| Strength of branch attachment in Acer rubrum L. was
related to the ratio of diameter of the branch relative to the diameter
of the stem to which the branch was attached (aspect ratio). Linear correlation
coefficients ranged from -0.24 to -0.90 between aspect ratio and load (force)
required to separate branches from stems at the branch union. Slopes of
the lines describing this relationship increased with increasing branch
diameter. This indicated that larger branches required greater force to
pull them from the trunk provided they were small compared to the trunk.
However, diameter had less on an influence on force required to pull codominant
stems apart. Force per unit of branch cross sectional area was related (r2
= 56%) to aspect ratio indicating that a branch of a given size was better
secured to the tree if it was attached to a much larger stem than a stem
of equal size. Angle of attachment was not related to strength of branch
attachment. Codominant stems were far easier to split apart than branches
that were small relative to stem size. Codominant stems broken by separating
at the union; branches failed by breaking at or near the collar. This information
has implications for arborists climbing trees and will help guide development
of pruning strategies. |