Влияние Лесных Пожаров На Микробиологические Свойства Торфяных Олиготрофных Почв И Торфяно-Подзолов Глеевых В Болотах Северной Части Сым-Дубчесского Междуречья (Красноярский Край)

Presented data on changes in the enzymatic activity of soils under pyrogenic effects in model experiments simulating natural fires. A series of experiments aimed at studying pyrogenic inhibition of enzyme activity and dynamics of their recovery in post-pyrogenic soils were performed under laboratory and natural conditions. The objects of the study were sandy soil (Seropeski, Arenosol) and migratory-segregation black soil (Haplic Chernozem (Loamic, Pachic) Rostov region. Model experiments were carried out by treating soil samples with gas burner flame (amount of heat 87–435 × 103 J) and pyrogenic action of wood fuel combustion (10–279 × 106 J). In the first case, the exposure duration was 1 to 5 min, and in the second case from 1 to 120 min. The response of enzymes (catalase, invertase, urease, peroxidase and phosphatase) to low-temperature plasma exposure (1–120 min) was found to differ depending on the enzyme group and degree of exposure. It was found that the depth of penetration of thermal effects in simulated fires was limited to the top soil layer (0–10 cm), and the radius of spread relative to the combustion source did not exceed 20 cm. Temperature values varied according to time, source of exposure and amount of fuel (400–600°C). Sandy soils and chernozem were heated and cooled down at different rates. The activity of catalase, invertase and urease were found to be inversely related to the intensity of pyrogenic exposure. The dynamics of enzyme activity recovery in post-pyrogenic soils was traced. Invertase activity recovered faster than catalase and urease activity, but full recovery after a year does not occur. The results obtained indicate a significantly prolonged effect of inhibition of enzymatic activity during simulation of natural fires.

Changes in Enzyme Activity in Post-Pyrogenic Soils (Physical Model Experiment)

Prikhodko,

Kazeev,

Vilkova

et al. 2023

Respiratory Activity and Biodiversity of Microbiomes in Podzolic Soils of Post-Pyrogenic Spruce Forests in the Krasnoyarsk Territory and the Komi Republic

Grodnitskaya,

Pashkeeva,

Startsev

et al. 2023

Data on the microbiological properties of podzolic soils (Retisols) of old-growth spruce forests in the middle taiga of the Krasnoyarsk Krai and the Komi Republic are presented. It is shown that, despite the geographical distance, the soils of the regions are characterized by similar morphological and physicochemical properties. It was noted that in the soils of the spruce forests of the European North (R. Komi) and middle Siberia (Krasnoyarsk Krai), no significant difference in the accumulation of microbial biomass and the rate of microbial respiration was found. However, the content of carbon and nitrogen in soils, as well as microbial biomass, had significant differences in the qualitative composition of microbiomes in pyrogenic and non-pyrogenic soil horizons. A significant effect of the pyrogenic factor on the α-diversity of bacteria and fungi was noted. It was shown that representatives of the dominant phyla of bacteria (Proteobacteria, Actinobacteria and Planctomycetes) and fungi (Ascomycota, Basidiomycota and Mucoromycota) actively participate in the assimilation of organic matter with the presence of pyrogenic carbon. The microbiomes of the upper pyrogenic subhorizons include groups of carbotrophic bacteria (Thermomonosporaceae, Isosphaeraceae, Bacillaceae, Xanthobacteraceae) and fungi from the classes Dothideomycetes (Cenococcum), Eurotiomycetes (Penicillium), Sordariomycetes (Trichoderma), Leotiomycetes (Oidiodendron), Umbelopsidomycetes (Umbelopsis), which are capable of converting pyrolysis products into accessible and non-toxic substrates for other organisms.

Changes in the Microbiological and Physico-Chemical Properties of Soils after Fires in Pine and Birch Forests of Central Regions of the Zabaikal Krai

Bogorodskaya,

Kukavskaya,

Kalenskaya

et al. 2023

The microbiological and some physico-chemical properties of illuvial-ferruginous soddy-podburs (Entic Rustic Podzols) soils in Scots pine forests and gray-humic typical light loamy soils (Umbrisols) in secondary birch forests of the central regions of the Zabaikal krai have been studied. Fires in soddy-podburs pine forests resulted in decrease in the total exchangeable basis, total nitrogen, mobile forms of potassium and phosphorus, and in increase in the proportion of C : N; while in birch forests, on the contrary, an increase of the mentioned indicators and a narrowing of the C : N proportion in the gray-humic typical soils were observed. The content of humus in the upper soil horizon decreases only in recently burned Scots pine forests after a high-severity fire, while in other sites it increases. A decrease in the soil acidity was observed at all burned sites. High-severity fires lead to a significant decrease in the content of microbial biomass and the intensity of basal respiration, as well as to a change in the structure of ecological and trophic groups of microorganisms in the soils up to a depth of 10 cm of the mineral horizon, while low-severity fires mainly affect the duff. The qCO2 coefficient increased 2–5 times after fires in the duff and 1.5–2 times in the humus horizon only after high-severity fires. In recently burned Scots pine forests, the storage of microbial biomass and microbial production of carbon dioxide significantly decreased up to a depth of 10 cm of the mineral soil layer. In the steppe site formed after the impact of fires in the pine forest, and in the birch forest after a high-severity fire, in the humus horizon the carbon storage of microbial biomass decreased by 15–20%, and the microbial production of CO2 increased by 10–20%, predetermining the predominance of mineralization processes. The considered post-fire transformation of the structural and functional parameters of soil microbiocenosis, as well as a 20–40% decrease in the total carbon storage of microbial biomass in the soils of all sites demonstrate a long recovery period of soils after fires in light coniferous and deciduous forests of the central regions of the Zabaikal krai.