California Department Of Forestry Research Articles

Impact of wildfires on radiotherapy adherence in patients with cancer: A multi-clinic study.

e23154 Background: Recent surges in wildfire activity due to climate change pose significant threats to the delivery of consistent oncological care. Assessing the impact of such environmental disasters on the continuity of radiotherapy treatments is essential to mitigate healthcare disruptions and informing policy. Our study investigates the association between California wildfires from 2017-2021 and the adherence to scheduled radiotherapy sessions in cancer patients across multiple clinics, highlighting the interplay between environmental catastrophes and cancer care outcomes. Methods: We retrospectively analyzed 539,292 visits across eight clinics, including Providence Northern California (Petaluma), Providence at St. Joseph Hospital (Eureka), UCSF, and Stanford, extracting data on completed and missed radiotherapy sessions from their Oncology Health Information systems. In conjunction with CAL FIRE wildfire data, we performed univariable and multivariable logistic regression analyses with robust standard errors, adjusting for seasonal variations, clinic-specific effects, and temporal trends. Covariates in the multivariable model included seasonal effects modeled as sine/cosine functions, a linear date to capture time trends, and fixed effects for each clinic. All analyses were conducted using Stata 18.0 and R 4.2.3. Results: Univariable analysis indicated a slight increase in missed appointments when a wildfire occurred within 50km (OR = 1.06 [1.00, 1.11], p = 0.039). Specifically, the missed visit rate was 4.8% without a fire and 5.1% with a fire. Multivariable analysis, controlling for seasonality, temporal trends, and clinic-specific factors, revealed a stronger association (OR = 1.07 [1.02, 1.13], p = 0.007) with adjusted missed rates of 4.8% and 5.2%, respectively. The overall missed visit rate was 4.9%, with 8.8% of visits coinciding with active wildfires within 50 km of a clinic. Conclusions: This initial investigation suggests a potential trend towards higher non-adherence to radiotherapy sessions in the context of wildfire events. While our findings indicate a statistically significant association, they should be regarded as hypothesis-generating. There is a clear imperative for more comprehensive research to delineate which clinics, patient demographics, and disease sites are most susceptible to the deleterious effects of wildfires. Future studies should aim to incorporate a broader array of variables, including physical, psychological, and socioeconomic factors that may confer increased vulnerability to climate-related disruptions. This nuanced understanding is critical to inform targeted strategies that bolster the resilience of healthcare delivery systems and protect cancer patients from the escalating risks posed by climate change.

First report of Cryptostroma corticale causing sooty bark disease in California and first worldwide report of silver maple as a host.

In November 2022 and February 2023, CAL FIRE tree health experts examined four maples (Acer spp.) planted decades earlier in a residential setting in Elk Grove, Sacramento Co., California (USA). Three of the trees were silver maples (Acer saccharinum ) and one was a Norway maple (A. platanoides); both species are exotic to California. The trees were in an irreversible state of decline, with the canopy substantially thinned and browning. Extensive bark cankers elongating longitudinally along the stem were visible on all trees (Fig. S1). Cankers were filled by fungal stromata protruding through the bark and producing masses of elliptical dark brown conidia (Fig. S2), approximately 5.5 x 3.7 um in size, giving the cankers a sooty appearance. The cankered bark could be peeled off easily, revealing dark and discrete lesions in the phloem and xylem. Samples from the three trees were shipped to the U.C. Berkeley Forest Pathology and Mycology Laboratory and to the CDFA PPDC in Sacramento, CA. In the laboratories, small wood chips were taken from the margins of the lesions, surface sterilized by dipping them for 30 seconds in 70% Ethanol, rinsed for 30 seconds in sterile water and plated onto 2.5% Malt Extract Agar amended with 0.3g/L Streptomycin or onto one-half strength acidified potato dextrose agar (APDA). Two morphologically identical cultures were obtained, one (T2) from a silver maple and one (T6) from the Norway maple. Cultures were then grown in liquid 2.5% malt extract broth and, after one week, DNA was extracted using the Qiagen Plant DNeasy DNA extraction kit. The ITS sequences are diagnostic for this fungus (Li et al. 2021) and those of the two cultures (GB OR064033 and OR933565) were 100% homologous to GenBank sequences of Cryptostroma corticale ( e.g. GB OP474010-11). The RPB2 sequence of T2 ( GB OR992132) was 100% homologous to that of C. corticale (GB HG934116.1). The isolate obtained from silver maple was inoculated in four potted silver maples by removing a bark disk 50 mm in diameter with a cork borer in three spots staggered at different heights and sides on the stem, placing a colonized agar plug of C. corticale in contact with the phloem, replacing the bark disk and wrapping with parafilm. Two control trees were mock inoculated using sterile agar plugs. Trees were in 57 L pots, had an average stem caliper of 2.7 cm, an average height of 3.5 m and were kept in a lath house at average high temperatures of 18-24 degrees C. After ten weeks, average lesion length was 15.4 cm (SE= 4.6) and 4.3 cm (SE=2.3) in the fungus-inoculated and control trees, respectively. An ANOVA test, nesting lesions sizes within tree, determined lesions lengths were different between inoculated and mock trees (P= 0.04). The fungus was reisolated from all points in all inoculated trees but never from control trees. C. corticale was first described in the UK from sycamore maple (Acer pseudoplatanus) (Gregory et al. 1949) and is an emerging problem in Europe (Muller et al. 2023). In North America, it has been reported from A. negundo, A. campestre, A. macrophyllum and Cornus nuttallii (Worral 2020), and it appears to be present in the Pacific Northwest (Brooks et al. 2023, Goree 1969). Norway maple is included in the European Plant Protection Organization list of hosts for C. corticale (EPPO 2023), however our finding of C. corticale on silver maple is a first report of this host worldwide and of this pathogen in California. This report is noteworthy, given that C. corticale is also a human pathogen infecting the respiratory system (Braun et al. 2021).

Dwelling proximity to wildfire and spina bifida risk in offspring

Objective To evaluate the association between wildfire exposure in pregnancy and spina bifida risk. Methods This retrospective cohort study used the California Office of Statewide Health Planning and Development Linked Birth File with hospital discharge data between 2007 and 2010. The Birth File data were merged with the California Department of Forestry and Fire Protection data of the same year. Spina bifida was identified by its corresponding ICD-9 code listed on the hospital discharge of the newborn. Wildfire exposure was determined based on the zip code of the woman’s home address. Pregnancy was considered exposed to wildfire if the mother lived within 15 miles of a wildfire during the pregnancy or within 30 days prior to pregnancy. Results There were 2,093,185 births and 659 cases of spina bifida between 2007 and 2010. The births were analyzed using multivariable logistic regression models and adjusted for potential confounders. Exposure to wildfire in the first trimester was associated with higher odds of spina bifida (aOR= 1.43 [1.11–1.84], p-value = 0.01). Wildfire exposure 30 days before the last menstrual period and during the second and third trimesters were not associated with higher spina bifida risk. Conclusion Wildfire exposure has shown an increased risk of spina bifida during the early stages of pregnancy.

Effects of Wildfire Events on California Radiation Oncology Clinics and Patients

PurposeThe impact of climate-driven events, such as wildfires, on healthcare delivery and cancer care is a growing concern. Patients with cancer undergoing radiotherapy are particularly vulnerable to treatment interruptions, which have a direct impact on survival. We report the results of a study characterizing the impact of wildfires on radiation oncology clinics and their patients. Methods and MaterialsA survey of California radiation oncologists was used to evaluate emergency preparedness and the impact of wildfires on the delivery of radiotherapy services between 2017-2022. Descriptive statistics and Pearson's chi-squared tests were performed to investigate potential relationships between provider characteristics, practice settings, and perceptions of the impact of wildfire events. California Department of Forestry and Fire Protection (CAL FIRE) data were employed to map the geographic distribution of wildfires to clinic locations. ResultsResponse rate was 12.3% (51/415 radiation oncologists), representing 25% of clinics (43/176) in 41% (24/58) of California counties. 61% (31/51) of respondents reported being impacted by a wildfire, two of which are rural clinics (100%, 2/2) and 29 are (59%, 29/49) metropolitan practices. Of these, 18% (9/51) reported a clinic closure, and 29% (15/51) reported staffing shortages. Respondents reported impacts on patients, including having to evacuate (55%, 28/51), cancel/reschedule treatments (53%, 27/51), and experiencing physical, mental, or financial hardship due to wildfires (45%, 23/51). Respondents described impacts on clinical operations, including being forced to transfer patients (24%, 12/51), transportation interruptions (37%, 19/51), regional/community evacuations (35%, 18/51), and physical/mental health impacts (27%, 14/51) on clinic personnel. Less than half of the respondents (47%, 24/51) reported their workplace had a wildfire emergency preparedness plan. Additionally, geographic analysis revealed that 100% (176/176) of clinics were located within 25 miles of a wildfire. ConclusionsThis study highlights the impact of wildfires on radiation oncology clinics and patients, and underscores the need for emergency preparedness planning to minimize the consequences of such disasters.

UAV-Based Wildland Fire Air Toxics Data Collection and Analysis.

Smoke plumes emitted from wildland-urban interface (WUI) wildfires contain toxic chemical substances that are harmful to human health, mainly due to the burning of synthetic components. Accurate measurement of these air toxics is necessary for understanding their impacts on human health. However, air pollution is typically measured using ground-based sensors, manned airplanes, or satellites, which all provide low-resolution data. Unmanned Aerial Vehicles (UAVs) have the potential to provide high-resolution spatial and temporal data due to their ability to hover in specific locations and maneuver with precise trajectories in 3-D space. This study investigates the use of an octocopter UAV, equipped with a customized air quality sensor package and a volatile organic compound (VOC) air sampler, for the purposes of collecting and analyzing air toxics data from wildfire plumes. The UAV prototype developed has been successfully tested during several prescribed fires conducted by the California Department of Forestry and Fire Protection (CAL FIRE). Data from these experiments were analyzed with emphasis on the relationship between the air toxics measured and the different types of vegetation/fuel burnt. BTEX compounds were found to be more abundant for hardwood burning compared to grassland burning, as expected.

Spatial and temporal strategies of resprouting and seeding in a chaparral shrub species.

There is no conflict of interest. Seedling and resprout data (Keeley, 2023) are available in the USGS ScienceBase Catalog at https://doi.org/10.5066/P9713QT4. Fire history data were from annual reports known as Redbooks obtained from CAL FIRE downloaded from https://www.fire.ca.gov/stats-events/.

Creation of Wildfire Susceptibility Maps in Plumas National Forest Using InSAR Coherence, Deep Learning, and Metaheuristic Optimization Approaches

Plumas National Forest, located in the Butte and Plumas counties, has experienced devastating wildfires in recent years, resulting in substantial economic losses and threatening the safety of people. Mapping damaged areas and assessing wildfire susceptibility are necessary to prevent, mitigate, and manage wildfires. In this study, a wildfire susceptibility map was generated using a CNN and metaheuristic optimization algorithms (GWO and ICA) based on images of areas damaged by wildfires. The locations of damaged areas were identified using the damage proxy map (DPM) technique from Sentinel-1 synthetic aperture radar (SAR) data collected from 2016 to 2020. The DPMs’ depicting areas damaged by wildfires were similar to fire perimeters obtained from the California Department of Forestry and Fire Protection (CAL FIRE). Data regarding damaged areas were divided into a training set (50%) for modeling and a testing set (50%) for assessing the accuracy of the models. Sixteen conditioning factors, categorized as topographical, meteorological, environmental, and anthropological factors, were selected to construct the models. The wildfire susceptibility models were evaluated using the area under the receiver operating characteristic (ROC) curve (AUC) and root mean square error (RMSE) analysis. The evaluation results revealed that the hybrid-based CNN-GWO model (AUC = 0.974, RMSE = 0.334) exhibited better performance than the CNN (AUC = 0.934, RMSE = 0.780) and CNN-ICA (AUC = 0.950, RMSE = 0.350) models. Therefore, we conclude that optimizing a CNN with metaheuristics considerably increased the accuracy and reliability of wildfire susceptibility mapping in the study area.

An analysis of factors influencing structure loss resulting from the 2018 Camp Fire

Despite the intensity of the 2018 Camp Fire, many structures survived in heavily burned areas. Logistic regressions were run to determine which structural and parcel characteristics predicted structure survival using two data sets. The first, CAL FIRE’s Damage Inspections (DINS) dataset, included 14 518 destroyed and 622 partially damaged structures. The second, combining information from the DINS and Defensible Space (DINS+DSPACE) databases, had many more attributes and was better balanced between destroyed (n = 728) and surviving (n = 676) structures, but was much smaller. Several approaches were compared for filtering out records with null values. Results were largely consistent with previously literature, finding that structural hardness factors (e.g. double-paned windows, enclosed eaves, ignition-resistant roofs and siding, no vents, etc.) are important in determining structure survival. Newer structures, built after California’s recent (2005 and 2007) fire safe building code updates, were more likely to survive, as were homes with higher improvement values. Mobile homes were far more likely to be destroyed. The role of fuel mitigation around structures was less conclusive; defensible space clearance had only a weak association with structure survival, although DINS+DSPACE results suggested a slight reduction in risk due to removing leaves and needles from gutters/roofs and keeping surrounding dead grass mowed.

Relationships between building features and wildfire damage in California, USA and Pedrógão Grande, Portugal

Background Buildings in communities near wildlands, in the wildland–urban interface (WUI), can experience wildfire damage. Aims To quantitatively assess the relationship between building features and damage, a building wildfire resistance index is developed and validated with the 2013–2017 CAL FIRE (DINS) database from California, USA, and the 2017 Pedrógão Grande Fire Complex post-fire investigation from Portugal. Methods Three statistical dependence tests are compared to evaluate the relationship between selected building features and damage. The Wildfire Resistance Index (WRI), range: [–1, 1], is proposed and validated as a rating for building wildfire susceptibility. Key results The most correlated features to wildfire damage are the presence of vent screens and deck materials in California, and exterior walls material and deck materials in Portugal. For Portugal, as WRI increases by 50%, linear regression estimates a 48% decrease in proportion of highly damaged buildings, and a 42% increase in proportion of low damage buildings (R2 of 0.93 and 0.90, respectively). A total of 65% of California buildings with WRI = 1 were destroyed, compared to average 85% for WRI ≥−0.33. Conclusions The WRI quantifies the wildfire damage experienced by buildings in two diverse WUI regions. Implications The WRI could be used as an estimator of wildfire damage but it needs further development.

Accurate tracking of forest activity key to multi-jurisdictional management goals: A case study in California

An essential component of sustainable forest management is accurate monitoring of forest activities. Although monitoring efforts have generally increased for many forests throughout the world, in practice, effective monitoring is complex. Determining the magnitude and location of progress towards sustainability targets can be challenging due to diverse forest operations across multiple jurisdictions, the lack of data standardization, and discrepancies between field inspections and remotely-sensed records. In this work, we used California as a multijurisdictional case study to explore these problems and develop an approach that broadly informs forest monitoring strategies. The State of California recently entered into a shared stewardship agreement with the US Forest Service (USFS) and set a goal to jointly treat one million acres of forest and rangeland annually by 2025. Currently, however, federal and state forest management datasets are disjoint. This work addresses three barriers stymying the use of federal and state archival records to assess management goals. These barriers are: 1) current databases from different jurisdictions have not been combined due to their distinct data collection processes and internal structures; 2) datasets have not been comprehensively analyzed, despite the need to understand the extent of previous treatments as well as the rate of current activity; and 3) the spatial accuracy of archival datasets has not been evaluated against remotely-sensed data. To reduce these barriers, we first aggregated existing archival forest management records between 1984 and 2019 from the USFS′ Forest Activity Tracking System (FACTS) and the California Department of Forestry and Fire Protection (CAL FIRE) using a qualitative scalar of treatment intensity. Combined FACTS and CAL FIRE completed footprint acres – defined as unique areas of land where a treatment was completed at any time since 1984 – have decreased since a peak in 2008. At most, 300,000 footprint acres are completed each year, 30% of the million-acre goal. Prescribed fires – defined as direct burning operations – have risen over time, according to the FACTS hazardous fuels dataset but prescribed fire records in CAL FIRE's dataset have rapidly increased since 2016. We also refined the spatial and temporal detail of the aggregated management record using the Continuous Change Detection and Classification algorithm on satellite remote sensing data to produce a state-wide time series map of harvest disturbances. A comparison of the algorithm's refined data to the archival record potentially suggests over-reporting in both FACTS and CAL FIRE's archival datasets. Our integrated dataset provides a better assessment of current treatments and the path towards the 1-million-acre a year goal. The refined dataset leverages the strengths of complementary, albeit imperfect, monitoring strategies from archives and remotely-sensed detection.

Facilitating Prescribed Fire in Northern California through Indigenous Governance and Interagency Partnerships

Prescribed burning by Indigenous people was once ubiquitous throughout California. Settler colonialism brought immense investments in fire suppression by the United States Forest Service and the California Department of Forestry and Fire Prevention (CAL FIRE) to protect timber and structures, effectively limiting prescribed burning in California. Despite this, fire-dependent American Indian communities such as the Karuk and Yurok peoples, stalwartly advocate for expanding prescribed burning as a part of their efforts to revitalize their culture and sovereignty. To examine the political ecology of prescribed burning in Northern California, we coupled participant observation of prescribed burning in Karuk and Yurok territories (2015–2019) with 75 surveys and 18 interviews with Indigenous and non-Indigenous fire managers to identify political structures and material conditions that facilitate and constrain prescribed fire expansion. Managers report that interagency partnerships have provided supplemental funding and personnel to enable burning, and that decentralized prescribed burn associations facilitate prescribed fire. However, land dispossession and centralized state regulations undermine Indigenous and local fire governance. Excessive investment in suppression and the underfunding of prescribed fire produces a scarcity of personnel to implement and plan burns. Where Tribes and local communities have established burning infrastructure, authorities should consider the devolution of decision-making and land repatriation to accelerate prescribed fire expansion.

Networks within networks: scaling response operations in the lightning complex fires in northern california, August 2020

Wildfire risk has increased dramatically in California over more than two decades, 2000 - 2021, reflecting the intense impact of climate change on the state’s environmental and ecological systems. Most urgent is the impact of wildfire at the wildland-urban-interface (WUI), and the challenge to prevent cascading disaster for regions connected via interdependent lifelines of transportation, communications, electrical power, water, sewer, and gas line distribution systems that characterize geographic regions. To what extent do large, multi-organizational, multi-jurisdictional networks of organizations learn from experience and adapt their performance in response to the dynamic conditions of an actual extreme event? This article identifies four types of networks operating in the 2020 Lightning Complex Wildfires in northern California and documents the rapid escalation of risk and costs based on a preliminary analysis of the 209 incident reports filed by California Department of Forestry and Fire Protection (CalFire) for the SCU Fire that engulfed large sections of five counties in the southeastern San Francisco Bay Region. The article concludes that Interagency Incident Management Networks provide essential intelligence to support local management of operations in the dynamic context of wildfire risk.

Alternative Options for Resolution of Property and Casualty Claims Arising out of Natural Disasters

At the time of this Article, at least twelve large wildfires are burn- ing in California across more than 1,000 square miles, having damaged or destroyed over 2,000 structures, according to the California Department of Forestry and Fire Protection (CAL FIRE). At least eight people have lost their lives. The Kilauea volcano continues to erupt in Hawaii, having destroyed 600 homes. The 2018 hurricane season is in full swing, and while there have been no catastrophic events to date, residents in Houston, Florida, Puerto Rico, and elsewhere are still recovering from the devastating winds and rains wrought by Har- vey, Maria, and Irma last year. Those hurricanes are estimated to have caused more than $200 billion in damages, making the 2017 hurricane season the costliest in U.S. history. Around the world, natural disasters such as deadly heat waves, flooding, mudslides, hurricanes, and tornadoes will cause untold losses as temperatures across the globe are rising. After the smoke clears, the ash settles, the waters subside, and initial recovery efforts restore basic functions like the delivery of food, water, and electricity, survivors face the task of rebuilding. Inevitably, property and business owners either look to their insurance carriers for relief or initiate tort actions against alleged wrongdoers. In 2007, more than 2,000 law suits were filed against San Diego Gas & Electric following a series of wildfires that engulfed San Diego County in California, where faulty power lines were blamed for some of the fires. Dozens of cases have been filed in Ventura and Santa Barbara counties in California relating to the deadly Thomas Fire and related devastating mudslides that killed twenty people and destroyed hundreds of homes late last year. Traditional litigation used to resolve these disputes has the potential to overwhelm the courts, consume limited resources of insurance carriers and others, and be unduly burdensome to survivors. Alternative dispute resolution (“ADR”) mechanisms such as mediation can offer significant relief to the parties, permitting them to negotiate a resolution in a less formal setting than the courthouse, and usually within a shorter time frame than typical litigation would require. In situations where a mass disaster does not easily lend itself to individual mediations, however, providers can customize the process to ensure that all parties—those parties that have suffered losses, insurance carriers, and potentially responsible parties—experience a fair, economic, and efficient resolution. National ADR providers such as JAMS and the American Arbitration Association offer comprehensive, customized processes that can be tailored to meet the needs of the parties and the unique requirements of each case. Individual mediators around the country routinely provide assistance with ADR process design for complex, multi-party matters. Some examples follow.

Under Threat: One Archive's Tale from the 2017 Napa and Sonoma County Fires

Under ThreatOne Archive’s Tale from the 2017 Napa and Sonoma County Fires James Mockoski (bio) and Courtney Garcia (bio) Francis Ford Coppola and George Lucas founded American Zoetrope as an independent film company in the San Francisco Bay Area in 1969. It was created to bring together talented young filmmakers at a distance from the traditional ways of filmmaking that were entrenched in Hollywood. Zoetrope provided a welcoming space in which to experiment and craft stories in a much different way, appealing to filmmakers like Walter Murch, John Milius, and Carroll Ballard. Films made there left their mark, including American Graffiti (1973), The Conversation (1974), Apocalypse Now (1979), and The Black Stallion (1979), to name only a few. In its almost fifty-year history, Zoetrope has amassed an archive of film, artwork, and movie memorabilia, including the acquisition of the old RKO Research Library.1 While these items are stored in various locations, the bulk of the collection is housed in the Napa Valley, on the famed Inglenook Estate.2 FIRESTORM In early October 2017, wildfires quickly spread throughout Napa and Sonoma Counties in the middle of the night, catching everyone off guard. According to the California Department of Forestry and Fire Protection (CAL FIRE), 11,000 firefighters combated the fires that would burn more than 245,000 acres.3 In addition to Inglenook in Napa County, the Coppola family owns two properties in Sonoma County. At the start of the firestorm, neither was in immediate danger. As the hours went on, however, and the aggressive winds fed the flames, we began implementing a disaster plan, which would mean evacuating the property in the Napa Valley. Our disaster plan wasn’t one that was codified and kept in a binder; instead, it had been developed orally by long-standing colleagues over the last fifteen years. We had discussed what we would do in case of emergency and how we would provide geographical separation by storing our most valuable, unique, and irreplaceable items in off-site vaults more appropriate for assets such as negatives and sound masters. We discussed how we would prioritize our property assets, how to secure the site if assets were to remain on property, the need to find a safe haven for evacuated items, and how we would transport these items to the selected refuge. We were very fortunate that our company has a wealth of resources— transportation key among them. We had an amazing fleet of vehicles at our service. What’s more, we had a wonderful group of dedicated employees who worked hard and diligently to relocate materials from a total of ten buildings (from family homes to production facilities), with assets ranging from the smallest video tape to the largest painting. One of our safe havens was a wine cave on the property, situated far enough away from the fire area that we could use it to safely store our paper documents and other archival materials too large to transport off property; we also used it to store our Ford Model T from The Godfather: Part II (1974). Mr. Coppola is a car enthusiast and has several rare vehicles in his collection, and when the garage where many [End Page 67] of these cars are housed became threatened by the fires, we moved the majority of them to the front of the property, where they could be stored outside of the immediate danger area and covered to protect them from the falling ash. Our off-site facility was a roomy, versatile airport hangar that we used as our designated evacuation area—a place we also could occupy as a command post and set priorities from as the situation unfolded. There, we processed all the materials that had been evacuated from the property, photographing, cataloging, and packing each item securely so that the collection would be safe during the emergency and could be returned to the property efficiently once we received the all-clear. Click for larger view View full resolution Figure 1. The famed Inglenook Estate on a normal day. Photograph by Gundolf Pfotenhauer. Courtesy of American Zoetrope. We have experienced threats to our collections due to natural disasters in the past...

Historical patterns of wildfire ignition sources in California ecosystems

State and federal agencies have reported fire causes since the early 1900s, explicitly for the purpose of helping land managers design fire-prevention programs. We document fire-ignition patterns in five homogenous climate divisions in California over the past 98 years on state Cal Fire protected lands and 107 years on federal United States Forest Service lands. Throughout the state, fire frequency increased steadily until a peak c. 1980, followed by a marked drop to 2016. There was not a tight link between frequency of ignition sources and area burned by those sources and the relationships have changed over time. Natural lightning-ignited fires were consistently fewer from north to south and from high to low elevation. Throughout most of the state, human-caused fires dominated the record and were positively correlated with population density for the first two-thirds of the record, but this relationship reversed in recent decades. We propose a mechanistic multi-variate model of factors driving fire frequency, where the importance of different factors has changed over time. Although ignition sources have declined markedly in recent decades, one notable exception is powerline ignitions. One important avenue for future fire-hazard reduction will be consideration of solutions to reduce this source of dangerous fires.

Seeds of Rebellion

The Redwood Wars were largely defined by dramatic confrontations between activists and timber companies in the woods, in the courts, and in the legislature. The iconic images of those late twentieth-century conflicts include Julia “Butterfly” Hill standing atop the giant redwood she named Luna, and other tree sitters hanging large banners from their perches across the North Coast. Some Americans might conjure images of Charles Hurwitz and junk bond dealer Michael Milken, or of the bombed-out car of Judi Bari. Headwaters Forest in Humboldt County became the center of the Redwood Wars. By the end of the 1980s, most of the popular imagery had emerged from the battles over the fate of that forest. However, the seeds of those tumultuous years were planted during the late 1970s and early 1980s at a less well-known location in southern Humboldt County. At Sally Bell Grove, near the Sinkyone Wilderness and the Lost Coast, local activists embarked on a campaign to resist the ever-expanding industrial logging of multinational logging companies, and protect old-growth redwood groves. To fight industrial liquidation logging, activists commingled direct action, public protest, public comment, and citizen participation provisions for forestry regulation, litigation, and lobbying in ways that drove timber companies mad and compelled reform by the California Department of Forestry (CDF). Organizations and partnerships were formed during the fight over Sally Bell. Legal expertise and “tree-hugging” tactics were honed and coordinated in the courtrooms and the woods. And activists fashioned a style and tone of activism suited to their values and demands. Those tools, tactics, and strategies were repeated over and over again from 1985 through at least the end of the twentieth century. Thus, when Julia “Butterfly” Hill and the scores of other activists perched in trees and filed lawsuits, they operated from a foundation constructed by a generation of Bay Area refugees and native North Coasters who had worked to save their neighborhood from industrial logging.

Mapping areas at elevated risk of large-scale structure loss using Monte Carlo simulation and wildland fire modeling

This work presents, and demonstrates through application to California, a data-driven methodology that can be used to identify areas at elevated risk of experiencing wildland fires capable of causing large-scale structure loss. A 2D Eulerian level set fire spread model is used as the computational engine for Monte Carlo simulation with ignition points placed randomly across the landscape. For each randomly-placed ignition point, wind and weather conditions are also selected randomly from a 10-year climatology that has been developed by others using the Weather Research and Forecasting (WRF) mesoscale weather model at a resolution of 2km. Fuel and topography inputs are obtained from LANDFIRE. Housing density is estimated from 2010 Census block data. For each randomly-selected combination of ignition location and wind/weather, fire progression is modeled so that fire area and number of impacted structures can be recorded. This is repeated for over 100 million discrete ignition points across California to generate “heat maps” of fire probability, fire consequence, and fire risk. In this work, fire volume (spatial integral of burned area and flame length) is used as a proxy for fire probability since quickly spreading fires with large flame lengths are most likely to escape initial attack and become extended attack fires. Fire consequence is taken as the number of impacted structures. Fire risk is then estimated as the product of probability and consequence. The methodology is assessed comparing the resultant fire risk raster with perimeters from California's 20 most damaging fires as tabulated by the California Department of Forestry and Fire Protection (CALFIRE). It is found that these historical perimeters from damaging fires correlate well with areas identified as high risk in the Monte Carlo simulation, suggesting that this methodology may be capable of identifying areas where similarly damaging fires may occur in the future.

Underreporting of wildland fires in the US Fire Reporting System NFIRS: California

The absence of a comprehensive and accurate database on fire occurrence means that some proportion of wildfires is not reported. This paper examines wildfires reported in the National Fire Incident Reporting System (NFIRS) database and compares it with the satellite-based Moderate Resolution Imaging Spectroradiometer (MODIS) fire detection data and the CAL FIRE Fire and Resource Assessment Program (FRAP) geodatabase to understand underreporting of wildland fires in the NFIRS system. The paper discusses a series of large wildland fires and uses a Generalised Linear Model to identify the conditions where large wildfires go unreported. This paper shows that the NFIRS database, which is the primary fire database in the US, significantly underreports wildland fires. Evidence from California suggests that 32% of fires within local jurisdictions detected via MODIS satellite were identified in the NFIRS database; thus, there could be a significant number of fires going unreported nationwide. Examining eight large fires in California, only 16% of the structures damaged or destroyed, as reported in CAL FIRE, were reported in NFIRS. Areas with underreporting tend to have a higher level of poverty, higher population density, higher level of people without vehicles, lower income and a higher level of single parents with children under 18, as well as a higher level of people under the age of 18.

Historical reconstructions of California wildfires vary by data source

Historical data are essential for understanding how fire activity responds to different drivers. It is important that the source of data is commensurate with the spatial and temporal scale of the question addressed, but fire history databases are derived from different sources with different restrictions. In California, a frequently used fire history dataset is the State of California Fire and Resource Assessment Program (FRAP) fire history database, which circumscribes fire perimeters at a relatively fine scale. It includes large fires on both state and federal lands but only covers fires that were mapped or had other spatially explicit data. A different database is the state and federal governments’ annual reports of all fires. They are more complete than the FRAP database but are only spatially explicit to the level of county (California Department of Forestry and Fire Protection – Cal Fire) or forest (United States Forest Service – USFS). We found substantial differences between the FRAP database and the annual summaries, with the largest and most consistent discrepancy being in fire frequency. The FRAP database missed the majority of fires and is thus a poor indicator of fire frequency or indicators of ignition sources. The FRAP database is also deficient in area burned, especially before 1950. Even in contemporary records, the huge number of smaller fires not included in the FRAP database account for substantial cumulative differences in area burned. Wildfires in California account for nearly half of the western United States fire suppression budget. Therefore, the conclusions about data discrepancies and the implications for fire research are of broad importance.

Different fire–climate relationships on forested and non-forested landscapes in the Sierra Nevada ecoregion

In the California Sierra Nevada region, increased fire activity over the last 50 years has only occurred in the higher-elevation forests on US Forest Service (USFS) lands, and is not characteristic of the lower-elevation grasslands, woodlands and shrublands on state responsibility lands (Cal Fire). Increased fire activity on USFS lands was correlated with warmer and drier springs. Although this is consistent with recent global warming, we found an equally strong relationship between fire activity and climate in the first half of the 20th century. At lower elevations, warmer and drier conditions were not strongly tied to fire activity over the last 90 years, although prior-year precipitation was significant. It is hypothesised that the fire–climate relationship in forests is determined by climatic effects on spring and summer fuel moisture, with hotter and drier springs leading to a longer fire season and more extensive burning. In contrast, future fire activity in the foothills may be more dependent on rainfall patterns and their effect on the herbaceous fuel load. We predict spring and summer warming will have a significant impact on future fire regimes, primarily in higher-elevation forests. Lower elevation ecosystems are likely to be affected as much by global changes that directly involve land-use patterns as by climate change.