Phenology of leaf development in European beech (Fagus sylvatica) on a site in Ljubljana, Slovenia in 2020Škrk Dolar, Nina (Avtor) Črepinšek, Zalika (Avtor) Čufar, Katarina (Avtor) phenologyleaf developmentvariabilityEuropean beech (Fagus sylvatica)Sloveniaresearch dataIn spring of 2020 we observed leaf phenology in mature European beech (Fagus sylvatica) trees in Tivoli, Rožnik and Šišenski hrib Landscape Park in Ljubljana, Slovenia (46.05°N, 14.49°E, 310 m a.s.l.). A group of 11 trees was selected for daily monitoring of leaf development. We recorded seven phases from dormant buds, through leaf unfolding till development of mature leaves. At thesame time,photos were taken to illustrate the leaf development. First developing leaves were observed on 4 April in one tree. General leaf unfolding, as defined by International Phenological Gardens (IPG),was in different trees observed between 7 and 25 April 2020. Occurrence and duration of individualphases of leaf developmentshowed great variation within and between trees. General leaf unfolding of the tree included in long-term monitoring program of the Environmental Agency of the Republic of Slovenia (ARSO) occurred on DOY 105(14April 2020) which is 4days earlier then long-term averageof the same tree whichis ascribed to above average temperatures in winter of 2019/2020. Repozitorij Univerze v Ljubljani20202020-06-11 14:01:46Neznano116807UDK: 630*181.8:630*176.1COBISS_ID: 269175811sl