Fig. 5

Boxplots showing standardized ring width (RW), wood density (RD), concentrations of aluminum (Al), sulfur (S), potassium (K), calcium (Ca) and calcium to manganese ratio (Ca/Mn) stability during extreme droughts from C. fissilis trees from the southern Amazon. Different letters indicate significant differences (p < 0.05) between droughts. In the box plots, the boundary indicates the 25th percentile, a solid line within the box marks the median, an asterisk within the box marks the mean, and the upper boundary of the box indicates the 75th percentile. Whiskers above and below the box indicate the 10th and 90th percentiles. Blue lines show the relations between tree-ring parameters and years of extreme droughts, and Pearson’s correlation coefficient is presented at the bottom. Extreme drought events in 1981–1983, 1997–1998, 2005–2007, 2010–2011, and 2014–2015 in the southern Amazon basin were selected (Espinoza et al. 2019)