The Post-Fire Transformation of Forest Stand Рhytomass in Plantations of the Lower Angara Region

Forest fires affect on tree stands during combustion and for a long period after a fire. The work objective is an assessment and monitoring of the transformation of stand phytomass under the impact of large-scale experimental forest fires of varying intensity in pine and larch forests of the Lower Angara region, Krasnoyarsk Krai. Stand phytomass is estimated by the enumeration sur-vey method of the model trees according to the diameter classes. A five-years monitoring of stand phytomass changes after fires of varying intensity has been carried out. A link of pine and larch phytomass and their individual fractions with morphological features and the tree age has been revealed. Up to 90 % of tree mortality happens in the first 2–3 years after a fire. The close link between the fire intensity and the amount of post-fire tree mortality is established. 3 years later after a fire of high intensity in the pine forest the tree mortality reached 62 %, after the mid-dle and low intensity fires – 22 and 17 % respectively of the total number of trees. The mortality of the first layer trees in the larch stands after the fire of high intensity was 49 %, after the middle and low intensity fires – 35 and 20 % respectively. The mortality of the second layer trees in the larch stands varied from 18…34 % after the low intensity fires, and reached up to 62 % and 100 % after the middle and high intensity fires, respectively. The phytomass of living trees de-creased after the fires by 16…62 % in the pine stands and by 15…50 % in the larch forests depending on the fire intensity. The post-fire dynamics of the aboveground stand phytomass in the pine and larch forests was determined by the fire intensity. The fires contribute to the phytomass redistribution of living trees into mortmass that increases as a result of the tree mortality, needle litter and cladoptosis from the trees damaged by fires.