I would agree that for comparison purposes that this multitrunk tree should not be directly compared to single trunk trees. However for species like cotonwood, balck willow, silver maple and similar trees which are often subject to stem damage, a multitrunk form is a normal habit for these trees. Along rivers fro example, flooding will push debris into the tree trunks growing in the floodplains, damaging and break ing them off. This commonly leads to the sprouting of secondary stems.These giants should not be ignored because a common or normal growth habit for these trees does not comform to the typical single stem pattern of other trees grwoing in other conditions.
I am trying to develop a listin of some of these exceptional mutitrunk trees separate from those of singel trunk trees and have a start posted to the website. Because of the varied forms a measurement protocol is difficult to standardize for every tree. On the multitrunk page: http://www.nativetreesociety.org/multi/index_multi.htm
I proposed this set of measurements be taken:
"The different stems of these multi-trunked trees often flair outward. The fused base should be measured at a height of 4.5 feet, if it extends that high, or measured at the narrowest point below 4.5 feet when it does not extend that high. The number of individual stems making up the measured girth should be noted, in addition any stems not included in the girth measurement should also be noted. Where possible the girth of the largest single stem should be measured at 4.5 feet or at whatever height it becomes separate from the multi-trunk mass for comparison with single trunk trees. Optionally the girth and height of each individual stem making up the multitrunk tree can be measured. The height of the tallest stem, and the crown spread of the multi-trunk mass should also be measured. "
I found it interesting that when looking at the tree shapes of the various live oaks on Larry' Tucies Live Oak list, in which I plotted the ratio of girth, height, and crown spread on a terniary diagram, that the shape of the mutlitrunk trees on the list plotted within the same tight group as the trees with only a single stem.
"I love science and it pains me to think that so many are terrified of the subject or feel that choosing science means you cannot also choose compassion, or the arts, or be awe by nature. Science is not meant to cure us of mystery, but to reinvent and revigorate it." by Robert M. Sapolsky