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Abstract

The work presents the results of the onset and the development of phenological phases: leaf sprouting and flowering of silver fir (Abies alba Mill.) in the conditions of the Borová hora Arboretum (Technical University Zvolen, Slovakia). The onset of the phenophase was considered on the day, when the particular phenophase was observed on at least 10% of trees. Phenological monitoring was performed in the period of 2006–2014 on 26 autochthonous populations originating from Slovakia and elevations of 550–1,100 m above sea level that were divided into three elevation groups. Needle sprouting started on average between April 15 and May 2. Under new conditions, autochthonous populations retained their onset of leaf sprouting that occurred first in the group representing the lowest elevations and last in the third group from highest elevations with a lapse of 9 days. The onset of the phenophase in individual years was related to air temperatures before and during the phenophase. The earliest leaf sprouting was observed in 2014, while the latest needle sprouting in 2006 was influenced by extremely low monthly mean temperature of March. Leaf sprouting lasted 6–9 days on average, and was not dependent on the elevations the populations originated from. Flowering was observed from April 23 to May 9 on average in all elevation groups. The elevation of populations is not a decisive factor for the onset of flowering. The earliest and latest flowering was recorded in 2009 and 2006, respectively, and was dependent on the course of air temperatures before the onset of the phenophase. It lasted 5–7 days on average regardless of the original elevations of populations. The results revealed some changes of phenological events of autochthonous tree species under new environmental conditions that can also occur in their natural distribution due to gradual climate changes.