Comparison FIA Vol Model to NTS

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dbhguru
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Comparison FIA Vol Model to NTS

Post by dbhguru » Fri Sep 13, 2019 12:07 pm

Ents,

For those interested in the volume modeling that we do, please see the attached Excel workbook. It allows comparisons between NTS and FIA volume, and separately, above ground biomass for white pine. You enter the DBH in inches (cell G2), height in feet (cell H2), NTS trunk form factor (cell J10), and circumference at 1-foot above base (cell G42). From there , you can see what the FIA-based Jenkins model gives versus an NTS-modeled volume. However, there are things to explain. I'm trying to establish an apples to apples comparison. The NTS-FIA comparisons is just for: (1) trunk volume, and (2) trunk and limb volume. Limb volume for us is a tricky proposition since we measure only the main limbs, if we measure them at all. So, I'm using the FIA-Jenkins top volume factor to arrive at the volume for limbs, branches, and twigs - one of the returns of the FIA-Jenkins model. We handle the stump within the trunk form factor. FIA-Jenkins breaks it out. They do it on the basis of mass to be able to deal with small branches and twigs. I used the ratio of top mass to that of the bole and stump as a surrogate for the volume equivalent.

Bob
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[The extension xlsx has been deactivated and can no longer be displayed.]

Robert T. Leverett
Co-founder, Native Native Tree Society
Co-founder and President
Friends of Mohawk Trail State Forest
Co-founder, National Cadre

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