconsider broad approaches in public awareness campaigns and regional planning, as well as fire management policies and strategies. Preference for higher density forests implies that if left to homeowners, fuel treatments in public spaces will be underinvested.

Abstract  The extreme cost of fighting wildland fires has brought fire suppression expenditures to the forefront of budgetary and policy debate in the United States. Inasmuch as large fires are responsible for the bulk of fire suppression expenditures, understanding fire characteristics that influence expenditures is important for both strategic fire planning and onsite fire management decisions. These characteristics then can be used to produce estimates of suppression expenditures for large wildland fires for use in wildland fire decision support or after-fire reviews. The primary objective of this research was to develop regression models that could be used to estimate expenditures on large wildland fires based on area burned, variables representing the fire environment, values at risk, resource availability, detection time, and National Forest System region. Variables having the largest influence on cost included fire intensity level, area burned, and total housing value within 20 mi of ignition. These equations were then used to predict suppression expenditures on a set of fiscal year 2005 Forest Service fires for the purpose of detecting “extreme” cost fires—those fires falling more than 1 or 2 SDs above or below their expected value.

Abstract  Soil organic carbon (SOC, kg C m-2) is an important component in evaluating global C stores. The nitrogen (TN, kg N m-2) cycle is closely linked to C and understanding its role is also important. Contents and distributions of SOC and TN in soil profiles, to 1-meter depth, were estimated from 79 soils pits, in old-growth forests, in 7 physiographic provinces in western Oregon and Washington. Soils were sampled in four layers, forest floor, 0- to 20-cm, 20- to 50-cm, and 50- to 100-cm, and analyzed on a LECO CN Analyzer. Material 2-mm. Forest floor SOC ranged from 0 to 14 kg C m-2 (mean = 2.7) and forest floor TN ranged from 0 to 0.4 kg N m-2 (mean = 0.07). The SOC of mineral soil ranged from 1.0 to 18 kg C m-2 (mean = 6.6) for 0- to 20-cm depth and 2.2 to 57 kg C m-2 (mean = 17) for 0- to 100-cm depth. The TN of mineral soil ranged from 0.04 to 1.0 kg N m-2 (mean = 0.31) for 0- to 20-cm depth and 0.12 to 3 kg N m-2 (mean = 1.0) for 0- to 100-cm depth. Up to 66% of SOC and TN measured was found below 20-cm, illustrating how failing to sample at depth can grossly underestimate SOC. As much as 44% of SOC and TN measured was found in C-bearing material >2-mm, material for which many methods neglect to account. Longitudinal differences in SOC and TN contents were evident between Coastal, Cascade, and Eastside Cascade sites, implying effects from site and climatic factors. Regression analysis was used to quantify relationships of SOC and TN to site and climatic factors. Response variables included forest floor, forest floor plus 0- to 20-cm, 0- to 20-cm, and 0- to 100-cm layers. Moisture and soil texture played important roles in most cases examined. The results of this study, and of other studies assessing the effects of site and climatic characteristics on the factors controlling soil organic matter accumulation, suggest the relationships are regionally specific.

Abstract  This paper examines the effect wildfire mitigation has on broad-scale wildfire behavior. Each year, hundreds of million of dollars are spent on fire suppression and fuels management applications, yet little is known, quantitatively, of the returns to these programs in terms of their impact on wildfire extent and intensity. This is especially true when considering that wildfire management influences and reacts to several, often times confounding factors, including socioeconomic characteristics, values at risk, heterogeneous landscapes, and climate. Due to the endogenous nature of suppression effort and fuels management intensity and placement with wildfire behavior, traditional regression models may prove inadequate. Instead, I examine the applicability of propensity score matching (PSM) techniques in modeling wildfire. This research makes several significant contributions including: (1) applying techniques developed in labor economics and in epidemiology to evaluate the effects of natural resource policies on landscapes, rather than on individuals; (2) providing a better understanding of the relationship between wildfire mitigation strategies and their influence on broad-scale wildfire patterns; (3) quantifying the returns to suppression and fuels management on wildfire behavior.

Abstract  Background Wildfires are increasingly a significant source of fine particulate matter (PM2.5), which has been linked to adverse health effects and increased mortality. ESKD patients are potentially susceptible to this environmental stressor. Methods We conducted a retrospective time-series analysis of the association between daily exposure to wildfire PM2.5 and mortality in 253 counties near a major wildfire between 2008 and 2012. Using quasi-Poisson regression models, we estimated rate ratios (RRs) for all-cause mortality on the day of exposure and up to 30 days following exposure, adjusted for background PM2.5, day of week, seasonality, and heat. We stratified the analysis by causes of death (cardiac, vascular, infectious, or other) and place of death (clinical or nonclinical setting) for differential PM2.5 exposure and outcome classification. Results We found 48,454 deaths matched to the 253 counties. A 10-μg/m3 increase in wildfire PM2.5 associated with a 4% increase in all-cause mortality on the same day (RR, 1.04; 95% confidence interval [95% CI], 1.01 to 1.07) and 7% increase cumulatively over 30 days following exposure (RR, 1.07; 95% CI, 1.01 to 1.12). Risk was elevated following exposure for deaths occurring in nonclinical settings (RR, 1.07; 95% CI, 1.02 to 1.12), suggesting modification of exposure by place of death. “Other” deaths (those not attributed to cardiac, vascular, or infectious causes) accounted for the largest portion of deaths and had a strong same-day effect (RR, 1.08; 95% CI, 1.03 to 1.12) and cumulative effect over the 30-day period. On days with a wildfire PM2.5 contribution >10 μg/m3, exposure accounted for 8.4% of mortality. Conclusions Wildfire smoke exposure was positively associated with all-cause mortality among patients receiving in-center hemodialysis.

Abstract  Wildfires affect watersheds in myriad ways, from reducing evapotranspiration to changing soil repellencies, but new research suggests impacts on snowpack and runoff are the most significant.

Abstract  Wildfires are increasing in severity and frequency in the American West, but there is limited understanding of their economic effects at the community level. We conducted a case study of the impacts of large wildfires in 2008 in Trinity County, California, by examining labor market, suppression spending, and qualitative interview data. We found that the 2008 fires had interrelated effects on several economic sectors in the county. Labor market data indicated a decrease in total private-sector employment and wages and an increase in public-sector employment and wages during the summer of 2008 compared to the previous year, while interviews captured more nuanced impacts for individual businesses

Abstract  This paper presents the first-ever comprehensive estimate of the total economic value of the National Parks Service. The estimate covers administered lands, waters, and historic sites as well as NPS programs, which include protection of natural landmarks and historic sites, partnerships with local communities, recreational activities and educational programs. Our estimate of the total economic value to the American public is $92 billion. Two-thirds of this total ($62 billion) is for National Park lands, waters and historic sites; the remaining $30 billion is attributed to NPS Programs. The estimate, which is based on very conservative assumptions, includes not only the value attributed by visitors to the parks, but also a significant “non-use” or “existence” value. This is the value derived by the public from simply knowing that NPS assets are protected for current and future generations, regardless of whether or not they actually choose to visit.

Abstract  This report presents the total cost of fire in the United States for the years 1980 to 2014. The cost of fire for the years 2015 and later are not calculated as most of the data sources used are available only until 2014. The total cost of fire is defined as the collective of all net expenditure on fire protection and all net losses due to fire incidents. For 2014, the total is $328.5 billion, which was 1.9% of the U.S. Gross Domestic Product (GDP). The expenditures constitute $273.1 billion (83.1% of total) and the losses constitute $55.4 billion (16.9% of total). The fire safety costs in building construction is the largest component at $57.4 billion (17.5% of total). This report provides updated prevention, protection, and mitigation costs. This has been achieved through (a) creating a taxonomy for mutually exclusive expenditures and losses based on findings from extensive literature review to ensure a complete accounting of the cost of fire, and (b) using analytical methodologies from literature review of fire and other hazard impacts to account for each defined facet of cost and loss. These methods will guide the calculation of the total cost of fire in being complete, precise, and standardized for future application by the National Fire Protection Association (NFPA) community. Future research directions, including regression analysis to find relationships between quantifiable factors of costs and losses, are also provided.