Growth responses of Pinus sylvestris L. to climate from the southeastern limit of its natural distribution area, Turkey

Abstract

Pinus sylvestris, the most widely distributed pine species, is commonly used in dendrochronological studies. Based on a lack of studies at its southeastern distribution, we analysed the growth responses of P. sylvestris to temperature and precipitation. We selected 13 sites to study the effects of climate on the growth of Scots pine stands throughout a geographic gradient over time. Trees were sampled from pure stands at different elevations and landscape conditions. The linear and non-linear associations between tree-ring widths and climate variables were calculated with locally specific linear correlation analysis and a mixed generalised additive model. Moving window correlation function was also performed to understand the temporal stability of limiting factors on growth from 1930 to 2013. Our findings showed that early spring temperature (March-April) and late springearly summer precipitation (May-June) are the major drivers of growth at all sites, where high temperature constraints and high precipitation enhances the growth. Moving window correlation analysis highlighted that the response to precipitation was stationary while temperature changed over time. Our non-linear analysis provided a threshold for March-April temperature. The threshold indicates that the relative additional increment sharply increases up to 7 degrees C and then slightly decreases.