Figure 5. Mean xylem lumen area (\(\pm\)SE) of Q. albaand L. tulipifera samples across chronosequences (Panel (a)) and
age (Panel (c)). Groups of bars not sharing the same uppercase letters
denote significant differences (p ≤ 0.05) between species, while
bars within groups not sharing letters denote differences within species
among ages or chronosequences from a two-way ANOVA with species and age
as fixed factors. Panels (b) and (d) show the relationship between mean
lumen area and mean specific embolism threshold of individual trees
assessed by linear regression. Lines are best fit from linear regression
when slope is significant (p ≤ 0.05).