Preliminary Analysis of the Degree of Naturalization in Some Euonymus Species (Celastraceae) in the Central Part of European Russia and the Caucasus: Results and Further Trends

Abstract

The article attempts to evaluate the degree of naturalization of a number of the Euonymus species in the Central Russia (E. europaeus L., E. nanus M. Bieb., E. maackii Rupr., and E. pauciflorus Maxim.) and in the Caucasus (E. japonicus Thunb. and E. fortunei (Turcz.) Hand-Mazz.). A critical analysis of the available data made it possible to establish that that the species run wild from the places of cultivation (old estate parks and gardens); for a long time, they grow in abandoned estates; they often give self-sowing and reproduce vegetatively; they occur in seminatural and synanthropic habitats (forest zones and forest plantations, forest parks, near housing, roadsides); sometimes, they go into the forests. All species are neophytes according to the time of immigration, ergasiophytes according to the vector of invasion, and colonophytes (most species) or even hemiepecophytes (E. europaeus) according to the degree of naturalization; they all have the status of potentially invasive plants. The “success factors” of these species, largely related to the peculiarities of their biology, as well as the proximity of the boundaries of their native ranges, are also considered. An increase in the degree of adaptation of certain species was noted when moving to more northern regions of the Center and Northwest of European Russia, and therefore it is necessary to monitor the state of their populations.