On the diagnostics of biochemical activity of alien plant species in the Non-Black Earth region of the Russian Federation

Background. The attention of researchers to adventive species, many of which have the status of invasive, is not accidental, since a powerful adventization process on a global scale reduces the elements of biological diversity, changes the properties of the community biotope, causes soil fatigue, increases the ecological and economic costs when calculating the environment-forming function and necessitates remediation measures. Domestic and foreign authors study the features of advents to identify the features of florogenesis, to produce sorbents of various action spectra from the biomass of invasive species, as well as to identify the features of ecological-biological and ecological-biochemical effects on inorganic components of communities and to develop an action plan for rehabilitation, limiting the number of coenopopulations. For the Bryansk region as the administrative center of the Non-Black Earth Region of the Russian Federation, the creation of a biomonitoring base for the ecological-biochemical and allelopathic activity of advents is relevant.

The aim of the work is to summarize the data on the allelopathic and ecological-biochemical activity of adventitious species in the habitats of the Bryansk region for the initial stages of creating a biomonitoring base.

Methods and research techniques. The studies were conducted for 8 adventitious species as a supplement to the existing ecological-phytocenotic studies. Adventitious communities were studied within natural boundaries using the geobotanical, gravimetric method, soil-ecological methods and research techniques. In office conditions, the features of the allelopathic effect were established using the phytotoxicity method; using laboratory chemical methods, the activity of urease, catalase and cellulase was detected to establish the features of soil transformation during the expansion of adventitious species.

Results. In field conditions, it was found that the greatest biomass is developed by the species Echinocystis lobata (Michx.) Torr. Et Gray, Lupinus polyphyllus Lindl., Helianthus tuberosus L., Rudbekia hirta L.; determined by the sizes, the highest densities of placement of adventitious individuals were found for Xanthoxalis stricta (L.) Small, Erigeron annuus (L.) Pes., Oenothera biennis L. The determination of phytotoxicity showed that the soil extract in the areas of distribution of the species Echinocystis lobata, Rudbekia hirta, Aster salignus Willd., Helianthus tuberosus inhibits the germination of biotester seeds to the greatest extent; the smallest growth of biotester roots to the control was recorded in the soil extract for the same species. The lowest phytotoxicity was found in the soil for the species Oenothera biennis, the highest - for Echinocystis lobata, Rudbekia hirta, Aster salignus, Helianthus tuberosus. Species features of adventitious species affecting the dynamics of enzymes in the soil were established. The enzymatic activity of urease is most indicative for the soil under Lupinus polyphyllus, Xanthoxalis stricta, Erigeron annuus, Oenothera biennis. Catalase activity was found to the greatest extent for soils with the growth of communities of Erigeron annuus, Oenothera biennis, the minimum indicators – Rudbekia hirta, Aster salignus. A significant number of microorganisms are formed in soils under coenopopulations of Lupinus polyphyllus, Xanthoxalis stricta; minimal cellulose decomposition was recorded for Echinocystis lobata and Helianthus tuberosus. According to urease, catalase and celluase activity, the soils under adventitious species are classified as «moderately enriched».

Conclusion. The conducted studies confirmed the hypothesis of possible use of the impact of root allelopathic secretions on native species by adventitious species: all substances are produced by adventites in accordance with species characteristics. The greatest soil fatigue is caused by settlement in habitats of Echinocystis lobata, Rudbekia hirta, Aster salignus, Helianthus tuberosus, which necessitates large-scale and deep soil remediation by chemical, agrotechnical or biological means. The studies recorded increased data on enzymatic activity compared to natural meadow habitats. Stimulation of oxidoreductase and hydrolase activity is also a species-specific feature of plants, although catalase activity is almost the same for the studied species. The increase in the rate of cellulose decomposition, registered in foreign studies, is due to some stimulation of bacterial diversity, apparently specific to adventites. The introduction of adventitious species into natural communities affects the rate and intensity of biogeochemical cycles. In practical terms, the studied patterns are recommended for planning measures for the mechanical removal of adventites from communities; it is also important to design combined microbial preparations for biotechnological remediation of substrates, which involves a radical transformation of the microbiota.