Fig. 2

a Relative basal area increment (relBAI) for fir, oak, and birch measured between 1997 and 2002. Box plots The box length covers the first and third quartile value of the trees, and the bold line inside the box is the median. Notches define a confidence interval of the median. Whiskers extend to the most extreme data point between the box and 1.5 times the box length. b Growth–mortality (expressed in logits) relationship according to the variable relBAI for fir, oak and birch