Single Fire Research Articles

Effects of repeated fire on Florida oak-saw palmetto scrub

BackgroundThe dominant species of Florida oak-saw palmetto scrub sprout after burning from belowground rhizomes or fire-resistant aboveground buds with rapid reestablishment of cover. Responses to single fires are well documented; however, responses to repeated fires may differ. Fire return intervals, differences among sites, and species may influence responses. We used transect data from four sites on Kennedy Space Center/Merritt Island National Wildlife Refuge to test whether growth differed through repeated fires. Two sites burned five times in 36 years, one site burned five times in 25 years, and one burned four times in 18 years. We used linear mixed models that account for repeated measures to determine if the number of fires affected height, total cover ≥ 0.5 m and < 0.5 m, bare ground, and cover of the dominant oak (Quercus) ≥ 0.5 m and of saw palmetto (Serenoa repens) ≥ 0.5 m. We compared community composition through repeated fires using nonmetric multidimensional scaling ordination.ResultsHeight, total cover ≥ 0.5 m, and cover of the dominant oak ≥ 0.5 m and of saw palmetto ≥ 0.5 m increased with time since burn; total cover < 0.5 m and bare ground decreased. A quadratic term in the growth model was significant except for total cover < 0.5 m. There were site differences for all variables except bare ground. The number of fires decreased height, total cover ≥ 0.5 m, and cover of the dominant oak ≥ 0.5 and increased total cover < 0.5 m and bare ground but had no effect on cover of Serenoa repens ≥ 0.5 m. Community changes after repeated fires were similar in nonmetric multidimensional ordinations with time since burn correlated to the first or second axis.ConclusionsScrub recovered from repeated fires at a range of intervals and seasons, but short return intervals reduced growth with responses differing among species.

Assessment of flame height of two unequal turbulent diffusion flames: Experimental interpretation and quantification

Multiple fires burning is a fairly common phenomenon in wildland fires and urban process industries. The burning of multiple fires is much more dangerous than single fire due to the merging of flames. This work aims to study the flame height of two unequal buoyant turbulent diffusion flames, which has not been well revealed. Total 168 experimental tests were performed using two square gas burners with different side lengths of 10 cm and 15 cm as the fire sources. The heat release rates (HRRs) in fire group and burner spacing (S) were changed. Results showed that for a given HRRs group, with the increase of S, the flame height presents a decay trend first, followed by a rise trend, and finally it maintains unchanged. This non-monotonic trend is explained from the view of interaction mechanisms. Three states of fully merging, intermittent merging and non-merging of two flames are divided to illustrate and quantify the flame height. By introducing a normalized parameter λ to characterize the air entrainment difference, a correlation for flame height of intermittent merging is developed. For the fully merging and non-merging, the equations for flame heights are respectively established based on the assumed equivalent single flame. The accuracy of the proposed model for flame height is validated using experimental data of this work and in literatures. And the application scope of model is expanded to the flame height in merging state of two identical fires.

Collapse mechanisms of multi-story steel-framed modular structures under fire scenarios

Modular building is an innovative construction method and imposes unique assembly requirements. Modular structures may exhibit different global responses and unexpected resisting mechanisms under loading scenarios. However, there is limited research dealing with collapse behavior of steel-framed modular structures exposed to fire. This paper studies numerically the fire-induced collapse behavior of the modular framed steel structures. A six-story modular structure is designed. Finite element analysis is conducted to investigate global deformation, load transfer pattern, structural resisting mechanisms and collapse process of the structures exposed to fire. A series of parametric analysis is conducted to study influences of load ratio, cross-sectional dimensions of columns and fire locations. Results show that the modular structure designed based on Hong Kong building code survives against single module fire, but collapses during traveling fire. The overturning action, bracing effect and double-beam system are developed under fire scenarios. A geometrically unstable system is developed against traveling fire. Moreover, damage spreads from the columns close to the fire compartment to those far away. The robustness of modular structures is greatly influenced by its load ratios and cross-sectional dimensions of the columns. The findings can be adopted as valuable tools for recognizing the vulnerable structural components and critical loading mechanisms of modular structure exposed to fire. A practical design method is proposed to evaluate the final collapse state of the modular structures exposed to fire with good accuracy and efficiency and this provides a practical solution for the structural engineers to process the collapse state of modular structures.

Building a small fire database for Sub-Saharan Africa from Sentinel-2 high-resolution images

Coarse resolution sensors are not very sensitive at detecting small fire patches, making current estimations of global burned areas (BA) very conservative. Using medium or high-resolution sensors to generate BA products becomes then a priority, particularly in areas where fires tend to be small and frequent.Building on previous work that developed a small fire dataset (SFD) for Sub-Saharan Africa for 2016, this paper presents a new version of the dataset for 2019 using the two Sentinel-2 satellites (A and B) and VIIRS active fires. Total estimated BA was 4.8 Mkm2. This value was much higher than estimations from two global, coarser-spatial resolution BA products based on MODIS data for the same area and period: 80 % greater than estimates from FireCCI51 (based on MODIS 250 m bands) and 120 % larger than MCD64A1 (based on MODIS 500 m bands). The main differences were observed in those months with higher fire occurrence (November to January for the Northern Hemisphere regions and June to September for the Southern Hemisphere ones).Accuracy assessment of the SFD product was based on a novel sampling strategy designed to obtain independent fire reference perimeters. Validation results showed remarkable high accuracy values comparing to existing global BA products. Overall omission errors (OE) were estimated as 8.5 %, commission errors (CE) as 15.0 %, with a Dice Coefficient of 87.7 %. All of these estimations implied significant improvements over the global, coarser spatial resolution BA products (OE > 50 % and CE > 20 % for the same area and period), as well as over the previous SFD product for 2016 of the same area, generated from a single Sentinel-2 satellite and MODIS active fires (OE = 26.5 % and CE = 19.3 %). Temporal accuracies greatly increased as well with the new product, with 92.5 % of fires detected within the first 10 days of occurrence.

Performance of ceiling jet induced by dual unequal strong plumes in a naturally ventilated tunnel

• Thermal property of two unequal flames in a naturally ventilated tunnel is studied. • Temperatures induced by the small plume decay faster than that of the large plume. • A new model for maximum ceiling temperature of two unequal plumes is proposed. • Correlations for ceiling temperature decay profiles of dual plumes are developed. The catastrophic tunnel fire accidents are usually accompanied with multi-source burning. Ceiling gas temperature in tunnel is an important parameter in monitoring the daily operation process and unexpected combustion process. Previous studies are mainly focused on single fire or multiple equal fires in tunnel, while multiple unequal fires burning is common in real tunnel fires. Till now, the law of asymmetrical temperature distribution of multi-source below a ceiling is unknown. This paper aims to experimentally study the thermal performance of two unequal fire sources of propane in a naturally ventilated tunnel. A total of 90 experimental tests were conducted. The side lengths of two burners are fixed at 10 cm and 15 cm. The heat release rate (HRR) of each burner are changed with the HRRs ratio of 1–6. And the spacing between two sources along the longitudinal centerline of tunnel varied from 0–45 cm. Analysis shows that there is only one peak temperature with small spacings, while two peak temperatures appear with large spacings. Then the impingement point position and the maximum ceiling gas temperature of each burner are illustrated. The force analysis is adopted to explain the variation of impingement point position. A parameter α is innovatively introduced to characterize the promoting effect of spacing on maximum temperature at small spacings. Then a new normalized HRR is proposed to establish a unified model for the unequal maximum temperature rises below the ceiling of both sources, which indicates that the maximum temperature rise increases with the normalized HRR and then it maintains at 754 K. By introducing the plume radius, models for asymmetrical temperature decay profiles on both sides of two plumes below the ceiling are proposed, which shows that the temperature in the upstream of the small burner decays faster than that in the downstream of the large burner. The proposed models for maximum temperature and temperature decay profiles can be used to predict the ceiling gas temperatures of two unequal fires in tunnel.

Numerical study on fire-induced smoke temperature characteristics in small curvature radius UTLT-like tunnels under emergency state

Extensive studies have usually focused on an ordinary single straight or large curvature radius tunnel fire. However, the curvature effect of small curvature radius curved tunnel on the fire-induced smoke temperature characteristics still needs to clarify. Therefore, a three-dimensional transient computational fluid dynamics (CFD) fire model for small curvature radius urban traffic link tunnel (UTLT)-like tunnel was established to understand the scope and extent of curvature effect on the fire-induced smoke under emergency state. The results show that, in the curved tunnel area, small curvature radius or large critical ventilation velocity results in stronger centrifugal force of the fire smoke, readily destabilizing the fire smoke downstream of the fire source. Compared with large radius of curvature and straight tunnels, due to the greater resistance of curved walls in small curvature radius tunnel, the length of smoke back-layering is longer. Simultaneously, the temperature of the high-temperature smoke on the outer wall of the ceiling cross section is higher than the inner wall. Prediction mathematical models for the maximum temperature and longitudinal temperature profiles were further developed by taking the curvature and ventilation velocity effect, which is basically consistent with experimental and simulated results.

What do you mean, ‘megafire’?

AbstractBackground‘Megafire’ is an emerging concept commonly used to describe fires that are extreme in terms of size, behaviour, and/or impacts, but the term’s meaning remains ambiguous.ApproachWe sought to resolve ambiguity surrounding the meaning of ‘megafire’ by conducting a structured review of the use and definition of the term in several languages in the peer‐reviewed scientific literature. We collated definitions and descriptions of megafire and identified criteria frequently invoked to define megafire. We recorded the size and location of megafires and mapped them to reveal global variation in the size of fires described as megafires.ResultsWe identified 109 studies that define the term ‘megafire’ or identify a megafire, with the term first appearing in the peer‐reviewed literature in 2005. Seventy‐one (~65%) of these studies attempted to describe or define the term. There was considerable variability in the criteria used to define megafire, although definitions of megafire based on fire size were most common. Megafire size thresholds varied geographically from &gt; 100–100,000 ha, with fires &gt; 10,000 ha the most common size threshold (41%, 18/44 studies). Definitions of megafire were most common from studies led by authors from North America (52%, 37/71). We recorded 137 instances from 84 studies where fires were reported as megafires, the vast majority (94%, 129/137) of which exceed 10,000 ha in size. Megafires occurred in a range of biomes, but were most frequently described in forested biomes (112/137, 82%), and usually described single ignition fires (59% 81/137).ConclusionAs Earth’s climate and ecosystems change, it is important that scientists can communicate trends in the occurrence of larger and more extreme fires with clarity. To overcome ambiguity, we suggest a definition of megafire as fires &gt; 10,000 ha arising from single or multiple related ignition events. We introduce two additional terms – gigafire (&gt; 100,000 ha) and terafire (&gt; 1,000,000 ha) – for fires of an even larger scale than megafires.

A novel route to synthesize metal titanium phosphate ceramic pigments: Co, Ni, and Cu-incorporated α-Ti(HPO4)2⋅H2O from ilmenite

Solid-state reaction of α-Ti(HPO4)2·H2O (α-TiP) and acetates of Co, Ni, or Cu at 500 °C and 800 °C produce a number of different metal titanium phosphate (MTiP) inorganic pigments with different colors and shades. At a given metal to α-TiP ratio and calcination temperature, the reaction produces several types of pigments such as phosphates M0.5TiO(PO4), M0.5Ti2(PO4)3, M2P2O7, and M3(PO4)3 (M = Co, Ni, and Cu) with a unique color. α-TiP, an iron free base material was prepared by digestion of high-grade natural ilmenite beach sand (FeTiO3) with 85 wt% H3PO4 at 120 °C. TGA, XRD, SEM/EDX, Diffuse reflectance UV–vis, and Raman spectroscopy techniques were used for characterization. Synthesized MTiP pigments after enameling at a single fire glazing at 1100 °C for 45 min exhibit vivid colors, ranging from purple, yellow, and green with different shades.

The burning process and temperature profile of double fires in a tunnel: An experimental study

In the event of double fires in tunnels, the combustion is strengthened and the smoke movement is restricted by the strong flame plumes. Heavy smoke accumulates rapidly between the two fires, which can result in serious casualties. For this paper, a series of experiments was carried out using a 1:10 scale tunnel, to primarily investigate the fire evolution and ceiling temperature distribution as a function of burner size and spacing. The burning process, the longitudinal ceiling temperature profile and the maximum temperature rise were measured and analyzed. The results show that the time from ignition to when the fire reaches a stable stage is obviously shorter than for a single fire. Furthermore, the steady burning rate is greater than that for a single fire with the same burner size. This higher steady-burning rate decreases as burner spacing increases, but increases with increasing burner size. This is due to the change in radiative heat feedback from the flame to the fuel surface. The longitudinal ceiling temperature profile shows a “double-hump”, with the hump values being dependent on the burner spacing. The ceiling temperature between the two fires in a double fire is obviously increased compared to that of a single fire, which can be attributed to the accumulation of smoke and heat between the two flames. The longitudinal ceiling temperature away from the double fires shows an exponentially attenuated trend and the corresponding model is revised. Finally, a maximum temperature rise model is established by introducing burner spacing. This model was validated with the experimental data. These new findings can be used for risk assessment of double fire accidents and to determine the best strategies for personnel evacuation from a tunnel.

Fire and forage quality: Postfire regrowth quality and pyric herbivory in subtropical grasslands of Nepal.

Fire is rampant throughout subtropical South and Southeast Asian grasslands. However, very little is known about the role of fire and pyric herbivory on the functioning of highly productive subtropical monsoon grasslands lying within the Cwa climatic region. We assessed the temporal effect of fire on postfire regrowth quality and associated pyric‐herbivory in the subtropical monsoon grasslands of Bardia National Park, Nepal. Every year, grasslands are burned as a management intervention in the park, especially between March and May. Within a week after fire, at the end of March 2020, we established 60 m × 60 m plots within patches of burned grassland in the core area of the Park. We collected grass samples from the plots and determined physical and chemical properties of the vegetation at regular 30‐day intervals from April to July 2020, starting from 30 days after fire to assess postfire regrowth forage quality. We counted pellet groups of cervids that are abundant in the area for the same four months from 2 m × 2 m quadrats that were permanently marked with pegs along the diagonal of each 60 m × 60 m plot to estimate intensity of use by deer to the progression of postfire regrowth. We observed strong and significant reductions in crude protein (mean value 9.1 to 4.1 [55% decrease]) and phosphorus (mean value 0.2 to 0.11 [45% decrease]) in forage collected during different time intervals, that is, from 30 days to 120 days after fire. Deer utilized the burned areas extensively for a short period, that is, up to two months after fire when the burned areas contained short grasses with a higher level of crude protein and phosphorus. The level of use of postfire regrowth by chital (Axis axis) differed significantly over time since fire, with higher intensity of use at 30 days after fire. The level of use of postfire regrowth by swamp deer (Rucervus duvaucelii) did not differ significantly until 90 days after fire, however, decreased significantly after 90 days since fire. Large‐scale single event fires, thus, may not fulfil nutritional requirements of all species in the deer assemblage in these subtropical monsoon grasslands. This is likely because the nutritional requirements of herbivores differ due to differences in body size and physiological needs—maintenance, reproduction, and lactation. We recommend a spatiotemporal manipulation of fire to reinforce grazing feedback and to yield forage of high quality for the longest possible period for a sustainable high number of deer to maintain a viable tiger population within the park.

Investigation of the maximum tunnel ceiling temperature caused by two fires

This paper investigated the maximum ceiling temperature and equivalent single fire source induced by two fires combined with small-scale experimental data and numerical simulations. The influences of fire size and spacing on the maximum temperature expressed by the heat release rate (HRR) for two fires were considered. The results demonstrate that the experimental maximum temperatures in the tunnel are smaller than those obtained by Li's model. Accordingly, a model to describe the maximum temperature for two fires expressed by the HRR was proposed, and the change trend of the HRR ratio was analyzed. The predicted values agree well with the experimental and numerical values, verifying that the proposed model is reliable.

Effects of spacing on flaming and smoldering firebrands in wildland–urban interface fires

Firebrand (ember) attack has been shown to be one of the key mechanisms of wildfire spread into wildland–urban interface communities. After the firebrands land on a substrate material, the ignition propensity of the material depends on not only the attributes (e.g. shape, size, and numbers) but also the distribution of the firebrands. To help characterize this process, this study aims to investigate the effects of gap spacing on the burning behaviors of a group of wooden samples. Experiments are conducted using nine wooden cubes, 19 mm on each side. These samples are arranged in a 3 × 3 square pattern on suspension wires and are ignited by hot coils from the bottom surface. The gap spacing (s) between the samples varies in each test (ranging from 0 to 30 mm). After ignition, the samples are left to burn to completion. The burning process is recorded using video cameras. Sample mass loss and temperatures are monitored during the flaming and smoldering processes. The results show that the flame height and the sample mass loss rate have non-monotonic dependencies on the gap spacing. When the gap spacing reduces, the flame height and the mass loss rate first increase due to enhanced heat input from the adjacent flames to each sample. When s ≤ 10 mm, flames from individual samples are observed to merge into a single large fire. As s further decreases, the air entrainment at the flame bottom decreases and the flame lift-off distance at the flame center increases, resulting in an increased flame height, decreased flame heat feedback to the solid samples, and a decreased mass loss rate. The decreased mass loss rate eventually leads to a decrease in the flame height as well. The gaseous flame height is correlated to the solid burning rate. The correlation generally follows previous empirical equations for continuous fire sources. For the smoldering combustion, compared to a single burning sample, the smoldering temperature and duration significantly increase due to the thermal interactions between adjacent burning samples. To help interpret the results of the burning experiments, thermogravimetric analysis is also performed in air and nitrogen, resulting in heating rates ranging from 10 to 100 K/min.

The occurrence, distribution, and risks of PFAS at AFFF-impacted sites in Finland

Per- and polyfluoroalkyl substances (PFAS) comprise a wide group of persistent chemicals, whose ubiquitous occurrence in the environment, particularly due to their extensive use for fire suppression in aqueous film forming foams (AFFFs), has raised global attention. We evaluated the impacts of PFAS at three firefighting training sites and one industrial site in Finland, to highlight key elements to be considered in the retrospective risk assessment of these chemicals. The site assessments covered the occurrence and distribution of 23 PFAS in multiple environmental matrices, i.e., soil, sediment, surface water, groundwater, and biota, and the subsequent risks to human health and the environment owing to the migration of and exposure to the selected compounds. Our study showed that the extensive use of nowadays restricted or substituted PFAS, particularly PFOS, are still often the predominant compounds detected at AFFF-impacted sites and will continue to cause long-term risks to the environment. The most significant environmental or health risks at these sites are likely to concern aquatic ecosystems, fish consumption or groundwater usage due to the off-site migration of PFAS. Here, even a single fire extinguishing event can be a considerable contributor. We also illustrate that conventional procedures based on simple mass-balance, and exposure models, with a focus on PFOS and other site-specifically relevant PFAS may provide sufficient means to assess the risks. Moreover, we address that despite the exceedance of the very stringent regulatory threshold values issued recently for PFAS, the actual site-specific risks to human health and the environment may remain reasonably low.

Study on Coupled Combustion Behavior of Two Parallel Line Fires

In this study, the interaction of two parallel line fires with a length-width ratio of greater than 50 was investigated and compared to a single line fire. Considering different length–width ratios and spacings between the fire sources, experiments were carried out to analyze the fire characteristics, such as the burning rate, the flame-merging state, the flame height, the flame tilt angle, and the flame length of the line fires. Its regularity was revealed by combining two mechanisms, namely, heat feedback enhancement and air entrainment restriction. The results revealed that the burning rate under different length–width ratios shows a uniform law, which increases first and then decreases with a greater spacing between the fire sources. There is a special relationship between the flame-merging probability Pm and the dimensionless characteristic parameters (S/ZC)/(L/d)0.27. Based on this relationship, a critical criterion of flame merging can be obtained as (S/ZC)/(L/d)0.27 = 2.38. In addition, the height and the length of the flame were studied to better describe the flame shape when the flame is tilted. Since the flame is bent, the flame length has an abrupt change at a specific position, and the inclination angle also has the same phenomenon. Finally, it was found that the influence of the length–width ratio on the line fires is relatively limited, which is further weakened under a greater length–width ratio.

An improved theoretical model for the maximum smoke temperature rise in a tunnel based on equivalent fire source

The maximum smoke temperature rise underneath tunnel ceiling is of great importance for the assessment of heat exposure, estimation of fire detection time and possibility analysis of fire spread. Previous studies mainly focused on the scenario with a single fire source, but the existence of two fire sources is common due to the increase traffic volume. The maximum smoke temperature rise induced by two fire sources is studied through theoretical analysis in this study. A virtual equivalent fire source is proposed, which is mainly affected by the total fire heat release rate (HRR) of two fires, longitudinal ventilation velocity, effective tunnel height and separating distance between two fires. The HRR of the equivalent fire source decreases with a longer separating distance, which indicates that the influences of the downstream fire on the maximum ceiling temperature weakens gradually as the separating distance increases. An improved model on the maximum ceiling smoke temperature rise caused by two fire sources was developed, and the predictions based on the revised model agree well with the experimental data.

Themes and patterns in print media coverage of wildfires in the USA, Canada and Australia: 1986–2016

Background Media wildfire coverage can shape public knowledge on fire-related issues, and potentially influence management decisions, so understanding the content of its coverage is important. Previous research examining media wildfire coverage has primarily focused on either a single fire or issue, and provides little insight about the range of wildfire-related topics discussed in the media. Aims We aimed to assess wildfire topics covered in print media between 1986 and 2016 across the USA, Canada and Australia. Methods Machine learning-based automated content analyses were conducted to identify primary topics within news articles and to map relationships between topics. Key results News articles related to wildfire were clustered into four topic areas: Fire Response, Management, Environmental Conditions and Property Preparedness. Notable between-country differences emerge: the US media coverage focuses most on firefighting; Canadian coverage, climate change; and Australian coverage, preparedness. Conclusions Our results reveal that: (1) wildfire media coverage has increased over the past 30 years; (2) coverage is more varied than the common perspective, i.e. media continues to portray fires in a negative light; and (3) topic coverage varies significantly between countries. Implications These findings can help identify gaps in media coverage, and provide insights into critical topics, or relationships between topics, that may need additional emphasis in conversations about how to better learn to live with fire.

Проблемные вопросы управления Федеральной противопожарной службой и пожарной охраной других видов

Introduction. The activities of fire and rescue units can be conditionally divided into extinguishing a large number of ordinary fires and single large fires. Considering these categories of fires from the point of view of economic efficiency and ensuring the level of combat readiness of fire departments, a decision tree model is proposed to identify the most promising ways to develop the organization. The functioning of fire and rescue units within the garrison is studied from the standpoint of assessing the long-term cyclical development of the organization, taking into account various external and internal factors. The tasks of the research are to identify problematic issues of management of fire and rescue units of the Federal Fire Service and fire protection units of other types stationed on the territory of the fire and rescue garrison, taking into account the scale of fires and evaluating the effectiveness of the organization of activities. Methods. Big Data technologies based on the methods of mathematical statistics of the software modules Panda and NumPy of the high-level programming language Python 3 are applied. The "Decision Tree" method implemented by means of the sklearn Python module and the packages CHAID and rpart of the programming language for statistical data processing R is used. Results and discussion. The frequency of occurrence of large fires, when the involvement of almost all available forces and means of the fire and rescue garrison is required, is about one case for an interval of 4-5 years. The number of ordinary fires during the same time is approximately 100-130 thousand cases. Such a ratio of ordinary and large fires is a source of significant contradiction and leads to a number of problematic issues related to the organization of management of Federal Fire Service units, as well as units of other types of fire protection. To study the proposed issues in the context of comparing the categories of economic efficiency and the level of combat readiness of units, the "decision tree" method was applied. Conclusions. The analysis of the results of the functioning of the fire and rescue garrison at the limit of permissible possibilities arising in the process of eliminating a large fire shows that all the management structures of the garrison are affected and, based on the results of the study of the actions of the garrison units, objective prerequisites for a leap (qualitative) reform of the management system can be formed. Keywords: large fire, operational activity, busy time, mobile fire and rescue equipment, fire extinguishing devices, histogram, decision tree.

Novel Video Surveillance-Based Fire and Smoke Classification Using Attentional Feature Map in Capsule Networks.

A fire is an extraordinary event that can damage property and have a notable effect on people’s lives. However, the early detection of smoke and fire has been identified as a challenge in many recent studies. Therefore, different solutions have been proposed to approach the timely detection of fire events and avoid human casualties. As a solution, we used an affordable visual detection system. This method is possibly effective because early fire detection is recognized. In most developed countries, CCTV surveillance systems are installed in almost every public location to take periodic images of a specific area. Notwithstanding, cameras are used under different types of ambient light, and they experience occlusions, distortions of view, and changes in the resulting images from different camera angles and the different seasons of the year, all of which affect the accuracy of currently established models. To address these problems, we developed an approach based on an attention feature map used in a capsule network designed to classify fire and smoke locations at different distances outdoors, given only an image of a single fire and smoke as input. The proposed model was designed to solve two main limitations of the base capsule network input and the analysis of large-sized images, as well as to compensate the absence of a deep network using an attention-based approach to improve the classification of the fire and smoke results. In term of practicality, our method is comparable with prior strategies based on machine learning and deep learning methods. We trained and tested the proposed model using our datasets collected from different sources. As the results indicate, a high classification accuracy in comparison with other modern architectures was achieved. Further, the results indicate that the proposed approach is robust and stable for the classification of images from outdoor CCTV cameras with different viewpoints given the presence of smoke and fire.

Late-Summer Fire Provides Long-Term Control of the Invasive Old World Bluestem (Bothriochloa ischaemum)

Bothriochloa ischaemum (Old World Bluestem) is a problematic invasive grass throughout the southern United States. We measured the long-term effects (12 years) of a single growing-season fire (September 2006) in a grassland dominated by Old World Bluestem. Prescribed fire drastically reduced Old World Bluestem cover (prefire: 76 ± 4% [mean ± standard error], 2007: 8 ± 2%) and cover remained low (21 ± 6%) in 2018 with no additional management. Surprisingly, Old World Bluestem cover in unburned plots decreased 12% during the same time. After the burn, native graminoid cover peaked after 3 years (29 ± 7%) but decreased to 18 ± 5% by 2018, and native annual forb cover, almost absent before the fire, increased dramatically to 39 ± 7% in 2007, then quickly decreased to pre-burn levels. Native perennial forb cover more than doubled in 2007 and continued to increase to 58 ± 5% in 2018. A single growing-season fire greatly reduced the cover of Old World Bluestem, likely due to high fuel loads, low rainfall, and phenological timing; the fire also allowed perennial forbs to establish. Restoring dominance of native grasses after removal of this invasive species will require additional active restoration such as seeding or planting.

Combining remote sensing and field data to assess recovery of the Chilean Mediterranean vegetation after fire: Effect of time elapsed and burn severity

It has been debated if Chilean sclerophyllous vegetation can recover after fire of different severity and short and long term. We evaluated the resiliency of this vegetation type after single-occurrence fires of different severities that occurred 30, 20 and 10 years in Central Chile before the study. Two approaches were followed: satellite image analysis and vegetation sampling. Wildfires that occurred between 1985 and 2015 were identified based on Landsat images. We selected 30 sites burned by a single fire in either 1985, 1995 or 2005, and that was not converted to another land use by 2015, then determined the percentage cover by vegetation type. We recorded or estimated the independent variables of burn severity, slope, altitude, pre-fire vegetation type and latitude of the sites. Composition, richness, and abundance of adult and regeneration of woody vegetation and herbaceous cover were sampled. Generalized linear models were used to evaluate the effect of the independent variables and the time elapsed since the fire on vegetation recovery. The proportion of dense vegetation forest cover was significantly higher with more time elapsed since the fire, while semi-dense forest/shrubland and open shrubland vegetation cover returned to pre-fire levels more quickly. The richness and abundance of regenerated woody species was significantly greater with more time elapsed since the fire. However, no relationship was found between species richness and abundance of adult woody species and time elapsed post-fire. We found that vegetative recovery over time was not related to burn severity. Forested and mixed forest/shrubland cover is reached 10–20 years after the fire, if no further intervention occurs. Richness and species abundance was similar to that of unburned sites after 20 or more years post-fire. This study provided evidence thatforestvegetation in the Chilean Mediterranean ecosystem is resilient to fires of at least low and medium intensities.