Climate signal in tree-ring chronologies of Pinus peuce and Pinus heldreichii from the Pirin Mountains in Bulgaria.

Numerous proxy climate reconstructions have been developed for Europe, but there are still regions with limited data of this kind. One region is the Balkan Peninsula, which is characterized by complex interactions between mountains and climate. We present and discuss two tree-ring chronologies—a 758-year-long one of Pinus heldreichii Christ and 340-year-long one of Pinus peuce Griseb. from treeline locations in the Pirin Mountains in Bulgaria. Climate–growth relationships were computed with bootstrap correlation functions and their consistency over time assessed by calculating the correlations over shortened periods. In addition, we reviewed and analyzed climate situations in years with unusually narrow or wide tree rings. Both species were negatively influenced by previous summer drought conditions and cold winters. Early summer temperatures were positively correlated with P. peuce radial growth, whereas P. heldreichii displayed dependence on summer precipitation. In the second half of the twentieth century, the P. heldreichii trees displayed higher sensitivity to summer drought, which was probably a result of increased summer temperatures and decreased winter precipitation. Our findings contribute to more reliable proxy climate records for the region. [ABSTRACT FROM AUTHOR]