| Abstrakt: |
The increasing number of fires leads to the constant increase of the proportion of pyrogenic soils in Russia. The objective of this study is to determine the extent to which contrasting environmental conditions can trigger wildfires and affect postfire recovery scenarios. Post-pyrogenic podzols and podzolic soils have been studied in the taiga regions, in the Pinega and Pechoro–Ilych nature reserves at the European part of Russia and in the Sukhoi Poluy River basin in the north of Western Siberia. Soil-morphology descriptions, analysis of anthracomass concentration (calculated as the sum of charcoal particles >0.5 mm), and a set of chemical methods have been carried out. We demonstrate that some fires dramatically change the direction of soil-formation processes, which in turn, leads to the presence of one of the following specific features in the formed soils: (1) loss of organic horizon(s), (2) partial loss of mineral horizon(s), and (3) restart of soil formation if the soil stratum has been completely degraded. We propose to distinguish such soil varieties as pyrogenic-extreme soils of a new research area "geography and genesis of soils in extreme environments." Both weakly transformed full-profile soils (para-extreme) and strongly degraded soils (ortho-extreme) can coexist in the burnt areas. It is proposed to call ecosystems with properties (e.g. climate, topography, fire-return intervals, etc.) that contribute to severe fire damage to vegetation and soil cover and the subsequent erosion are proposed "pyrogenically vulnerable ecosystems." Among the studied factors, the postfire erosion has proven to be a predominant factor influencing the long-term changes in the direction of soil formation. We propose a concept of "fire centers" for description of spatial heterogeneity in burning, which can be tracked using changes in the anthracomass concentration. The dynamism of different extremeness classes in the same territory is shown. [ABSTRACT FROM AUTHOR] |
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