22.05.2017

Tree-ring information and climate response data were applied to investigate the potential of the Carpathian
Mountains to influence tree-growth patterns. Recent studies reveal the importance of constructing a dense spatial
network of oak tree-ring chronologies in this area, which may be the key to linking the North Central
European and East Mediterranean tree records. We establish sixteen oak (Quercus robur L.) and sessile oak
(Quercus petraea (Matt.) Liebl.) site chronologies along a longitudinal gradient (from 22.47 to 26.58 E) in Northern
Romania in an attempt to elucidate the impact of climate on oak growth. Even with differences generated by
interspecific features, habitats and climatic regimes, a common macroclimatic marker for the NW and NE sites
was established by comparing two groups of chronologies separated by the Carpathian chain. Wefound that precipitation
in April (P4) and June (P6)were the primary climate factors that affected tree growth in theNWregion.
For the NE region, the temperature in January (T1) and March (T3) and precipitation in May (P5) were revealed
to be the major limiting climatic factors. The spatial variability of the correlation coefficients indicates a decreasing
trend in correlation intensity with precipitation fromNWto NE, particularly during the current growing season
(March–July). Oak trees fromthe NWand NE regions have adapted to different local climatic conditions and
only respond uniformly to severe climate events (e.g., the 1904 drought). The higher occurrence of extreme years
during the 20th century, particularly in the NE region,was in accordancewith the rise of precipitation variability
in the current growing season. The changes in the tree-growth pattern and climatic response of the chronologies
of the studied sites in the NW and NE regions were linked to the local climates induced by the Carpathian
Mountains.

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