Variation in earlywood vessels mean diameters (D, D_s) at breast height of European ash trees, representing different health conditions at time of sampling, over the calendar years 1978–2007. A – mean calculated for nonweighted data (mean diameter D), B – hydraulically weighted ones (mean hydraulic diameter D_s). Calculations are based on at least twenty vessels diameter measurements within each annual ring and records averaged for three trees representing the group of healthy (solid line), weakened (dashed line) or dead trees (dotted-dashed line), respectively, and for 5-y time intervals. Vertical bars denote standard errors.