SUMMARY
The research data on activities of invertase (as one of the most important enzymes for soil biological activity, humus content and soil fertility) and urease (as an enzyme of nitrogen metabolism, which transforms the inorganic nitrogen compounds into the organic ones) in soils of artificial afforestations of Robinia pseudoacacia L., Betula pendula Rosh., Quercus robur L. and Acer platanoides L. at the reclamated lands of the Western Donets Basin are presented. The seasonal dynamics of soil activity subject to the type of biogeocenosis is shown.