Volume 9 (2021): Edizione 4 (December 2021)
Special issue: The current status of invasive plants in Central-Eastern Europe

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.

This article provides a review of the current status of plant invasions in Belarus. As a result of this research into the alien flora between 2008 and 2020 a list of 52 invasive plant species that threaten biodiversity, human health, and economic has been compiled. About 300 taxa of non-native plants are currently classified as potentially invasive. The list of invasive plant species has been proposed in this article in accordance with trends in the invasive processes is the basis for the monitoring and management of plant invasions in Belarus. The preliminary data from the previous field seasons showed a significant increase in the population abundance and distribution of Swida alba, Rudbeckia laciniata and Artemisia abrotanum. Enrichment of the flora occurs due to the introduction of aggressive plants. Hybridization between native and alien plant species leads to the appearance of hybrids, which often have an invasive potential, and can invade not only disturbed habitats but also natural plant communities. The invasive properties, expansion, and aggressive behavior of these invasive plants of the alien flora of Belarus has led to significant, often irreversible, changes in the natural vegetation and vegetation cover. Invasive species such as Solidago canadensis, S. gigantea, Echynocystis lobata, Impatiens glandulifera are marked by rapid expansion over past decades, and Heracleum sosnowskyi, Solidago canadensis, S. gigantea, Echinocystis lobata, Impatiens parviflora, Acer negundo, Robinia pseudoacacia, Bidens frondosa, have invaded more recently.

This article summarises the history of research into alien plants and plant communities in Slovakia (Central Europe). Earlier periods are reviewed briefly with reference to literature sources dealing with those periods more comprehensively. A milestone in the research was the publication of the Inventory of the alien flora of Slovakia in 2012 with a complete list of alien vascular plants. The last ten years are discussed more extensively in the article in four sections devoted to i) newly found alien plants, ii) distribution and habitat relations, iii) plant invasions, iv) citizen science based on the comprehensive excerption of literature sources. A list of 51 newly published alien taxa within the last ten years is also included with information on the year of their first occurrence in the wild in Slovakia.

An assessement of the alien plants of Romania was conducted which considered the requirements of Regulation 1143/2014 of the European Union (EU). Thus, available data about the presence, invasiveness, distribution, pathways of introduction and their known impact in the territory of Romania were analysed. We found that of 36 plant species of EU concern, four are already established in Romania and widespread, at least locally or regionally: Ailanthus altissima, Asclepias syriaca, Elodea nuttallii and Impatiens glandulifera. For Humulus scandens there are some reports, but its presence and status require confirmation. Heracleum sosnowskyi and Ludwigia peploides are confirmed for only one location for each species. The presence of Cabomba caroliniana and Myriophyllum aquaticum in Romania is not confirmed. Most of the records are intentional introductions for ornamental purposes. Regarding their invasiveness, given the geographical origin and history of invasion in warmer climate regions (e.g., tropical, subtropical), many of the species listed as being of EU concern do not currently constitute a real threat to Romania, for the time being, but may do in a climate change scenario for the 2070s. Data about the impact of alien plant species and their management in Romania are scattered or completely missing. Coordinated institutional efforts are needed to increase the efficiency of the management of alien species at national and local level. These efforts should include: enhancing the legislation and the capacity of public institutions to manage invasive species, increasing the research interest in the science of this topic and promoting real measures to mitigate, control and remove alien plants.

This article is focused on the analysis of major approaches to plant invasion research used by Russian researchers. They fall within three main groups: 1. Conventional approaches to floristic analysis based on the Russian scientific tradition of floristic research, 2. Approaches focused on the study of the fraction of invasive flora, making blacklists and regional Black books, 3. New comprehensive approaches based on a synthesis of methods used in botany, geo-information technology and population genetics. Multivariate statistical methods allow for the visualization of various data, including those on alien species group structures in various regions. They make it possible to identify boundaries of ecological niches occupied by plants in respect to climate-and-environmental or ecological variables. An assessment of current statistical interdependence between alien plant characteristics and scores of factors limiting their dissemination facilitates the making of predictive models of plant invasion. Examples of multivariate statistical methods used in invasion biology were analyzed, along with different approaches to the study of the variability of alien species. Alien and invasive fractions of the flora of the Trans-Siberian Railway were analyzed not by administrative units but by natural biomes. This approach allowed us to assess the correlation between the number of invasive species with different natural-climatic and floristic characteristics of biomes. The publication of "Black Books" of various administrative subjects of Russia according to a unified methodology allowed us to make an inventory of invasive species over the vast territory of the country. The experience gained by Russian researchers may be further used for developing universal approaches to plant invasion research.

The article presents the results of an analysis of the alien flora of the ruderal vegetation of Ukraine. A total of 325 alien species which belong to 58 families and 198 genera were identified. The total anthropogenization index of the ruderal phytocoenoses is 19.8%. It was established that the highest level of anthropogenization was found in the phytocoenoses of Polygono-Poetea annuae, Stellarietea mediae and Plantaginetea majoris. The leading families of the non-native fraction of the studied plant communities were Asteraceae, Brassicaceae and Poaceae. It has been revealed that in the biomorphological spectrum of alien plants therophytes prevailed. The ecological analysis has shown the predominance of submesophytes, acidophytes, semieutrophytes, acarbonatophytes and heminitrophytes plants. It was established that according to the arrival time the kenophytes predominate and by the degree of naturalization – the epoecophytes. Comparison of the alien species composition of the ruderal plant communities by means of Jaccard’s indices showed the most similarity between the classes Polygono-Poetea annuae and Plantaginetea majoris, Robinietea and Galio-Urticetea, Stellarietea mediae and Artemisietea vulgaris. For the separate classes the indices of archaeophytization, kenophytization, modernization and fluctuation of the flora were calculated. It has been established that there are 23 highly invasive species in the ruderal vegetation of Ukraine and among these Ambrosia artemisiifolia, Anisantha tectorum, Grindelia squarrosa, Heracleum mantegazzianum, H. pubescens and Xanthium oreintale ssp. riparium are transformers.

The participation of species of alien origin in the flora of individual regions of the world is increasing. A large proportion of these species pose a threat to biodiversity. Issues of the dynamics of changes in the flora and the scale and pace of the processes, with particular emphasis on the biology, ecology, chorology, and genetic variability of the populations of plants of alien origin, including those alien species which are invasive, have been the subject of many years of research in this field in Poland. The present study is an overview of the state of research on invasive plant species in Poland, including the main results of the basic and applied research which have provided the basis for (i) the preparation of a list of invasive plant species for Poland; (ii) assessing the degree of invasiveness of the species analysed, in accordance with the adoption of criteria and the development of methodological solutions. In this work, a new version of the list of invasive plant species has been prepared on the basis of earlier studies, combining theoretical and practical aspects of definition, and it is compared with the list of invasive alien plant species considered to constitute a threat to the EU and Poland as a member country. The categorization (risk assessment) of invasive alien species along with the identification of the most endangered types of natural habitats is often used in practice in the management of invasive plants in Poland. The results of our research have fed into the formulation of legal regulations at the global and regional levels.