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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” 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.
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