Forest communities formed on a part of ash dumps during their existence can be taken into account when assessing forest lands. The aim of this study is to identify the features of forest communities and soils formed on a fly ash dump located in southern taiga. The structure of forest communities and physico-chemical characteristics of soils formed during spontaneous overgrowth of an ash dump of Sredneuralskaya Thermal Power Plant (TPP) were studied. Mixed forest phytocoenoses with a predominance of Populus tremula L. and Betula pendula Roth aged 45-50 years age have formed on the non recultivated area of the ash dump. They are close in composition to the zonal secondary forests, have less species richness and similar reserves of living aboveground phytomass. The soils formed on the ash dump have horizons with low thickness, in which pH has shifted towards the neutral, and organic matter and basic nutrients have accumulated. Technosol humus horizons in terms of the main biogenic element content (C, N, Ca, Mg, K, P) are close to that of the background soil or even contain them in larger quantities. The formation of forest communities and soils on the ash dump is proceeding according to the zonal type. Studying forest phytocoenosis forming on the ashes with different properties and a varied combination of natural conditions will make it possible to establish patterns in the formation of forest communities on technogenic substrates and influence their speed. © 2022 Lesotekhnicheski Universitet (University of Forestry). All rights reserved.