Back to Dendromorphometry dbhg-@comcast.net Aug 18, 2007 19:16 PDT
 ENTS,      With my Holyoke house sold, my toe on the mend, and being semi-retired, it is time to for me return to working on the dendromorphometry guide. So, today I began by modeling a northern red oak in Monica's woods. The statistics for Monica's oak are height = 103.2 feet, CBH = 5.8 feet. The oak is one of several on Monica's land that exceed 100 feet. The tree presents an exceptionally inviting target from the deck of the house. It is an exercise in modeling in comfort. The trunk of the oak is only 67 feet away at eye levelfrom the deck and the height from tree base to eye level from the deck is 31 feet. The tree is fully visible except for the very tips of the broccoli-shaped crown.      On modeling the oak with the Macroscope 25, I calculated 147.1 cubic feet of trunk volume with allowance for the crown as will be explained. I was able to model past the first point of branching. It occurs between 56 and 58 feet above base. From 58 feet, I followed the larger of the trunks, regarding it as the main trunk, up to 67 feet where there was a second branching and there the continuation is less distinct in terms of a main trunk. So at 67 feet, I cheated and used a straight conical volume to the top although I fully acknowledge that the form is hardly conical. After getting the 147.1 modeled volume, I calculated the concical volume based on the CBH just above the root collar and the full height. The CBH at that point is exactly 7.0 feet. The conical volume for a height of 103.2 feet and a diameter at 1 foot of 2.22 feet is also 147.1 feet. Yes, this is a coincidence, but I think the closeness is revealing. I believe that the conical volume calculated for full tree height ht and CBH at just above the root collar will usually equal or be slightly more than the full modeled volume for most straight-trunked, middle-aged eastern trees be they conifer or hardwood. For older trees, the conical volume is likely to understate the modeled volume for some forms and overstate it for others. If there is a big root flare, then the volume will be overstated.      Applying the concept of conical volume just above root flare to the Grandmother tree in Pack Forest, one gets 997 cubic feet - which is too much. But Grandmother has a big root flare. Using Grandmother's diameter at breast height in the cone volume formula, you get 760 cubes, which slightly understates Grandmother's volume. I am doubtful that I modeled the Grandmother tree sufficiently accurately. The mosquitoes were very bothersome and I could have misread the reticle, swatting with one hand. Monica and I will return to the Daks in late October, if not sooner, and the mosquitoes will be gone. I'll have no excuse then.      For the large Dunbar Brook hemlock in Monroe State Forest, the reverse pattern is true. The Dunbar Tree has been modeled to 720 cubic feet of trunk volume. However, the conical volume taken to a broken top height of 116.3 feet with a girth at that point of a foot and a root collar girth of 14.3 feet gives 705 cubes, which falls just short. The tree was probably about 123 feet tall before the dieback. I remembered it when it first started to die back and got a height of 122 feet then. Taking a height of 122 feet, the conical volume would be 662 cubes and the modeled volume would be 721 cubes. The bulging hemlock trunk causes the conical volume to be significantly understated. The form of the Dunbar hemlock trunk is much more columnar than that of the white pines.      We have modeled the huge Dunbar Brook Grandfather white pine to a volume of 932 cubes. The conical volume using its 145-ft height and 16-foot circumference just above the root collar yields a volume of 985 cubes. I will make a prediction at this point that for the vast majority of white pines, the conical volume using full tree height and girth just above the root flare will overstate the volume typically by 5% to 10% and sometimes more. But hemlocks are a different story and Will Blozan well understands hemlock architecture. I look forward to his final Tsuga report. Bob