The mechanical degradation of land surface and the present state of the loess “islands” plant cover of Chernihiv Polesie (Ukraine)

The causes of the mechanical degradation of the loess lands of Chernihiv Polesie have been determined, in particular, the ability of the loess to be washed out and subside easily, deforestation (the end of the 13th – the beginning of the 14th centuries) and the excessive increase of the anthropogenic pressure on the agricultural lands (the end of the 19th – the beginning of the 21st centuries). It has been cleared that the degradation of the loess “islands” soils of Chernihiv Polesie is manifested in the form of erosion and suffusion. The areas at the fifth stage of erosion prevail. The largest percentage of the eroded areas is on the Mykhailo-Kotsiubynsk and Ripky-Chernihiv loess “islands”. The lands with suffusion forms dominate on the Berezna-Mena-Sosnytsia loess “island”. Long-term use of the arable lands contributed to the increase of erosion and suffusion forms of the relief. The potential places of the beginning of the mechanical degradation are post-sowing, neglected lands, which were repeatedly violated mechanically. The plant communities, which are the indicators of different stages of mechanical degradation of the lands, have been identified. The plant communities of Digitario sanguinalis-Eragrostietea minoris Mucina, Lososová et Šilc 2016 and Bidentetea Tx. et al. ex von Rochow 1951 are the indicators of eroded lands at the stages of formation, expansion and deepening of washouts. The phytocenoses of Bidentetea tripartiti are the indicators of the initial stages of suffusion, and the complexes of Magnocaricetalia are the indicators of suffusion increase and deepening. Over the past 120 years, there has been a slight increase in the area occupied by plant communities other than agrocenoses on the loess “islands” due to the anti-erosion planting of Pinus sylvestris and Robinia pseudoacacia. The agronomic, fitomeliorative and prohibitive measures that can slow down the pace of the mechanical degradation of the loess lands of Chernihiv Polesie have been suggested

The vegetation of the cretaceous outcrops of Novhorod-Siverskyi Polesie loess “islands” (Ukraine) and the new locality of Gentiana cruciata L.

The vegetation of the cretaceous outcrops of Novhorod-Siverskyi Polesie loess “islands” is represented by the grasslands communities of the Artemisietea vulgaris Lohmeyer et al. in Tx. ex von Rochow1951, Festuco-Brometea Br.-Bl. et Tx. ex Soó 1947, TrifolioGeranietea sanguinei T. Müller 1962 classes and shrubby phytocoenoses of the Robinietea Jurko ex Hadač et Sofron 1980 class. The structure and composition of the plant communities are influenced by the degree of anthropogenic influence (both in the past and present) on the ecosystems of cretaceous outcrops. The determining anthropogenic factors contributing to the formation of the ruderal communities were chalk mining and gardening. The influence of erosive processes is manifested in the spatial delimitation of plant communities of various syntaxonomic belongings. The anthropogenic successional communities: semiruderal grasslands and herblands of the immoral and subboreal zones of Europe (ConvolvuloAgropyretum repentis Felföldy (1942) 1943, Poo compressae-Tussilaginetum farfarae R. Tx. 1931) and scrub communities of temperate Europe, represented by the Elytrigio repentisRobinietum Smetana 2002 phytocoenoses typical for Steppe zones, prevail. Semixerothermic communities were found on the steep slopes of the cretaceous outcrops (eastern and southwestern expositions) – early successional stages with a significant amount of the characteristic species of the Festuco-Brometea Br.-Bl. et Tx. ex Soó 1947 class. On the cretaceous outcrops of Novhorod-Siverskyi Polesie loess “islands” the communities of Trifolion medii T. Müller 1962 (meso-subxerophytic fringe phytocoenoses on nutrient-poor but base-rich soils at lower altitudes of temperate Western and Central Europe) is localized on the slopes of the eastern and southeastern parts of the expositions which do not undergo anthropogenic influence and are separated by erosion forms. Such conditions were favorable for preserving the Gentiana cruciata L. relict species in this locality. The population of this species was found in the area of 50 m2 in the Trifolio medii-Agrimonietum Th. Müller 1962 association community and represented by two compact groups of individuals (the area of 0.5 m 2 each) and individual plants. In order to preserve the habitat of this rare species, it is worth creating here a reserve

Prediction on the content of radionuclides and heavy metals of the Solidago canadensis L. use as a honey resource in Polesie

In the context of the problem of the rational use of the meadow ecosystems of Polesie, which have been exposed to radioactive effect and have not been used economically for a long time, the indicators of radionuclides and heavy metals in soil and plants predict the possibility of using Solidago canadensis L. as a honey resource in summer and autumn periods. The article presents new research results in the direction of studying the species specificity of plants for the accumulation of radionuclides and heavy metals, which are aimed at solving the problem of obtaining the environmentally friendly bee-keeping products from non-traditional honey resources. The habitats of Solidago canadensis were studied in the floodplain of the Dnieper river, its tributaries of various orders and loess “islands” in Polesie – the transformed meadow ecosystems, phytocenoses of which belong to the Molinio-Arrhenatheretea R.Tx. 1937 class, and the ruderal Artemisietea vulgaris Lohmeyer et al. in Tx. ex von Rochow 1951 communities. The content of the radionuclides (137Cs та 90Sr) and heavy metals (Zn, Cd, Pb, Cu) in the soil and inflorescences of Solidago canadensis of 18 sites were analyzed. 11 sites of them, that were not contaminated by the Chernobyl disaster, were analyzed for honey samples. The linear regression equations for honey-plant and honey-soil systems, Pearson’s correlation coefficient (r), significance level (p) and the determination coefficient (r2) for predicting (by indicators of radionuclides and heavy metals in soil and plant) the possibility of honey gathering have been determined. According to the predicted indicators of the heavy metal content and specific activity of radionuclides, it was found that only the meadow ecosystems in the floodplain of the Iput river (the Zalissia village, Dobruskyi district, Gomel region, Belarus) out of 7 studied sites, which were exposed to radioactive contamination in 1986, are suitable for gathering goldenrod honey. In the case of honey gathering on the infested with the Canadian goldenrod meadows in the floodplains of the Dnieper, Sozh and Pakulka rivers, the maximum permissible concentration of cadmium or radionuclides in the products may exceed. It is emphasized that to assess the possibility of obtaining the environmentally friendly goldenrod honey, it is advisable to predict the content of radionuclides and heavy metals in both plants and soil. To do this, it is also necessary to take into account the calculated values ​​of the highest content of heavy metals and the specific activity of radionuclides in soil and plants, at which the metal content in honey will be at the level of the maximum permissible concentration (MPC)

The contemporary distribution of the aquatic Tertiary relict plant species of the Bern Convention in eastern Polesye

In spite of modern trends in the development of the eastern Polesye flora, the relict have been preserved in the aquatic ecotopes of Europe, including eastern Polesye. The paper highlights the peculiarities of the distribution in the region of three aquatic Tertiary relics preserved by the Bern Convention. According to the results of a field research, the degree of a modern rarity of the aquatic relict species in eastern Polesye was established, in particular, a very rare species (Aldrovanda vesiculosa), a moderately rare species (Trapa natans) and a relatively rare species (Salvinia natans). The current distribution of these relict species in the region has been positively affected by the increase in the values of maximum temperatures and isotherms of the summer months. A negative impact is made by the abrupt changes in the hydrological regime and the growth of anthropogenic eutrophication of reservoirs. Aldrovanda vesiculosa eliminates with minor changes in living conditions; Salvinia natans is the most tolerant to anthropogenic factors, but shows annual fluctuations in numbers; Trapa natans is stable distributed and has a tendency to expanding of its populations. The relics are the dominants of the Salvinio–Spirodeletum (polyrrhizae), Lemno Utricularietum vulgaris, Spirodelo–Aldrovandetum vesiculosae, Trapetum natantis and Trapо–Nymphoidetum (peltatae) communities