Influence of forest-peat fires on soils and carbon losses in the phytogenic hammock of mountain swamps in the south of Central Siberia
T. T. Efremova, A. V. Pimenov, S. P. Efremov, A. F. Avrova
Sukachev Institute of Forest SB RAS, Federal Research Center “Krasnoyarsk Science Center SB RAS”, Krasnoyarsk, Russia
Keywords: eutrophic peat soils (Hypereutric Sapric Histosol), pyrogenic soil clusters, carbon losses, multidimension al statistical an alysis, forest-peat fires
Abstract
The estimation of the contrast the physical and chemical properties and carbon losses of pyrogenic peat soils is given 20 years after the large fire in a swamp spruce forest ( Picea obovata Ledeb.) located in the valley complexes of small rivers of the Kuznetsk Alatau (Khakassia Republic). The area of the fire at present occupied by shrub-sedge-green moss birch forest ( Betula pubescens Ehrh.), belonging to the group of short-term-derived postfire grass forests. Pyrogenic peat soils (mechanical and chemical underburning) formed due to passive smoldering - thermal effects below the point of ignition, are characterize by a high variation of physical and chemical parameters ( Cv 26-37 %). Using the methods of multidimensional statistical analysis (cluster, discriminant, canonical), four clusters were formed that identify pyrogenic series of peat soils. In the total contribution of chemical indicators to the differentiation of clusters, the largest proportion belongs to organic carbon (83 %), and a much smaller proportion belongs to moisture of peat soil bulk (15 %). Based on the diversity and abundance of fire traces in the profile of pyrogenic peat soils, we conditionally associate them with the effect of light, moderate, medium and high fire severity. In proportion to the fire severity, pyrogenic series of peat soils are 1.6-2.7 times enriched with ash components, the content of which ranges from 18.9 to 77 %, are 2.2-4.3 times compacted - the bulk density reaches 0.147-0.421 g/cm3, the pH value is consistently shifted from 6.8 to 7.6. A new approach is proposed to estimating carbon losses in the process of passive peat smoldering by the difference in the content before and after a fire, which complements the traditional method of accounting by the depth of burning of the peat layer. In the 0-20 cm layer of the pyrogenic peat soils, additional carbon losses range from 1.6 to 4.0 kg/m2, which is equivalent to 5.9-14.8 kg/m2 of CO2 emission. Data about the additional loss of carbon at the stage of passive smoldering of the peat substrate are provide for the first time.
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