Pyrogenic Transformation Research Articles

Pyrogenic transformation of the phosphate state of permafrost forest soils of Central and Southern Yakutia

For the first time, the phosphate state of permafrost forest post-pyrogenic polycyclic soils of Central and Southern Yakutia, formed respectively in arid and humid climates, was studied and evaluated. These soils with a polycyclic profile, formed in the transaccumulative facies of this regions of the permafrost zone, contain, in addition to the modern one, 2–3 buried humus horizons with abundant inclusion of black charcoal. These pyrogenic humus horizons are characterized by an increased content of humus, total nitrogen and phosphorus soluble in iron oxalates, exchange bases, as well as fractions of physical clay and silt compared to neighboring mineral horizons of the soil profile. At the same time, the brown soil of Southern Yakutia, formed under less severe and humid climatic conditions, compared with those of the pale soil developed under cryoarid conditions of Central Yakutia, was more biogenic, and the total content of phosphorus here was 98.0–427.2, whereas in the second soil – only 11.0–257.1 mg P2O5/100 g of soil. Organophosphates predominated in the composition of the total phosphorus of burozem, amounting to 51.8–81.3%, and in pale soil – mineral forms of phosphorus, which accounted for 52.2–78.8%. The fractional composition of mineral phosphates of both types of permafrost soils was mainly dominated by phosphates of one and a half oxides (Al-P and Fe-P), totaling 43.3–94.3%, and among the latter – Fe-P, which accounted for 34.8–87.4% of the total amount of all fractions of mineral phosphates. It is assumed that the high content of iron phosphates, and in some cases occluded aluminum-iron phosphates in the studied permafrost soils, is due to the manifestation of both cryogenic and biogenic pyrogenic ferruginization in their genesis.

PYROGENIC CHANGES OF BOG VEGETATION AND PEAT IN WESTERN SIBERIA

Wildfires are an important environmental factor which determines the carbon cycle intensity in mires. The article presents the assessment of the consequences of pyrogenic transformation and the current state of burntout mires in the taiga and forest-tundra zones of Western Siberia 6-8 years after the wildfire, with regard to their microhabitat heterogeneity. Field studies were conducted in 2022 on three mires (a total of 13 post-pyrogenic and pristine plots) and included a total-station survey of the surface, an assessment of the occurrence of species in the grass-dwarf shrub and moss-lichen tiers, sampling for laboratory analysis of the physical properties and botanical composition of peat. Sphagnum mosses, Polytrichum strictum, lichens and dwarf shrubs were considered as recovery indicator species. As a result of the study, it was found that the intensity of pyrogenic transformation is determined by the initial state of bog ecosystem and increases in a row: the hydro forestation site on the Bakchar raised bog - palsa - the Ust-Bakchar raised bog drained for peat extraction. At most of the studied plots, microdepressions were more susceptible to burnout, while hummocks were preserved or only partially burned out. The transformation of peat deposit properties extends beyond the layer directly exposed to burnout, and manifests itself in a decrease in water content, and an increase in ash content, bulk density and degree of humification. At the first stages of post-pyrogenic successions, similar patterns were revealed for the mires of taiga and forest-tundra zones, i.e. an intensive overgrowth with P. strictum. According to the results of the study, it was concluded that the hydroforestation site in the Bakchar bog could possibly restore the species composition of vegetation cover and resume peat accumulation. Irreversible changes in vegetation cover have occurred in the Ust-Bakchar bog, where the restoration of sphagnum mosses does not occur even 20 years after the fire.

Post-fire restoration of pine forests in the Badary area, Tunkinskiy National Park, Russia

A morphological variety of pyrogenic transformations characterises burnt areas of the Badary area of the Tunkinskiy National Park (Russia), from heavily damaged areas with a partially remained forest stand to bare spaces of tens of square metres. This enabled us to study the dynamics of the post-fire reproduction of Pinus sylvestris (hereinafter – pine) forests in areas with various environmental conditions. The main goal of our study was to determine the nature of the pyrogenic transformation of ecosystems and to evaluate the success of the forest reproduction. The studies were based on the geobotanical monitoring in two burnt-out areas, differing in the degree and area of wildfire damage due to a creeping fire in 2010. Between 2014 and 2020, we considered the multi-temporal specificity of the species composition of the forest stand, shrub layer, and plant communities. The emergence of the first shoots of undergrowth and new growth has been recorded. The projective cover and the dynamics of the species abundance in all forest layers were fixed. The analysis of the natural reforestation dynamics revealed a similarity of the main geobotanical indicators. Pine seedlings dominated in the undergrowth of the study sites, with a small proportion of Betula pendula. The shrub layer consisted of Rosa acicularis. Rhododendron dauricum has been found there only at the late stage of the study. In the herbaceous layer, the largest proportion was represented by meadow species, with a small participation of forest plants. Differences were revealed during the emergence of first seedlings of undergrowth and new growth, as well as in the size of projective cover of species in all forest layers. The first pine seedlings on a heavily burnt-out study plot were recorded a year earlier than on a less transformed plot. Nevertheless, the height increment and the projective cover of the undergrowth were significantly higher on the burnt-out area of a medium damage degree. On the heavily fire-damaged area, we observed pine seedlings planted by the staff of the Tunkinskiy National Park. A satisfactory rate of seedling survival at the initial stage and further deceleration of growth parameters have been noted. The obtained results indicate the reforestation success and, therefore, a favourable forecast of post-fire recovery of light-coniferous forests in the Badary area of the Tunkinskiy National Park.

Pyrogenic Carbon Colloids Facilitate Transport and Transformation of Cr(Vi) in Soil: Steric Competition Coupling with Reduction Reaction

Pyrogenic Carbon Colloids Facilitate Transport and Transformation of Cr(Vi) in Soil: Steric Competition Coupling with Reduction Reaction

Natural and anthropogenic transformation of geosystems of Tunkinsky national park: identification and mapping

The paper focuses on the specifics of landscape medium scale mapping employing traditional methods. We selected a key site in Tunkinsky National Park (Republic of Buryatia) and the Tunkinskaya depression located within it and its mountain framing (south of Eastern Siberia) to display the modern structural and dynamic features of the geosystem functioning. The map compiled at a scale of 1 : 100 000 illustrates the differentiation into categories of landscape structures by types of altitudinal-belt conditions of the natural environment, differing in morphological and phytocenotic properties, as well as the nature of natural-anthropogenic transformation. The main factors of landscape discreteness are morphological features of the surface structure of the intermontane territories; the complexes with natural vegetation and their derivative biocenoses, formed as a result of agricultural and pyrogenic transformation, reflected the dynamic nature of the geosystem functioning. The complexes have been formed in river valleys due to debris flows and are assigned to variable states.

Pyrogenous transformations of steppe landscapes in the south-east of the Russian plain (natural parks in Volgograd region as a case study)

For a long time fires have been and still are one of the powerful factors for transforming steppe landscapes. The current condition and pyrogenous transformations of geosystems in the south-east of the Russian Plain were examined. The following methods of field complex landscape research were used, such as semi-portable methods of “key sites”, of crop (quadrat) areas and others. The article focuses on the conclusions about the pyrogenous transformations of geosystems drawn on the basis of long-term field observation on the territory of the Donskoy natural park and the Elton natural park of Volgograd Region. Monitoring has revealed that pyrogenous transformations of geosystems appear to pose a serious threat to biological and landscape diversity of steppe. Under the influence of fire, self-regulation processes in steppe geosystems slow down and resistance to external influence reduces. The structure simplifies, the homogeneity of vegetation cover increases, grass stand and overall projective cover decreases, wood-shrub vegetation dies out. The colourful aspects of the steppe are vaguely displayed. For the long term (up to 3-5 years) biological productivity of geosystems considerably reduces from 1.5 to 3 times. The upper layer of humus burns out, soil fertility decreases and aridization of local pyrogenous geosystems increases. Evaporation speeds up, soil humidity deficit goes up, underground water level goes down, springs run dry. Wind and water erosion processes are being activated. Fires destroy sites of reproduction, recreation and feeding for animals and also habitats of rare and endangered species. Pyrogenic transformation is the most serious real threat to the biological and landscape diversity of the steppes.

Пирогенное преобразование геосистем Западного Прибайкалья: факторы, условия, современное состояние

The factors of pyrogenic impact on the taiga geosystems of the Western Baikal region against the background of the modern transformation of the global atmospheric circula-tion are studied in the paper. The results of world scientific research on modeling climate change and related adverse weather phenomena (prolonged droughts, thunderstorm activity, etc.) are presented. The natural factors contributing to the increase in the pyrogenic transformation of geosystems are described. The study of the spatio-temporal distribution of fires is carried out on the basis of data from remote sensing of the Earth. Information about unfavorable weather conditions and dangerous hydrometeorological phenomena, data on atmospheric phenomena (thunderstorm activity), daily values of air temperature and soil temperature under natural cover at different depths are analyzed in order to factorial analysis of forest fire sources in the study area. The characteristic of the current stage of geosystems is given based on field research conducted in June 2020. It was revealed that catastrophic fires registered in the study area in 1997 and 2015 occurred against the background of minimal thunderstorm activity. At the same time, in the central part of the Western Baikal region thunderstorms were the leading factor in the 2015 fires. Five years after the fire, the restoration of mountain taiga light coniferous forests is characterized by the predominance of the community of Chamaenerion angustifolium (L.) Scop. The successional dynamics of the geosystems of mountain taiga dark coniferous forests is going through the Betula rotundifolia Spach. with Ledum palustre L. and cereal-forb ground cover. Undergrowth of tree species (mainly pine) is rare and uneven about 800–1200 specimens per hectare.

Постпирогенная динамика растительного покрова верхового болота Барское (Вологодская область)

The study deals with the issues of restoration of peat bogs exposed to the pyrogenic factor. The work was carried out in the Barskoe raised bog, at sites unaffected and directly affected by the ground fire of 2002. A decade later, these sites differed in species composition, phytocoenosis structure, and biomass accumulation rates. Post-pyrogenic changes in the vegetation cover of the raised bog were associated with a slight decrease in species richness, loss of moisture-demanding bog species and an increase of mesophyte’s and xerophyte’s roles, simplification of the mire sites structure towards the loss of complexity, reduction of phytocoenotic diversity, as well as an increase in the dry biomass stocks with a 1.3–1.4-fold decrease in the photosynthetic phytomass and a 6.4–6.7-fold increase in the mortmass. The restoration rate of the mire exposed to pyrogenic transformation can be accelerated by increasing its water table and the prevention of new fires.

Pyrogenic transformation of old pine forests in the Middle Volga Integrated Biosphere Reserve and its effect on the nesting birds

The effects of the pyrogenic transformation of old pine forests of the Middle Volga Integrated Biosphere Reserve on the nesting birds were studied, based on the original surveys performed in 2006-2009. The changes of the breeding ornithological fauna’s parameters were traced during the restoration of the lower tiers of vegetation after local lower fires. The response of particular species and guilds of nesting birds to the changes in nesting conditions due to a single bottom fire was determined, as well as the changes in the total number of nesting birds and in the number of particular guilds of nesting birds during the vegetation recovery after the fire. The bird species vulnerable to the changes in nesting conditions were identified. The relationship between post-pyrogenic vegetation restoration processes in old pine forests and the species composition and ecological preferences of birds nesting was shown.

Зональность лесных горючих материалов и их пирогенная трансформация в сосняках Средней Сибири

Fires in the forests of Siberia occur annually and cause enormous damage to natural resources. Therefore, studies of the natural forest fire hazard, one of the components of which are forest fuels, are relevant. The research carried out on 53 sites in the pine forests growing along the Yenisei meridian transect revealed that surface fuel loads in pine stands of different zones of Central Siberia are defined by geographical latitude and increase from the forest-steppe zone to the northern taiga subzone. The largest forest fuel loads are concentrated in the pine stands of the northern and middle taiga. Their composition is dominated by loads of duff, the fraction of which in surface fuel loads increases from the forest-steppe zone (57.4 %) to the northern taiga zone (71.3 %). The obtained dynamic equations of the reserves of grass-shrub understory over the season may be applicable to grassy types of pine forests. Combustion of surface forest fuels in pine forests during surface fires of differentintensity varies from 10.8 to 31.4 t/ha, which is from 26.1 to 74.1 % of their loads before the fire. The intensity of fires determines not only the number of burned forest fuels, but also their post-pyrogenic accumulation regardless of zonal and environmental conditions. The variation of fuel loads in forest areas is related to pyrogenic effects and the recovery period after the last fire, as well as to the mosaic distribution of living ground vegetation. Equations of accumulation of surface forest fuels after fires of different intensity that can be applied to pine forests of Central Siberia are developed. A change of dominants in the ground cover and a decrease in the productivity of the grass-shrub understory occurs in a long-term absence offires in pine forests. The development of moss cover contributes to the decrease in litter reserves. The data obtained on the loads of surface forest fuels and their transformation during a fire provide the basis for understanding and simulation fire behavior, estimating emissions and impacts of fires on fuel loads, and can be used for improvement the existing global and regional models. For citation: Ivanova G.A., Ivanov V.A. Zonality of Forest Fuels and Their Pyrogenic Transformation in Pine Forests of Central Siberia. Lesnoy Zhurnal [Russian Forestry Journal], 2020, no. 4, pp. 9–26. DOI: 10.37482/0536-1036-2020-4-9-26Funding: The research was supported by the Siberian Branch of the Russian Academy of Sciences and the Russian Foundation for Basic Research (grant projects No. 07-04-00562 and 19-58-80002 BRICS-t).

Картографирование антропогенной и спонтанной (природной) преобразованности геосистем Тункинской котловины

The article focuses on the specifics of medium-scale landscape mapping using traditional methods. For mapping studies of modern tendencies of geosystem’s functioning was chosen the part of the Tunkinskaya depression and the mountains surrounding it (Southwestern Cisbaikalia). A landscape map was created in the scale of 1 : 100000. It reflects the differentiation of the territory into categories of landscape structures according to the types of zonal-altitude-belt conditions of the natural environment. The conditions differ in morphological and phytocenotic properties, as well as in anthropogenic transformation. The main factors of landscape discreteness are the geomorphological features of the surface structure of mountain-valley territories. The dynamics of the geosystem’s functioning reflects the complexes with natural vegetation and their derivatives biocenoses formed in the process of agricultural and pyrogenic transformation. The variable states include complexes formed in river valleys as a result of the manifestation of debris flows activity. The result is an image of the current state of geosystems. This is the scientific basis for predicting the development of geosystems, taking measures to optimize environmental management and addressing the risk of hazardous natural processes.

The natural regeneration of desert ecosystem vegetation at the 2013 crash site of a Proton-M launch vehicle, Republic of Kazakhstan

Restoration of vegetation at the crash sites of space launch vehicles (LV) and chemical effect of rocket propellant on ecosystems are understudied. We investigated the restoration of vegetation at the crash site of LV Proton-M (Baikonur Cosmodrome, the Republic of Kazakhstan) since launch failure in 2013. Crash area was subdivided into zones defined by differences in the character and intensity of technogenic disturbance. Detailed geobotanical assessments were carried out in 2014 and 2017. We have found that communities dominated by annual species of Salsola have colonized the zone of total destruction of vegetation following the detoxification of spilled rocket fuel and the removal of topsoil, which resulted in specific edaphic conditions. Species-poor communities of Ceratocarpus arenarius on clay loams and relatively species-rich communities of clump-forming grasses (Agropyron fragile, Stipa hohenackeriana) on sandy loams were formed within the zone of pyrogenic transformation of phytocenoses. The zones of an irregular mosaic of mechanical disturbances and weak mechanical disturbances of phytocenoses were occupied by Artemisia terrae-albae communities that showed no significant differences from the background phytocenoses. Only zone of total destruction of vegetation and zone of pyrogenic transformation still demonstrate high levels of phytocenoses modification. The discussion offers a best interpretation of the observed trends and findings given certain unavoidable uncertainties.

Seasonal and Daily Dynamics of the CO2 Emission from Soils of Pinus koraiensis Forests in the South of the Sikhote-Alin Range

The presented study shows the results of measuring soil respiration in typical burozems (Dystric Cambisols) under mixed Korean pine–broadleaved forests in the southern part of the Primorskii (Far East) region of Russia growing under conditions of monsoon climate. The measurements were performed in 2014–2016 by the chamber method with the use of a portable infrared gas analyzer. Relative and total values of the CO2 efflux from the soil surface on four model plots were determined. The intensity of summer emission varied from 2.25 to 10.97 μmol/(m2 s), and the total CO2 efflux from the soils of four plots varied from 18.84 to 25.56 mol/m2. It is shown that a larger part of seasonal variability in the soil respiration is controlled by the soil temperature (R2 = 0.5–0.7); the soil water content also has a significant influence on the CO2 emission determining about 10% of its temporal variability. The daily dynamics of soil respiration under the old-age (200 yrs) forest have a significant relationship with the soil temperature (R2 = 0.51). The pyrogenic transformation of Pinus koraiensis forests into low-value oak forests is accompanied by an increase in the СО2 efflux from the soil.

Pyrogenic transformation of tundra soils: Laboratory simulation

Pyrogenic losses of carbon and nitrogen from the surface horizons of soils in shrub ecosystems of mountain tundra, which are the most affected by fires in natural environments, have been estimated in laboratory simulation tests. The specific features of pyrogenic transformation of the physical and chemical properties and microbiological processes after exposure to high temperatures simulating the effect of fires of different intensity have been identified. Pyrogenic nature of the impact depends not only on the intensity of a fire, but also on the soil type. Its impact on tundra soils leads only to short-term increases in CO2 emissions due to the destruction of pyrogenic organic compounds. A high level of fire impact leads to a significant reduction in microbiological processes in soils and shows no trend toward recovery in the long term, even under optimal conditions.

Pyrogenic transformation of oil-bearing biomass into biodiesel without lipid extraction

This study mechanistically investigated the pseudo-catalytic transesterification of oil-bearing biomass through a thermo-chemical pathway. As a case study, all experimental work was conducted with sesame seed and sesame oil. The pseudo-catalytic transesterification occurred in the presence of porous material (silica) since porous material provided reaction space as a micro reactor and drove the heterogeneous reactions between the mobile phase of methanol and the stationary phase of triglycerides (TGs) in sesame. The experimental work verified that the main driving force of pseudo-catalytic transesterification was temperature in the presence of porous material, which led to the direct derivatization of oil-bearing biomass into fatty acid methyl esters (FAMEs). Thermal cracking was observed at temperatures higher than 350°C and the main experimental parameter initiating this thermal cracking was temperature and time. However, the optimal conditions identified in this study were temperatures lower than 350°C, where the total yield of FAMEs reached up to 96.4±0.3% of lipid in sesame seed. The introduced technology would be applicable to the production of biodiesel and comprehensive lipid analysis in oil-bearing biomass.

Pyrogenic transformation of Nannochloropsis oceanica into fatty acid methyl esters without oil extraction for estimating total lipid content

This study fundamentally investigated the pseudo-catalytic transesterification of dried Nannochloropsis oceanica into fatty acid methyl esters (FAMEs) without oil extraction, which was achieved in less than 5min via a thermo-chemical pathway. This study presented that the pseudo-catalytic transesterification reaction was achieved in the presence of silica and that its main driving force was identified as temperature: pores in silica provided the numerous reaction space like a micro-reactor, where the heterogeneous reaction was developed. The introduced FAME derivatization showed an extraordinarily high tolerance of impurities (i.e., pyrolytic products and various extractives). This study also explored the thermal cracking of FAMEs derived from N. oceanica: the thermal cracking of saturated FAMEs was invulnerable at temperatures lower than 400°C. Lastly, this study reported that N. oceanica contained 14.4wt.% of dried N. oceanica and that the introduced methylation technique could be applicable to many research fields sharing the transesterification platform.

Postcatastrophic successions of a rodent population

Successions of a rodent population have been investigated in the forest biocenoses of the Visim Nature Biosphere Reserve (Sverdlovsk oblast, Middle Ural) after a catastrophic windfall and two fires. Differences in the values of the total abundance of rodents and their ratio in the community before natural catastrophes and at different postcatastrophic demutational succession stages are revealed. Structural alterations in a rodent population are associated with different responses of the species to the anemogenic and pyrogenic transformation of their microhabitat environment and can be considered compensatory mechanisms maintaining the sustainability of small mammal communities under the impact of natural catastrophic factors.

Pyrogenic changes in microelement content in soils and plants from the pine forests of western Transbaikal

The pyrogenic transformation of the microelement content in soils and plants from western Transbaikal (Republic of Buryatia) has been studied. As is found, ground fires, under the studied conditions, lead to the transformation of soil properties and slightly elevated concentrations of Mn, Zn, Cu, and Pb in the surface soil (0–40 cm) and and Mn, Zn, and Pb in plants. It has been also found that the soil Fe: Mn ratio becomes lower. A pyrogenic transformation of vegetation and the soil properties, the elemental composition in particular, is shown to be traced over several years after the fire.

Post-pyrogenic changes in the hydrothermal parameters of soils in middle-taiga pine forests

Results of long-term studies in middle-taiga pine forests on sandy podzols after controlled surface fires are presented. The changes in the soil hydrothermal conditions caused by the pyrogenic transformation of the soil and the pyrogenic and postpyrogenic changes in other components of the forest biogeocenoses were revealed. Along with the general character of the changes in the soils’ hydrothermal conditions, some differences in the degree of their manifestation between different regions due to the different fire intensities were revealed. It was concluded that the pyrogenic impact disturbed the existing material and energy exchange between the atmosphere and the soil, which is the main process of soil formation and development. Consequently, forest fires are a powerful and active factor of recent pedogenesis.

Pyrogenic transformation of organic matter in soils of forest bogs

Natural fires on forest bogs significantly affect all the groups and fractions of peat organic matter. The type and intensity of the fires are responsible for the depth of the pyrogenic transformation of peat. In the course of thermal destruction of peat organic matter, humus substances (humic acids in particular) are accumulated, which leads to changes in the type of humus; the humus reserves may increase by 1.5–8 times. Several ways of the formation of humus components related to the intensity of a fire are suggested. The regressive evolution of bog ecosystems caused by fires is a reversible process. The humus status of pyrogenically transformed horizons and their morphology are preserved within the peat deposit as a relic characteristic of the discrete metamorphosis of the soils.