Home – Home – Jornals – Contemporary Problems of Ecology 2017 number 5

We provide a quantitative analysis of post-outbreak wildfire frequency within the confluence of the Yenisei and Angara affected by the Siberian silkmoth (Dendrolimus sibiricus Tschetv.). That catastrophic outbreak was observed in 1993-1995, extended for about one million ha and caused stands mortality in the area of about 460 thousands ha. For outbreak area the fire frequency was about 7 times higher compared to the reference, burned area - 20 times higher. The peak of fire activity within outbreak areas occurs in May - June, while that for undamaged coniferous stands - in July. The number of fires is correlated with the average monthly (June) air temperature ( r = 0.65). The area of fires has a negative correlation with the moisture conditions: precipitation ( r = -0.53), drought index (SPEI: r = -0.57), and ground cover moisture content ( r = -0.57). Extensive fires prevail within outbreak areas ( S > 1000 ha), while within control - smaller area fires. The multiple (re-occurred) wildfires are typical of pest outbreak area. The area of these fires is related to their re-occurrence by logarithmic dependency (17 % of the territory burned by forest fires twice, 5 % - three times, and 0.5 % four times). Wildfires in outbreak areas hinder initial forest recovery by destroying regeneration of coniferous: 20 years after the outbreak >90 % of disturbed areas are occupied by the grass-bush and small-leaved cenoses.