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

Abstract

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.