I'm probably a little late on this, but coming to grips with what should be a simple task, like defining "big" in the context of champion tree candidates, has proven not so simple.
My thought process has been to begin with my physical approach. In retrospect, every tree that I have encountered as a potential champion candidate was 'big', and reasonably categorized by the trees emergent crown (tree height), and as I got closer, it's trunk (diameter to me is what is visible on approach, not the girth, I know separate argument, but this is still me approaching the champ candidate); and probably the most definitive aspect of a tree's bigness is it's crown.
I think we cut the crown short, or at least measure it short...when I was feeding "tree bio-mass" into FARSITE (a fire area growth assimilation program), we took a measure of the crowns portion of the tree, taking readings on base of tree, base of crown, and the tree's top; and an average crown spread (estimates that were challenged WHENEVER a team member disagreed (two-person team).
I'll say this separately for emphasis....for conifers year around, and deciduous trees when leafed out,
THE TREE'S CROWN IS FOR ME, OFTEN THE DEFINING "BIGNESS".
In the context of champion tree measurements, I like your walk-around/EXCEL table approach...my only thought on improving it would be the incorporation of the GRS Densitometer in determining the accurate "edge" of the crown.
Enough rambling...: > }
Don Bertolette - President/Moderator, WNTS BBS
Restoration Forester (Retired)
Grand Canyon National ParkBJCP Apprentice Beer Judge
View my Alaska Big Tree List Webpage at:http://www.akbigtreelist.org