Wildfire Research Articles

Prediction of Cervical Cancer Using Boosting Techniques

Cancer of the cervix, commonly called cervical cancer, is a type of cancer that develops in the cells of the cervix, which is the lower portion of the uterus that attaches to the vagina. It hardly shown symptoms in its early stage. To detect the disease, regular is required, however larger population of women not aware of this approach while many shy away and refuse to take the test. Hence cervical cancer spread like wild fire among women and being the most common cause of cancer disease it result to untimely death among women in our society today. In this research, the performance of a few sophisticated ensemble models, such as Bagging Classifier and Adaptive Boosting (AdaBoost) Classifier, is shown for the purpose of predicting a diagnosis of cervical cancer based on recorded cancer risk factors and target variables. Accuracy, sensitivity, and specificity were the measures that were used in the evaluation of the models. Python library was adopted for the classification and the cervical cancer dataset used for the experiment was acquired from UCI (University of California at Irvine), the classification was carried using voting approach by combining three classifiers: Decision Tree (DT), K-N Neighbour(KNN) and Random Forest (RF). The results indicated that the proposed model was highly accurate in predicting the risk of cervical cancer, with 119 instances classified as ‘class zero’ and only three instances classified as ‘class one’ based on the predictions.

Intelligent Deep Learning Enabled Wild Forest Fire Detection System

The latest advancements in computer vision and deep learning (DL) techniques pave the way to design novel tools for the detection and monitoring of forest fires. In this view, this paper presents an intelligent wild forest fire detection and alarming system using deep learning (IWFFDA-DL) model. The proposed IWFFDA-DL technique aims to identify forest fires at earlier stages through integrated sensors. The proposed IWFFDA-DL system includes an Integrated sensor system (ISS) combining an array of sensors that acts as the major input source that helps to forecast the fire. Then, the attention based convolution neural network with bidirectional long short term memory (ACNN-BLSTM) model is applied to examine and identify the existence of danger. For hyperparameter tuning of the ACNN-BLSTM model, the bacterial foraging optimization (BFO) algorithm is employed and thereby enhances the detection performance. Finally, when the fire is detected, the Global System for Mobiles (GSM) modem transmits messages to the authorities to take required actions. An extensive set of simulations were performed and the results are investigated interms of several aspects. The obtained results highlight the betterment of the IWFFDA-DL technique interms of various measures.

Covid-19 and Pre-Morbid Lifestyle-Related Risk Factors-A Review.

Since its outbreak in December 2019 in China, COVID-19 has spread like wild fire to affect many communities of the world. The high infectivity and case fatality rates of the disease among the general population and the severely ill patients respectively drew the attention of the global community. Our review showed that socio-demographic and lifestyle-related risk factors and underlying comorbid diseases were directly and indirectly associated with increased susceptibility and severity of COVID-19. These factors included older age (⩾60 years), male gender, and ethnic minority groups (especially blacks), smoking, low serum level of vitamin D, unhealthy diet, physical inactivity (with poor exposure to sunlight), overweight/obesity, high blood pressure/hypertension, high blood cholesterol, cardiovascular diseases (like stroke and coronary heart disease), diabetes mellitus, chronic obstructive pulmonary disease, chronic kidney disease, chronic liver disease, and some cancers (like leukemia, lymphoma, or myeloma). The literature further revealed that the clinical progression of the majority of these associated risk factors can be modified through effective and comprehensive risk reduction through healthy living and lifestyle modification. COVID-19 preventive and treatment guidelines that give adequate attention to risk reduction and healthy lifestyle among people-either in the pre-, peri-, or post-COVID-19 stage, should be developed by public health policymakers and clinicians. This will play a significant role in the global effort to combat the pandemic, and reduce its negative impact on the life expectancy and socio-economic development of the world particularly in low- and middle-income countries (LMICs).

Forest foliage fuel load estimation from multi-sensor spatiotemporal features

• Spatiotemporal features of spaceborne SAR and optical data were combined first time. • The addition of spatiotemporal features greatly improves the estimation of FFL. • Temporal features seem more important than spatial features. • Both spatial and temporal changes in FFL can indicate forest fire risk. Foliage fuel is the most flammable component in crown fires. Spatiotemporal dynamics of foliage fuel load (FFL) are important for fire managers to assess fire risk. Here, we integrated optical data from the Landsat 8 Operational Land Imager (OLI) with synthetic aperture radar (SAR) data from Sentinel-1 to estimate FFL. We first reconstructed seamless time series from the Landsat 8 and Sentinel-1 imagery by accounting for unequal time intervals between image observations and outliers. We then extracted temporal features that are proxies of the intra- and inter-annual dynamics from these time series. In addition, we derived spatial features from the imagery that quantify spatial context and therefore used varying window sizes. The random forest regression was implemented to assess the importance of the spatiotemporal features, reduce errors, and derive robust FFL estimates. The satellite estimates were validated against 96 field measurements from Pinus yunnanensis forests in the Liangshan Yi Autonomous Prefecture, Sichuan Province, China. Both the spatiotemporal features of SAR and optical data importantly contributed to FFL estimation. When only optical data was used, the model achieved a R 2 of 0.75 (relative Root Mean Squared Error (rRMSE) = 25.3 %), while when only SAR data was used the R 2 was 0.76 (rRMSE = 25.6 %). However, when optical and SAR data were combined, the R 2 increased to 0.81 (rRMSE = 23.2 %). We also found that temporal features were more important predictors of FFL than features that captured spatial context. We demonstrated our FFL mapping method by a case study in the Chinese Sichuan Province, in relation to the occurrence of a fire. Our method needs additional validation over different tree species and forest types, yet has potential for mapping forest fuel loads and fire risk.

Solutions to fire and shade: resprouting, growing tall and the origin of Eurasian temperate broadleaved forest.

Tree species of Eurasian broadleaved forest possess two divergent trait syndromes with contrasting patterns of resource allocation adapted to different selection environments: short-stature basal resprouters that divert resources to a bud bank adapted to frequent and severe disturbances such as fire and herbivory, and tall trees that delay reproduction by investing in rapid height growth to escape shading. Drawing on theory developed in savanna ecosystems, we propose a conceptual framework showing that the possession of contrasting trait syndromes is essential for the persistence of broadleaved trees in an open ecosystem that burns. Consistent with this hypothesis, trees of modern Eurasian broadleaved forest bear a suite of traits that are adaptive to surface and crown-fire regimes. We contend that limited opportunities in grassland restricts recruitment to disturbance-free refugia, and en masse establishment creates a wooded environment where shade limits the growth of light-demanding savanna plants. Rapid height growth, which involves investment in structural support and the switch from a multi-stemmed to a monopodial growth form, is adaptive in this shaded environment. Although clustering reduces surface fuel loads, these establishment nuclei are vulnerable to high-intensity crown fires. The lethal effects of canopy fire are avoided by seasonal leaf shedding, and aerial resprouting enhances rapid post-fire recovery of photosynthetic capacity. While these woody formations satisfy the structural definition of forest, their constituents are clearly derived from savanna. Contrasting trait syndromes thus represent the shift from consumer to resource regulation in savanna ecosystems. Consistent with global trends, the diversification of most contemporary broadleaved taxa coincided with the spread of grasslands, a surge in fire activity and a decline in wooded ecosystems in the late Miocene-Pliocene. Recognition that Eurasian broadleaved forest has savanna origins and persists as an alternative state with adjacent grassy ecosystems has far-reaching management implications in accordance with functional rather than structural criteria. Shade is a severe constraint to the regeneration and growth of both woody and herbaceous growth forms in consumer-regulated ecosystems. However, these ecosystems are highly resilient to disturbance, an essential process that maintains diversity especially among the species-rich herbaceous component that is vulnerable to shading when consumer behaviour is altered.

Crown Fire Modeling and Its Effect on Atmospheric Characteristics

The article is concerned with the experimental study of the crown fire effect on atmospheric transport processes: the formation of induced turbulence in the vicinity of the fire source and the transport of aerosol combustion products in the atmosphere surface layer at low altitudes. The studies were carried out in seminatural conditions on the reconstructed forest canopy. It was established that the structural characteristics of fluctuations of some atmosphere physical parameters in the case of a crown fire practically coincide with the obtained earlier values for a steppe fire. The highest concentration of aerosol combustion products was recorded at a height of 10–20 m from the ground surface. It was found that the largest number of aerosol particles formed during a crown fire had a particle diameter of 0.3 to 0.5 µm. As a result of experimental data extrapolation, it is concluded that an excess of aerosol concentration over the background value will be recorded at a distance of up to 2000 m for a given volume of burnt vegetation. It is of interest to further study these factors of the impact of wildfires on atmosphere under the conditions of a real large natural wildfire and determine the limiting distance of aerosol concentration excesses over background values.

Essential Role of Forest Fires in Humic Acids Structure and Composition Alteration

Pyrogenic components of soil organic matter are practically not taken into account when assessing the implications of global climate changes on the SOM sequestration rate and its stability. In this regard, both the amount and structural stability of SOM were investigated for postpyrogenic forest–steppe environments. Mature unaffected by fire Psamment Entisols were investigated in comparison with same soil strongly affected by surface and crown fires in 2010 in Tolyatti city. This article discusses postpyrogenic succession when comparing the results of field works in 2010 with 2020. The elemental composition of humic acids as well as 13C NMR spectra were investigated for the studied humic acids. Moreover, for the first time ever, integrated indicators of HAs’ molecular composition were presented for postpyrogenic soils. The data obtained showed that there are significant changes in the structural organization of organic matter as a result of forest fires. A simultaneous decrease in the H/C and O/C atomic ratios was identified as a result of fire, which indicates a slight loss of oxygen-containing functional groups, while the aromaticity degree of molecules increases. An increase in the content of oxygen-containing groups in the HA molecules was shown for 10 years after the fires, which was accompanied by the oxidation of the HA molecule with the same increase in the aromaticity degree of the HA molecule. The HA molecules of 2020 turned out to be more resistant to environmental factors compared to analogues in 2010. As a result of fires, the aromaticity degree of HAs molecules significantly increases.

Investigation of Forest Fire Characteristics in North Korea Using Remote Sensing Data and GIS

Forest fires cause damage to property and the environment around the world every year. North Korea has suffered from fires every year. Fires may lead to temporary or permanent damage to forest ecosystems, long-term site degradation, and alteration of hydrological regimes, producing detrimental impacts on economies, human health, and safety. In North Korea, fires cause serious damage to the affected mountainous environment. However, it is very difficult to obtain ground information or perform field checks because of the political isolation of North Korea. Thus, there are few studies that have investigated North Korean fires. In this situation, remote sensing techniques and digital topographic data can be used to investigate fire characteristics in North Korea. In this study, fire trends were analyzed using Moderate Resolution Imaging Spectroradiometer (MODIS) data from the Land Processes Distributed Active Archive Center (LPDAAC) from 2004 to 2015, and Landsat data were processed to estimate burned areas in South Hamgyong Province (SHP) and Gangwon Province (GWP) in North Korea. The burn severity of large fires in elevation, slope, and landform features was also analyzed to investigate large fire-burned areas using 30-m-resolution Global Digital Elevation Model (DEM) data from the United States National Aeronautics and Space Administration (NASA). After the results were compared and discussed, the following conclusions were derived. (1) In terms of location, fires in SHP were relatively concentrated along BaekDu-DaeGan (BDDG), while fires in GWP were scattered throughout the province. (2) In terms of size, the large fire-burned areas with an area greater than 1000 ha are significantly more frequent in SHP than in GWP. In brief, large fires occurred more frequently and were more serious in SHP than in GWP. (3) In terms of forest type, coniferous areas were more susceptible to damage from fires and large fires than deciduous areas in both GWP and SHP. This is attributed to the combustible resin within the coniferous trees. Particularly, when a crown fire occurs, it tends to spread rapidly throughout the coniferous forest. (4) Regarding landforms, most large fires occurred along windward-side open slopes, while there were very few fires in shallow valleys, high ridges, or U-shaped valleys. It is believed that cultivation in high-elevation terrain and a lack of fire-extinguishing equipment and systems allow large fires to spread quickly. North Korea is very susceptible to large fire damage and must develop preparation measures against such situations.

Prescribed fire after thinning increased resistance of sub-Mediterranean pine forests to drought events and wildfires

Vegetation structure affects the vulnerability of a forest to drought events and wildfires. Management decisions, such as thinning intensity and type of understory treatment, influence competition for water resources and amount of fuel available. While heavy thinning effectively reduces tree water stress and intensity of a crown fire, the duration of these benefits may be limited by a fast growth response of the understory. Our aim was to study the effect of forest structure on pine forests vulnerability to extreme drought events and on the potential wildfire behaviour after management, with a special focus on the role of the understory. In three sub-Mediterranean sites of NE Spain dominated by Pinus nigra, two intensities of thinning (light: aiming at 70–75% canopy cover; and heavy: aiming at 50–60% canopy cover) followed by two understory treatments (mechanical only and mechanical plus prescribed burning) were applied, resulting in four differently managed stands plus an untreated control per site. Four to five years after management, we measured forest structure (overstory in one 314 m2 circular plot and understory in 20 quadrats of 1 m2 per treatment unit) and fuel load (in two 10 m transects per treatment unit) and simulated water balance and fire behaviour under extreme weather conditions. Understory contribution was assessed comparing the real structure with a virtual forest stand where understory vegetation equalled the one of the untreated control. Our results suggest that the resulting mid-term structure following treatments effectively reduced water stress and fire behaviour compared with untreated control, and that the most effective treatments were the ones where prescribed burning was applied after light or heavy thinning. While understory clearing contributes to increase the resistance to both disturbances, an additive effect of burning the debris reduced the vulnerability to drought and wildfires after treatments. Our study highlights the importance of managing the understory to further increase forest resistance to both disturbances.

Grass species with smoke-released seed dormancy: A response to climate and fire regime but not photosynthetic pathway.

Both C3 and C4 photosynthetic pathways and smoke-released seed dormancy occur among grasses. C4 species evolved from C3 species as seasonality and fire frequency increased and might therefore imply that their smoke sensitivity increased. I searched the worldwide literature for reports on germination responses among grasses, whose photosynthetic pathway was known, to treatment by smoke. Data were obtained for 217 species and 126 genera. While subfamilies tended to be C3 (Pooideae), C4 (Chloridoideae) or a mixture (Panicoideae), a beneficial smoke response was independent of their photosynthetic pathway. The only exceptions were Danthonioideae (C3, non-smoke responsive) and Triodia (C4, smoke responsive). One third of both C3 and C4 genera were smoke responsive. Even within genera, 90% of species showed contrasting smoke responses, confirming that smoke sensitivity is rarely taxonomically constrained. Data on photosynthetic pathway, climate, fire regime and vegetation were compiled for 15 regions that formed four distinct groups: 1) In warm climates with aseasonal rainfall, C4 grasses are moderately better represented, with crown fires and limited smoke responses. 2) In cool regions, most species are C3, with surface-crown fires and lack smoke responses. 3) In warm regions with summer rain (savannas), most species are C4, with surface fires and lack smoke responses. 4) In Mediterranean-climate regions with summer drought, most species are C3, with crown fires and smoke-released dormancy. Thus, even though C3 and C4 grasses are equally capable of expressing smoke sensitivity, their response depends on the region's climate and fire regime that also dictate which photosynthetic pathway dominates.

Calculating minimum safety distance against wildfires at the wildland-urban interface in Chile and Spain

Wildfires in the urban-forest interface constitute a civil protection emergency, causing considerable personal injury and damage to properties. The potential impacts of wildfires on buildings can be minimized by reducing the surrounding fuel and the use of structural materials with low flammability. However, the costs associated with implementing these actions and the responsibility for maintenance usually present conflicts with the property owners. This study aimed to identify minimum safety distances in wildland-urban interfaces within priority areas. The priority areas were identified based on the integration of fire risk and fuel hazard. Radiant heat is a variable in the behavior of fire that directly influences the definition of safety distances. In this research the radiant heat transfer was calculated based on the potential fire behavior for each study area. A comparative study of the horizontal heat transfer method and the radiant heat flux model was carried out. The horizontal heat transfer method indicated the highest vegetation-free distances, ranging from 23 m to 32 m. Some safety distances were validated using experimental fires and wildfires. The findings from the experimental fires and wildfires emphasize the need for a progressive fuel load reduction to mitigate radiant heat transfer. This may include both the removal of surface fuel and removal of trees to mitigate against crown fires. Our findings provide relevant information for decision-making on the effectiveness and efficiency of safety distances at the wildland-urban interface.

Limited seed viability in long-dead serotinous lodgepole pine trees in the Southern Rockies, USA

Serotinous cones, those that remain closed until heated, confer post-disturbance resilience on many lodgepole pine forests throughout the Southern Rockies. The record-breaking extent of wildfires in northern Colorado and southern Wyoming in 2020 raised concerns about tree regeneration in areas where crown fires burned lodgepole pine stands that had experienced high levels of mortality during bark beetle outbreaks occurring more than a decade previously. We measured seed germination and assessed the relationship between cone age and seed viability for serotinous cones on beetle-killed lodgepole pine in eight stands adjacent to four of those wildfires (n = 1160 cones). On average, germination was 34 % with three viable germinants produced per cone. Seed germination declined and the proportion of cones that contained no seed increased across the age range of cones sampled (17–51 yrs at the time of the 2020 wildfires). Germination of seed retained within the canopy seedbank of these long-dead stands was roughly half of that measured on live or recently killed lodgepole pine. Though pre-fire tree mortality from bark beetles can exceed 90 % in this area, serotinous cones on the remaining live trees and cones buried in the soil seedbank will contribute viable lodgepole seeds for tree regeneration on some burned landscapes. The decreased germinant levels from these cones may regenerate into pine stands that are less dense than after harvesting, bark beetles or wildfire alone, but they will likely create forest structure within a range of conditions expected for this region.

Utilizing Sentinel-2 Data for Mapping Burned Areas in Banjarbaru Wetlands, South Kalimantan Province

Sentinel-2 imagery can identify forest and land fires in underground parts, surface fires, and crown fires. The dNBR and RBR spectral indices on Sentinel-2 images proved accurate in identifying. This study analyzed the index value for burned area mapping in wetland areas using Sentinel-2 imagery data in 2019 and hotspot data from the MODIS data. The indices used to identify the burned area and the severity of the fire was the differenced normalized burn ratio (dNBR) and relativized burn ratio (RBR). Visual validation tests were performed by comparing RGB composite images to check the appearance before and after combustion with dNBR and RBR results. The dNBR value accuracy was 91.5%, and for a kappa, the accuracy was 89.58%. The RBR accuracy was 92.9%, and the kappa accuracy was 0.91. The results confirmed that in the Banjarbaru area, RBR was more accurate in identifying burned areas than dNBR; both indices can be used for burned area mapping in wetland areas.

Trajectories of wildfire behavior under climate change. Can forest management mitigate the increasing hazard?

Mediterranean forests and fire regimes are closely intertwined. Global change is likely to alter both forest dynamics and wildfire activity, ultimately threatening the provision of ecosystem services and posing greater risks to society. In this paper we evaluate future wildfire behavior by coupling climate projections with simulation models of forest dynamics and wildfire hazard. To do so, we explore different forest management scenarios reflecting different narratives related to EU forestry (promotion of carbon stocks, reduction of water vulnerability, biomass production and business-as-usual) under the RCP 4.5 and RCP 8.5 climate pathways in the period 2020–2100. We used as a study model pure submediterranean Pinus nigra forests of central Catalonia (NE Spain). Forest dynamics were simulated from the 3rd National Forest Inventory (143 stands) using SORTIE-nd software based on climate projections under RCPs 4.5 and 8.5. The climate products were also used to estimate fuel moisture conditions (both live and dead) and wind speed. Fuel parameters and fire behavior were then simulated, selecting crown fire initiation potential and rate of spread as key indicators. The results revealed consistent trade-offs between forest dynamics, climate and wildfire. Despite the clear influence exerted by climate, forest management modulates fire behavior, resulting in different trends depending on the climatic pathway. In general, the maintenance of current practices would result in the highest rates of crown fire activity, while management for water vulnerability reduction is postulated as the best alternative to surmount the increasingly hazardous conditions envisaged in RCP 8.5.

Wildlife Corridors and Regional Biodiversity Conservation around Selected Wildlife Protected Areas in Uganda

Wildlife corridors play a vital role in regional biodiversity conservation. Ecological attributes, changes in corridors and wildlife populations, threats to wildlife corridor functionality were evaluated using a case study of the eight wildlife protected areas in Uganda. A survey was conducted from September 2017 to May 2019, using document review, interviews, the Nature Conservancy’s Conservation Action Planning methodology, and Geographical Information System/remote sensing. The findings revealed a total of 20 key wildlife corridors in the landscape with key ecological attributes that augment regional biodiversity conservation. These corridors experience reducing vegetation cover, degradation, loss of connectivity, and degraded stepping stone habitats. They (corridors) are threatened by illegal activities, poaching and illegal wildlife tracking, unsustainable natural resource use, human population pressure, habitat transition/changes, wild fires, trans-boundary threats, infrastructure development, and climate change which affect habitat quality, diversity, and continuity. Despite the existing changes and threats, the elephant population, a migratory animal population increased. The wildlife corridors are important in conservation of regional biological diversity through maintaining the nativeness, pristineness, diversity, and resilience or adaptability of the ecosystems. The policy makers, wildlife managers, local authorities and other conservation bodies and practitioners should develop plans, policies or strategies to sustainably manage and conserve migratory animal biodiversity. Further research should be conducted to establish the functional connectivity of wildlife corridors including trends in their width across the landscape and come up with corridor restoration options. Keywords: Biodiversity, Connectivity, Landscape, Protected areas, Threats, Wildlife DOI: 10.7176/JRDM/87-05 Publication date: September 30 th 2022

Risk Assessment of Environmental Conditions Affecting the Useful Lifetime of Cherenkov Telescopes at El Roque de Los Muchachos Observatory

Construction and operation of ground astrophysical facilities can be affected by adverse weather conditions. Some weather risks are obvious, but still there are times when an unforeseen event distorts the perception of how relevant a climate-related risk is. On the other hand, adverse weather conditions can delay or entirely halt the construction project of an astronomical facility. The impact of weather risks becomes stronger if the facility is built at a site far from urban areas, where maintenance activities and hardware availability become more challenging. This paper aims at proposing a procedure to analyze the impact of environmental risks for an astronomical facility. This procedure is illustrated with a case study: El Roque de Los Muchachos Observatory (ORM). ORM hosts a number of large scale instruments for astrophysics research, which will significantly increase during this decade. We analyze in this paper the environmental conditions affecting the useful lifetime of Cherenkov Telescopes installed at the ORM. After a detailed analysis, we conclude that the risks of strongest magnitude are connected to wild fires. This conclusion diverges from the current risk perception, which is strongly influenced by the recent Cumbre Vieja Eruption event.

Analysis of Wildfire Detection using CNN Model

Abstract: Forest is viewed as one of the most significant and essential asset. It is an enormous surface of region loaded up with trees, bunches of dried leaves, woods, etc. These components support the fire when it begins. The fire can be lighted through many reasons, for example, high temperature in summer seasons, smoking, or firecrackers. When fire begins, it will stay until it recognized totally. The harm and the expense for recognize firein view of wild fire can be decreased when the fire distinguished right on time as could be expected. Thus, the fire discovery is significant in this situation. There are various kinds of fire location techniques utilized by the Government specialists, for example, satellite observing, tower checking, utilizing sensors, optical cameras, etc. In any case, these strategies actually have a few disadvantages in distinguishing the beginning phase of the fire. In our project, we propose an original framework for distinguishing wildfire utilizing Convolutional Neural Networks (CNN). CNN and a classification network, named ResNet50 is used as a feature extraction network to achieve rapid and accurate extraction of image feature information.

Characteristics of humic acids isolated from burned and unburned topsoils in sub-boreal Scotch pine forests by 13C-NMR spectroscopy

Postpyrogenic soil dynamics is an informative tool for studying soil elementary processes in extreme temperature conditions and for predicting short time environmental changes in conditions of catastrophic landscape changes. Soil organic matter (SOM) system evolution is the most rapid process of postpyrogenic soil development. In this relation, the focus on humus structure is important for understanding these important dynamics. Soil restoration after spontaneous forest fires near Togljatty City (Samara Region, Russia) was abandoned in 2010 and further monitoring over the next ten years was organised to evaluate the speed of humus accumulation dynamics. The aim of this study was to apply the 13C-NMR (nuclear magnetic resonance) spectroscopy to analyse the effect of forest fires on SOM degradation in Scotch pine forests on Psamment Entisols of the fragmented steppe in the Samara Region. Three key soil plots were studied for estimating SOM quality changes under the forest fire effect: surface forest fire, crown forest fire and control, i.e. 18 soil samples of top soil horizons were analysed in three replicates. The data obtained indicate that the humus molecular composition was substantially affected by the wildfires. Investigation of the humic acids’ (HAs) molecular structure by 13C-NMR showed a relative increase in aromatic compounds and decrease in aliphatic ones. The aromaticity degree of HA molecules increases in 5.7 and 3.8 times in cases of surface and crown forest fires, correspondingly. In general, crown and surface fires plots are not very different in terms of 13C-NMR spectra of HAs (p = 0.34); however, HAs of control plot have essential differences from pyrogenic ones (p < 0.05). 13C NMR spectra have shown a change in the proportion of oxygen-containing functional groups as well. One of the most important effects observed in wildfire-affected SOM is that the proportion of lignin-like structures increases as a concomitant effect of depletion of C,H-alkyl groups, especially in the case of crown fires.

Record of Middle Jurassic wildfire and its incidental mercury emissions in northern Qaidam Basin, China: Evidence from the inertinite and mercury anomalies in coal

Inertinite in coals contains important information regarding the palaeo-wildfire history and can provide insights into its triggers and relationship with the evolution of local ecosystems. However, such information in the Middle Jurassic coal is often overlooked, and the impacts of incidental mercury emission from wildfires on the mercury enrichment in coal are also underestimation. In this study, the organic petrology, geochemistry and palynology of coal seams from the coal-bearing member of Shimengou Formation in northern Qaidam Basin (NQB) were investigated. Results show that these coal seams generally contain abundant records of palaeo-wildfire: inertinite and combustion-derived polycyclic aromatic hydrocarbons (PAHs). The high consistency of these two evidences confirms the existence of widespread wildfires during the late Middle Jurassic (Bathonian) in NQB. These widespread wildfires also indicate a high level of atmospheric oxygen concentration during this period. The overall low inertinite reflectance (avg. 1.27%) and low content of coronene in coal seams indicate that these wildfires were dominated by ground and surface fire with some small-scale crown fires. These frequent wildfires under the overall humid climate are attributed to the sufficient atmospheric oxygen, fuel and intermittent dry season. The co-occurrence of wildfires records and mercury anomaly in coal seams suggests that incidental mercury emissions from wildfires enhanced mercury input in the peatlands, which is the direct trigger for mercury anomaly in the coal from the Shimengou Formation in NQB. This study not only revealed the characteristics and causes of the widespread wildfires during the late Middle Jurassic in NQB, but also provides a new insight into the abnormal enrichment of mercury in coal.

Widespread wildfires linked to early Albian Ocean Anoxic Event 1b: Evidence from the Fuxin lacustrine basin, NE China

Wildfires are an important source of disturbances in the Earth's system and are of great significance for understanding the interactions between environmental, atmospheric and vegetation changes over deep time. The early Cretaceous was a “high-fire” interval with frequent and widespread wildfires globally, but the timing and global significance of these wildfire events during this time remain uncertain. We undertook a multi-proxy study evaluating kerogen macerals, inertinite reflectance, and polycyclic aromatic hydrocarbons (PAHs) from mudstones to characterize wildfire activity in the Albian coal-forming Fuxin lacustrine Basin, and correlate these with (i) environmental and floral changes on land, and (ii) well-dated marine events including the early Albian Oceanic Anoxic Event 1b (OAE 1b), to consider their environmental and climatic significance. The presence of high inertinite contents demonstrate that multiple, widespread wildfire events occurred during the early Albian, which are correlated stratigraphically to the Kilian, Paquier and Leenhardt sub-events of the early Albian OAE 1b. Inertinite reflectance values ranging from 0.6% to 3.8%Ro show that wildfires in the early Albian were dominated by ground fires, with a smaller proportion of surface fires and almost no crown fires. Atmospheric oxygen concentration (pO2) levels, estimated from inertinite contents, attained ~25% during the early Albian, which exceeded the present atmospheric oxygen level of 21% and was able to support sustained combustion. Climatic conditions and frequent wildfire activity in the early Albian might have acted as an important control on vegetation distribution and diversification, which possibly further promoted the evolution of early angiosperms during the early Cretaceous. Wildfire activity resulted in the burning and destruction of both vegetation and soil structure, enhancing the post-fire erosion associated with intensified continental weathering under warmer and more humid conditions during the early Albian OAE 1b interval. These episodes of high wildfire activity correlate with high nutrients and organic matter levels in lakes and thereby contributed to eutrophication and anoxia in lacustrine and in contemporaneous oceanic systems.