The results of an investigation of the ergasiophytes (species deliberately introduced to a region for cultivation) of the Ukraine (458 species) are presented. The systematic, life forms and morphological types of plants with respect to soil moisture spectras, origin and degree of naturalisation of species of thіs group are analyzed. A annotated list of ergasiophytes is provided

Cities and Disturbed Areas as Man-made Shelters for Orchid Communities

We present a comprehensive review of the plant invasions of 42 alien species and their impact on vegetation cover in Ukraine. Among these species, those currently posing the greatest threat to the environment have been identified. The structural features of this group were analyzed. In the life form spectrum the phanerophytes and therophytes are dominant, in the ecological spectrum the mesophytes are dominant, and kenophytes predominate at the time of immigration. Among the examined species, plants of North American origin predominate, agriophytes prevail by their degree of naturalization, and ergasiophytes are predominant by their way of entry. The participation of invasive species in natural and anthropogenic plant communities and biotopes was analyzed. These species are a stable component of grasses, scrub and forest habitats. Most of these invasive plants (33 species) are observed in anthropogenic habitats (I). Slightly fewer species of the studied group prefer habitat types E (25), F and G (22 each), although the largest invasions are observed exactly in these biotopes. Invasive species are characterized by eurytopicity. Four species have the greatest ecological plasticity, each of these is found in six types of habitats: Ailanthus altissima (B, F, G, I, J, H), Amaranthus retroflexus (C, E, F, G, I, J), Opuntia humifusa (B, E, F, G, H, I) and Xanthium albinum (B, C, E, F, G, I). Erigeron canadensis is found in five habitat types (C, E, F, G, I). The studied group is characterized by an insignificant regional specificity of the species composition, high invasive potential and stability of population reproduction.

Invasions of nonnative plants are widely recognized as one of the major threats to the biodiversity of natural ecosystems on a global scale. Pioneer and ruderal habitats are the primary locations for the penetration of alien plants. Both pioneer and ruderal vegetation are very close in their genesis and beginning of development; therefore, a comparative analysis of their alien components and historical trends would contribute to clarifying the direction of successional changes and the possible management of destructive processes caused by anthropogenic influences in different types of habitats. The results of a structural and comparative analysis of the alien fractions of the coenofloras of the pioneer and ruderal vegetation of Ukraine indicated that the systematic, biomorphological, ecological, and geographical structures of these species show a high similarity, according to many of the main indicators, which allows them to successfully implement a strategy of invasion, particularly in communities characterized by instability and weak coenotic connections. It was established that the ecotopes of both types of vegetation are very favorable to the penetration and establishment of alien species; however, disturbed habitats of the ruderal type are more prone to invasions. In the communities of both pioneer and ruderal vegetation, alien species can become successfully established at the coenotic level, forming phytocoenoses of different hierarchical ranks. The results of this study will contribute to the identification of general patterns of invasions and the optimization (management) of disturbed and unstable natural ecosystems.

The investigation results of the transformer species participation (Echinocystis lobata (Michx.) Torr. & A. Gray, Heracleum sosnowskyi Manden., Impatiens glandulifera Royle, I. parviflora DC., Reynoutria japonica Houtt., Robinia pseudoacacia L.) in different plant communities of the Ukrainian Polissya (Forest zone of Ukraine) are presented. All the abovementioned species are strong edificators in the region that can significantly change important species composition parameters of communities and character of landscape.