Alien Species in the Pioneer and Ruderal Vegetation of Ukraine

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

Alien Species in the Pioneer and Ruderal Vegetation of Ukraine

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

Grindelia squarrosa (Pursh) Dunal in Ukraine: current distribution and ecological and coenotic peculiarities

Grindelia squarrosa (Pursh) Dunal. (Asteraceae) is a species with high invasiveness capacity in Ukraine, especially in the Steppe zone. The first data on the finding of escaped plants in Europe were recorded in the 40's of the last century. There were three naturalization centres in Ukraine, from where the species began to spread. In the secondary range in Ukraine, G. squarrosa is characterized by high levels of seed productivity and germination, variable modes of dispersal, wide ecological and coenotic amplitudes and CSR-strategy. The trend continues with the spread of the species in western, north-western and northern directions, and today more than 300 localities confirming this trend are already known. In the past 20 years, 92 new localities have been recorded. G. squarrosa is a transformer, widespread in the southern regions of the Steppe zone. As a result, new plant communities are formed, reaching the syntaxonomic level of associations. In general, this species is recorded in communities of five vegetation classes. G. squarrosa has been identified within the territory of many protected areas of Ukraine. In terms of ecological indicators, the optimum of the species is in the Steppe zone. A distinctive feature of all the scales is that the amplitude towards the minimum is wider than the mean values of the maximum. It can be predicted that, due to the potential ability of the species to adapt and under the influence of climatic change, there is a higher probability that the species will spread in the future in northern and western directions. The condition for such an expansion is disturbance of meadow-steppe fringe xeromesic communities, with decreased coenotic competition