In result of monitoring ordinary chernozems in Priazovie area under perennial (about · 10s years) afforestations it is determined that forest's soil-protective role (antierosion and moisture preservating functions) stimulates the growth of the biomass produced. It also assists the formation and accumulation of dead organical substance in the form of forest littei on the soil's surface, deepar penetration of rotts into the soil. In the process of evoiution morphogenetic qualities of soils are defined. These are the increase of humus horizon A, horizon AB- and carbonateles strata, intensive accumulation of humus, increase of acid in soil solution, etc. Thus, forest biocoenose assist in preservation and partially improvement of fertility of ordinary chernozems of stepp zone.