Distribution, ecology and variability of <i>Galanthus reginae-olgae</i> Orph. along the northern limit of its Balkan distribution (Croatia)

Galanthus reginae-olgae Orph. occurs in mainland Greece, the Ionian Islands, Corfu, Albania, Italy, Sicily, Montenegro, Bosnia and Herzegovina, and Croatia. This paper aims to extend the knowledge of the distribution and ecology of G. reginae-olgae in Croatia and the northwestern Balkans. A field study in 2023 revealed as many as 35 populations in southern Croatia, some of them counting up to 100.000 individuals. Most of the populations exhibit semi-sciophilic behaviour within transitional habitats (ecotones) from insolated grassland to shaded eu- and sub-Mediterranean thickets and forests, and are found in the altitudinal range from sea level to 664 m a.s.l., at an average distance of 5.44 km from the coastline. Analysis of the bioclimatic variables reveals that the populations studied find an optimum in Mediterranean conditions with a mean annual air temperature of 14.61 °C and mild winters. The annual precipitation is high, exceeding 1600 mm, although it is limited to the winter period. The analyses of the temperature data provided insight into the environmental conditions that might serve as triggers for the initiation and duration of anthesis. In view of the the observed leaf length and flowering time, the populations are designated G. reginae-olgae subsp. vernalis Kamari. Since the Croatian populations are sparsely scattered along the northern limit of the species’ distribution on the Balkan Peninsula, future research should investigate the adaptability of this species to habitat and climate changes in the eastern Mediterranean region.