Table 1.

Estimates of the scaling exponents α and β in C∝D^α and C∝H^β, where C is the hydraulically weighted conduit diameter; D is stem diameter; and H is the distance from the treetop. (The estimates are the averages (with 95% confidence intervals) obtained from 15 trees of Nothofagus solandri and 10 trees of Pinus sylvestris and Picea abies, and these were obtained by type II regression of log–log transformed data. The column labelled p indicates whether a cubic function gave a better fit to the transformed data than a linear function (^*p=0.01, ^**p=0.001).)

species	α (95% CI)	p	β (95% CI)	p
Nothofagus (earlywood)	0.23 (0.22–0.25)	n.s.	0.24 (0.22–0.25)	n.s.
Nothofagus (latewood)	0.26 (0.24–0.28)	*	0.27 (0.25–0.29)	*
Pinus	0.23 (0.21–0.25)	**	0.15 (0.14–0.17)	**
Picea	0.26 (0.23–0.28)	**	0.16 (0.14–0.18)	**
WBE theory	>0.166	>0.20