Another opportunity to participate in carbon

General discussions of measurement techniques and the results of testing of techniques and equipment.

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dbhguru
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Another opportunity to participate in carbon

Post by dbhguru » Sun Mar 03, 2019 6:53 pm

Ents,

Earlier my friend Bart Bouricious called from Costa Rica. among the things we discussed is an opportunity for us to assist a couple of Dutch scientists who are looking to measure carbon in tropical trees. Bart met them somewhat accidentally, but they evidently all bonded quickly. In what transpired, it was apparent that the Dutch scientist needed advice on tree measuring and modeling. They had been given advice on height measuring that uses a surveyor's chain and a clinometer. I'm dead serious. That's like suggesting to someone to use a 1920s telephone handset for communications.

Well, according to Bart, the scientists suspected that advice and were glad to get a quick view of where tree measuring has been going. Hopefully, we can help them. We'll keep everyone informed. But it is another example of opportunities for us to participate in some pretty heady stuff.

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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JHarkness
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Re: Another opportunity to participate in carbon

Post by JHarkness » Sun Mar 03, 2019 7:28 pm

Bob,

Great news! I've been considering modeling more mature sugar maples and red oaks on Perry Hill and comparing them to small trees, say around 40-50 years old, similar to what you did with Saheda, but my main focus would be to see how much of a correlation there is between hardwood crown volumes and age. Let me know if you are interested in results from that.

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

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Re: Another opportunity to participate in carbon

Post by dbhguru » Mon Mar 04, 2019 6:23 pm

Joshua,

I'm interested in anything you can pass on. Every bit helps. So far a comparison between our modelings and U.S.F.S. allometric equations differs by 13.6% volume wise. It is hard to discern the trends, though. It isn't as simple as I initially thought.

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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Re: Another opportunity to participate in carbon

Post by dbhguru » Thu Mar 07, 2019 9:26 am

Ents,

In the past year, I have come to appreciate that quantifying carbon in forests, both absolute amounts and rates of sequestration, is monumentally complicated. I should have realized this all along, and may have at some level, but the subject is often treated cavalierly by popular Internet sources in our time of sound bites. It is easy to get caught up in the over-simplifications. There is the carbon in live tree trunks, limbs, and leaves; carbon in logs and snags; carbon in the litter layers and carbon in the soil. There is the efficiency with which carbon is added to existing trunks, which changes with age. There are rates of decay, different for different species, and forest conditions. Decay proceeds more slowly in cold climates, and so on. It was only with dim awareness of this complexity that I set out to try to understand what was going on in stands of white pines in MTSF mainly because I saw growth rates that exceeded what I was told was the norm by DCR's and consulting forester friends. That puzzled me. Weren't they supposed to know? What was happening that they weren't on top of?

After a number of years of measuring trees and observing the processes of stand development, I find myself in the unexpected position of possessing data and methods that may be useful for tweaking the models of others here in New England for the carbon in white pine forests. It's kind of heady and easy to get out over the tips of one's skis. I'm presently trying to sort out what I can say and what I should keep away from in the PPPs that I'm frequently asked to give. Luckily, I'm getting help from a couple of forest biometrician acquaintances who are topnotch. At this point, I can say that my best contribution is to continue perfecting our tree-measuring methods to be in an ever better position to model the forms for volume and be able to differentiate how different species distribute their wood between trunk and limbs. In this one area, we, in NTS, have the advantage. We can do the direct measuring required better than others except those who climb and model like BVP and Sillett.

In terms of active measurers, as of now, we have Michael Taylor, Jared Lockwood, John Eichholz, Doug Bidlack, Dale Luthringer, Bryan Beduhn, Jess Riddle, Erik Danielsen, Elijah Whitcomb, Joshua Harkness, Andrew Joslin, Ryan LeClair, Don Bertolette, and myself - a baker's dozen plus one. Others have come and gone, and we miss them. We wish they would return, because this is an opportunity for NTS to have a role, however small, in a monumentally important issue - forests and trees in climate change. The big players like the scientists at Woods Hole Research Center who look at forests across entire landscapes don't possess the tools to evaluate how individual trees are behaving in mature stands. They are still dependent on yesterday's technology and on the datasets contributed by student measurers. We can provide them with volume growth data on trees at different ages, especially past 100 years, that they can't get by examining pixels on computer screens. At least, we can provide ground-truthing to a much higher level of accuracy than what they would otherwise get.

As a final commentary, a year ago, I might have added American Forests to the list of carbon analysis contributors, but although Don Bertolette and I carry the titles of senior advisors to the champion tree program, those impressive handles plus a couple dollars wouldn't cover our morning coffee. Apparently, American Forests is engaged in a continued de-emphasis of what was to be the scientific side of the champion tree program. AF is now pretty much irrelevant in any serious use of champion tree data. Sad, but true.

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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JHarkness
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Re: Another opportunity to participate in carbon

Post by JHarkness » Thu Mar 07, 2019 1:18 pm

Bob,

I recently volume modeled a young (mature according to most foresters) 40-45 year old sugar maple on Perry Hill to compare to the already modeled mature tree, likely somewhere in the neighborhood of 200 years of age. I chose these two trees for this as they both exhibit common forest grown forms for the species. My results show that it would take 9.2 trees of comparable size to the young tree squeezed into the same space as the mature tree to equal its volume, but only 3.8 can fit within its crown area. I did find a correlation between higher crown volume and age, only 28.2% of the young tree's volume is within its crown, while 39.2% of the mature tree's volume is within its crown, that wasn't as significant as I was expecting, but is still pretty substantial. The other thing I find interesting is that if the calculated conical volume (using height and taped CBH) is compared to the modeled volume, there is an almost equal error between them (53.3% for the young tree and 53.0% for the mature one).

Attached is a spreadsheet highlighting my results in greater detail.
SugarMapleComparison.xlsx
(9.47 KiB) Downloaded 21 times
I'm hoping to volume model multiple sugar maples in the same size/age group as the two used in this comparison and average the data for more accurate stand-level results. I will probably also do this for white ash and northern red oak.

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

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dbhguru
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Re: Another opportunity to participate in carbon

Post by dbhguru » Thu Mar 07, 2019 6:55 pm

Joshua,

Great work! May I share your spreadsheet with several scientists who would find the information interesting?

Here is some added information. The FIA carbon-based model gives 317.8 ft^3 for the older maple. The difference between your modeled trunk volume and the FIA trunk volume is 49.72 ft^3, which is slightly larger than the entire trunk volume of the younger sugar maple. The FIA model gives 32.34 ft^3 for the young maple versus your 46.9 ft^3. This surprised me slightly. I expected the FIA value for the smaller tree to be closer.

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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JHarkness
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Re: Another opportunity to participate in carbon

Post by JHarkness » Thu Mar 07, 2019 11:12 pm

Bob,

Please do. I am happy to contribute anything that can be useful to our collective mission of volume measurement and carbon sequestration.

I also found it odd that forestry standards for volume measurement fell substantially short even for the smaller tree, I figured it would only be off by a small amount. Perhaps this is just the case with all hardwoods with any decent crown volume, regardless of age?

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

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dbhguru
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Re: Another opportunity to participate in carbon

Post by dbhguru » Fri Mar 08, 2019 9:28 am

Joshua,

Thanks very much. I don't want to mislead anyone. In fairness to the growth modeling done by forest biometricians, there are more sophisticated models, but they require more inputs and time to apply. One model that relies on integration came within 17 ft^3 of my reticle modeling of the Jake Swamp trunk. Can't get closer than that, but the model requires a very large set of calculations - not for the faint of heart.

Unfortunately, today, we have an endless circulation of old and new methods and their inter-mixing among researchers. Some of the new work is extraordinarily insightful in terms of forest succession, response to disturbance, etc., but the complex computer simulations stretch the brain and I doubt that few forest managers really understand these complex models. Scientific papers are a mix of models of different sensitivity and accuracy. For our purposes, it leaves lots of room for misconceptions about how forest carbon accumulates over time. That's why the work of ecologists like Sillett and Van Pelt and their Australian counterparts is so important. Nothing from the standard models could predict what happens in the canopies of redwoods as the centuries pass by, and as a consequence, a lot gets missed.

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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dbhguru
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Re: Another opportunity to participate in carbon

Post by dbhguru » Sun Mar 10, 2019 3:59 pm

Ents,

Forest managers often maintain that young forests sequester more carbon than older ones. But what do they really mean by this assertion? Do they believe that the young forests are adding more carbon per annum than older ones? When does the higher rates start? Not at year one. Do they distinguish between percentage increases versus absolute amounts? On a tree by tree basis, do they think younger trees are adding more carbon than when older? Recently I got a partial answer from an associate professor from UMASS. He wasn't talking about the behavior of individual trees, but stand behavior. His point was that at the stand level, more carbon is gained early on and especially between ages 20 and 40, and that results from the stem densities. He wasn't arguing about carbon held in individual trees. Of course, he recognized that bigger trees hold more carbon than smaller ones. It is all in stem densities and maybe efficiency of CO2 uptake. I wanted to see if I could model stand behavior by making some simple assumptions and following them. my analysis is crude, but maybe provides some insights.

To start, a forest biometrician friend first did some queriers of the FIA database for stem counts plotted against site index and stand age. I averaged the the stem densities across the range of site indices for ages 35 and 45 years, and got 591 stems per acre. Suppose they are white pine. Some will be stronger, dominant stems and others will be subordinate. Also, some will be dead since the stem count will drop to between 25 and 75 by age 150. In case of the Trees of Peace, the current stem count for live white pines is 44.

Can we construct scenarios for stem size and density at age 40 years to estimate carbon at that time using the 591 stems per acre? The following table is one of a half dozen scenarios that I've run, thus far. Double click on the image to expand to a readable size.
Screen Shot 2019-03-10 at 3.40.44 PM.png
As can be seen, the total stem volume at 40 years is 7239 ft^3. This compares to 13,543 ft^3 using an average stem size for the Trees of peace. However, taking the 44 pines in the acre we inventoried gave us 14,473. The big trees have an influence. By this construction, and using the actual volume, the amount of carbon would have doubled between 40 and 150 years, but a lot of the carbon at 40 is in dead stems. if we assume that the two smallest diameter classes consists of dead systems, live tree volume comes to 3809 ft^3. The ratio of 14473 to 3809 is 3.8 to 1. The ratio of the age at 150 versus 40 is 3.75 to 1. What this implies (I think) is that at the stand level, the amount of live wood at 150 years has kept up with what was there at the presumed peak of productivity at 40 years. However, there is a lot more carbon in the stems at 150 years consistent with all my previous analysis.

Some of the other scenarios I ran favor carbon sequestered in the older stand, but they don't all. At this point, it certainly looks like there is a strong growth pulse between 20 and 40 years, as many forest managers maintain, but tree size at 40 years is too small to support commercial harvesting. In addition, the stems consist mostly of sapwood as opposed to the more durable heartwood. This suggests that the early growth pulse has less overall significance than the generalizations would suggest made by advocates of young forests. However, fair is fair. In terms of atmospheric CO2 absorption, the period of 20 to 40 years is important.

Observations/suggestions by others are most welcome.

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: Another opportunity to participate in carbon

Post by Erik Danielsen » Sun Mar 10, 2019 4:50 pm

It's good to clarify that stand dynamics are what is referred to, as I have seen some reporting off that recent publication confuse the two, but the issue I think is still looming is talking about the stand's proportional annual increase vs. gross annual increase. And that itself raises interesting problems in how we might go about modeling or measuring the annual carbon sequestration of older trees and the stands that include them. Modeling their static dimensions is one thing. I'm still trying to wrap my head around eddy flux methodologies and am not entirely convinced they're an ideal proxy. I have a vague memory of a study from several years back that used lasers to model surface area of some tropical tree and projected annual carbon gains from that and had concluded older trees sequestered more than expected by virtue of sheer surface area for growth to cover. Maybe I can find it.

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