ORIGINAL PAPER A recent growth increase of European beech (Fagus sylvatica L.) at its Mediterranean distribution limit contradicts drought stress Willy Tegel • Andrea Seim • Dietrich Hakelberg • Stephan Hoffmann • Metodi Panev • Thorsten Westphal • Ulf Bu¨ ntgen Received: 6 June 2013 / Revised: 10 September 2013 / Accepted: 18 September 2013 Ó Springer-Verlag Berlin Heidelberg 2013 Abstract Future changes in tree growth, associated with a warmer and drier climate, are predicted for many species and locations across the European Mediterranean Basin. How- ever, quantification of the intensity and severity of related consequences for forest ecosystem functioning and produc- tivity remains challenging. Species-specific distribution limits that are particularly sensitive to small changes in the ambient climate may provide an ideal test bed to assess the nature of past growth trends and extremes and their respon- sible controls. Here, we seek to understand how twentieth century climate change affected the growth of European beech (Fagus sylvatica L.) nearby its south-eastern distri- bution limit in Albania and Macedonia on the Balkan Pen- insula. We sampled 93 living trees from undisturbed mixed forest stands at *1,450 m a.s.l. and 29 timbers from nearby historical buildings. Application of different tree-ring detrending techniques allowed robust composite chronolo- gies with varying degrees of high- to low-frequency vari- ability to be developed back to 1648 AD. Comparison with local meteorological station measurements and continental grid-box climate indices revealed spatiotemporal instability in growth–climate response patterns. Nevertheless, year-to- year and decadal-long fluctuations in radial beech growth were significantly (P \ 0.001) negatively correlated at - 0.61 with June–September temperature over the 1951–1995 period. This (inverse) relationship between increased beech growth and decreased summer temperature is somewhat indicative for the importance of plant-available soil mois- ture, which likely controls ring width formation near the species-specific south-eastern distribution limit. Significant positive correlations between beech growth and drought (scPDSI; r = 0.57) confirm metabolistic drought con- straints. However, an unexpected late twentieth century growth increase not only contradicts the previously observed growth dependency to summer soil moisture, but also denies any putative drought-induced forest ecosystem suppression in this part of the Mediterranean Basin. Keywords Albania  Balkan Peninsula  Dendroclimatology  Fagus sylvatica L.  Macedonia  Tree-ring width Introduction The natural distribution of European beech (Fagus sylvat- ica L.) covers most of the Old World’s land mass, spanning a broad biometeorological zone from temperate to warm climates (Ellenberg 1996). From an ecological (e.g. bio- diversity, carbon allocation) and socio-economical (e.g. timber harvest, tourism) perspective, beech is one of the Communicated by C. Ammer. W. Tegel (&)  D. Hakelberg  S. Hoffmann  M. Panev Institute of Forest Sciences, IWW, University of Freiburg, Tennenbacher Straße 4, 79085 Freiburg, Germany e-mail: tegel@dendro.de A. Seim Regional Climate Group, Department of Earth Sciences, University of Gothenburg, 40530 Gothenburg, Sweden T. Westphal German Archaeological Institute, DAI, 14195 Berlin, Germany U. Bu¨ntgen Swiss Federal Research Institute, WSL, 8903 Birmensdorf, Switzerland U. Bu¨ntgen Oeschger Centre for Climate Change Research, OCCR, 3012 Bern, Switzerland 123 Eur J Forest Res DOI 10.1007/s10342-013-0737-7