Shevchuk N. Biogeocenotic features of afforestation and steppe natural communities of Southern Kryvorizhya

The object of our research is the transforming effect of artificial forest plantations on floristic diversity, grass productivity and soil cover of steppe communities of Southern Kryvyi Rih Area. The aim of the work is to find out the biogeocoenic peculiarities of artificial forest plantations of the Southern Kryvyi Rih Area in comparison with steppe communities to determine the transforming influence of forests. Methods of research: geobotanical (floristic, ecological, taxonomic, geographic, biomorphological, coenotic analysis), field (route and semi-stationary), chemical methods of soil study, statistical methods of processing and analysis of data. For artificial forest plantations, it was revealed that low floristic diversity (2-90 species) is characteristic in comparison with steppe communities (128-251 species). It was found out that the largest number of species in the grass cover of plantations has low occurence rates with significant participation of ruderal species. We found that the largest biomass reserves of wood are set for 40-year-old plantations of Gleditsia triacanthos, compared with Quercus robur of the same age. It is ascertained that the peculiarities of the grass storey and litter in artificial forest biogeocoenoses are due to their environment-transforming influence and the dynamics of climatic conditions. We defined that the overweight of herbaceous vegetation within plantations plays an insignificant role, changes over the years, and underground mass - ranges from 32.5 to 94.8 g/m2 and significantly depends on the species and age characteristics of trees. The underground and underground phytomass of steppe communities depends on their species composition, biological peculiarities of the dominant, weather conditions and stony substrate. The largest indices of above-ground and underground phytomasses are noted for the vegetation community of the “Natural Landmark Stepok” reserve, compared with the steppe areas on the slopes. We ascertained the sequence for degrees of increasing content of organic carbon in the litter of plantations in different sub-horizons: Pinus pallasiana (9.7%) → P. pallasiana and P. sylvestris (10.3%) → Q. robur on the slopes (17.0%) → Robinia pseudoacacia (18.1%) → G. triacanthos (38.0%) → Q. robur (47.2%). It was revealed that the content of humus in the soil layer of 0-10 cm of artificial forest communities is in the range from 1.1 to 3.1% (stony sands) and from 6.2 to 8.7% (southern forest black soils). For steppe communities on the slopes, the content of humus in the soil layer 0–10 cm is in the range of 4.5%–6.3%, and in the reserve – 7.9%. Materials of work on estimation of productivity of artificial forest communities and their energy indices were transferred to Kryvyi Rih State Forestry Enterprise and State Enterprise "Volodymyrivka Forestry"; materials on steppe communities – to Kryvyi Rih Department of Agriculture, where they are used for forecasting the development of forest plantations in the conditions of the steppe and rational planning of grazing pressure on steppe ecosystems, the allocation of protected areas, etc. The results of research can be useful for the design of protective artificial forest plantations of the steppe zone.