Euonymus nanus (Celastraceae) in Europe and in the Caucasus Mountains: geographi-cal distribution, habitats and modern state of populations

Abstract

The study of the current state of populations and habitats of rare and threatened species of plants is a relevant task of ecological research. The paper presents the results of investigation of the geographical distribution, habitats and modern state of populations of a rare species of the European and Caucasian floras Euonymus nanus M. Bieb. (Celastraceae), included in the Red Data Books of Ukraine, Moldova, the Russian Federation and the Red List of Romania. The structure of the European and Caucasian parts of its range is described. The natural range of Euonymus nanus includes Romania (the Carpathian Mountains and the Moldavian Plateau), Moldova (the Moldavian Plateau and Southern Podillia Upland), Ukraine (Podillia and Dnieper Uplands and Dnieper Lowlands, Crimean Mountains) and the Russian Federation (North Caucasus). There are near 100 localities of E. nanus in Europe and 6 localities in the Caucasus Mountains. A phytocoenotical peculiarity of European habitats of E. nanus is their confinement exclusively to deciduous forests. This is their difference from Caucasian habitats, connected with scree slopes and from Asiatic habitats, connected with coniferous forests. Biogeographical and paleontological data and some biological peculiarities of E. nanus (low reproductive potential) confirm its relic nature (Tertiary relic) in Europe. The claim that E. nanus has an alien origin in Europe is insufficiently scientifically substantiated. The current state of E. nanus populations in Europe and in the Caucasus Mountains is shown. Known local populations of E. nanus are few in number, with relatively low densities, and their gradual decline is observed everywhere. Due to the uniqueness of E. nanus populations, it must be included to the European Red List. Modelling of E. nanus populations in cultivated coenoses is an effective method of ex situ conservation for this species.