Fig. 3
Results of the bootstrapped correlation analysis between tree-growth indices and monthly (a) air temperature and (b) precipitation data for site Kratzeburg. Correlation coefficients are shown for the pre (left) and post (right) resin-extraction periods as highlighted in Fig. 2. Dark and light gray bars indicate correlations for tree-ring chronologies derived from resin-tapped and non-tapped trees. Months are abbreviated with lower- and uppercase letters for the previous- and current-year growing season, respectively