Wetlands of the Volhynian Polissia (Western Ukraine) : classification, natural conditions of distribution and spatial difference

The post-glacial areas are characterized by favorable conditions for the formation of wetlands as a result of the widespread occurrence of depressions without outflow - center for the development of wetlands. The studies of morphogenetic conditions of the wetland development in Volhynian Polissia within the territory of Ukraine and the formation of their water regime reveal several features of their distribution and typological variety. The location of wetlands were characterized in reference to the shape of base/subsoil and its lithology. The typical structure of post-lacustrine, paludificational, riverside and spring peatlands of the Volhynian Polissia were shown and their development were also discussed. The wetland evolution under the influence of the postglacial landscape degradation leads to disappearance of the depression wetlands in glacial forms, increase of the peat bog trophicity and the level of peat dissolution. The supply conditions and characteristics of water regime are determined for separate peatlands. According to the origin and water flow/supply four types of wetland were extracted: ombrogenic, topogenic, soligenic and fluviogenic. It was found that the reasons of the high marshes areas (21%) in Volhynian Polissia are the geological and geomorphological conditions retaining/stopping the runoff and also local groundwater circulation system.