Fire Type Research Articles

Woodland wildfire enables fungal colonization of encroaching Douglas‐fir

Abstract Self‐reinforcing differences in fire frequency help closed‐canopy forests, which resist fire, and open woodlands, which naturally burn often, to co‐occur stably at landscape scales. Forest tree seedlings, which could otherwise encroach and overgrow woodlands, are killed by regular fire, yet fire has other effects that may also influence these feedbacks. In particular, many forest trees require symbiotic ectomycorrhizal fungi in order to establish. By restructuring soil fungal communities, fire might affect the availability of symbionts or the potential for symbiont sharing between encroaching trees and woodland vegetation. To investigate this possibility, we performed a soil bioassay experiment using inoculum from burned and unburned oak woodlands and Douglas‐fir forests. We examined how fire, ecosystem type, and neighboring heterospecific seedlings affect fungal root community assembly of Douglas‐firs and oaks. We asked whether heterospecific seedlings facilitated fungal colonization of seedling roots in non‐native soil, and if so, whether fire influenced this interaction. External fungal colonization of oak roots was more influenced by fire and ecosystem type than by the presence of a Douglas‐fir, and oaks increased the likelihood that Douglas‐fir roots would be colonized by fungi in oak woodland soil. Yet, fire increased colonization of Douglas‐fir in oak soil, diminishing the otherwise crucial role played by oak facilitation. Fire also strengthened the positive effect of Douglas‐firs on oak root‐associated fungal diversity in Douglas‐fir forest soil. Prior work shows that fire supports woodland ecosystems by stemming recruitment of encroaching seedlings. Here, we find evidence that it may contrastingly reduce fungal limitation of invasive seedling growth and establishment, otherwise relieved only by facilitation. Future work can investigate how these opposing effects might contribute to the net impact of changes in fire regime on landcover stability. Read the free Plain Language Summary for this article on the Journal blog.

Effects of ventilation system design on flame behavior and smoke characteristics for mitigating marine engine room fire hazards

Engine room fires are one of the most harmful types of ship fires, the development of which is closely related to the design of marine ventilation system. In this paper, a full-scale numerical study of ship's engine room fire is carried out using a fire dynamics simulator, and the effects of vent layout and air velocity on the flame behavior, smoke stratification and diffusion are investigated. The three-dimensional model of the engine room is built based on the ocean-going training ship Yukun of Dalian Maritime University. First, the variations of flame behavior under different air vent layouts and wind speeds are explored, and a mathematical model is derived to quantify the flame deflection angle. Then, the effects of ventilation conditions on the smoke stratification in the cabin are analyzed, and the characteristics of hot smoke diffusion are revealed. The results show that a higher ventilation velocity is beneficial to the rapid cooling of the ship's engine room, and the symmetric ventilation layout of Method 3 with a central intake on the upper side and a bottom exhaust on both sides is more conducive to the safety of the engine and other heat source equipment in a fire. This study provides references to the design and optimization of ventilation systems on ships, which can improve the safety of the important equipment in the engine room and prevent further expansion of fire.

Modernization of Fire Vehicles with New Technologies and Chemicals

Fire is a stable exothermic chain reaction of flammable materials brought together with oxygen or other oxidizing substances under certain conditions, occurring uncontrollably. Fire vehicles interfere with many types of fire, such as wildfires, factory fires, building fires, etc. During this intervention, fire vehicles generally use water or foam. In this study, new effective fire suppression applications are investigated. Thermal camera applications in fire trucks and also new extinguishing agents—boron-based chemicals—were tested in forest fire simulations. In these experiments, it was observed that the thermal camera detected the fire as soon as it occurred. It seemed appropriate to use thermal cameras for all types of fire vehicles (foam trucks, water tankers, rescue trucks, etc.). It was seen that the thermal camera application could detect and monitor the fire during the fire-extinguishing work of the firefighters. The boron-based fire suppressant had a better extinguishing and cooling effect than water in the experiments. Compared to the water used as a traditional method, the liquid boron-based extinguisher provided 22% faster—while the solid boron-based extinguisher provided 42% faster—suppression and cooling. With three separate experiments, it is predicted that thermal camera applications and the use of boron-based extinguishers in fire vehicles can lead to an effective and positive transformation in the coming years.

GIS‐based spatiotemporal analysis of forest fires in Turkey from 2010 to 2020

AbstractForests are essential in contributing to the continuity of the natural balance. Therefore, their protection and sustainability are vital. However, all over the world, forest fires occur, and forests are destroyed due to both human factors and unknown causes. It is necessary to carry out studies to prevent this destruction. At this point, GIS‐based location–time relationship‐based hot spot clustering analysis can provide significant advantages in detecting risky spots of forest fires. In this study, GIS‐based emerging hot spot clustering analysis was carried out to determine the risky areas where forest fires will occur and to carry out preventive studies in the relevant areas. Turkey was chosen as the pilot region, and analyses were carried out using the data obtained from the official statistics of the Ministry of Agriculture and Forestry General Directorate of Forestry according to the causes of the fires (negligence, intentional, accidental, unknown cause and natural) between the years 2010 and 2020. Spatial autocorrelation analysis was conducted for each fire type, and threshold distances were determined {with a number of distance bands = 20,000, distant increment = 10,000}. Emerging hot spot analyses were then conducted, and the results were presented as maps and statistical outputs. According to all fire types, 15 new hot spots, 14 persistent hot spots, 33 sporadic hot spots, 9 consecutive hot spots, 15 intensifying, and 2 diminishing hot spot regions were obtained throughout the country.

An Analysis of Prescribed Fire Activities and Emissions in the Southeastern United States from 2013 to 2020.

Prescribed burning is a major source of a fine particular matter, especially in the southeastern United States, and quantifying emissions from burning operations accurately is an integral part of ascertaining air quality impacts. For instance, a critical factor in calculating fire emissions is identifying fire activity information (e.g., location, date/time, fire type, and area burned) and prior estimations of prescribed fire activity used for calculating emissions have either used burn permit records or satellite-based remote sensing products. While burn permit records kept by state agencies are a reliable source, they are not always available or readily accessible. Satellite-based remote sensing products are currently used to fill the data gaps, especially in regional studies; however, they cannot differentiate prescribed burns from the other types of fires. In this study, we developed novel algorithms to distinguish prescribed burns from wildfires and agricultural burns in a satellite-derived product, Fire INventory from NCAR (FINN). We matched and compared the burned areas from permit records and FINN at various spatial scales: individual fire level, 4 km grid level, and state level. The methods developed in this study are readily usable for differentiating burn type, matching and comparing the burned area between two datasets at various resolutions, and estimating prescribed burn emissions. The results showed that burned areas from permits and FINN have a weak correlation at the individual fire level, while the correlation is much higher for the 4 km grid and state levels. Since matching at the 4 km grid level showed a relatively higher correlation and chemical transport models typically use grid-based emissions, we used the linear regression relationship between FINN and permit burned areas at the grid level to adjust FINN burned areas. This adjustment resulted in a reduction in FINN-burned areas by 34%. The adjusted burned area was then used as input to the BlueSky Smoke Modeling Framework to provide long-term, three-dimensional prescribed burning emissions for the southeastern United States. In this study, we also compared emissions from different methods (FINN or BlueSky) and different data sources (adjusted FINN or permits) to evaluate uncertainties of our emission estimation. The comparison results showed the impacts of the burned area, method, and data source on prescribed burning emission estimations.

Global recovery patterns of soil microbes after fire

Soil microorganisms are a fundamental component of ecosystems and mediate biogeochemical cycles and ecosystem productivity. The frequency and extremity of fire weather is expected to increase under global warming; however, postfire soil microorganisms' patterns and trends remain unclear. By performing a global meta-analysis of 1019 paired observations of burned and unburned sites from 123 publications, we show that fungal biomass, microbial biomass carbon (C), soil respiration, autotrophic respiration, and C acquisition enzymes decrease in response to fire. The recovery times of microbial biomass and functional groups were shorter than those of soil C emissions and extracellular enzymes. Importantly, the postfire recovery of microbial biomass C and/or N as well as soil respiration and its components varied with mean annual temperature and precipitation, fire severity and type, and ecosystem type, with longer recovery times under high-severity fire/wildfire and in forests. Our study highlights the differential recovery patterns of microbial attributes after fire across global terrestrial ecosystems and reveals the importance of climate and the fire regime in regulating the postfire recovery of the soil microbial community and functioning.

Indoor Fire Simulation in Low-Rise Teaching Buildings Based on BIM–FDS

School buildings gather a large number of underage students, and the disastrous consequences of fire in such buildings are very serious, which is one of the key concerns of society in fire prevention and control. This study takes a “[” type kindergarten teaching building as the background and constructs a BIM–FDS building fire simulation model to reveal the fire smoke dispersion law under the coupling of the typical building structure and fire protection systems. The results show that the stairwells on both sides of the “[” type building are the main channels for the diffusion of fire smoke, and the asymmetry of the stairwell structure will cause apparent differences in the diffusion of smoke. Using the natural smoke exhaust in the stairwells of low-rise buildings does not aggravate the spread of smoke in the building and is conducive to smoke emissions. The high-pressure water mist system is superior to the water spray system in fire extinguishing and controlling room temperature. While it reduces smoke exhaust performance, it does not adversely affect personnel evacuation. This study systematically reveals the law of diffusion of fire smoke from “[”-type teaching buildings, which can support the design of similar building structures, ventilation, fire protection, and the formulation of fire escape plans.

Brown carbon absorption in the Mediterranean basin from local and long-range transported biomass burning air masses

This study examines the impact of light absorption from biomass burning (BB) brown carbon (BrC) in the Mediterranean basin from local and distant fire incidents during a typical fire season in August 2019 and under severe fire activity in August 2021. The approaches of Saleh et al. (2014) and Wang et al. (2018) are used to describe the BrC absorption within the WRF-Chem model. Focusing on three regions in the Mediterranean (around the islands of Sicily, Malta, and Crete) that are most affected by BB activity, BrC absorption approximates 5 Mm−1 in OC concentrations up to 3 μg m−3 and can approach 15 Mm−1 in extreme conditions (up to 10 μg m−3). When photochemical bleaching is considered, BrC undergoes almost immediate bleaching upon emission due to high levels of OH radical in the Mediterranean atmosphere during summertime, decreasing light absorption between 56% and 75% under both average and extreme BB conditions. Cloud formation is facilitated above the PBL due to moisture increase induced by BrC at the area of fire events, while transported drier and warmer air masses tend to dissipate cloud formation further away from the BB source. The impact of BrC absorption on irradiances is small (up to −6 W m−2 in extreme conditions) and is often overlapped by the absorption from water vapour variations. BrC direct radiative effect (DRE) is estimated at 0.04 W m−2 (∼10% of BC) in average and 0.18 W m−2 in extreme BB activity under clear sky. Under all sky, low-level clouds dissipation in 2019 with average BB emissions enhances DRE (at 0.15 W m−2), while the higher clouds dissipation in 2021 limits DRE (at 0.11 W m−2) resulting in lower DRE despite the extreme BB conditions.

Impacts of fire on soil respiration and its components: A global meta-analysis

As a general disturbance in terrestrial ecosystems, fire can have far-reaching consequences on the carbon (C) cycle. Although soil respiration (SR) is important in regulating atmospheric CO2 concentrations, a general pattern of the response of SR to fire in terrestrial ecosystems remains unclear. In this study, a meta-analysis of 91 studies on fires across 116 global sites was conducted to investigate the effects of fire on SR and its components. The results revealed that the responses of SR and heterotrophic respiration (HR) to fire were dependent on fire severity (low-, moderate-, and high-severity) and types (wildfire and prescribed fire). Specifically, the high- and low-severity fires reduced SR and HR, whereas moderate-severity fires had negligible effects on these parameters. On average, wildfires significantly decreased SR and HR by 13.9% and 18.6%, respectively, across all ecosystems, while prescribed fire reduced SR by 8.4% but did not change HR. In addition, the responses of SR and HR varied with the ecosystem types. Fire decreased SR in all three types of forests (boreal forests: -14.8%, temperate forests: -13.8%, and tropical forests: -28.9%), whereas decreased HR only in boreal and temperate forests (-23.8% and 20.7%, respectively) but not in tropical forests. Moreover, SR decreased directly followed by an increase, whereas HR declined with time after low- and high-severity fires. At a global scale, the responses of SR and HR to fire largely resulted from the changes in soil organic C, dissolved C, microbial biomass C, and belowground biomass, as indicated by the correlation analysis. In addition, the response of SR to fire was negatively affected by the mean annual precipitation in the forests. Overall, our study revealed the mechanisms driving the effects of fire and provided a framework for understanding soil C emissions under intensified fire regimes.

Informal Settlement Fires in Colombia

AbstractThe problem of fires in informal settlements has been recognized as a global phenomenon, affecting thousands of people annually and representing an extreme risk for millions. Informal settlements are characterized by poor infrastructure, lack of access to essential services and dwellings built from flammable materials. Their vulnerability to fire is extreme as even where losses are minimal fires ruin lives, damage property, and undermine socioeconomic development. Currently, there is a great need to understand the proportion and characteristics of the problem around the world. As an attempt to help fill this knowledge gap, this paper presents a detailed description of the problem of informal settlement fires in Colombia. This investigation includes the contextualization of the problem, a morphological description of several common dwelling types, and their socio-economic characteristics in terms of the number of people, physical conditions, and provision of services. The statistics associated with informal settlement fires in Colombia are reported, with emphasis on the number of dwellings destroyed, people affected, ignition sources and challenges for fire suppression operations. Finally, a case study highlighting the development of a typical informal settlement fire in Colombia is presented. The results reported in this paper are suitable to support emergency protocols and prevention strategies aiming to mitigate the risk associated with informal settlements.

Indoor Fire Detection Algorithm Based on Second-Order Exponential Smoothing and Information Fusion

With the increasing complexity of building structures and interior materials, the danger of indoor fires has become more severe. It is effective to improve the accuracy and timeliness of fire-sensing devices in order to reduce the harm caused by fires. This paper focuses on the temporal characteristics of sensor information, creatively introducing second-order exponential smoothing into the information fusion algorithm. The RNN structure is used to fit the formula and adaptively trained with various types of fire data. Experimental results show that the proposed algorithm achieves an accuracy of 98% in fire recognition, significantly improving the accuracy of fire recognition. To avoid the issue of imbalanced positive and negative samples, this paper comprehensively evaluates parameters such as F1-score and Matthews correlation coefficient (MCC). The achieved scores are 0.97 and 0.95, respectively, indicating the algorithm’s good performance in detecting the presence or absence of fire. Furthermore, the proposed algorithm is tested for its alarm time. The experimental results show that the proposed algorithm can timely identify various types of fires and can give an alarm earlier than traditional fire alarms.

Instrumental monitoring for the location of endogenous fires in the coal mine wall

Introduction. Endogenous fire is a fire initiated by the process of self-ignition of coal. Detection of this type of fire is carried out visually by fire and smoke or by the results of temperature, gas or geophysical control. The occurrence of endogenous fires in coal mines leads to serious consequences, such as pollution of the environment and deterioration of sanitary and hygienic working conditions. It also leads to economic losses due to the suspension of technological processes and burnout of coal reserves. The prevention of endogenous fires includes measures to prevent the possible development of self-ignition processes in the identified areas of potential fire hazard. Research objective is to investigate areas of fire in active coal mines in order to determine the center of the profile of geophysical sounding, as close as possible to the epicenter of endogenous fire, to perform its binding to the mine plan and geological section. Methods of research. In order to achieve this goal, it is necessary to carry out a visual inspection of the areas of fire, to take photographs, as well as to carry out a thermal imaging survey with specialized equipment. Results. The results of photo- and thermal imaging surveys were recorded, the assessment of mining and geological conditions of formation of endogenous fires was carried out, and plans of the location of endogenous fires were presented. Conclusions and scope of results. After implementation of measures on inspection and survey in areas close to the centers of endogenous fires, as well as analysis of the results, we can conclude that direct visual inspections and thermal imaging measurements do not allow to fully determine the boundaries of fire zones in plan and depth. This is due to the fact that noticeable temperature anomalies are recorded only when the focus is directly on the ground surface due to the low thermal conductivity of coal and host rocks.

Community Abundance of Resprouting in Woody Plants Reflects Fire Return Time, Intensity, and Type

Plants in fire-prone ecosystems have evolved a variety of mechanisms to resist or adapt to fire. Post-fire resprouting is a key adaptation that promotes rapid ecosystem recovery and hence has a major impact on the terrestrial carbon cycle. However, our understanding of how the incidence of resprouting varies in different fire regimes is largely qualitative. The increasing availability of plant trait data and plot-based species cover data provides an opportunity to quantify the relationships between fire-related traits and fire properties. We investigated the quantitative relationship between fire frequency (expressed as the fire return time) and the proportion of resprouters in woody plants using plot data on species cover from Australia and Europe. We also examined the relationship between the proportion of resprouters and gross primary production (GPP) and grass cover, where GPP was assumed to reflect fuel loads and hence fire intensity, while grass cover was considered to be an indicator of the likelihood of ground fire and the speed of fire spread, using generalised linear modelling. The proportion of resprouting species decreased significantly as the fire return time increased. When the fire return time was considered along with other aspects of the fire regime, the proportion of resprouters had significant negative relationships with the fire return time and grass cover and a significant positive relationship with GPP. These findings demonstrate that plants with the ability to resprout occur more often where fire regimes are characterised by high-frequency and high-intensity crown fires. Establishing quantitative relationships between the incidence of resprouting and the fire return time and fire type provides a basis for modelling resprouting as a consequence of the characteristics of the fire regime, which in turn makes it possible to model the consequences of changing fire regimes on ecosystem properties.

Deep learning health management diagnostics applied to the NIST smoke experiments

Fire is one of the most important hazards that must be considered in advanced nuclear power plant safety assessments. The Nuclear Regulatory Commission (NRC) has developed a large collection of experimental data and associated analyses related to the study of fire safety. In fact, computational fire models are based on quantitative comparisons to those experimental data. During the modeling process, it is important to develop diagnostic health management systems to check the equipment status in fire processes. For example, a fire sensor does not directly provide accurate and complex information that nuclear power plants (NPPs) require. With the assistance of the machine learning method, NPP operators can directly get information on local, ignition, fire material of an NPP fire, instead of temperature, smoke obscuration, gas concentration, and alarm signals. In order to improve the predictive capabilities, this work demonstrates how the deep learning classification method can be used as a diagnostic tool in a specific set of fire experiments. Through a single input from a sensor, the deep learning tool can predict the location and type of fire. This tool also has the capability to provide automatic signals to potential passive fire safety systems. In this work, test data are taken from a specific set of the National Institute of Standards and Technology (NIST) fire experiments in a residential home and analyzed by using the machine learning classification models. The networks chosen for comparison and evaluation are the dense neural networks, convolutional neural networks, long short-term memory networks, and decision trees. The dense neural network and long short-term memory network produce similar levels of accuracy, but the convolutional neural network produces the highest accuracy.

Remote Sensing and GIS tools for Forest Resource Management-A Review

Global importance and thus need to quantify the status of forest dynamics is increasing day by day. It is more so in the case of a country like India which is on the deficit side of forest cover in countering ecological balance. Information required for forest resource management includes extant, type of forest, felling/cutting, deforestation, afforestation, forest fire, forest flood, and extraction of bio-physical parameters like age of plantation, total biomass, canopy density etc. Widespread, vast span and difficult terrain, and inaccessibility makes it difficult to collect timely and periodic information about above mentioned parameter through conventional means. Forest mapping is one of the fields that witnessed the earliest application of remote sensing and GIS for nonmilitary purposes. using remote sensing data and GIS techniques, a forest manager can generate information regarding forest cover, types of forest present within an area of interest, human encroachment extent into forest land/protected areas, encroachment of desert-like conditions and so on [3].For the purpose of understanding the working of remote sensing and GIS, the basics are explained below.

Population dynamics and individual growth dynamics of Larix gmelinii under non-stand replacing fire

The population dynamics and individual growth dynamics of dominant tree species in boreal forests are associated with fire regimes. Fire regimes in the boreal forests of eastern Siberia are dominated by non-stand replacing (NSR) fire types. Fire drives population demographics by triggering tree mortality and births, and affects the post-fire growth dynamics of surviving individuals. When a non-stand replacing fire occurs, population dynamics fluctuate and individual growth changes occur simultaneously. The Great Xing’an Mountains is located at the southern edge of the eastern Siberia boreal forest and research on fire regimes and stand dynamics in this region are scarce. Understanding the effect of fire on the population structure and individual growth of the dominant species in the stand and the disturbance mechanisms are essential to understand the develop of boreal forests in the context of climate warming. In this study, three Larix gmelinii stands disturbed by NSR fire in the Great Xing’an Mountains were selected and established plots, and control stand plots were established at similar site conditions. We conducted a forest inventory and used dendrochronological methods to reveal the short- and long-term effects of NSR fire disturbance on the population dynamics and individual growth of the dominant species of L. gmelinii. Specifically, the effects of NSR fire on stand structure, the relationship between L. gmelinii demographics and disturbance, and the response of growth dynamics to disturbance were analyzed. Finally, the history of potential disturbance at stand level was reconstructed. The study found that common NSR fire affect the biomass and species composition of L. gmelinii forests. Fire disturbance contributes to the younger age structure of L. gmelinii populations. However, The NSR fire may limit the size of L. gmelinii populations but does not necessarily destroy population resilience depending on stand conditions. Irregular fluctuations in population survival and mortality curves are directly related to historical disturbance events. The NSR fire can inhibit the growth of surviving trees for 1–2 years, resulting in temporary growth asynchrony. The population dynamics fluctuations and temporal patterns of growth release signals can reconstruct historical disturbance events at the stand level. For example, the MH intra-group (Mohe Luogu River Nature Reserve burned stand&Mohe Luogu River Nature Reserve unburned stand) probably experienced a high-severity fire in 1880–1900, the TH intra-group (Tahe Nature Reserve burned stand&Tahe Nature Reserve unburned stand) experienced a high-severity fire around 1930, and THB (Tahe Nature Reserve burned stand) suffered stand-replacing. Overall, irregular fluctuations in population survival and mortality curves have been directly related to historical disturbance events. These findings provide direct evidence of the short- and long-term effects of fire on the survival and growth of L. gmelinii populations.

Upwind thermal radiation prediction of multi-scale aviation kerosene pool fire on the flight deck for emergency rescue: Experiment, numerical simulation and machine learning

The fire caused by aviation kerosene leakage on the flight deck under the environmental wind is a typical pool fire, which can seriously harm to human and damage to the equipment nearby by thermal radiation. The previous studies paid high attention to the more dangerous downwind radiation, but the key requirement of exact upwind radiation prediction for the emergency rescue is often ignored. The aim of current study is to explore the dimensionless relationship among radiant heat flux, wind speed and pool scale. Three different scale pool fire experiments were chosen and coupled with numerical simulation to provide the validation data. Based on the verified simulation setup, more predicted radiant heat fluxes in the upwind area are obtained according to a wider wind speed range. Furthermore, the Artificial Neural Network machine learning method is applied to obtain more data at wider pool scales by training the simulation data. Eventually, the fitting process is conducted and the dimensionless relationship of radiant heat flux, wind speed and scale is deduced: Qr″*=2.19(u*L*)−1. The radiant heat flux in the upwind area can be estimated by the proposed equation, and similarly, the horizontal distances according to critical heat fluxes can also be obtained. The current proposed dimensionless equation can be used as an important reference to avoid radiation harm or damage of aviation kerosene pool fire in the upwind area for emergency rescue.

Fire‐suppression efficiency and extinguishing mechanisms of calcium acetate using heptane cup‐burner flames

AbstractTo address the global requirement for a phosphorus‐free fire‐extinguishing agent, this study elucidated the ability of calcium acetate to extinguish cup‐burner flames. The inhibition efficiency of calcium acetate powder (<50 μm) was compared with that of silica‐uncoated ammonium dihydrogen phosphate (<50 μm), a chemical contained in agents used in typical ABC fire extinguishers. Calcium oxide and calcium carbonate powders were also used to investigate the suppression mechanisms of calcium acetate. The cup‐burner experiments demonstrated that (i) calcium acetate, calcium hydroxide, and ammonium dihydrogen phosphate could extinguish cup‐burner flames; (ii) calcium carbonate could not extinguish cup‐burner flames; and (iii) the fire‐suppression ability of calcium acetate was higher than that of ammonium dihydrogen phosphate, which was in turn higher than that of calcium hydroxide. Thermogravimetric analysis (TG) and X‐ray diffraction measurements revealed that, although the calcium‐compound powders decomposed and produced calcium oxide during flame extinction, significant differences existed among the fire inhibition efficiencies of the calcium compounds. TG and particle‐size measurements proved that the high fire‐suppression ability of calcium acetate resulted from the high ability of calcium acetate to generate inert gases during its decomposition, which diluted the oxygen concentration, thereby extinguishing the fires.

Using simulated wildland fire to assess microbial survival at multiple depths from biocrust and bare soils.

Surface soil microbial communities are directly exposed to the heat from wildland fires. Due to this, the microbial community composition may be stratified within the soil profile with more heat tolerant microbes near the surface and less heat tolerant microbes, or mobile species found deeper in the soil. Biological soil crusts, biocrusts, are found on the soil surface and contain a diverse microbial community that is directly exposed to the heat from wildland fires. Here, we used a simulated fire mesocosm along with a culture-based approach and molecular characterization of microbial isolates to understand the stratification of biocrust and bare soil microbes after low severity (450°C) and high severity (600°C) fires. We cultured and sequenced microbial isolates from 2 to 6 cm depth from both fire types. The isolates were stratified along the soil depth. Green algal isolates were less thermotolerant and found in the deeper depths (4-6 cm) and the control soils, while several cyanobacteria in Oscillatoriales, Synechococcales, and Nostocales were found at 2-3 cm depth for both fire temperatures. An Alphaproteobacteria isolate was common across several depths, both fire types, and both fire temperatures. Furthermore, we used RNA sequencing at three depths after the high severity fire and one control to determine what microbial community is active following a fire. The community was dominated by Gammaproteobacteria, however some Cyanobacteria ASVs were also present. Here we show evidence of stratification of soil and biocrust microbes after a fire and provide evidence that these microbes are able to survive the heat from the fire by living just below the soil surface. This is a steppingstone for future work on the mechanisms of microbial survival after fire and the role of soil insulation in creating resilient communities.

The thermal assessment of GFRP reinforced concrete bridge decks in fire scenarios

If a concrete structure survives a fire, several questions can arise regarding the safety of the structure and the extent of repair. This paper combines the results of a set of comprehensive material tests on various Glass Fibre Reinforced Polymer (GFRP) reinforcing bars at high temperatures with heat transfer analysis to approximate the extent of the fire-induced damage. The paper discusses the most common fire types in bridges (i.e., hydrocarbon fire and pool fire) occurring at various locations of bridges. A simple guideline for quick assessment of the GFRP reinforced concrete bridge decks is proposed, enabling the bridge authorities and practitioners to make an informed preliminary decision following a fire incident. This paper provides a quick visual inspection method to approximate the level of damage to GFRP reinforcing bars and correlate their mechanical properties to the available information on the post-fire residual properties of GFRP bars. The limitations of this method are presented in section 6. The paper outlines one example to show how to use the method and the information from the paper to determine the reliability and the conditions of GFRP bars at key locations. The findings of this example indicate that GFRP bridge decks can retain sufficient strength although the long-term performance of the bridge must be assessed carefully.