Rare phytocoenotaxonomic diversity of the steppe zone of Ukraine: analysis and applied aspects

Preservation of rare phytocenotic diversity is one of the priority tasks in the integral problem of biodiversity protection. The implementation of these tasks requires a transition to such principles as the use of a system of preventive/prophylactic and direct methods and modes of conservation depending on the type of vegetation and the homeostasis of plant communities. It was established that the state of rare groups of Ukraine has changed significantly over the past few decades, It is noted that the Steppe biome under the influence of a huge anthropogenic press not only underwent significant changes, but also lost its structure and regulatory properties, which led, in fact, to its destruction and the complete death of numerous elements. The purpose of the work was to compile information on the current state of rare groups in the steppe zone using data from ecological-cenotic and floristic studies, to assess their presence in the territories of biosphere and natural reserves and national natural parks in the region. Field research was carried out using classical geobotanical methods (detailed routing, establishment of test sites, geobotanical description). A critical analysis of the current rare phytocenophyte, the data of modern synphytosozological studies and the latest geobotanical information on the rare phytocenotic diversity made it possible to establish the modern rare phytocenophyte of the steppe zone of Ukraine. It has 321 associations of 48 formations. The forest vegetation has only 16 associations of 3 formations. Steppe vegetation is characterized by the most numerous rare phytocenophand, which is represented by 180 associations of 19 formations, grass and shrub communities of the xerotic type on outcrops and sands have 23 associations of 5 formations, 3 associations of one formation are established for swamp vegetation, halophytic vegetation is characterized by the presence of 13 associations of 5 formations. Higher aquatic vegetation is represented by 86 associations of 1 formation. Summarization of materials based on the results of geobotanical studies of rare taxa carried out in the region after the release of the state document «Green Book of Ukraine» in 2009 allowed to identify 96 associations (1 forest, 79 steppe, 7 grass and shrub communities of the xerotic type on outcrops, 3 halophytic, 6 water), which are new rare associations. The levels of their representation in biosphere reserves (BZ) and nature reserves (NP) and national natural parks (NPP) have been established. They are protected in 22 nature reserve territories (NPAs) of higher categorical ranks, in particular – in 3 BZ, 6 – PZ, 13 – NPP It was concluded that the state of protection of the rare vegetation of the region is typologically and syntaxonomically representative in the PZT system of the highest sociological rank. The level of security for most rare associations is high and average, in a small number of formations it is low. A small number of rare associations are protected in only one PZT, which is insufficient. A number of protected associations are represented by small fragments or groups with a weakened edifying value of the main components.