Fire Intensity Research Articles

ОСОБЕННОСТИ ОБЖИГА СОСУДОВ СУРГУТСКОГО ВАРИАНТА КУЛАЙСКОЙ КУЛЬТУРНО-ИСТОРИЧЕСКОЙ ОБЩНОСТИ (ПО ДАННЫМ ТЕРМИЧЕСКОГО АНАЛИЗА)

The Barsova Gora is a unique landscape object where a great number of archaeological sites from the Neolithic to the modern period have been discovered. One of the most studied cultural formations is the Surgut variant of the Kulai cultural-historical community. Pottery firing skills among potters of various archaeological cultures are of particular interest for studying. By the present time on a wide range of archaeological ceramics the thermogravimetric method allowing to receive the data about intensity and quality of firing has been tested. Ceramics from seven sites of Surgut variant of the Kulai cultural-historical community (50 samples in total) served as a source base. According to the results of the ceramics thermogravimetric analysis, all sites can be divided into three groups depending on intensity of firing. Group 1 (two sites) — the pottery of this group was exposed to the most intensive firing compared to the pottery from other sites. This means that the vessels of this group were fired at a higher temperature and/or for a longer time. Group 2 (three sites) — it includes vessels from the sites, which firing intensity is intermediate between the indicators of groups 1 and 3. Group 3 (two sites) — the pottery from the sites of this group has greater porosity, indicating that it was subjected to less intensive firing than the dishes of all other groups. This means that the vessels of this group were fired at a lower temperature than on the other sites and/or for a shorter period of time. The groups highlighted reflect the significant differences between the intensity of firing on different sites. This points to the presence of heterogeneity of firing traditions among the Kulai cultural-historical community potters at different settlements and differentiation of their skills.

Physics-based simulations of grassfire propagation on sloped terrain at field scale: motivations, model reliability, rate of spread and fire intensity†

This study focuses on physics-based modelling of grassfire behaviour over flat and sloped terrains through a set of field-scale simulations performed using the Wildland–urban Interface Fire Dynamics Simulator (WFDS), with varying wind speeds (12.5, 6 and 3 m s−1) and slope angles (−30° to +30°). To ensure the accuracy of this Large Eddy Simulation (LES), a sensitivity study was carried out to select the converged domain and grid sizes. Fire isochrones, locations of fire front, dynamic and quasi-steady rates of spread (RoS), and fire intensity results from the simulations are presented. Within the simulations conducted, the RoS and fire intensity were found to be higher with increasing slope angles, as well as with wind velocity. RoS comparisons are made with various empirical models. At different slope angles and driving wind velocities, different empirical quasi-steady RoS broadly match with particular dynamic maximum, minimum and averaged RoS values from this study. It appears that the ideal nature of grassfire propagation simulation and challenges related to measuring quasi-steady values in experimental studies are likely reasons for the observed differences. Additionally, for lower wind velocities, the RoS–fire intensity relationship (Byram’s) deviates from linearity for greater upslopes.

Cement quality in thermochemical clinker activation

Improving the quality of cement while reducing the energy costs of its production is one of the most important tasks of the cement industry. Cement properties are determined by the hydration activity of clinker minerals. In turn, the activity of clinker minerals is determined by the degree of disorderliness of the crystal cell. The disorder of the crystal cell depends on the chemical composition of minerals, the type and concentration of modifying additives. It also depends on the modes of clinker synthesis, both during firing and cooling. An effective way of activating clinker minerals is intensive firing of the components of the raw mixture. This method can be carried out by thermal activation of calcium oxide, as well as by bilateral introduction in different zones of the rotary kiln of polycomponent waste of chemical and metallurgical industries The composition and morphology of the main mineral of Portland cement clinker, alite, have been studied by methods of physical and chemical analysis. It was found that the crystals being formed are characterized by a nonstoichiometric composition. Their rapid growth is accompanied by intensive introduction of impurity elements into the crystal cell of the mineral. The hydration activity of clinkers of conventional and intensive firing has been determined. An increase in the rate of hydration of intensive firing clinkers has been established, which leads to an increase in the strength characteristics of cement by 7-10 MPa.

林火干扰对广东木荷林生态系统碳库的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 林火干扰对广东木荷林生态系统碳库的影响 DOI: 10.5846/stxb202004240980 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研发计划重点专项(2018YFE0207800);广东省自然科学基金项目(2021A1515010946);广东省林业科技创新项目(2020KJCX003);广西自然科学基金项目(2014GXNSFBA118108) Effects of forest fire disturbance on carbon pools of Schima superba forest ecosystem in Guangdong Province Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:森林碳库在调节CO2浓度及减缓温室效应中发挥重要作用。选择广东木荷林为研究对象,通过相邻样地法,进行植被生物量、凋落物生物量和土壤样品的采样与分析,研究不同林火干扰强度对生态系统各碳库(植被、凋落物和土壤有机碳)及生态系统碳库产生的变化规律和空间分布格局及其影响因素。结果表明:(1)植被碳密度随着林火干扰强度增强而减少,但不同组分的植被碳密度表现不同,乔木碳密度在不同林火干扰强度下变化与植被碳密度变化一致,而草本碳密度则呈现相反的变化趋势。相同林火干扰强度下,植被各组分碳密度均以乔木层降低幅度最大。林火干扰均显著降低了凋落物碳密度(P<0.05),并随林火干扰强度的增加其降低幅度增大,但不同林火干扰强度对凋落物碳密度的影响有所差异。林火干扰降低了土壤有机碳密度,且降低幅度随土层深度增加而逐渐变小。(2)林火干扰有效改变了生态系统碳库的空间分布格局。对照样地木荷林土壤有机碳库占比为61.59%,重度林火干扰后,土壤有机碳库占比为70.96%呈上升趋势,占生态系统碳库的优势地位,而植被和凋落物碳库占比呈下降趋势,处于生态系统碳库的次要地位。(3)双因素方差分析表明,林火干扰强度和土层深度及其交互作用均对土壤有机碳密度有显著影响。林火干扰强度解释了土壤有机碳密度变异的8.78%,土层深度解释了土壤有机碳密度变异的70.29%,林火干扰强度和土层深度之间的交互作用解释了土壤有机碳密度变异的8.16%。研究发现:林火干扰降低了生态系统碳库,且随林火干扰强度增加,生态系统碳库减少幅度增大。轻度林火干扰对森林生态系统碳库的影响差异不显著,而中度和重度林火干扰对森林生态系统碳库的影响差异显著。研究结果对深化亚热带森林固碳效应的影响机制提供理论支撑。 Abstract:Forest carbon pools play an important role in regulating CO2 concentration and mitigating the greenhouse effect. In this study, the Schima superba forest in Guangdong was selected as the research object. Through the adjacent plot method, the sampling and analysis of vegetation biomass, litter biomass and soil samples were conducted to study the impact of different forest fire disturbance intensities on the various carbon pools (vegetation, vegetation, litter and soil organic carbon) and the change law and spatial distribution pattern of ecosystem carbon pool and its influencing factors. The results showed that the vegetation carbon density decreased with the increase of forest fire disturbance intensity, but the vegetation carbon densities of different components were different. The change of tree carbon density under different forest fire disturbance intensities was consistent with the change of vegetation carbon density. The carbon density showed the opposite trend. Under the same fire disturbance intensity, the arbor layer had the largest decrease in the carbon density of each component of vegetation. The forest fire disturbance significantly reduced the litter carbon density (P<0.05), and the decrease range increased with the increase of the forest fire disturbance intensity, but the effects of different forest fire disturbance intensities on the litter carbon density were different. The forest fire disturbance reduced soil organic carbon density, and the reduction range gradually became smaller with the increase of soil depth. Forest fire disturbance has effectively changed the spatial distribution pattern of the ecosystem carbon pool. The proportion of soil organic carbon reservoir in the control plot was 61.59%. After severe forest fire disturbance, the proportion of soil organic carbon pool was 70.96%, showing an upward trend, accounting for the dominant position of ecosystem carbon pool, while the proportion of vegetation and litter carbon pool showed a downward trend, which was in the secondary position of ecosystem carbon pool. ANOVA showed that the intensity of forest fire disturbance and the depth of soil layer and its interaction had a significant impact on soil organic carbon density. The intensity of forest fire interference explained 8.78% of the soil organic carbon density variation, the soil layer depth explained 70.29% of the soil organic carbon density variation, and the interaction between the forest fire interference intensity and the soil layer depth explained 8.16% of the soil organic carbon density variation. The study found that forest fire disturbance reduced the ecosystem carbon pool, and as the intensity of forest fire disturbance increased, the reduction in ecosystem carbon pool increased. The impact of low forest fire disturbance on forest ecosystem carbon pool was not significant, while the impact of moderate and high forest fire disturbance on forest ecosystem carbon pool was significant. The research results provide theoretical support for the impact mechanism of deepening the carbon sequestration effect of subtropical forests. 参考文献 相似文献 引证文献

On the interaction of wind, fire intensity and downslope terrain with implications for building standards in wildfire-prone areas

Background Wildfires can have detrimental impacts on the environment and urban structures when they spread from wildland areas. Aims In this work, a numerical study was performed to investigate the effect of downslope terrain on fire-induced flows in the presence of a building structure. Fires with intensities of 4 and 15 MW m−1 were considered on inclined terrain with downslope angles varying from 0° to −30°, and wind speeds of 6 and 12 m s−1. Methods Simulations were conducted using a large eddy simulation (LES) solver, implemented in the open-source platform FireFOAM. Key results The results were validated with experimental measurements of a full-scale building model. Results show that at a wind velocity of 12 m s−1, structures on steeper downslope terrains are at higher risk of wildfire damage, whereas at a constant wind velocity of 6 m s−1, these structures are at a lower risk. Conclusions The outcomes of the study highlight the physical effect of sloped terrain on buildings downwind of a line fire. Implications The results from this study can be used to evaluate the validity of risk management measures including building standards and asset protection zones and can better inform ways of improving these measures.

Fire whirls induced by a line fire on a windward slope: a laboratory-scale study

Background Fire whirls are often reported to occur in wildland fires and can induce serious difficulties in firefighting by abruptly modifying fire behaviour, exposing firefighters and even causing casualties. Aims The aim of this study was to examine the formation of fire whirls on a windward slope. Methods Straight and V-shaped heated wires and burners were used to emulate fire spread fronts of various fire intensities. Different slope angles and ambient wind speeds were considered, to observe the formation and behaviour of fire whirls. Key results A fire whirl appeared over a straight-line fire in the presence of wind, and a couple of counter-rotating fire whirls appeared over the two flanks of a V-shaped line fire. Conclusions Two interaction regimes were experimentally observed and theoretically explained for the interaction of two fire whirls. We found that an effective wind speed instead of the local wind speed in sloped terrains can quantify the critical condition for the formation of fire whirls over line fires of different burning intensities. Implication A critical effective wind speed correlation that couples slope angle, burning intensity and radiative fraction of a line fire can predict fire whirl risk in wildland fire fighting.

Fire in the bog: responses of peatland vegetation in the Australian Alps to fire

Context Peatlands in the Australian Alps are important ecologically and recognised in national environmental legislation. Increasing fire frequency over the past 40years has put the community at greater risk of degradation.Aims Using published studies of fire effects in peatlands and new data, we investigate general responses of peatlands to fire so that risk can be evaluated and appropriate management adopted.Methods We present four case studies that employ repeated measures of floristic composition or chronosequences to assess fire-related changes.Key results Cover of frequently-occurring species declined after fire but most had returned to pre-fire cover after 10years. Recovery of the obligate seeder shrub Dracophyllum continentis (B.L.Burtt) S.Venter and the dominant moss Sphagnum cristatum Hampe was much slower, but variable for the latter, apparently depending on fire intensity and post-fire moisture availability; both species favoured less frequently burnt peatlands with high soil moisture. Some herbs (including non-native species) benefitted from fire, briefly becoming abundant soon afterwards. Overall species richness and diversity were unaffected by fire.Conclusions Peatlands in the Australian Alps tend to be resilient to single fires with effects on species composition being short-lived. However, species cover (especially Sphagnum cristatum) requires perhaps 20years between fires for full recovery. Fire can cause localised community extinction and this is likely to be exacerbated by other pressures such as trampling and drought.Implications Fire will be difficult to manage in peatlands but resilience might be built by removing other pressures such as trampling by feral animals.

Application of FY-4B Geostationary Meteorological Satellite in Grassland Fire Dynamic Monitoring

In this study, the channel data related to fire point identification of Advanced Geostationary Radiation Imager on Fengyun-4B (FY-4B/AGRI) and Advanced Meteorological Imager on GEO-KOMPSAT 2A (GK-2A/AMI) were cross-compared. A total of 267 sampling points in China (Guangdong, Guangxi, Guizhou, Yunnan, Hainan) were selected to carry out fine positioning correction on the data in different elevation intervals. Then, a fire monitoring algorithm based on FY-4B was proposed, in which the self-adaptive threshold adjustment of the underlying surface parameters and the reprocessing module of fire point identification were added. The algorithm can realize the high-precision and stable monitoring of fire. The continuous dynamic monitoring was carried out using the grassland fire Mongolia from April 18 to 20, 2022 as an example. The results showed that the parameters of FY-4B/AGRI and GK2A/AMI channels have high consistency. The root mean square error (RMSE) of reflection channel was 1.33%, and the maximum RMSE of brightness temperature channel was less than 1.3 Kelvin (K). Through the positioning analysis in different elevation intervals, the average longitude offset of FY-4B satellite data was -0.5°–0° and the average latitude offset was -0.9°–0.6°. Overall, these findings indicate that the high-frequency observations of FY-4B can be fully utilized to monitor forest and grassland fires, which can continuously track the dynamic evolution of fire and can distinguish the spatial distribution of different fire intensities in large-scale fire field.

Nature inspired firefighter assistant by unmanned aerial vehicle (UAV) data

One of the most hazardous phenomena in forests is wildfire or bush fire and early detection of massive damage prevention is vital. Employing Unmanned Aerial Vehicles (UAV) as a visual and extinguisher tool in order to prevent this tragedy which brings fatal effects on humans and wildlife has high importance. Additionally, using aerial imagery could assist firefighters to recognize fire intensity and localize and route the fire in the forest which shrinks down casualties of firefighters. All these benefits and more is just possible by employing cheap UAVs. The proposed research uses nature-inspired image processing techniques in order to segment and classify fire in color and thermal images. Multiple nature-inspired and traditional computer vision techniques, including Chicken Swarm Algorithm (CSA) intensity adjustment (contrast enhancement), Denoising Convolutional Neural Network (DnCNN), Local Phase Quantization (LPQ) feature extraction, Bees Image Segmentation, Biogeography-Based Optimization (BBO) feature selection, Firefly Algorithm (FA) classification and more are employed to achieve high classification and segmentation accuracy. The system evaluates nine performance metrics including, F-Score, Accuracy, and Jaccard for the segmentation stage and four performance metrics for the classification stage. All experiments are conducted on the two most recent UAV fire datasets of FLAME (2021) and DeepFire (2022). Additionally, fire intensity, fire direction, and fire geometrical calculation are calculated which assists firefighters even more. As smoke shows the location of the fire, a smoke detection workflow is proposed, too. Proposed system Compared with traditional and novel methods for segmentation and classification leading to satisfactory and promising results for almost all metrics. The trained model of this system could be used in most of the current rescue UAVs in real-time applications. For the FLAME dataset (color data), segmentation precision is 95.57 % and classification accuracy is 91.33 %. Also, For the DeepFire dataset segmentation precision is 91.74 % and classification accuracy is 96.88 %.

Simulated behaviour of wildland fire spreading through idealised heterogeneous fuels

Homogeneous vegetation is widely used in wildland fire behaviour models, although real vegetation is heterogeneous in nature and composed of different kinds of fuels and non-combustible parts. Many features of fires can arise from this heterogeneity. For land management and firefighting, creating heterogeneous fuel areas may be useful to reduce fire intensity and rate of spread (ROS), and alter fire geometry. Recently, an empirical model for fire spread in spinifex grasslands was developed and validated against experimental measurements. In this study, physics-based grassland fire behaviour simulations were conducted with varying percentages of fuel cover and alternating square and rectangular patches of burnable and non-burnable material. The environmental conditions and thermophysical properties of the grassland were kept constant throughout the simulation to separate the effects of fuel heterogeneities from other parameters. For three sets of nominal wind velocities, 3, 5.6 and 10 m s−1, we identified ‘go’ and ‘no go’ fires. Reasonable agreement between the non-dimensionalised simulated ROS and observed ROS in spinifex was found. There is a significant reduction of fire intensity, ROS, flame length, fire width and fire line length due to the heterogeneous effect of vegetation.

Dispersal Limitation Dominates the Spatial Distribution of Forest Fuel Loads in Chongqing, China

The forest fuel load influences the spreading rate and fire intensity during a forest fire. However, the mechanism of environmental filtering and dispersal limitation that affects the spatial distribution of the forest fuel load remains unclear. In this study, live (tree, herbaceous, and shrub) and dead fuel loads (litter and humus) were estimated based on the plot investigation results of 4 typical stands ( Pinus massoniana , Platycladus orientalis , Ficus microcarpa , and Cinnamomum camphora ) in Chongqing, China. The results demonstrated that the tree, shrub, herbaceous, litter, and humus fuel loads of the 4 typical stands were 66.92 to 118.54 Mg/ha, 2.93 to 4.04 Mg/ha, 0.77 to 1.01 Mg/ha, 0.90 to 1.39 Mg/ha, and 1.49 to 1.98 Mg/ha, respectively. The forest fuel load varied significantly among the different stands. The Mantel test revealed that the forest fuel load had significantly positive correlations with the geospatial distance and stand environment but no significant correlation with the topographic factor. Additionally, the redundancy analysis demonstrated that the stand factors, canopy density and average canopy height, and the topographic factor, altitude, had significant impacts on the forest fuel load. The variance partitioning analysis revealed that the spatial heterogeneity of the forest fuel load was mainly attributed to the covariation of environmental and spatial factors (29.55%). Moreover, the geospatial distance was a dominant independent factor for the fuel distribution (14.66%), followed by the stand environment (9.51%) and topographic factor (0.35%). In summary, the spatial distribution of the forest fuel load was dependent on niche-based and random processes, and dispersal limitation was the dominant factor.

The role of helicity and fire–atmosphere turbulent energy transport in potential wildfire behaviour

Background Understanding near-surface fire–atmosphere interactions at turbulence scale is fundamental for predicting fire spread behaviour. Aims This study aims to investigate the fire–atmosphere interaction and the accompanying energy transport processes within the convective boundary layer. Methods Three groups of large eddy simulations representing common ranges of convective boundary layer conditions and fire intensities were used to examine how ambient buoyancy-induced atmospheric turbulence impacts fire region energy transport. Key results In a relatively weak convective boundary layer, the fire-induced buoyancy force could impose substantial changes to the near-surface atmospheric turbulence and cause an anticorrelation of the helicity between the ambient atmosphere and the fire-induced flow. Fire-induced impact became much smaller in a stronger convective environment, with ambient atmospheric flow maintaining coherent structures across the fire heating region. A high-efficiency heat transport zone above the fire line was found in all fire cases. The work also found counter-gradient transport zones of both momentum and heat in fire cases in the weak convective boundary layer group. Conclusions We conclude that fire region energy transport can be affected by convective boundary layer conditions. Implications Ambient atmospheric turbulence can impact fire behaviour through the energy transport process. The counter-gradient transport might also indicate the existence of strong buoyancy-induced mixing processes.

PMU-Driven Non-Preemptive Disconnection of Overhead Lines at the Approach or Break-Out of Forest Fires

The number and intensity of forest fires in the United States have been steadily increasing and causing massive economic and ecological damage. Overhead transmission and distribution lines are typically disconnected preemptively near fires, a practice that causes high social cost. Deployment of Phasor Measurement Units (PMUs) and their ability for synchronized real-time measurement of voltage and current inspire the here proposed method for the just-in-time disconnection of overhead lines at the ignition or approach of fires. PMUs can detect ambient temperature changes caused by fires through the change of line resistance. An ambient temperature model at the vicinity of a fire seat and the dynamic heat exchange model of the IEEE 738 dynamic line rating standard for bare overhead conductors are used in MATLAB Simulink to assess the performance of the proposed control method. Extensive testing shows that, under various conditions, the proposed technique can detect a forest fire approaching an overhead line, while avoiding, almost completely, any false alarms.

Community Capacity and Resilience in Facing The Threat of Fire Disaster (Case Study: Barrang Lompo Island, Makassar City)

This research is based on the high intensity of fires in dense residential areas of Makassar City, which is caused by high vulnerability to fire and low community capacity and resilience. Barrang Lompo Island is an area with a fairly high population and density of buildings. So that the potential of fires is also likely to occur on Barrang Lompo. This study aimed to identify the level of community capacity and resilience using a community capital framework approach. The capacity stage analysis is carried out by converting qualitative data into a capacity assessment scale. Then, using expert opinion to assess the value of each variable using AHP method. Furthermore, classifying the level of Community capacity is classified using the scoring method. The results show that community capacity are classified as moderate to high, with a score of 1.89-2.31. In general, the capacity and resilience of fire, including individual capabilities, social capital, local culture, natural and physical capital, are moderate to high. Meanwhile, policy and financial aspects are quite low. In conclusion, to improve community resilience, it is recommended to improve individual preparedness through education, create a small island fire management policy, provide emergency transport and improve the local economy.

Wildfire hazard mapping in the eastern Mediterranean landscape

Background Wildfires are a growing threat to many ecosystems, bringing devastation to human safety and health, infrastructure, the environment and wildlife. Aims A thorough understanding of the characteristics determining the susceptibility of an area to wildfires is crucial to prevention and management activities. The work focused on a case study of 13 countries in the eastern Mediterranean and southern Black Sea basins. Methods A data-driven approach was implemented where a decade of past wildfires was linked to geoclimatic and anthropic descriptors via a machine learning classification technique (Random Forest). Empirical classification of fuel allowed linking of fire intensity and hazard to environmental drivers. Key results Wildfire susceptibility, intensity and hazard were obtained for the study area. For the first time, the methodology is applied at a supranational scale characterised by a diverse climate and vegetation landscape, relying on open data. Conclusions This approach successfully allowed identification of the main wildfire drivers and led to identification of areas that are more susceptible to impactful wildfire events. Implications This work demonstrated the feasibility of the proposed framework and settled the basis for its scalability at a supranational level.

Interval Type-2 Fuzzy Model for Intelligent Fire Intensity Detection Algorithm with Decision Making in Low-Power Devices

Interval Type-2 Fuzzy Model for Intelligent Fire Intensity Detection Algorithm with Decision Making in Low-Power Devices

Drivers of wildfire burn severity in the montane rainforests of northern Vietnam

Background Fire impacts and drivers of wildfire burn severity remain poorly understood for tropical forests. Aims To assess variation and environmental drivers of burn severity for nine forest fires in northern Vietnam. Methods Burn severity was estimated from satellite image analyses, and associations with a remotely sensed index of annual fuel production, topographic factors (elevation, slope, aspect) and weather variables (temperature, rainfall, relative humidity, wind speed) were evaluated. Key results High severity burn areas were found to be fairly uncommon and were associated with steeper, south-west facing slopes, higher elevations and lower fuel abundance. There was a weak tendency for higher burn severity on days with lower relative humidity. Conclusions Conditions that increase fire intensity and the dryness and flammability of fuels are important contributors to high severity fires in wet tropical systems. However, the pattern of higher burn severity at high elevation, where forests tend to be denser and more humid, is counter to this interpretation and may be due to species compositional changes and greater vulnerability of high-elevation forests to fire impacts. Implications Better understanding of fire risk and where in the montane forests of northern Vietnam fires are most likely to burn at high severity will assist forest fire management and recovery strategies.

The response of Nassella trichotoma (serrated tussock) seeds and seedlings to different levels of fire intensity

Context Fire is an important disturbance regime in grassland communities, since it is responsible for stimulating the regeneration of many species and for maintaining levels of biodiversity. When invasive plants, such as Nassella trichotoma, establish and become widespread in a grassland community, these important fire events can be altered in intensity and frequency, which means that they are able to facilitate the establishment of the exotic species. Therefore, before fire can be recommended as a suitable control technique for invasive species, or alternatively to be integrated into grassland restoration programs, understanding the response of the seeds of exotic species to high temperatures, such as those experienced during a fire, should be well understood. Aims Our aim was to identify their response to a gradient of temperatures associated with different levels of fire intensity. We examined how increased duration of exposure affects their response, and whether seed age or seed moisture content affect the germination response of this species. Methods To gain a fuller understanding of the fire response of N. trichotoma’s seedbank, seeds were collected in 2016, 2017, 2018 and 2019 and then stored until the commencement of the experiments in 2020. Selected seeds were first subjected to an increasing temperature gradient (80°C, 100°C, 120°C, 140°C, and a control), and an increasing duration of exposure (of 1, 3, 6, and 9 min). In the second experiment, one population was selected to test these same temperatures and duration of exposure after the seeds were hydrated to 15%, 50%, or 95%. Last, seedlings were grown for 3 months under glasshouse conditions and then exposed to increasing temperatures (20°C, 60°C, 80°C, 100°C, and 120°C), and an increasing duration of exposure (3, 6, and 9 min). The seedlings were assessed 2 weeks after the heat exposure for signs of damage. Key results It was found that increased temperatures and duration of exposure had a subtle negative effect on germination parameters, including reduced total germination and increased time to 50% germination. The 140°C treatment was seen to be a significant threshold because it killed all the seeds at any duration of exposure. A significant difference among the ages of each seed lot was observed to be a factor on the tested germination metrics, with the oldest tested population (2016) demonstrating the highest germination percentage, uniformity, and rate. Seed germination percentage was significantly reduced for seeds hydrated to 95% compared with the control treatment, whereas no significant difference was observed for the seeds hydrated to 15% and 50%. For the heat treatment of the seedlings, damage to the leaves was observed in the 80°C, 100°C, and 120°C treatments, with some plants in the 120°C treatment experiencing extensive damage prior to resprouting. No seedlings were killed at the tested temperatures. Conclusions Results of this study indicated that fire may be a useful tool for reducing seedbank density by killing a high proportion of the seeds on the soil surface, or located within the top 1 cm of the soil profile, but not for seeds buried more deeply. Efficacy of fire on surface and shallow-buried seeds is improved with high seed moisture content; however, these seeds buried below this depth are still protected by the soil from the lethal effects of temperature. Implications Fire implemented before seed set could be used to effectively kill a large proportion of N. trichotoma seeds. However, for more comprehensive control, it is recommended that chemical treatment is integrated with the fire treatment to improve the overall control efficiency.

Fractal analysis revealed persistent correlations in long-term vegetation fire data in most South and Southeast Asian countries

Vegetation fires are most common in South/Southeast Asian countries (S/SEA). Characterizing the statistical nature of long-term fire datasets can provide valuable information on fire management. Specifically, distinguishing random noise from correlated noise in long-term signals is critical for linking with the underlying processes. Fractal methods can help to assess long-range correlations in long-term timeseries data. This study tested the daily time-series fire data retrieved from the VIIRS satellite (2012–2021) for fractal behavior. Descriptive statistics and popular Detrended Fluctuation Analysis (DFA) were used to assess fire characteristics and persistent versus non-persistent correlations. Results over South Asia (SA) suggested India with the highest mean fire counts (FC) and the least in Bhutan. Fire radiative power (FRP), an indicator of fire intensity, was highest in India and least in Afghanistan. Among Southeast Asia (SEA), Myanmar had the highest mean FC and FRP and least in Timor Leste. The DFA results revealed the fractal nature of FC in different countries. In SA, FC over India, Nepal, Sri Lanka, Afghanistan, and Bhutan showed persistent correlation behavior, whereas anti-persistence in Bangladesh and Pakistan. In addition, FRP showed anti-persistent behavior in Afghanistan, Bangladesh, and Pakistan and a persistent signal for Bhutan, India, Sri Lanka, and Nepal. In contrast to SA, FC and FRP showed persistent behavior in all SEA countries. The persistent or non-persistence nature of the data can help model fire behavior to aid in management and mitigation efforts.

Effects of late-Holocene fires on the carbon sequestration capacity of peatlands in the Sanjiang Plain

Peatland fires are frequent, but the effect of fire on soil organic carbon in peatlands is still currently variable. Especially at long time scales, it has not been clarified. In order to reveal the relationship between carbon accumulation patterns in peatlands at long time scales in response to local fire changes, high-resolution peat sediments from peatlands in the Three River Plain were selected and analysed for stratified charcoal debris and organic carbon in this paper. The results showed that the stronger carbon sequestration capacity in the periods of 0.6, 0.75, 1.25, 2.3, 2.75, 2.9, 3.6 and 5 ka BP corresponded to weaker fire intensity or even no fire. Late-Holocene fires in the Sanjiang Plain reduced the rate of carbon sequestration, suggesting that fires have been an important driver of the reduction in carbon sequestration capacity over the last 6000 years.