Importance of the White Pine

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dbhguru
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Importance of the White Pine

Post by dbhguru » Sun Oct 07, 2018 7:32 am

Erik, Elijah, Jared, et al.,

Any help you all could render would be most appreciated to the evolving mission to profile volume growth in Pinus strobes. Basically, it is to model white pines for volume toward calculating its form factor for different age and size classes. For those unfamiliar with this discussion, we can estimate trunk volume of stand-grown white pines (and other conifers) with the following formula:

Trunk Vol = (Trunk Cross-sectional Area at 4.5 Feet) x (Full Tree Height) x (Trunk Form Factor)

The form factor can be. thought of as the proportion that the trunk takes up of a cylinder that has dimensions: height -= full height of tree and base = cross-sectional area of trunk at 4.5 feet.

The stand-grown pines that I've been modeling in the 120 to 160-year age class appear to have form factors ranging from 0.4 to 0.42 with an average of 0.41 probably being a could compromise. Pine approaching 200 years have moved up to into the 0.42 to 0.44 range with 0.43 being a good compromise. Really old pines appear to be in the 0.43 to 0.45 range with a very few around 0.46. Of course, if a 120-year old pine visually tapers rapidly, its form factor is probably 0.37 to 0.39.

Pines say under 70 to 100 years are apt to have factor around 0.35 or 0.37. At 15 to around 60, the factor will be 0.33 to 0.35. I don't know if we should expect a more rapid change to occur in the 50 to 70 to 75-year range, but it appears that way.

White pine is now being seen as an important climate mitigator in the Northeast because of its fast growth rates. The more we can hone or measuring skills and knowledge of this species, in ages above 50 years, the greater our contributions can be.

A simple way to begin developing form factors is to calculate them for reticle-modeled trunks. The reticle modeling gives us our best determination of trunk volume. Then we can compute the factor as follows.

Trunk Form Factor = (Trunk Vol)/[(Trunk Cross-sectional Area at 4.5 Feet) x (Full Tree Height)].

Don't worry about this method appearing arbitrary. There are lots of trade-offs and averaging processes employed in conventional volume models using by the Forest Service. They are buried in the factors expressed in the tables. We could develop visual trunk profiles and associate a form factor with each to help the inexperienced (and experienced also, for that matter).

Well, it is off to the Trees of Peace to refine measurements. It appears that my test acre holds between 90 and 95 tons of above ground carbon, but more measuring is needed.

Bob
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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Erik Danielsen
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Re: Importance of the White Pine

Post by Erik Danielsen » Sun Oct 07, 2018 10:30 am

Unfortunately white pine is scarce and widely scattered in my region at this moment in history, but I'll make sure to check in on those I can locate (Lilydale, Chautauqua Gorge, Zoar, etc) this winter. For many of these I'm not sure how reliably I'll be able to suggest age ranges.

In my region a common tree in secondary forests as well as a component of old forests with a very high growth rate is black cherry, and I've been more and more drawn to that species for similar examination. Expectations for crown volume are the tricky part, of course- sometimes the crown volumes just seem so high (as much as 50% of trunk volume, increasing with age)! Serendipitously some old black cherries in my area with heavy crown architecture have recently suffered wind damage that is enabling ground-truthing with a tape measure on large downed limbs. Results are similar to reticle-modeling of limbs aloft with similar starting diameters and path length, which is encouraging. Not sure if hardwoods like this may benefit from developing separate form factors for both trunk and crown.

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