Branch morphology impacts compartmentalization of pruning wounds

The objectives of this study were to determine: 1) the maximum aspect ratio associated with strong BPZ-forming potential, and 2) if the amount of discolored wood that formed after branch removal was related to branch union morphological characteristics such as aspect ratio, angle of branch attachment, and the presence of observable branch collars. [UMN] 

"Branch diameter relative to the trunk diameter (aspect ratio) impacted the amount of discolored wood that developed in the trunk after branch removal in seedling-propagated red maple (Acer rubrum L.) and live oak (Quercus virginiana L.). More discoloration resulted from removing codominant stems than removing branches that were small compared to trunk diameter. Limbs with aspect ratios greater than 0.39 and 0.59, for live oak and red maple, respectively, resulted in severe trunk discoloration after removal. The presence of branch collars was an indicator of strong compartmentalization potential in both species. Branches having pith that was continuous with trunk pith developed more extensive discoloration after removal than those without pith connections for both red maple and live oak. Pith connections could be predicted in both species based on the presence of branch collars and angle of branch attachment. There was more variability in discoloration among individual live oak trees than among red maples. Cambium dieback, which is often associated with removing codominant stems, was not affected by any of the branch characteristics measured including aspect ratio." [Abstract]