3.2 The branch L-d scaling exponent among tree
performance and branch position
The branch L -d scaling
exponent of all individuals was 1.31 (95 % CIs = 1.27 - 1.35, p< .001; Table 2; Fig 3A). Likewise, the branch scaling
exponent showed significant differences across tree performance
(p < .01). The L-d scaling exponent significantly
decreased from 1.50 (95 % CIs = 1.42 - 1.59, p < .001)
for inferior trees to 1.33 (95 % CIs = 1.25 - 1.41, p< .001) for moderate trees, and 1.34 (95 % CIs = 1.27 - 1.41,p < .001) for superior trees (Table 2; Fig 3B). TheL -d exponent also numerically decreased as branches
deepened within the crown (p < .001), i.e., from 1.34
(95 % CIs = 1.25 - 1.44, p < .001) for upper branches,
to 1.09 (95 % CIs = 1.04 - 1.14, p < .001) for
intermediate branches, and 1.02 (95 % CIs = 0.97 - 1.08, p< .001) for lower branches (Table 2; Fig 4A).
In the intermediate and lower canopy layers, the branchL -d scaling exponent decreased as tree performance
deteriorated (Table 2, Fig 4CD).
Furthermore,
numerical differences in the branch L -d exponent of trees
among different growth vigour were significant only in the intermediate
canopy layer (p < .001, Fig 4BCD). Specifically, theL -d scaling exponent of inferior trees (a = 1.34,
95 % CIs = 1.23- 1.46, p < .001) was significantly
numerically larger than that of moderate trees (a = 1.08, 95 %
CIs = 0.97- 1.20, p < .001) or superior trees (a= 1.04, 95 % CIs = 0.98-1.14, p < .001) (Table 2; Fig
4C).