Kotliarevska U. Woody debris of black alder stands of Ukrainian Polissya

The dissertation is devoted to the study of the dead biomass dynamics in alder stand of Ukrainian Polissya, including the patterns of formation of the tree decay in young alder forests, the features of the destruction of snags in the stand, the rate of the components decomposition of the black alder, the features of the biomass structure of the alder forests, and the dynamics of sequestrated carbon dead biomass components of alder stand. The forest biometric parameters of tree stands are investigated and the peculiarities of the formation of litter in young alder forests of seed and vegetative origin are determined. It has been established that in young alder forests, the litter was formed not only by weakened and depressed trees, but also by stands without signs of weakening, which may account for up to 1 % of the total number of trees per year. The general term of stay of snags at the root is determined which can range from 6 years old in young alder forests to 10 years in mature stands. It is noted that the logs dead biomass in alder forests in the conditions of Ukrainian Polissya can be fully decomposed within 45–50 years. It has been established that the structure dynamics of alder biomass of experimental alder forest is characterized by reduction of the share of aboveground live biomass of the tree stand (from 65 to 57 %), increase of the share of undergrowth live biomass up to 5 %, reduction of the proportion of coarse branches fallout to 1 %, reduction of organic matter to 9 %, increase of total dead biomass to 20 % with age of stands. Based on the developed models for the establishment of a common dead biomass of alder forests and a section database of the forest fund of Ukraine, it was established that in the total alder forests dead biomass of the Ukrainian Polissya 4.22 Tg of carbon was accumulated, and the total energy content is 120.6 PJ. It was established that the indexes of sequestrated carbon of alder forests dead biomass of the experimental region according to the forest management data are 95 times lower than the data obtained from the research results.