ECOLOGICAL AND GEOGRAPHICAL POTENTIAL OF AMBROSIA ARTEMISIIFOLIA L. DISTRIBUTION TO THE NORTH OF THE EUROPEAN RUSSIA BASED ON A COMPARISON OF THE NORTHERN BOUNDARIES OF THE PRIMARY AND SECONDARY RANGES

During the expeditionary research, we specified the modern actual border of naturalization of in the European territory of Russia. This border passes through Kursk Region, as well as the north of Voronezh and Saratov regions. The total length of the expeditionary routes was around 8900 km with 777 locations surveyed. In order to identify the potential for its further spread to the north we performed comparative ecological and geographical analysis and modeling of the ragweed distribution in the north of its secondary range in the European Russia and in the primary range in Canada. Insufficient heat supply during the seed ripening period is the main factor limiting the spread of ragweed to the north. To determine the ecological and geographic niche of ragweed, we compiled a global map of the distribution of accumulated degree days above 10 °C for the period from the transition of the day length under 14 hours to the stable frosts in autumn (ADDfp). The ADDfp values were determined at the northernmost points of naturalization of in the European Russia and in Canada. Comparison of the ecological and geographical boundaries regarding the heat supply in the European Russia and in Canada showed that the ecological and geographical niche realized by ragweed in the North America is now generally wider than the one on the European Russia. We considered the possible reasons for the under-occupation of a potential ecological niche in the European Russia and made assumptions about the possibility of its further spread to the north. Regarding the factor of heat supply in the European Russia, ragweed can spread further to the north - in Bryansk, Oryol, Lipetsk, Tambov, Saratov, Orenburg regions, southern half of Penza Region, the south of Ulyanovsk and Samara regions and Bashkortostan. Additional difficulties with the species’ distribution in the northeastern direction in the European Russia can be attributed to an adverse effect of an additional factor: insufficient moisture supply, since in the Saratov Region and to the east ragweed is in the ecological pessimum simultaneously in terms of heat and moisture supply at its northern limit of distribution.