Thesis for the Candidate degree of Biological Sciences, specialty 03.00.16 - ecology. State Environmental Academy of Postgraduate Education and Management, Kyiv, 2015. The problem of impact assessment of invasive plant species on the plant diversity of the Transcarpathia is devoted in the thesis. The group of the invasive plant species of the Transcarpathia consists of 43 spontaneous alien species, characterized by broad ecological amplitude, allowing them to spread and penetrate in natural and seminatural habitats types. It is shown that three types of spatial distribution of invasive species, which reflect biological characteristics of the species, are identified for the Transcarpathia: (1) “gallery” type, along the river-valley corridors, (2) “continuous” type, cover almost entire area and (3) “mixed” type, got features of both previous types. The majority of invasive species findings are located within the belt of lowland oak forests and floristic region of the Transcarpathia Lowland. The distribution pattern of the model invasive plant species consists of a long lasting “lag” phase and “exponential” phase. The “exponential” phase has started in 1993 (averaged data). The catastrophic floods in 1998 and 2001 have contributed to rapid spread of invasive species propagules and played a crucial role to support an exponential phase of distribution. Climate predictions by Maxent and BIOMOD for 2050 and 2100 which include climate change and anthropogenic activity (deforestation, habitat fragmentation, farming, road developments etc) will break the altitude distribution limit of giant Hogweed and let it to penetrate into higher altitudes. This will be a threat to the structural and functional integrity of the high mountain river habitat types, meadows, subalpine and alpine areas. The seeds germination data of most highly invasive Heracleum sosnowskyi is also presented. The negative impact of invasive species on the vegetation structure and the number of native species, including rare species in plant communities, begins from reaching the critical level of invasive plant cover, resulting in a negative effect. Between plants cover of invasive and native species exist inversely proportional relationship. The invasive plant species have got negative impact on plant diversity of eight aquatic habitat types, five – coastal, three – xerothermic, eight – meadow type, five – bush type, twelve – forest and one sand-pioneer types (in total 42 habitat types). These habitats are residence for 49 regionally rare plant species and 38 plant species listed in the Red Data Book of Ukraine. The lowest impact of invasive species on habitats is among alpine, bog, stream-source and rock habitat types which are the most resistant to invasion. The most threatened types of CORINE biotopes are located within the low oak forests belt. The areas with high and medium level of impact of invasive species on CORINE biotopes cover 16 % each (management concern). The 45,5 % of CORINE biotopes has got the non-significant level of impact, 20,5 % have got the low level of impact and 18 % covers the area of “no impact” of invasive species. The disturbed natural and human-made habitats along the river-valley corridors of the Transcarpathia rivers (Tisza, Latorytsya, Uzh, Borzhava and others) and human settlements reflect the suitability to invasion of the most densely populated and anthropogenic transformed areas where invasive species are frequent. As a result of assessment systems analysis we have selected the group of invasive species with a high impact on plant diversity and estimated likelihood of effective control populations of these species. The tested control invasion methods show a high efficiency, when it applied systematically and in terms that take into account the ecological and biological characteristics of invasive plants. The management control of Heracleum sosnowskyi is developed based on field experiments. The proposals on improving national law and the basic principles of the national concept of invasive species are presented in the thesis.
