Volume Measurement of Gene's Oak

Moderators: edfrank, dbhguru

User avatar
JHarkness
Posts: 245
Joined: Sun May 13, 2018 5:44 pm

Volume Measurement of Gene's Oak

Post by JHarkness » Fri Jan 11, 2019 7:42 pm

ENTS,

A few weeks ago I purchased a Vortex Solo R/T 8 x 36 tactical monocular and have been working to begin volume measuring some of the more exceptional trees on Perry Hill. I put up a post on a hemlock I had modeled as a test, but I have removed that post as I now have a better understanding of the methodology behind reticle/rangefinder based volume measurement and figured it would be better to have a post on volume measurement of a big-crowned hardwood as an alternative.

The purpose of this post is to run my methodology/volume measurement technique by more experienced measures in the hope that if there are any errors, they will address them. It should also serve as a means for those new to volume measurement to get at least a rough understanding of the techniques involved.

The tree I chose to volume model is the largest forest-grown tree on Perry Hill, and is likely the second largest overall if open grown specimens are included. The tree is Gene's Oak, a northern red oak (Quercus rubra) which grows along the upper reaches of Perry Hill Brook in a small protected glen.

IMG_8690.jpg
As of 1/11/2019, Gene's statistics are:
Height: 110.3'
Circumference: 12.58'
Trunk Volume: 606.6ft3
Limb/Crown Volume: 210.3ft3
Total Volume: 816.9ft3



On to the measurement process, I began by modeling the trunk from the creekbed from 71' to the north, this isn't the best viewpoint and provides now view of the tree's crown, but knowing that the tree has a fairly elliptical trunk, I needed a second angle. I took slope distance (71.5') and angle (-11.1) with my TruPulse 200 from this site to the tree's midslope location, the reticle reading at this location was 97, and that may be a little conservative as I couldn't quite see the edge of the root flare from my vantage point, at most it was 3-4 hashmarks short. I treated the first frustum as a neiloid given its very evident concave shape. I then began working my way up the trunk repeating the process treating each frustum as a paraboloid until I reached where one of the tree's main leaders had snapped off a little over 55' up the trunk nearly a decade ago, there is a significant bulge in the trunk just below this limb, however it is not much of a concave shape, so I treated this as conical. At this point I lost visibility of the upper trunk and the crown, so I moved to a position approximately 90 degrees opposite my first, I repeated the same process on the main trunk working up to the broken limb, interestingly I found that while the diameter at ground level from my first position was 7.44', and the diameter at ground level from my second position was only 5.34', the trunk above the basal flare is wider from this viewpoint overall. Including the radius of the trunk at the point of measurement into my slope distance measurements produced a resulting trunk volume below the broken limb of 405ft3. Continuing onto the upper trunk, which is technically a very large near-vertical leader, I measured several more parabolic frustums to a height of 70' above midslope, resulting in a total trunk volume of 606.6ft3.



Next would be the hard part, modeling the tree's extremely complex crown.
IMG_8668.jpg
I knew right away that I wouldn't be able to measure every last significant limb in the crown, so I would have to volume measure what I could and take an educated guess at the total volume. The biting cold wind chill (around -3F this afternoon) prompted me to model the crown as quickly as possible.

The process I've personally adopted for crown modeling of hardwoods, is to sketch the crown and label all significant limbs to be modeled, I labeled them as "A" through "I" for this tree. For the purpose of limb modeling, I switched to using the trapezoidal method, utilizing one of Bob Leverett's Excel spreadsheets. At the point where the trunk ends, it splits into two large leaders, the largest of which was to be Segments A through C. Segment D became a smaller limb branching from the main leader, I was not able to continue modeling frustums for this limb, as well as several others, due to poor visibility through the tree's dense crown, so I recorded slope distance and reticle width measurements for both ends of this segment. Segment E became a smaller limb branching of Segment D, I modeled this as it visually appeared to be an "average" sized limb for the crown and could be multiplied to account for poorly visible limbs elsewhere in the crown that would be difficult, if not impossible to model. Segments F and G were of the slightly smaller of the two main leaders, and like Segment D, I lost visibility of these limbs after a certain point and was unable to finish modeling them, this is where my usage of Segment E would be helpful. Segments H and I were assigned to two much lower limbs on the main trunk, both of which had been snapped off over the years and were completely dead, effectively acting as small snags projecting from a much larger live tree.
Cropped view of crown, mapped out with Segments marked and labeled.
Cropped view of crown, mapped out with Segments marked and labeled.
Segments A through C contained 46.4ft3 of volume, D contained 8.2ft3, E contained a mere 6.7ft3, however I estimated that 13 of limbs of equivalent size would make up for the unmodeled sections of crown. E x13 equals 87.2ft3 of volume. Segment F and G were modeled to 28.6ft3, and the two dead limbs, Segments H and I, were modeled to 10.2ft3 and 29.7ft3, respectively. That produced a total crown volume of 210.3ft3. Giving the tree a total volume of 816.9ft3.


In hindsight, I see how I could have improved the result, such as modeling more limbs and breaking modeled ones up into smaller frustums, therefore more segments. Perhaps mapping the crown out ahead of time and analyzing it carefully would have allowed for more accurate modeling, however I feel that this is close enough for the time being.


I am also learning just how susceptible volume modeling is to human error, I had recorded the crown volume as 193ft3, but I double checked the results while writing this post and found that the measurements I took of the crown in fact equaled to 210.3ft3, boosting the total volume from 800ft3 to 816ft3. If my methodology is sound, I am likely to maintain this process for future volume measurements of this tree to record annual increases. Going forward, I plan to volume model additional trees on Perry Hill, preferably enough to establish an RVI10, and apply volume modeling to other stands in the area, the largest hemlocks at Corbin Hill and the majestic old growth hemlocks, white pines and white ashes of Ice Glen come to mind.


Joshua Harkness
"Be not simply good; be good for something." Henry David Thoreau

User avatar
dbhguru
Posts: 4467
Joined: Mon Mar 08, 2010 9:34 pm

Re: Volume Measurement of Gene's Oak

Post by dbhguru » Sat Jan 12, 2019 8:41 am

Joshua,

Oh, oh, you got my attention with this post. If we were giving out periodic awards or special recognitions, you and Doug would win this round. And volume modeling in sub-zero air is worthy of at least a bronze star, if not silver.

Gorgeous tree! The biggest return of an exercise such as what you've gone through will probably be the experience you gained. You get a good sense of what to measure in greater detail and what to estimate. What I really like about the modeling is that it gives us an important ratio of crown to trunk volume, i.e. the ratio of 210.3/606.6 or 34.65%. It is difficult to eyeball a tall in-forest tree, especially a hardwood, and make a good judgment because we're viewing the crown at a greater distance than the trunk. But this modeling suggests that we can expect greater crown to trunk volumes for large in-forest hardwoods than I have believed for the shape exhibited by this particular tree.

If you will permit, I'd like to share this important post with several forest biometrician friends who I regularly correspond with. One is at Woods Hole Research Center. Another is at Virginia Tech. We are at the beginning of developing better estimations for the really big eastern hardwoods in terms of their biomass and carbon sequestration, and the implications. For example, assuming your numbers are close enough, the oak holds 9.0 regular tons of carbon in its trunk and limbs - or 8.2 metric tons (tonnes). We would need a white pine with a volume of 1,440 ft^3 to hold same amount of carbon. Viva la northern red oak!

I'll comment on taking the methodology to another level in a future post, but for this tree, using my best John Wayne impersonation: You did well, pilgrim.

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

User avatar
JHarkness
Posts: 245
Joined: Sun May 13, 2018 5:44 pm

Re: Volume Measurement of Gene's Oak

Post by JHarkness » Sat Jan 12, 2019 12:08 pm

Bob,

Go for it, I'm perfectly fine with you sharing this post with them. If this post or any future one can be helpful for better understanding hardwood volumes please let me know as I'd be happy to contribute any important data on them.

Given the carbon mass of a red oak, I can't help but wonder what other species of similar wood weight can attain in terms of stored carbon, sugar maple has approximately the same dry wood weight as red oak, beech and white ash are also similar, where as most hickories have much heavier wood. I think it would be very interesting if we, as an organization, were able to compile a more complete database of total volumes and trunk to crown ratios for eastern hardwoods which would provide insight for research organizations, that don't have the field experience or equipment to accurately model many tree species across their ranges, of what various eastern trees can achieve in terms of volume and carbon sequestration across their ranges.


I find the ratio of trunk to crown volumes, most interesting as well. While practicing with volume modeling last week, I volume modeled the trunk and one major limb on my tallest white ash, the trunk had approximately 370ft3 of volume, but an estimate of the total crown volume suggests the tree will be between 650 and 700 cubes when fully modeled. There is another white ash nearby, however, that is nearly as tall but smaller in circumference, though it has a much taller trunk that doesn't branch for almost 90', these two trees likely have very similar trunk volumes, but massively different crown volumes, yet the interesting thing is that they're probably both around the same age.


Joshua
"Be not simply good; be good for something." Henry David Thoreau

User avatar
Erik Danielsen
Posts: 854
Joined: Mon Mar 17, 2014 5:46 pm

Re: Volume Measurement of Gene's Oak

Post by Erik Danielsen » Sun Jan 13, 2019 8:57 am

Excellent work, Josh.

When working on hardwood volumes the method I've adopted is more or less identical to yours, down to using letters to designate segments on sketches for each major limb. It certainly can be a time-consuming process, but as you note the process is worth it. Trunk-to-crown ratios in old hardwoods can really surprise, and I think it does hinge on the math Bob noted that for each doubling in the diameter of a cylinder, its volume is quadrupled.

Good observations on those ashes. Those differences are what presents the main difficulty on developing useful allometrics for old hardwoods- crown structure can vary so greatly depending on life history and growing environment.

User avatar
dbhguru
Posts: 4467
Joined: Mon Mar 08, 2010 9:34 pm

Re: Volume Measurement of Gene's Oak

Post by dbhguru » Sun Jan 13, 2019 5:14 pm

Joshua, Erik, et al.,

This work can become sooooo important. As I think you all know, I interface with lots of people in the forest sciences and in mainstream forestry. Figuring out what is actually growing fast in absolute terms versus fast percentage-wise growth that is easy to visually track is a real skill. If a 100-year old, 100-foot tall N. red oak grows in height 3 or 4 inches across a 60-foot wide crown and adds a 1/10th of foot of girth in a season, who's to notice? Suppose the oak is 6 feet in circumference. The above growth rates may not add up to much, but if the oak is 12 feet in circumference, the increase in growth is a different animal.

If a white pine doubles its height and doubles its diameter, its conical volume will increase by a factor of 8. If we allow for the change in the trunk form factor, creeping upward over time, the volume increase can be 9 or even 10 times. This almost always surprises people because our eyes and brains are not trained to make the conversions. Besides, we're always juggling images that are held hostage to the meaningful interpretation of the impact of distance. A 4-foot diameter oak doesn't look like much from 200 feet away. In fact its trunk width appears the same as a 2-foot diameter trunk at 100 feet. The better we are at judging distance and sizing up objects, the better we may be at realizing what's larger, just father away. However, it is my experience that most people don't develop these image conversions for trees.I was recently at an event for the Kestrel Land Trust at nearby Look Park. Naturally, I took Sparky and was re-measuring a white pine just far enough to get a good view of its top. The pine is 136 feet tall. A friend was curious what I was measuring it. She thought the pine was not much to get excited about, and she's pretty natural savvy. One example of a million.

Lot's of fun stuff to play with.

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

User avatar
JHarkness
Posts: 245
Joined: Sun May 13, 2018 5:44 pm

Re: Volume Measurement of Gene's Oak

Post by JHarkness » Sun Jan 13, 2019 6:00 pm

Erik, Bob,

It astounds me how so many people are completely unaware of differences in tree size, a perfect example is when I showed some of the tall trees on my property to a friend a few years ago, she remarked shortly after entering the forest that a youthful red oak double was the tallest tree she had ever seen, it is fairly tall, around 110' as best as I can tell, but it is far from exceptional, yet she did not pay any apparent notice to the presence of 120'+ and 130'+ white ashes, not even some of the ones much larger than the combined girth of the fused red oaks. I find it strange how so many people can walk into a grove of big/tall trees and not see it as something special, and yet I hear so many people locally referring to anything more than about a foot in DBH as "large".


I think I've always been pretty aware of distances, at least more so than some of the people I know, but I certainly have to admit that using a rangefinder has massively improved my ability to judge distance.

Joshua
"Be not simply good; be good for something." Henry David Thoreau

User avatar
DougBidlack
Posts: 425
Joined: Sun Mar 14, 2010 4:14 pm

Re: Volume Measurement of Gene's Oak

Post by DougBidlack » Mon Jan 14, 2019 10:22 pm

Joshua,
it's nice to see northern red oak as your first really big tree to measure for volume. I've long thought that this species could compete with white pine and tuliptree if we're talking about mass...at least for the northeastern US. Of the other trees that you mentioned, I think white ash would be especially interesting because it can outgrow beech, sugar maple and hickories. Unfortunately EAB is a big problem for the future of that species. Sycamore might also be interesting since it grows very fast, gets really big and the wood is more dense than white pine or tuliptree.

Bob,
the wood density that I found online shows Northern Red Oak to be about 41.02 pounds per cubic foot vs 23.29 pounds per cubic foot for white pine. I'm assuming you used similar numbers to come up with your white pine volume of 1440 cubic feet needed to equal the 816.9 cubic feet of Joshua's Northern Red Oak. Is that right?

Doug

User avatar
a_blooming_botanist
Posts: 70
Joined: Fri Mar 11, 2016 10:09 pm

Re: Volume Measurement of Gene's Oak

Post by a_blooming_botanist » Mon Jan 14, 2019 10:34 pm

Joshua,

Great post! That northern red oak is a fantastic specimen, and your methodical approach to volume calculation seems sound to me! Hats off to you, especially for doing this on a bitterly cold day.

I have the same equipment as you (Vortex Solo RT 8x36 and a TruPulse 200X), but I haven’t spent as much time as I would like practicing volume calculations and becoming acquainted enough with the methods to be able to refine it. I did spend an afternoon a couple months ago taking measurements of one of the exemplary white pines of Massachusetts (the Thoreau pine), but I have yet to post my results to the BBS. I give you a lot of credit for taking on a hardwood, as the structure is a lot more complex than a well-formed, straight-trunked conifer. I also really like the approach you took for estimating the volume of the unmodeled portions of the crown. Ideally we would be able to take reticle measurements along the entire length of every limb. Aside from taking a long time, I think we would also encounter limitations with our equipment, like not being able to get a reliable laser return or reading on the reticle. I’m curious to know more about how you estimated that the equivalent of 13 “E” segments had not been modeled. Was this a “gut feel” estimate or was your approach more methodical?

When I first modeled the Thoreau pine I treated all frustums (except the lowest) as paraboloid. In sharing my results with Bob he suggested that I see how the result would change if the frustums were treated as conical sections. The volume calculation of the trunk as conical sections (986 ft^3) was 16 cubic feet smaller than with paraboloid sections. What effect would this change have on your calculations?

Your report inspires me to get out there and do more volume measurements! Keep up the good work and detailed reports!

Jared

User avatar
JHarkness
Posts: 245
Joined: Sun May 13, 2018 5:44 pm

Re: Volume Measurement of Gene's Oak

Post by JHarkness » Tue Jan 15, 2019 10:12 am

Doug,

Personally, I think sugar maple may end up exceeding similarly sized white ash in the mass competition, what I'm seeing with a lot of white ash is that their limbs tend to taper fairly quickly, where sugar maple has a slightly slower taper, so a white ash may have a higher volume than a sugar maple, but the sugar maple could have a greater mass, and therefore contain more carbon. A similar situation could be said with beech, which has the densest wood of the three, a relatively large beech should hold more carbon than a larger (by volume) ash, sugar maple or red oak. I agree, sycamore would be a really interesting species to compare to white pine and tuliptree, unfortunately there isn't much forest grown sycamore near me so I can't be of much help in that regard. However, I believe Erik mentioned that he was intending to volume measure a couple of the Zoar Valley sycamores?


Jared,


Thank you. Interesting questions. Yes, that is precisely the reason I turned to estimating the remaining crown volume, a combination of being time consuming and equipment limitations. Due to how many "sharp turns" this tree's limbs take (as is the case with most red oaks) it probably would have been near impossible to volume measure the entire crown without losing track of a reference point, and if so the calculated crown volume would no longer have been accurate. In addition, this tree grows literally on the bank of a creek, and there is no easy crossing within several hundred feet of the tree, so it would have been difficult to switch to the opposite side of the crown without losing a reference point. In regards to estimating the number of "E" segments, it wasn't just a gut feel, but I wouldn't be keen on calling it "methodical" either, perhaps practical is a better word for it? Essentially, I visually examined the crown from as many angles as I could while keeping a line of sight to Segment E, and estimating from each of my viewpoints how many "E" segments it would take to approximately make up for what was unmodeled in the crown, from each of my viewpoints I estimated 12 or 13 "E" segments would total the unmodeled portions of the crown, I went with 13 as I felt one of the major limbs that was left unmodeled would be sold a little short by just one "E" segment, in reality, two for that limb is probably still lower than its true volume. Evidently, distance learning has a lot to do with this technique, perhaps one way to improve upon this would be to take handheld SD measurements with a rangefinder to some of the limbs of that are to be estimated to get a better understanding of how far away from you they really are and what you could be missing by just visually estimating it. I believe my crown volume was conservative, and like I said in the original post, more careful modeling of it would likely increase the total somewhat.

As for the trunk, I'm still unsure of when conical or paraboloid is most appropriate, though my understanding was that slow tapering hardwoods generally are better treated with paraboloid frustums, if someone has a better answer to that, please elaborate. I will recalculate the trunk volume tonight using conical frustums instead of paraboloid to see what effect it has.


I look forward to your post about the Thoreau Pine.


Joshua
"Be not simply good; be good for something." Henry David Thoreau

User avatar
Erik Danielsen
Posts: 854
Joined: Mon Mar 17, 2014 5:46 pm

Re: Volume Measurement of Gene's Oak

Post by Erik Danielsen » Tue Jan 15, 2019 11:28 am

Josh,

Yes, there should be a Zoar sycamore or two modeled soon. Zoar is one of a couple sites where I'm working on the idea of Rucker Volume Indexes. I'm expecting Zoar's largest ash specimens to come in between 4-500 ft3 based on some early trunk-only modeling. Zoar's superlative trees do tend towards the tall and slender, so many other sites with shorter canopies can probably match or exceed zoar in terms of maximum volumes. I don't think the largest red oaks will quite match the largest tulips for mass, as some of those 15x150s are probably over 1500 ft3, but they'll probably be one of the other main contenders for greatest mass in northeastern forest-grown trees. I've modeled the trunk of the largest at Long Point state park (109.5' x 17.1'cbh) to 760 ft3 alone, but haven't started the crown yet.

I've followed a similar methodology in selecting a "model" minor limb to measure and then count how many similarly sized minor limbs there are to multiply it by. I'm hoping to work out a method for better accounting for crown volume of minor limbs using photometry so that the process in the field can be streamlined. One practice I would suggest we may find useful is to take advantage to do some ground-truthing anytime a large limb falls, making measurements with a tape to model directly and see how well the results match up with optical measurements of limbs of similar proportions still in the trees. These results may be especially useful as supporting evidence where crown volumes are surprisingly high. As an example:

I modeled a large black cherry recently with a very full crown. Total trunk volume was a respectable 351 ft3, and then I modeled the larger of the two main crown leaders as I had a better view for it. The total for that section of the crown alone came to 170 ft3, with the implication that total volume may end up around 650 ft3 (so 350 ft3 trunk to 300 ft3 crown) if the second leader is about 75% of the volume of the first, which seems like a very high ratio of crown volume to trunk volume- high enough to bother me a bit! Shortly after that, at a different site, I discovered that one of the main sections of the crown of another large old black cherry had recently fallen. I was able to directly measure this and compare it to the upper 2/3 of the optically modeled limb from the first cherry. The optically modeled segment had a starting diameter of 2.07' and a total path length of 50.3', and its volume worked out to 57.78 ft3.. The directly modeled segment had a starting diameter of 2.1' and a total path length of 48.27', and its volume worked out to 52.3 ft3. So the ground-measured limb supports the validity of the optical measurements. On the other hand, I did notice while making the measurements on the ground that the taper of these upper limbs is "stepped," as in at each former or current point of branching, where there is usually a slight change in direction, there is an abrupt taper and the following segment carries the new diameter with little further taper to the next node where there is another abrupt taper, and so on. Across the length of the limb this could be expected to produce a lower volume than the simpler conical taper I used for the optical modeling, and there is in fact a difference of just over 5 ft3 between these two examples. This doesn't seem like a lot but is proportionally significant in the context of a ~55 ft3 limb. If that limb is being substituted as a model limb to multiply as a representative of other limbs, it increases the influence of that discrepancy. So I would interpret in this case that the extrapolated total volume of 650 ft3 is a bit high. At the same time, a final figure in the ballpark of 600 ft3 is supported as realistic.

I know Bob has a spreadsheet for checking taper forms, that lets you input diameters for the ends of a frustum and then add intermediate diameters and see whether the taper best fits nieloid, paraboloid, or conical and even intermediate taper models. This is probably one of those things that varies by species and life stage, so the more data we have on individual trees the better we'll be able to say in the future that a given projection is most appropriate for a given tree and segment.

Post Reply

Return to “New York”