Fire In May Research Articles

Vegetation dynamics after fire in the Brazilian Campo Rupestre: Effects on native plant communities and flower harvesting

We investigated the impact of both early and late fires on native plant communities of the Campo Rupestre in the Sempre-Vivas National Park (PNSV, Brazil). Everlasting flower harvesters use late fires to stimulate flowering, while park managers have been implementing early fires to reduce flammable biomass and, therefore, the risk of wildfires. We aimed to explore the effects of fire on species composition, vegetation cover, and plant and flower stalks height to evaluate post-fire vegetation recovery, especially considering Comanthera species, which are highly valued by flower harvesters. The experimental design involved two areas (A1 and A2) in PNSV from May/2019 to January/2021. We installed eight 50 × 50 m plots in each area, being half submitted to experimental burnings and the other half unburned (control plots). A1 experienced early fire in May, and A2 a late fire in September. Initial phytosociological surveys revealed differences between A1 and A2, therefore, fire effects were treated separately for each area. In both A1 and A2, fire initially impacted species richness and abundance but the effect dissipated over time, with vegetation becoming similar to unburned plots. Fire also affected vegetation cover, which returned to its original condition within a year, influenced by seasonality and plant phenology. Plant communities experienced a temporary reduction in height (∼4 cm) in the months following fire, and recovered in the subsequent rainy season. However, a tendency for smaller plants persisted, and the average height of flower stalks took almost two years to fully recover. In general, the late fire conducted in A2 led to a slower recovery trajectory. These findings indicate rapid post-fire biomass recovery and minimal impact on plant species composition, highlighting the resilience of Campo Rupestre to single fires. Further studies are crucial to understand plant response to fires at different fire frequencies.

Analysis and forecasting of the scale and impact of forest fires on ecosystems of Ukraine

Forest fires are one of the most significant environmental problems that have a major impact on biodiversity and climate conditions. The purpose of the study was to investigate the impact of military operations on the ground cover in the area of the Bekhy forestry, which was disturbed by fire. It was revealed that for the period 2022-2023, 15 forest fires were recorded on the territory of the Korosten forest hunting enterprise of the state enterprise “Forests of Ukraine”, while the total area covered by fires was 15.13 ha. Overall, the number of fires increased from 5 to 10, but the total area covered by fires decreased from 12.1 to 3.03 ha. At the site of fires in 2022, the pH level increased to lower horizons, with the highest values at microhills (7.55) and microdepressions (7.35). There was a slight increase in the organic carbon content in the upper humus horizon of soils (0.42% on microhills and 0.46% on microdepressions). Bekhy forestry suffered a large forest fire in May 2023, which covered an area of 1.2 ha. The fire hazard assessment of each quarter was carried out separately. In the 50th and 51st compartments, Scots pine was the most fire-prone type of plantings. The 2023 fire site also showed an increase in pH in the lower horizons, with the highest values in microhills (7.35) and microdepressions (7.55). The 2023 fire site showed a decrease in organic carbon content compared to the background sites, with minimal values in the lower parts of the soil profile (0.33% on microdepressions and 0.38% on microhills). The results of the study can be used to develop and implement environmental measures and programmes aimed at restoring forests damaged by fire

Foraminifera of the Eocene Shitakara Formation in eastern Hokkaido, with the designation of neotype specimens of Yoshida (1957)

Forty-three species belonging to thirty-seven genera of benthic foraminifera were differentiated from the Eocene Shitakara Formation in the eastern part of the Kushiro Coalfield, eastern Hokkaido. The foraminiferal assemblages show upward transgression from the inner to outer sublittoral condition. They contain abundant agglutinated and calcareous hyaline benthic species, including Labrospira crassiformis, Haplophragmoides subamakusaensis, and Cribroelphidium sorachiense, indicating similarity to the Eocene fauna in central Hokkaido. Two planktonic species Chiloguembelina ototara and Tenuitella insolita also indicate a late Eocene age. Neotype specimens of Cyclammina pacifica var. kushiroensis, Nonion kushiroense, and Nonion sorachiense var. konbumoriense described by Yoshida (1957) have been designated as replacements for holotype specimens that were lost in a fire in May 1965. A taxonomical reexamination based on the neotypes and topotypes indicates that Cyclammina pacifica var. kushiroensis is a distinct species, whereas Nonion kushiroense and Nonion sorachiense var. konbumoriense are junior synonyms of Cribroelphidium sorachiense (Asano 1954). All foraminiferal taxa are illustrated with taxonomical notes.

Herbivore Influence on Post-Fire California Sage Scrub Plant and Soil Microbial Assemblages

California sage scrub (CSS) is an endangered, shrub-dominated, southern California ecosystem type threatened by increasing fire frequencies and conversion to non-native grasslands. As CSS harbors a rich endemic flora and fauna and is critical for maintaining key ecosystem services; significant attention has been focused on understanding how many key factors (N-deposition, drought, and competition with non-natives) influence post-fire CSS recovery. Unfortunately, few studies have examined the role of herbivores. For five years, we investigated the influence of herbivores on post-fire CSS succession by annually surveying plant assemblages in control (herbivores allowed access) and experimental (herbivore excluded) plots at the Bernard Field Station following a fire in May 2017. We found that herbivores reduce the cover of both invasive grasses and native shrubs, and negatively impact Artemisia californica survivorship. Consequently, post-fire plant restoration efforts should not discount the effects of herbivores. While native forb cover was elevated in plots that permitted herbivores, plots near the fire edge experienced increased herbivory pressure and lower cover of most plants. Despite modifications in plant assemblages, we did not observe differences in soil microbe abundances, fungi assemblage structure, or nutrient concentrations. We suggest that restoration practitioners consider caging ‘shrub regeneration’ areas to facilitate post-fire CSS recovery.

The Canadian Optimized Statistical Smoke Exposure Model (CanOSSEM): A machine learning approach to estimate national daily fine particulate matter (PM2.5) exposure

Exposure to biomass smoke has been associated with a wide range of acute and chronic health outcomes. Over the past decades, the frequency and intensity of wildfires has increased in many areas, resulting in longer smoke episodes with higher concentrations of fine particulate matter (PM2.5). There are also many communities where seasonal open burning and residential wood heating have short- and long-term impacts on ambient air quality. Understanding the acute and chronic health effects of biomass smoke exposure requires reliable estimates of PM2.5 concentrations during the wildfire season and throughout the year, particularly in areas without regulatory air quality monitoring stations. We have developed a machine learning approach to estimate PM2.5 across all populated regions of Canada from 2010 to 2019. The random forest machine learning model uses potential predictor variables integrated from multiple data sources and estimates daily mean (24-hour) PM2.5 concentrations at a 5 km × 5 km spatial resolution. The training and prediction datasets were generated using observations from National Air Pollution Surveillance (NAPS) network. The Root Mean Squared Error (RMSE) between predicted and observed PM2.5 concentrations was 2.96 μg/m3 for the entire prediction set, and more than 96 % of the predictions were within 5 μg/m3 of the NAPS PM2.5 measurements. The model was evaluated using 10-fold, leave one-region-out, and leave-one-year-out cross-validations. Overall, CanOSSEM performed well but performance was sensitive to removal of large wildfire events such as the Fort McMurray interface fire in May 2016 or the extreme 2017 and 2018 wildfire seasons in British Columbia. Exposure estimates from CanOSSEM will be useful for epidemiologic studies on the acute and chronic health effects associated with PM2.5 exposure, especially for populations affected by biomass smoke where routine air quality measurements are not available.

The Health of Firefighters Deployed to the Fort McMurray Fire: Lessons Learnt.

Introduction: Firefighters were working in exceptionally difficult conditions during the Fort McMurray/Horse River fire in May 2016.Methods: From mid-May, we recruited firefighters from 13 fire services as they returned from the fire. In October 2016 we extended recruitment to all Alberta-based firefighters deployed to the fire. In December 2017–May 2018 we sent a first online follow-up: this concentrated on mental health supports. The second follow-up, in October 2018–January 2019, included screening scales for respiratory ill-health and PTSD. All three contacts included visual analogue scales for chest symptoms and the Hospital Anxiety and Depression Scale. We estimated exposure to PM2.5, and calculated an exposure mitigation index from reports of respiratory protective equipment (RPE).Results: We recruited 1,234 firefighters and examined the relation of respiratory symptoms to estimated particulate exposure. The relation was strong immediately post fire but weakened over time. We found less chest tightness and cough in those whose RPE in the first week mitigated exposure by at least 10%. We examined the relation between particulate exposure and mental ill-health from screening questionnaires and found those with high exposure (reflecting the ferocity of the fire) had poorer mental health scores. Firefighters reporting their “worst moment during the fire” was life threatening were more anxious at second follow-up. Overall both anxiety and depression scores increased at successive contacts, more so in those with mental ill-health recorded in physician billing records before the fire.Discussion: The results from this study overall suggest on-going fire-related health effects in a substantial minority of firefighters, similar to those reported in the longitudinal follow-up of firefighters after the collapse of the World Trade Centre. Self-reports of both respiratory symptoms and mental ill-health were strongly related, soon after the fire, to estimated particulate exposures. Anxiety increased over time since the fire in those who felt their life or safety had been threatened, underlining the need for ongoing support. Our conclusions about the benefits of rapid research relate particularly to the collection of biomarkers of exposure as quickly and widely as possible, and the establishment of a nominal list of participants before they are too widely dispersed.

Post-fire analysis and numerical modeling of a fire-damaged concrete bridge

Extreme fire hazard is not a typical design consideration for highway bridges because of the low probability of occurrence. However, historically, fire events caused higher numbers of bridge collapse than earthquakes on the nation’s highways, showing the criticality of fires on highway bridges. Despite this fact, the during and post-fire performance of highway bridges is still not well-understood. The current study evaluated the post-fire performance of a fire-damaged concrete bridge in Irving, Texas, through theoretical modeling and in-situ testing. The bridge sustained significant damage when a fuel tanker crashed and caught fire in May 2005, and was then repaired and strengthened with carbon fiber reinforced polymer laminates. A three-tiered calibrated numerical modeling scheme involving computational fluid dynamics-based fire model, heat transfer and stress analysis was developed. The accuracy of the scheme was validated through static bridge load testing. It was found that the modulus of elasticity of the fire damaged section of the bridge was reduced by more than 50%. The numerical model represented the bridge fire with reasonable accuracy. The model thermal profiles showed good correlation with actual post-fire observations. The concrete modulus of elasticity decreased by 10% and 75% for the girder and the deck, respectively. The actual strain and displacements from the load testing closely matched those from the calibrated model.

Hydroseeding increases ecosystem nitrogen retention but inhibits natural vegetation regeneration after two years of chaparral post-fire recovery

Fire is a natural disturbance in many ecosystems such as semi-arid chaparral shrublands, but rates of vegetation regeneration may be slow after intense fires. Thus, land managers may resort to practices such as mulching or seeding in areas that are prone to soil erosion and nutrient loss. These practices, in particular seeding with annual grasses, are controversial because they may inhibit rates of natural vegetation regeneration, introduce exotic species, and be ineffective at soil and/or nutrient retention. We assessed how hydroseeding affected rates of chaparral vegetation regrowth and ecosystem nitrogen (N) storage during the first 2 years of post-fire recovery. We selected three north-facing slopes that were within 500m of each other: one slope was unburned while the other slopes burned during the “Cocos” fire in May 2014 and were either hydroseeded with a mix of native grasses and suffrutescent shrubs (seeded) or left to naturally regenerate (control). We hypothesized that seeding would reduce native woody shrub cover and production but that ecosystem N storage would be higher in the seeded stand. Seeding significantly reduced woody shrub cover, aboveground biomass, shrub and total species richness, and rates of shrub growth. However, herbaceous biomass, dominated by grasses that were absent on the naturally regenerating slope, was significantly higher in the seeded areas, causing significantly higher total vegetation cover in the seeded area. The higher herbaceous cover led to an increase in plant N storage and a reduction in soil extractable NO3. Hydroseeding also caused a reduction in potential N mineralization, and during the growing season, an increase in soil microbial biomass. Our results suggest that seeding recently burned chaparral slopes reduces nutrient loss but at the expense of native plant abundance and diversity. While the long-term effects of seeding on vegetation composition are unknown, changes in vegetation from a shrub- to a grass-dominated system may fundamentally alter future fire regimes.

Epidemiological Survey on workers of Fiumicino Airport after a fire in May 2015

Introduction On May 7th 2015 a fire broke out in Fiumicino Airport Terminal T3. In the following weeks, workers were exposed to different pollutants (PM10, PAH, PCB, VOC and dioxin) with values exceeding limits. The Airport operated with reduced capacity ( 60%)for up to xx weeks in the weeks after. We estimated exposure, evaluated acute health effects and lung function parameters. Methods Workers underwent blood tests and respiratory function tests (spirometry, saturation) to assess their health status and completed a questionnaire on lifestyle and medical history. Exposure was defined in three levels based on area: red (affected by the fire and closed to the public), yellow (restricted security procedures), green (open to the public). A cumulative indicator weighting the total hours worked in the three different areas was used as individual exposure. Attack Rates(AR) were calculated for acute gastrointestinal and respiratory symptoms. A linear regression model was used to assess the lung function (FVC,FEV1,FEF25-75%). Results 755 employees (68% worked in security or as cleaners) completed the online questionnaire and medical tests. In the first two weeks after fire, security workers had very high acute symptoms decreasing from red to green area (gastrointestinal AR:38%,23%,14%; respiratory AR:35%, 33%, 24%). The same pattern was observed in cleaners (gastrointestinal AR:20%,17%,7%; respiratory AR:23%, 19%,12%). Respiratory function tests were in the norm, a reduction in FVC values was observed only in subjects reporting respiratory symptoms or asthma (ranging between -0.02 for low-exposed and -0.10 for those high-exposed),not significant. Conclusions Health impact assessments of fires in these contexts is complex due to the difficulty in reconstructing individual exposure and lack of direct measures of released pollutants. Since we observed only acute effects, a surveillance program to assess health effects in the long period, as for dioxin exposure, is needed.

Mitigating impacts of weeds and kangaroo grazing following prescribed fire in a Banksia woodland

SummaryBanksia woodlands are renowned for their flammability and prescribed fire is increasingly employed to reduce the risk of wildfire and to protect life and property, particularly where these woodlands occur on the urban interface. Prescribed fire is also employed as a tool for protecting biodiversity assets but can have adverse impacts on native plant communities. We investigated changes in species richness and cover in native and introduced flora following autumn prescribed fire in a 700‐hectare Banksia/Tuart (Eucalyptus gomphocephala) woodland that had not burnt for more than 30 years. Effectiveness of management techniques at reducing weed cover and the impacts of grazing by Western Grey Kangaroo (Macropus fuliginosus) postfire were also investigated. Thirty plots were established across a designated burn boundary immediately before a prescribed fire in May 2011, and species richness and cover were measured 3 years after the fire, in spring of 2013. Fencing treatments were established immediately following the fire, and weed management treatments were applied annually in winter over the subsequent 3 years. Our results indicate that autumn prescribed fire can facilitate increases in weed cover, but management techniques can limit the establishment of targeted weeds postfire. Postfire grazing was found to have significant adverse impacts on native species cover and vegetation structure, but it also limited establishment of some serious weeds including Pigface (Carpobrotus edulis). Manipulating herbivores in time and space following prescribed fire could be an important and cost‐effective way of maintaining biodiversity values.

Enhancement of Aerosol Concentration in Korea due to the Northeast Asian Forest Fire in May 2003

Enhancement of aerosol optical thickness (AOT) and surface aerosol mass concentration in Korea for an active forest fire episode in Northeast Asia were estimated by Community Multi-scale Air Quality (CMAQ) model. MODIS/TERRA remote detects of fires in Northeast Asia for May 2003 gave a constraint for estimation of wildfire emissions with an NDVI distribution for recent five years. The simulated wildfire plumes and enhancement of AOT were evaluated and well resolved by comparing multiple satellite observations such as MODIS, TOMS, and others. Scatter plots of observed daily mean aerosol extinction coefficient versus PM 10 concentration in ground level in Korea showed distinctively different trends based on the ambient relative humidity.

Enhancement of Aerosol Concentration in Korea due to the Northeast Asian Forest Fire in May 2003

Enhancement of Aerosol Concentration in Korea due to the Northeast Asian Forest Fire in May 2003

Effects of prescribed burning and seasonal and interannual climate variation on nitrogen mineralization in a typical steppe in Inner Mongolia

Fires in grasslands significantly alter nutrient cycling processes. Seasonal climatic changes can interact with fire to further modify nutrient cycling processes. To investigate the effects of fire on soil nitrogen transformation processes and their seasonal change and interannual variability in a typical steppe in Inner Mongolia, we determined the rates of net nitrogen mineralization and nitrification over two growing seasons and a winter following a prescribed spring fire in May 2006. Fire significantly decreased rates of both net nitrogen mineralization and net nitrification during the first growing season and winter following burning. Cumulative net nitrogen mineralization in unburned and burned plots in the 2006 growing season was 133% and 183% higher, respectively, than in the drier 2007 growing season. Nitrogen mineralization apparently occurred in winter and the cumulative net nitrogen mineralization from October 2, 2006, to April 27, 2007 in unburned and burned plots amounted to 1.18 ± 0.25 g N m −2 and 0.51 ± 0.08 g N m −2, respectively. Cumulative net nitrogen mineralization was higher in a wet 2006 than in a dry 2007 growing season, indicating that the net N mineralization rate was sensitive to soil moisture in a dry season. Our study demonstrated that a one-time prescribed fire decreased net N mineralization rates only for a short period of time after burning while interannual variation in climate had more significant effects on the process of nitrogen mineralization.

Stratospheric impact of the Chisholm pyrocumulonimbus eruption: 2. Vertical profile perspective

Extreme pyrocumulonimbus (pyroCb) blowups that pollute the stratosphere have been documented on at least five occasions. However, the frequency of these events is still uncertain. One published pyroCb case study, the Chisholm Fire in May 2001, was restricted to the convective phase and its immediate aftermath. Here and in a companion paper we describe the stratospheric impact of the Chisholm pyroCb. The companion paper focuses on nadir satellite views of the plume. This paper synthesizes a broad array of space‐, balloon‐, and ground‐based profile measurements. The Chisholm pyroCb, which we identify as the singular cause of stratospheric aerosol increase in northern spring/summer of 2001, created a doubling of the zonal average aerosol optical depth in the lowermost stratosphere. The meridional spread of the plume was from the tropics (20°N) to the high Arctic (79°N) within the first month. The stratospheric Chisholm smoke became a hemispheric phenomenon in midlatitudes and northern tropics and persisted for at least 3 months. A size‐resolved particle concentration profile over Laramie, Wyoming, indicated a lower stratospheric aerosol with a twofold to threefold increase in volume of particles with radii between 0.3 and 0.6 μm. We also find evidence of localized warming in the air masses of four of the lidar‐measured smoke layers. This work contains the first reported stratospheric smoke layers measured by lidar at Ny Ålesund, Esrange, Kühlungsborn, Garmisch‐Partenkirchen, Boulder, and Mauna Loa. In addition, the first detection of smoke‐enhanced aerosol extinction at near IR wavelengths by the Halogen Occultation Experiment (HALOE) is introduced.

Human intervened post-fire forest restoration in the Northern Great Hing’an Mountains: a review

The devastating fire in May 1987 in the northern Great Hing’an Mountains created a mosaic of burned severity. Subsequent log harvesting and tree planting complicated the restoration process. Based on intensive field work and GIS analysis for the burned area, we studied the landscape pattern change in relation with its influencing factors, the restoration of some ecosystem functions and the long-term effect of human planting on vegetation restoration. A post-fire vegetation restoration process was also established using spatial series instead of temporal series. The results indicated that coniferous forest, broad-leaved forest and mixed forest increased obviously in the burned area. Factors influencing the restoration process are ranked as the burned severity, way of restoration (planting, promoted restoration or natural restoration) and topographical factors. The latter was further ranked as the slope, elevation, slope position and aspect. Primary productivity, hydrological functions, habitats for wild animals and permanent frozen soil of the area have all largely been restored to the pre-fire level after more than 15 years. Parameters demonstrated a transitional character of the forest from the early succession stage to middle stage. LANDIS simulation for the long-term forest succession under pure natural restoration and human-intervened restoration indicated that post-fire tree planting largely influenced the age structure, spatial pattern and timber stock of dominant species such as Larix gmelini, Betula platyphylla and Pinus sylvestris var. mongolica. In general, the influence of post-fire human planting can remain for more than 200 years.

Predator‐mediated apparent competition between an introduced grass, Agrostis capillaris, and a native fern, Botrychium australe (Ophioglossaceae), in New Zealand

This study provides an example of how invasive plant species may indirectly affect native species through apparent competition by altering the local invertebrate community. The native New Zealand fern Botrychium australe (Ophioglossaceae) is thought to benefit from disturbances such as fire, because this species is generally found in disturbed habitats with low shade and increasing competition. However, in this study we show that a mapped population of B. australe experienced a marked decrease in survival and reproduction after an accidental fire in May 1995. Mortality was not due to the direct effects of fire; in the year following the fire, survival was normal and reproduction was higher than in previous years. However, after 1996 an introduced grass (Agrostis capillaris) spread across the area and B. australe survival in the second to fourth years after the fire (1996–1999, 59.63%) was significantly lower than survival before the fire, and plants did not produce spores at all during this 3‐yr period. B. australe survival was not lower in plots with dense A. capillaris growth. From 1997 onwards, B. australe plants suffered very extensive defoliation by a herbivore, and insecticide and molluscicide experiments in 1999 and 2000 showed that the introduced slug Deroceras reticulatum was responsible for the damage. The slug increased after the fire in association with the spread of Agrostis capillaris, probably because this plant created a suitable habitat for slugs.

Twenty Years of Prescribed Burning Influence the Development of Direct-Seeded Longleaf Pine on a Wet Pine Site in Louisiana

Abstract Prescribed burning treatments were applied over a 20 yr period in a completely randomized field study to determine the effects of various fire regimes on vegetation in a direct seeded stand of longleaf pine (Pinus palustris Mill.). Seeding was done in November 1968. The study area was broadcast-burned about 16 months after seeding. The initial research treatments were applied in 1973, and as many as 12 research burns were applied through 1993. Pines were measured in March 1995. Prescribed burning resulted in a greater stocking of longleaf pine (an average of 598 trees/ac) on treated plots than on unburned plots (30 trees/ac). However, on the burned treatments, longleaf pines were significantly smaller (2.5 ft3/tree of stemwood) than were the unburned trees (3.7ft3/tree of stemwood). Half of the treated plots were burned in early March, and the other half were burned in early May. Seasons of burning did not significantly influence longleaf pine stocking. However, use of fire in May resulted in significantly greater basal area (100 ft2/ac) and stemwood production (1,921 ft3/ac) than burning in March (59 ft2/ac and 909 ft3/ac). Fire effectively kept natural loblolly pine (P. taeda L.) seedlings from reaching sapling size, but loblolly saplings and poles dominated the unburned plots (710 trees/ac). When all pines were considered on all treatments, stocking ranged from 467 to 740 trees/ac, but stocking was not significantly different among treatments. The unburned plots had significantly greater total basal area (149 ft2/ac) and stemwood productivity (2,918 ft3/ac) than the burned treatments (82 ft2/ac and 1,459 ft3 /ac). Likewise, hardwoods that were at least 1 in. dbh were more common on unburned p lots (327 stems/ac) than on burned treatments (58 stems/ac). South. J. Appl. For. 24(2):86-92.

Postfire Tree Mortality in Relation to Wildfire Severity in Mixed Oak Forests in the Blue Ridge of Virginia

Abstract Tree mortality in relation to fire severity was investigated in eight mixed oak stands in the second growing season following the 1900 ha Big Run Fire in May 1986, in Shenandoah National Park in the Blue Ridge of Virginia. Plots were located in four stands each burned by high- and low-severity fire. Prefire stands were evenaged (55-60 yr), of medium quality (upland oak 50 yr site index 18-20 m ), and dominated by chestnut oak, scarlet oak, northern red oak and pignut hickory. High-severity fire top-killed 67% of stand basal area and 81% of the trees, whereas low-severity fire top-killed 8% of stand basal area and 15% of the trees. Height of stem-bark char accounted for 93 % and 96% of the variation in fire-killed basal area and number of trees, respectively. Logistic regression models relating probability of top-kill of individual trees with tree dbh and height of stem-bark char were developed for chestnut oak, scarlet oak, northern red oak, black oak, pignut hickory, red maple, blackgum, and serviceberry. Regression diagnostics indicated that the models predicted well for all species, with 79 to 95% concordance between predicted probabilities and observed outcomes. The models demonstrate the interaction of species-specific fire resistance, tree size, and fire severity in determining fire induced top-kill. These models can be used to estimate postfire mortality for a variety of purposes, including planning postwildfire timber salvage and regeneration operations, planning prescribed fires, and ecosystem process modeling. North. J. Appl. For. 11(3):90-97.

Aerosol spectral optical depths: Jet fuel and forest fire smokes

The Ames autotracking airborne sun photometer was used to investigate the spectral optical depth between 380 and 1020 nm of smokes from a jet fuel pool fire and a forest fire in May and August 1988, respectively. Results show that the forest fire smoke exhibited a stronger wavelength dependence of optical depths than did the jet fuel fire smoke at optical depths less than unity. At optical depths greater than or equal to 1, both smokes showed neutral wavelength dependence, similar to that of an optically thin stratus deck. These results verify findings of earlier investigations and have implications both on the climatic impact of large‐scale smokes and on the wavelength‐dependent transmission of electromagnetic signals.

The Holy War

Direct Action By day, antiabortion demonstrators who describe themselves as sidewalk counselors scream epithets and wave posters of bloody fetuses in the faces of abortion clinic patients and staff; by night, inflamed zealots are using bombs, torches and sledgehammers to bring their holy war against abortion to the facilities where abortion is performed. The new year had barely begun when a Washington, D.C., women's clinic that performs abortions was severely damaged by an explosive device. A man telephoned The Washington Times later in the day to claim credit for the bombing on behalf of the Army of God, East Coast Division, pledging that the bombings would continue-the next one in Ohio. Early on Christmas morning, bombs exploded at three medical facilities providing abortions in Pensacola, Florida; one facility was destroyed, the others suffered extensive damage. One of the targets had been forced to relocate last summer after an earlier bomb demolished the Four suspects have been arrested and charged with the bombings, which closed out a year that had seen a large increase in violent acts directed at abortion facilities. Among other major incidents during the year was one that occurred shortly before dawn on November 19, when a bomb exploded at the Metropolitan Medical and Women's Center in Wheaton, Maryland, setting off a two-alarm fire that destroyed the l1-year-old abortion Minutes later, another blast rocked a Planned Parenthood family planning clinic in nearby Rockville, causing an estimated $50,000 in damage. As of the end of 1984, no suspects had been arrested. On August 20, Cypress-Fairbanks Family Planning, an abortion clinic in Houston, was destroyed by a bomb, and it remains closed. Over the next two and a half weeks, three other abortion facilities in and around Houston were seriously damaged by bombs and fires. No one has been arrested in connection with any of the incidents. In April, the Feminist Women's Health Center in Everett, Washington, was completely destroyed by its third fire in less than a year of operation. Curtis A. Beseda, an unemployed roofer who had been active in antiabortion causes, was convicted of setting the fires and also of firebombing an abortion clinic in Bellingham, Washington. He has been sentenced to 20 years in prison and ordered to pay almost $300,000 in restitution. Beverly Whipple, executive director of the Everett clinic, says she hopes to reopen the facility, but she faces three serious obstacles that many of the other targets of violence also face-the loss of the clinic's lease, the cancellation of its fire insurance and a severe shortage of funds. The Hillcrest Clinic in Norfolk, Virginia, suffered $140,000 in damage as a result of a fire in May 1983. The abortion clinic closed for three weeks to make repairs. Then, in February 1984, it was the target of a bomb that damaged a bank in the same building instead. Like many clinics, the Hillcrest Clinic has had to take elaborate and expensive measures to protect itself and its patients from the threat of violence. In addition to spending $5,000 for a security system, Hillcrest has retained a 24-hour security guard at a cost of $4,000 a month, has installed double glass doors and a security wall in the corridor outside the clinic's suite and has hired a full-time employee, at a cost of $11,000 a year, to monitor traffic into the As these examples and their consequences illustrate, the controversy over abortion has taken a destructive turn. The National Abortion Federation (NAF) reports that in 1984, there were 24 incidents of arson and bombing of abortion facilities* in seven states f and the District of Columbia (Table 1, page 6). Six abortion clinics were totally destroyed, and others suffered extensive damage. An additional six clinics were the targets of unsuccessful attacks, and at least 38 others received bomb threats. In comparison, three incidents of bombing or arson occurred in 1983, eight in 1982 and one in 1981. Since 1982, damage from bombings and fires has cost well over $2 million, and that does not include the damage resulting from vandalism. According to the NAF, acts of vandalism have more than tripled in the last two years, from eight reported incidents in 1982 to 31 in 1984. During the same period, the number of invasions of clinics by antiWhen activists are told by their leaders that they have a mandate from God to get rid of abortion clinics . . ., some extremists must certainly believe that they are justified in destroying or vandalizing a clinic.