Temporal shifts in leaf phenology of beech (Fagus sylvatica) depend on elevation

Abstract

We analyzed the leaf phenology of European beech (Fagus sylvatica) and its variation due to spatial and temporal climatic variability, using a modified data set of the phenological network in Slovenia. We used first leaf unfolding (LU) and general leaf colouring (LC) time series of 47 sites (altitudes from 55 to 1,050 m a.s.l.) and corresponding climate series (52 of precipitation and 38 of temperature) for the period 1955-2007, collected by the Environmental Agency of the Republic of Slovenia. Across the network in average, LU occurred from 14 April until 13 May, and LC from 3 October until 29 October. LU was delayed by 2.6 days and LC was promoted by 1.9 days when the altitude increased by 100 m. Year-to-year variation of LU was significantly correlated with March and April temperatures. March temperatures had a greater effect at lower elevations and April ones at higher elevations. LC was related to August and September temperatures, and occurred later if the temperatures were higher.Recently, March and April temperatures showed an increasing trend and LU occurred 1.52 days earlier per decade at 1,000 m a.s.l. but no significant shifts were observed at lower altitudes. August temperatures were also increasing but the trends of LC were not significant and were not clearly related to altitude. Our detailed subregional data from a relatively small area with high geographic variability showed that changes in climate affect phenological response, mainly leaf unfolding, to a greater degree at higher altitudes than at lower ones.

Phenology of common beech (Fagus sylvatica L.) along the altitudinal gradient in Slovakia (Inner Western Carpathians)

“…Phenology of common beech was studied by several authors (Cicák, Štefančík 1993;Heide 1993;von Wuehlisch et al 1995;Falussi, Calamassi 1997;Štefančík 1997;Priwitzer, Miňďáš 1998;Chmura, Rozkowski 2002;Schieber 2006;Bednářová, Merklová 2007;Merklová, Bednářová 2008;Barna et al 2009;Schieber et al 2009). Only a few works were devoted to the investigation of phenological responses of beech along the vertical gradient Vitasse et al 2009;Čufar et al 2012).…”

Predicting phenology of European beech in forest habitats

“…It seems to be less sensitive to micro-topographical factors, as reported by Davi et al (2011) in France where the first leaf unfolding of beech did not significantly differ between northern and southern aspects in 2007, though showing a high year-to-year variability. This suggests that factors at a macroecological scale, such as altitude, are mainly affecting the beech first leaf unfolding (Cufar et al 2012). The results of this study show that first leaf unfolding of beech in forest habitats could be predicted based on phenological observations at national phenological stations.…”

“…Slovenia is characterised by fairly large gradients of climatic factors due to its position between the Alps, the Mediterranean and continental Europe (Cufar et al 2012, Luis et al 2014. Consequently, a great variety of forest habitats, from the lowlands to the high mountains, can be found in the country (Kutnar et al 2002).…”

“…However, phenological observations of tree phenological phases have proven to be one of the most effective indicators of the impact of climate change (Donnelly et al 2004). For instance, leaf unfolding is strongly influenced by temperature (Menzel 2000, Cufar et al 2012) and photoperiod . Apart from the global climate change, site characteristics (altitude, slope, aspect etc.)…”

“…also have strong influences on temperature and therefore on the phenology of lower plants and trees (Pellerin et al 2012). Altitude has an inverse relationship with temperature, and therefore phenological events occur later at higher altitudes (Dittmar & Elling 2006, Cufar et al 2012, Pellerin et al 2012). …”