Genesis and dynamics of the range of Daphne cneorum (Thymelaceae) within Ukraine

Abstract

A detailed study of the geographical distribution and populations status in historical aspects of Daphne cneorum (Thymelaceae), a rare species in Europe, was conducted to establish the dynamics of its range in Ukraine. Analysis of phytogeographic and paleological data showed that this is a migratory relict species (sensu Szafer, 1975). As a tertiary relic, D. cneorum survived in the Volhynian-Podolian Upland. From this refugium, it migrated to the Polissya and Dnipro lowlands as well as the Dnipro and Lublin uplands in the interglacial and postglacial periods. The range of D. cneorum in Ukraine currently consists of two separate areas, Volhynian-Podolian and Dnipro fragments. The disjunction apparently arose as a result of inconsistency of the ecological conditions (acid soils on crystalline rocks) of the Ukrainian shield and physiological needs of the calcephilous species D. cneorum. In our opinion, the disjunctions between the Volhynian-Podolian, Belarus and Lublin parts of the range are of anthropogenic origin. Over the last century, an intensive degradation of populations and fragmentation of the range of D. cneorum took place in Ukraine. Anthropogenic pressure has led to regressive changes in the species range in the country. Due to low seed productivity, plant death is not compensated by replenishment and therefore in disturbed habitats populations of D. cneorum are completely eliminated. The species has apparently disappeared from the flora of Roztocze, Volhynian Upland and the Kremenets Mountains. Since the absolute protection regime is ineffective for D. cneorum populations, the need to develop conservation management for this species in natural habitats is emphasized.