Modelling of Heracleum sosnowskyi Manden. and Heracleum mantegazzianum Sommier & Levier Population Area Increase Rate

On the basis of developed individual-based model and empirical data the importance of anemochory for the dispersal of giant hogweed mericarpia over long distances (up to 55 m from the parent plant) was proved. The use of cellular automate for modelling of the plant population area increase allowed to reveal the influence of weather condition, number and spatial distribution of hogweed plants in the period of the beginning of introduction on the rate of invasion. Verification of the results of the cellular automaton work based on satellite images and field observations showed a significant level of compliance of theoretical calculations and observed results. The logistic functions parameters describing the change in the area of giant invasive hogweed stands were determined. A retrospective analysis of satellite images of model plots, starting from the 1990s of the 20th century, showed an annual increase in the area of hogweed populations by 20% in the exponential population growth phase. A significant variability in the rate of invasion (from 5 to 70% per year) depended on the initial conditions and stage of invasion, usage modes and ecological capacity of the available sites.