PEST PLANT SCORE OF ALIEN Robinia pseudoacacia IN RiGA (LATVIA) AND KAUNAS (LITHUANIA)

Robinia pseudoacacia is an alien tree species that has wide distribution in green areas of Rîga and Kaunas. In recent years, the spread and invasion of this species was observed. The aim of this study was to determine the relative importance of invasiveness of R. pseudoacacia in Rîga and Kaunas. The degree of species invasion was estimated by applying the Pest Plant Prioritization Process, which is based on the Analytic Hierarchy Process method. The results showed that the invasive degree of R. pseudoacacia was near medium (0.4); the present compared to potential distribution rating was medium (0.57) and the social, environmental and economic impact score was very low (0.17). The Final Pest Plant Score for R. pseudoacacia was near medium (0.426). The obtained estimates indicated that black locust was medium invasive, and that well-lit conditions favour its establishment.