Vegetation changes within the Chornobyl Exclusion Zone, Ukraine

The article presents data from the study of vegetation dynamics in the Chornobyl Exclusion Zone 30 years after the nuclear disaster and the resettlement of its local people. The 1993 prognostic data on the further development of grass and forest community groups in this area was only partially correct. The new prognosis for demutation successions reflects deviations from the linear development with a possible horizontal "shift", depending on climatic conditions, bio-ecological features of plants, as well as the impact of fires. Based on the analysis of recent data from geobotanical studies of the vegetation, the values of ecofactors that determine the course of demutation of communities were calculated. In particular, the classic course of succession is now inherent in the former settlements of the exclusion zone where the formation of forests takes place. In the old fallow lands, the previously prevailing Elytrigia repens has lost its dominant position, and has been replaced by Calamagrostis epigejos, which we associate with a certain deficiency of nitrogen compounds in the soil. The allelopathic properties of cereals inhibit the process of replacing grass communities with forest ones, which affects the course of succession. The issues of demutation of residential areas of the Exclusion Zone are considered and the sequence of changes in different habitats is described. Post-pyrogenic changes in the forest vegetation are noted and the capacity of invasive plant species to invade natural ecosystems are characterized. It is emphasized that frequent and large-scale fires cause a significant imbalance in forest ecosystems, and result in the appearance of a largenumber of alien species.