Pyrogenic disturbances of the hydrothermic regime of cryogenic soils under light coniferous forests in southeastern Siberia

Pyrogenic transformations of the physical state of cryogenic soils in the southern and middle taiga were investigated. The long-term dynamics of the microclimate on burns and the soil temperature and moisture to the depth of 120 cm were studied. Data on the postfire restoration of the ground cover are presented. Experiments on artificial sprinkling of burned areas differing in the degree of the burning out of the forest litter, the slope gradient, etc., have been performed. An experimental model demonstrating the relationships between the surface runoff and five environmental factors has been proposed. The pyrogenic destruction of the ground cover and the lower phytocenosis layers was accompanied by significant disturbances of the microclimate and anomalous thawing of the permafrost on the burns. In the pine stand on the colluvial fan after the intense fire, the soil temperature at the depth of 10 cm (in the summer) exceeded the control value by 3–5°C; in the larch forest on the southern slope of the Stanovoi Ridge, it increased by 1.5–2.0 times after the fire of medium intensity. On the mountain slopes, the surface runoff was significantly intensified, which resulted in drastic environmental and silvicultural consequences.