Influence Of Forest Fires Research Articles

Spatiotemporal variation of polycyclic aromatic hydrocarbons in Tibetan lake sediment cores reveals the influence of forest fires

Despite declining anthropogenic emissions of polycyclic aromatic hydrocarbons (PAHs) due to global control strategies, forest fire emissions have been increasing, significantly affecting PAH dynamics in global sinks. This study investigated the spatiotemporal variations of sedimentary PAHs in three Tibetan lakes—Yiong Tso, Yamdrok Yumtso, and Urru Tso—to determine the influence of forest fires on PAH levels and historical trends. Yiong Tso Lake, located in a fire-affected watershed, exhibited the highest PAH concentrations (average of 43.4 ± 25.7 ng/g) with significant fluctuations since the 1920s, peaking in the 1960s (46.3 ng/g) and 1980s (91.3 ng/g), corresponding to periods of intense forest fires. This pattern aligned with source contribution estimates using the modified Cohen's d (mcd), indicating the dominance of forest fires as a PAH source until the 1990s. PAH concentrations decreased with increasing distance from the southeastern Tibetan Forest, as observed in Yamdrok Yumtso (average of 36.1 ± 19.9 ng/g) and Urru Tso (average of 16.4 ± 6.9 ng/g). Temporal variations in PAH concentrations and mcd values from these lakes also reflected a response to forest fires during the 1960s, suggesting a widespread influence of forest-fire-derived PAHs across the plateau. The impact of forest fires on sedimentary PAHs was expected to persist for decades, with an estimated half-life of approximately 11–12 years. These findings highlight significant emissions of PAHs from forest fires in the Tibetan Plateau, potentially transforming regional PAH dynamics and influencing global cycling.

Analysis of PM2.5 Concentration Released from Forest Combustion in Liangshui National Natural Reserve, China

(1) Background: In recent years, forest fires have become increasingly frequent both domestically and internationally. The pollutants emitted from the burning of fuel have exerted considerable environmental stress. To investigate the influence of forest fires on the atmospheric environment, it is crucial to analyze the variations in PM2.5 emissions from various forest fuels under differing fire conditions. This assessment is essential for evaluating the effects on both the atmospheric environment and human health. (2) Methods: Indoor simulated combustion experiments were conducted on the branches, leaves, and bark of typical tree species in the Liangshui National Natural Reserve, including Pinus koraiensis (PK), Larix gmelinii (LG), Picea koraiensis (PAK), Betula platyphylla (BP), Fraxinus mandshurica (FM), and Populus davidiana (PD). The PM2.5 concentrations emitted by six tree species under various combustion states were measured and analyzed, reflecting the impact of moisture content on the emission of pollutants from fuel combustion, as indicated by the emission factors for pollutants. (3) Results: Under different fuel loading and moisture content conditions, the mass concentration values of PM2.5 emitted from the combustion of different organs of various tree species exhibit variability. (4) Conclusions: Among the various tree species, broad-leaved varieties release a greater quantity of PM2.5 compared to coniferous ones. A positive correlation exists between the moisture content of the fuel and the concentration of PM2.5; changes in moisture content notably influence PM2.5 levels. The emission of PM2.5 from fuel with varying loads increases exponentially. Utilizing the Response Surface Methodology (RSM) model for simulation, it was determined that both moisture content and fuel load exert a significant combined effect on the release of PM2.5 during combustion.

Serra da Canastra National Park: Influence of forest fires on the RUSLE C factor and its impact on water erosion

The adverse impacts of soil degradation and nutrient loss resulting from water erosion are significant environmental concerns that have profound implications for both water quality and biodiversity. This study aims to evaluate the impact of forest fires on soil loss through water erosion in the Serra da Canastra National Park, in Minas Gerais state, Brazil. Using the Revised Universal Soil Loss Equation (RUSLE), which considers rainfall erosivity, soil erodibility, slope length and slope and vegetation cover, the C factor (vegetation cover) values were obtained from data from literature and methods based on the Normalized Differential Vegetation Index (NDVI). Validation was carried out using data on total sediment, water flow and daily runoff from the hydrosedimentological station and the InVEST software. The results highlight the significant impact of wildfires on soil loss through water erosion and indicate that areas recently affected by wildfires, especially on steep slopes and with more erodible soils, are subject to the highest rates of soil loss. Soil loss rates varied from 0.75 to 12.55 Mg ha-1 yr-1, in part due to the different ways of obtaining factor C. The research emphasizes the need to conserve vegetation cover to prevent soil erosion, particularly in regions impacted by forest fires. This study offers valuable insights that can contribute to enhancing the sustainable environmental management of the Serra da Canastra National Park.

THE IMPACT OF FOREST FIRES ON THE SOIL COVER IN THE CONDITIONS OF THE KUYAR FORESTRY OF THE REPUBLIC OF MARI EL

The influence of forest fires on the physico-chemical properties of sandy soils formed under pine plantations of the southern Taiga subzone in the conditions of the Republic of Mari El is shown. As a result of investigations of 4 soil sections, including 1 control and analysis of about 30 soil samples, soil parameters with the greatest and least variability were revealed. It was found that only the forest floor, which burned completely, with the formation of a specific Opir horizon, was exposed to a low forest fire, the upper mineral horizons have no signs of pyrogenicity. It was found that in the first post-fire year, the acidity in the upper soil horizons slightly increases compared to the control site, along with this, there is an increase in the amount of exchange bases and the degree of saturation with bases, the content of exchangeable potassium and loss indicators during calcination sharply decreases in forest litter. Regression equations are constructed on the basis of the revealed close relationships. It is concluded that, despite the absence of pyrogenic signs in the upper mineral horizons, their properties also change significantly under the influence of the combustion products embedded here together with the soil solution. To detail the data on the functioning of post-pyrogenic ecosystems, a long period of observations and scientific research is necessary.

Fire-Induced Alterations of Soil Properties in Albic Podzols Developed under Pine Forests (Middle Taiga, Krasnoyarsky Kray)

Fires are one of the most widespread factors of changes in the ecosystems of boreal forests. The paper presents the results of a study of the morphological and physicochemical properties and soil organic matter (SOM) of Albic Podzols under pine forests (Pinus sylvestris L.) of the middle taiga zone of Siberia (Krasnoyrsky kray) with various time passed after a surface fire (from 1 to 121 years ago). The influence of forest fires in the early years on the chemical properties of Albic Podzols includes a decrease in acidity, a decrease in the content of water-soluble compounds of carbon and nitrogen and an increase in the content of light polycyclic aromatic hydrocarbons (PAHs) in organic and upper mineral horizons. Podzols of pine forests that were affected by fires more than forty-five years ago are close to manure forest soils according to most physical and chemical properties. Significant correlations were found between the thickness (r = 0.75, p < 0.05), the moisture content (r = 0.90, p < 0.05) of organic horizons and the content of ∑PAHs in the organic horizon (r = −0.71, p < 0.05) with the time elapsed after the fire (i.e., from 1 to 121 years). The index of the age of pyrogenic activity (IPA) calculated as the ratio of ∑ PAHs content in the organic horizon to ∑ PAHs at the upper mineral horizon is significantly higher in forests affected by fires from 1 to 23 years than for plots with «older» fires (45–121 years). Thus, the article presents the conserved and most changing factors under the impact of fires in the boreal forests of Russia.

Wildfire Effects on Cryosols in Central Yakutia Region, Russia

Forest fires are one of the most significant types of disturbance on a global scale, affecting biodiversity and biogeochemical cycles and playing an important role in atmospheric chemistry and the global carbon cycle. According to a remote monitoring information system, forest fires in Yakutia were the largest wildfires in the world in 2021. In this regard, mature pale-yellow soils unaffected by fire were investigated in comparison with the same soils that were strongly affected by surface fire in 2021 in the area surrounding Yakutsk, Yakutia region. Data obtained showed an intensive morphological transformation of the topsoil layers, increase of total organic matter and slight increase of pH, and apparent decrease of basal respiration and content of microbial biomass. A slight accumulation of Zn and Ni in soils due to wildfires was recorded, as well as alteration in the distributions of heavy metals in the soil profile. Moreover, an electric resistivity study was carried out during field studies. An influence of forest fire on the electrical resistivity value was not reliably found, but the vertical electrical resistivity sounding provided precise data regarding the degree of soil-permafrost layer homogeneity and/or heterogeneity.

Research progress on the influence of forest fire on the eco-stoichiometric characteristics of carbon, nitrogen and phosphorus in forest ecosystem

Forest fire can change the eco-stoichiometric characteristics of forest ecosystem elements, reflect the biogeochemical cycle change mode of forest ecosystem environment after fire, and clarify the eco-stoichiometric characteristics of carbon (C), nitrogen (N), phosphorus (P) in forest ecosystem under forest fire disturbance, which is very important for understanding the response mechanism of forest ecosystem to forest fire disturbance. By consulting a large number of relevant literatures, the author summarized and analyzed the impact mode of forest fire disturbance on the C–N–P eco-stoichiometric characteristics of forest ecosystem, as well as the impact of forest fire disturbance on the C–N–P eco-stoichiometric characteristics of plants, C–N–P eco-stoichiometric characteristics of litter, and C–N–P eco-stoichiometric characteristics of soil. It is considered that the C–N–P eco-stoichiometric characteristics of forest ecosystem are mainly affected by fire factors (fire intensity, fire frequency, recovery time after fire), vegetation types and soil properties. In view of the scientific problems that forest fire urgently needs to be solved in the study of forest ecosystem eco-stoichiometry, three aspects: the impact mechanism of forest fire disturbance on the homeostasis of plant eco-stoichiometry, the study of multi-element eco-stoichiometry under forest fire disturbance, the establishment of the eco-chemometrics relationship of the plant–litter–soil composite system under the interference of forest fire are proposed, in order to deeply understand the plant regulation strategy under the interference of forest fire, clarify the mutual coupling mechanism between multiple chemical elements after the interference of forest fire, and improve the relationship between the input and output of aboveground and underground nutrients with the plant–litter–soil as a composite whole, which is of great significance for a deep understanding of the nutrient cycle and balance of the forest ecosystem under the background of global climate change, and reasonable formulation of forest fire management measures.

Forest fires and impacts of COVID-19 lockdowns on air quality in four Latin American megacities

Latin America, as other regions in the world, imposed mobility restrictions to tackle the COVID-19 pandemic. Although recent research has analyzed the effect of mobility restrictions on air quality in several regions, a scarce literature explores the causal effects of the lockdowns in Latin America at a city scale whose results may guide local policymaking. This article, based on a quasi-experimental approach, estimates the causal short-term impacts of lockdowns on air quality considering the influence of forest fires on pollution in four megacities in Latin America (Bogotá, Mexico City, Santiago, and Sao Paulo). Results show that nitrogen oxides and carbon monoxide consistently declined (from 16% to 68%), nevertheless, fine particles rarely decreased across cities. Only Bogotá exhibited an overall reduction in fine particles (45% for PM2.5). Mexico City obtained the lowest reduction in pollutants, whereas Bogotá outperformed other cities in several pollutants. Evidence from mobility statistics supports the decrease in air pollution by a reduction in driving, transit use, and other mobility indicators.

Forest Fire in the Hindu Kush Himalayas: A Major Challenge for Climate Action

Forest fire has been one of the compelling issues in the Hindu Kush Himalayan (HKH) region. To promote regeneration, clearing fields for agriculture, hunting, and security reasons, local people deliberately set forests on fire. In this paper, active fire incidents, temperature, precipitation, and the changes of Aerosol Optical Depth (AOD) and Carbon monoxide (CO) value associated with forest fire were evaluated. The active forest fire incidents obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite are supplemented by the ERA5-land dataset to see the relation between precipitation and temperature with forest fires. MODIS and Tropospheric Monitoring Instrument (TROPOMI) sensor datasets were used to see the changes in AOD and CO in the region. MODIS sensor detected more than 30,462 active fires incidents in March and April 2021 in the study areas. Shan State of Myanmar recorded the maximum number of active fire incidents which is due to the practice of shifting cultivation and minimum in Bhutan due to the awareness campaigns and technology improvement. The temperature recorded in the study sites shows an increasing trend as compared to the reference period (2010-2020). Apart from Shan and Bago of Myanmar, precipitation in the study sites is also less during the study period. AOD and CO values show prominent peaks in a fire season which coincide with days of the maximum number of fire counts inferring the influence of forest fire on air quality. Developing countries like Nepal, India, Myanmar, and Bhutan are willing to take part in climate finance and are bound to accept expensive insurance premium due to forest fire incidents. Unless forest fires are effectively managed and mitigated, achieving Nationally Determined Contributions (NDCs) and global agendas, including United Nations Decade of Ecosystem Restoration is onerous.

Spatiotemporal Dynamics and Climate Influence of Forest Fires in Fujian Province, China

Climate determines the spatiotemporal distribution pattern of forest fires by affecting vegetation and the extent of drought. Thus, analyzing the dynamic change of the forest fire season and its response to climate change will play an important role in targeted adjustments of forest fire management policies and practices. In this study, we studied the spatiotemporal variations in forest fire occurrence in Fujian Province, China using the Mann–Kendall trend test and correlation analysis to analyze Moderate Resolution Imaging Spectroradiometer (MODIS) data from 2001 to 2016 and meteorological data. The results show that forest fire occurrence rose first and then declined over the years, but the proportion of forest fires during the fire prevention period decreased. The forest fires increased significantly in spring and summer, exceeding the forest fires occurring in the fire prevention period in 2010. The spatial distribution of forest fires decreased from northwest to southeast coastal areas, among which the number of forest fires in the northwest mountainous areas was large in autumn and winter. The fire risk weather index was strongly and positively correlated with forest fire occurrence across various sites in the province. The findings accentuate the need for properly adjusting the fire prevention period and resource allocation, strengthening the monitoring and early warning of high fire risk weather, and publicizing wildfire safety in spring and summer. As the forest fire occurrence frequency is high in the western and northwest mountainous areas, more observation towers and forest fire monitoring facilities should be installed.

Distribution and influence of forest fires on the ecological and radiation situation in radioactively contaminated areas

The article discusses the main causes of forest fires in radioactively contaminated areas and the factors affecting the spread of fires and radioactive substances. It is certain that the main elements of influence on the ecological and radiation situation are the intensity and direction of migration of radioactive combustion products. It is proposed to use a model based on deflation parameters, such as radioactivity, maximum wind speed, using the results of experimental studies. The results obtained were verified by calculating the surface concentration of 137Cs released into the atmosphere after a forest fire in the Chernobyl exclusion zone. For the deflation intensity factor, graphical dependencies were obtained under various meteorological conditions.

Mathematical Simulation of Heat Transfer in the Structures of a Passenger Carriage Under the Influence of Forest Fires

Forest fires have a negative impact on the functioning of the railway. The aim of the work is a mathematical modeling of heat transfer in the structures of a passenger carriage under the influence of radiation from a forest fire front. The originality of the study is explained by modeling heat transfer in structural materials of a passenger carriage under the influence of radiation from a forest fire front. Low and high intensity surface forest fires, crown forest fires are considered. Most of the previously published works are devoted to the analysis of the causes of forest fires, including the ones near the railway. The software implementation of the mathematical model is performed in the RAD Studio software in the high-level programming language Delphi. Mathematically, heat transfer in the materials of a passenger carriage is described by non-stationary differential heat conduction equations with corresponding initial and boundary conditions. In order to solve the partial differential equations, the finite-difference method and the locally one-dimensional method are used. Difference analogs of differential equations are solved by the marching method. The main findings of the study are: 1) physical and mathematical models of heat transfer in the structures of a passenger carriage under conditions of exposure to radiation from a forest fire; 2) the obtained temperature distributions in the inhomogeneous structure of the passenger carriage wall; 3) simulation has shown that a low-intensity surface forest fire causes a relatively safe forest fire impact scenario, while a high-intensity surface forest fire impact is a potentially dangerous scenario; 4) the scenario of the impact of a crown forest fire is unambiguously dangerous at any parameters; 5) the results obtained in this paper and the expected in future investigations will create a physical basis for the development of software for fire safety systems for rolling stock on the railway. The presented results are proposed to be used for forecasting, monitoring, and assessing forest fire dangers during the operation of the rolling stock of JSC Russian Railways.

Remotely sensed trends in vegetation productivity and phenology during population decline of the Bathurst caribou (Rangifer tarandus groenlandicus) herd

The Bathurst caribou (Rangifer tarandus groenlandicus (Borowski, 1780)) herd declined from ∼349 000 animals in 1996 to ∼8200 in 2018. Climate-driven changes to tundra and boreal vegetation is one hypothesis for the decline. We modelled and mapped annual productivity and phenology across the herd’s range using enhanced vegetation index (EVI) data derived from a Moderate Resolution Imaging Spectroradiometer (MODIS) time series spanning 2000–2017. Maximum annual EVI, growing season length, and time-integrated EVI increased significantly on 16%, 18%, and 49% of the core annual range, respectively. Trends toward longer growing seasons were driven entirely by earlier spring green-up and, along with time-integrated EVI, were most prevalent in tundra regions. Trends in forested regions were overwhelmingly related to the influence of forest fires, which burned more than half of the range below the forest–tundra ecotone since 1965. These trends suggest that climate-driven changes in production and phenology have occurred in the tundra and forest–tundra portions of the range and could have contributed to the recent herd decline. However, the trends may also be a result of herd decline itself, given the loss of this large herbivore from the landscape. Elucidating cause and effect will require comprehensive analysis of interactions between climatic variables, herd dynamics, and vegetation change, complemented by targeted field investigations.

Forest fires facilitate growth of herbaceous bamboos in central Amazonia

AbstractSevere droughts in Amazonia caused by El Niño and Atlantic dipole events are expected to become more frequent due to anthropogenic climate change. These droughts lead the tropical forests of central Amazonia to become increasingly exposed to fire. Forest‐fire disturbances can create ideal scenarios for opportunistic plants, such as some bamboos. In this study, we investigate the influence of forest fires, canopy openness, and vertical distance to channel network (VDCN—a proxy for soil moisture availability) on the growth and expansion of Olyra latifolia and Taquara micrantha in the municipality of Autazes, Amazonas, Brazil. The density of these herbaceous bamboos was represented by the density of clumps (clumps ha‐1) and of culms (culms ha‐1), while bamboo growth was expressed as culms per clump and the average height of clumps. Forest disturbed by fire had a density of culms 116% higher than the value found in the control treatment. Plots affected by fire, which were at lower VDCN, showed evidence of higher potential for fire ignition in the low areas. The average number of culms per clump was significantly higher in post‐burn forests. While canopy opening revealed a significant positive linear relationship with the abundance of herbaceous bamboo in our study area, VDCN had a negative effect on bamboo growth, suggesting that, in addition to fire, light in the understory and access to the water table are limiting factors for these two species in the upland forests of central Amazonia.Abstract in Portuguese is available with online material.

Influence of forest fires on the formation processes of low molecular weight dicarboxylic acids, ω-oxocarboxylic acids, pyruvic acid and α-dicarbonyls in springtime fine (PM2.5) aerosols over Southeast Asia

The present study reports on homologous series of dicarboxylic acids (C2–C12), ω-oxocarboxylic acids (ωC2-ωC9), pyruvic acid, and α-dicarbonyls (glyoxal and methylglyoxal) in near source biomass burning influenced (PM2.5) aerosols collected at Doi Ang Khang (DAK), Thailand, during an intense forest fire (March 1 to April 13, 2015) occurred in the vicinity of the sampling site over Southeast Asia (SEA). The molecular distributions of diacids were characterized by a predominance of oxalic (C2) acid followed by succinic (C4) and malonic (C3) acids. The abundance of maleic acid (M) was almost three times higher than that of fumaric acid (F). The observed lower values of C3/C4 (mean: 0.54), C2/C4 (4.45) and F/M ratios (0.33), indicating the limited photochemistry of organic aerosols at DAK and these ratios were comparable to those reported for biomass burning influenced aerosols (C3/C4: 0.51–0.66, C2/C4: ~4.0, and F/M: 0.2–0.35). Further, strong positive correlations (R2 > 0.80) were observed for diacids and related organic compounds with levoglucosan (LG, a unique tracer for biomass burning emission), suggesting that enhanced biomass burning associated with forest fires are major sources of diacids at DAK. This inference was further supported by the air mass back trajectories and MODIS (moderate resolution imaging spectroradiometer) derived fire spots over the study region. The formation pathway of C2 was largely linked to biomass burning derived precursor compounds as inferred from the correlation coefficient matrix analysis. We also found that C3/C4 and C2/C4 ratios were negatively correlated with LG, although they have strongly correlated each other. This inference suggests that biomass burning affect not only the concentration levels of organic aerosols but also their formation processes in the atmosphere. The present study demonstrates that intensive biomass burning during forest fires in SEA largely control the levels of carbonaceous aerosols and seriously affect the climate in the outflow regions.

Effect of Natural Forest Fires on Regional Weather Conditions in Siberia

Effects of forest fires on regional weather conditions were analyzed for Central and Eastern Siberia after warm and dry weather conditions in summer 2019 using COSMO-Ru (COnsortium for Small-scale MOdeling; Ru—Russia) and COSMO-RuART (ART—Aerosols and Reactive Trace gases) model systems. Four series of numerical experiments were conducted (one control experiment and three forest fire experiments assuming total vegetation destruction within the burned areas) to evaluate possible effects of forest fires on surface albedo and vegetation properties as well as their influence on air chemistry and aerosol concentration in the atmosphere. The modeling results showed significant influence of forest fires on regional weather conditions that occurred over large areas situated even away from burnt regions. Decreased surface albedo and reduced latent heat fluxes due to fire-induced destruction of forest cover lead to higher near-surface air temperature and lower air humidity in both burned and surrounding unburned forest areas. On the other hand, reduced incoming solar radiation due to smoke from forest fire plumes decreased land surface temperatures and increased thermal atmospheric stability resulting in reduced regional precipitation.

Inter-annual and seasonal variations in optical and physical characteristics of columnar aerosols over the Pokhara Valley in the Himalayan foothills

ABSTRACT This study reports comprehensive analysis of seasonal and inter-annual variations of aerosol optical and physical properties over the Pokhara Valley in the foothills of central Himalayas in Nepal utilizing the high-quality multi-year columnar aerosol data observed recently from January 2010 to December 2017. The influence of forest fires and agro-residue fires on aerosol properties is also investigated. Seasonal mean aerosol optical depth (AOD) over Pokhara is ≥0.3 during the year, highest in pre-monsoon and lowest in monsoon season. AOD exhibits a consistent seasonal cycle every year with a peak in pre-monsoon. Fine mode fraction contributing to AOD and Angstrom exponent (α) corroborate seasonal pattern of AODs. AODs show good correlation with fire counts in the Pokhara Valley and surrounding region. The aerosol volume size distributions are bimodal. The peaks in volume size distribution and volume concentrations obtained in 2016 pre-monsoon are the highest during the 8-year observation period which coincided with peaks in the occurrence of highest number of fires in the Pokhara Valley and surrounding region. Effective radius of coarse mode aerosols is an order of magnitude larger than fine mode aerosols. The analysis of optical and physical properties of aerosols over the Pokhara Valley suggest that the aerosols observed over the Himalayan foothills are of urban/industrial, biomass burning and dust origin with proportional contributions varying in different seasons. The study provides observational constraints on aerosol physical and optical properties that can serve as inputs for model simulation of aerosol physiochemical processes and quantification of impacts on air quality, climate and sensitive ecosystems in this data-sparse region.

Application of learning vector quantization and different machine learning techniques to assessing forest fire influence factors and spatial modelling

This study assesses forest-fire susceptibility (FFS) in Fars Province, Iran using three geographic information system (GIS)-based machine-learning algorithms: boosted regression tree (BRT), general linear model (GLM), and mixture discriminant analysis (MDA). Recently, BRT, GLM, and MDA have become important machine-learning algorithms and their use has been enriched by application to various fields of research. A database of historical FFs identified using Landsat-8 OLI and MODIS satellite images (at 358 locations) and ten influencing factors (elevation, slope, topographical wetness index, aspect, distance from urban areas, annual mean temperature, land use, distance from road, annual mean rainfall, and distance from river) were input into a GIS. The 358 sites were divided into two sets for training (70%) and validation (30%). BRT, GLM, and MDA models were used to analyze the spatial relationships between the factors influencing FFs and the locations of fires to generate an FFS map. The prediction success of each modelled FFS map was determined with the help of the ROC curve, accuracy, overall accuracy, True-skill statistic (TSS), F-measures, corrected classify instances (CCI), and K-fold cross-validation (4-fold). The accuracy results of training and validation dataset in the BRT (AUC = 88.90% and 88.2%) and MDA (AUC = 86.4% and 85.6%) models are more effective than the GLM (AUC = 86.6% and 82.5%) model. Also, the outcome of the 4-fold measure confirmed the results from the other accuracy measures. Therefore, the accuracies of the BRT and MDA models are satisfactory and are suitable for FFS mapping in Fars Province. Finally, the well-accepted neural network application of learning-vector quantization (LVQ) reveals that land use, annual mean rainfall, and slope angle were the most useful determinants of FFS. The resulting FFS maps can enhance the effectiveness of planning and management of forest resources and ecological balances in this province.

Vertical distribution of 137Cs in forest soil after the ground fires

We studied the influence of forest fires on vertical pattern of 137Cs specific activity concentration in forest soils. Our experiments were organized in Bazar forestry of State Enterprise (SE) “Narodychi Forestry” (Ukraine). We sampled soil in the study sites where grassfires occurred at different times, and determined the specific activity of 137Cs in all soil horizons. We determined that the forest fires and burned forest litter intensify mineralization of forest litter nutrients and increase the radionuclide content in upper layers of soil mineral part. In the following years, the radionuclides gradually move to deeper soil horizons and the difference between the burned and control areas decreases. We determined the depth of soil layer, where the changes in 137Cs specific activity occur caused by the forest fires. The time required for restoration of the original distribution is calculated. The results obtained allow us to identify a group of plants (by the location of the root system) that may have increased levels of contamination in the years following a forest fire and to determine the period when we must conduct additional radiological control of them. We suggested the recommendations on usage of non-timber forest products on the territories contaminated with radionuclides.

Post-pyrogenic Evolution of Sandy Soils under Pine Forests in the Baikal Region

The development of sandy soils under pine forests and the influence of forest fires on the soil properties have been studied in the Baikal region, The profile of background soils consists of a litter layer and a thin humus-accumulative horizon with features of grain bleaching in the lower part. In the WRB system, such soils are classified as Eutric Arenosols (Ochric). They have an acid reaction, fulvate humus, and slightly developed features of the Al–Fe-humus process. Post-pyrogenic soil successions depend on the type of fire. In fifteen years after the ground fire, a soil with specific pyrogenic horizons in the upper part of the profile was formed. It had a high content of carbonaceous matter and humus, a slightly acid reaction, and a relatively high content of exchangeable and total calcium. The soil humus was of the fulvate–humate type, and the humus pool considerably increased. These changes were related to the presence of charcoal microparticles adsorbing dispersed substances on their surface and detected in thin sections. After the crown fire with the destruction of the tree stand and activation of wind erosion, the features of pyrogenesis were poorly expressed in the soils. In this case, post-pyrogenic soils had a weakly developed immature profile, acid reaction, and a low content of humus of the humate–fulvate type. The properties of the background soils allow us to classify them as podzolized humic psammozems (Eutric Arenosols (Ochric)); the soils of post-pyrogenic successions after the ground fire can be classified as post-pyrogenic humic psammozems; after the crown fire, as humic psammozems.