Catching up on several topics

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

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dbhguru
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Catching up on several topics

Post by dbhguru » Mon Nov 21, 2022 10:31 am

NTS

Over the last 6 years, I’ve been preoccupied with developing tree volume-biomass predictive models for several climate scientist friends and evaluating models that are already out there. Has it ever been an education! In addition, I’ve been trying to shine a spotlight on rampant misinformation about tree growth rates in terms of carbon sequestration. To this end, I’ve not been able to determine the original source of the truly misleading statement that a mature tree sequesters 48 lbs annually of CO2. One might argue that the Internet is loaded with misinformation, so why get disturbed about one more piece? The reason is that the statement is being used by people who seek to minimize the role of trees in combating climate change. Others push the importance of planting new trees at the expense of protecting mature ones when the latter is by far the more important strategy. Of course, there is need for both, but if big pulp, paper, and biomass companies can focus our attention on planting young trees, we won’t happen to notice when they slaughter entire landscapes of merchantable trees. Are we surprised?

Several sources attribute the 48-lb sequestration rate to the Arbor Day Foundation. American Forests has regrettably parroted the claim, despite my best efforts to dissuade them. But regardless, it is a ridiculous understatement for the performance of a mature tree and can be refuted by existing sources of information, including i-Tree, many volume-biomass models, the U.S Department of Energy, and simple common sense. Mature eastern trees that form fairly high canopies (oaks, maples, pines, hickories, ashes, etc.) can easily sequester between 150 and 350 lbs of CO2 per year.To talk about 48 lbs for West Coast behemoths is beyond ridiculous.

The most outstanding eastern performers can exceed 600 lbs into mid-to-late maturity. I won’t claim that true old growth specimens continue high rates, but well above the 48 can be achieved by an age of 40 to 50 and persist for another hundred years. So, why would an ostensibly tree-qualified organization put out or parrot such misleading information? I have a few ideas, but would appreciate hearing the thoughts of NTS members.

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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bbeduhn
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Re: Catching up on several topics

Post by bbeduhn » Tue Nov 22, 2022 9:26 am

Bob,

That is important work you are doing! Just like with accurate height measurement, misinformation spreads far more readily than accurate information. My daughter learned how to measure trees and buildings in her seventh grade class. Which method? Naturally by laying out tape and using the tangent method. As we all know, it can be accurate but in most cases, at least with trees, it is not. The battle for truth should have been won long ago.

Brian

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MikeK
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Re: Catching up on several topics

Post by MikeK » Thu Nov 24, 2022 9:04 pm

Bob,

I'm new to this but I've heard a number of arguments going one way or the other. Some sources have claimed younger forests sequester more carbon, at least at first, until they start to thin. Others have touted mature forests sequester far more in their root systems.

I'm familiar with the type of measurements you guys are doing here of above ground volume (although admittedly I don't think crown volume would be easy to estimate), but how do you estimate the volume of root systems? And on that particular note, I would assume different root systems store carbon in different volumes.

I would also assume a very important measure is the amount of trees that any given stand loses to natural disturbance, how long that carbon is left stored on the forest floor before it is completely oxidized, how long it takes for new trees to fill the gaps, and what rate they are absorbing carbon. The dynamics of this problem seem a bit staggering to estimate. It seems like it would be much easier, and convenient to measure and calculate second growth from clear.

I'd also be curious to know, or if anyone has estimated the amount of carbon that could be sequestered if we forested available land to the maximum level and how that might compare, fractionally, to the amount of hydrocarbons and coal (1000's of generations of forests) we've released.

Any sources would be appreciated.

I will say, whatever the estimates are I'm always in favor of mature, structured forests for a multitude of other reasons and although I don't deny climate change, I don't think I could be swayed away from that as a potential solution (if, in fact, second growth was a more effective system of carbon sequestration).

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dbhguru
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Re: Catching up on several topics

Post by dbhguru » Tue Nov 29, 2022 12:26 pm

Mike,

Lots to talk about. It is not too difficult to compute and compare growth rates of young versus mature trees when apples to apples comparisons are being made. Since you've asked, I'm willing to delve into the mechanics to whatever extent I can. I'm computing these days like mad, supporting several climate scientists who want to get down to the tree and stand level. Most of their analysis ends up on large landscape scale and depends on a lots of computer modeling that greatly varies in the returned results.

I'm happy to begin an extended discussion on carbon sequestration by trees based on my research and that of my colleagues if you are interested, But I'll offer a brief overview of what I've learned to date.

1. There are many tree biomass models that have been developed over the past 30 years or so by the U.S. Forest Service, the Canadian Forest Service, European counterparts, academics in several professions, and professionals working for both industry and conservation groups. Much of the research coming out of the U.S. Forest Service is very good, but different models lead to fairly widely varying results. I spend a lot of time comparing models and understanding their underlying assumptions. Most of that detail is lost when they are quoted in research papers by others. Opening the hood and looking at what is beneath is a real education.

2. Young forests do grow fast, but they don't accumulate much biomass for several decades, and eventually they aren't young forests any more. Individual trees are on one set of growth curves while stands of trees are on another. Of course, it is always species, site specific.

3. Management can increase growth rates of individual trees, but where cutting is heavy, the forest is always being returned to an earlier state. The carbon story of short stand rotations is one of continual loss of carbon. Management on that plan is never carbon neutral. wood products interests really feed the general public a line when they talk about how well young forests do.

4. The amount of carbon in the roots of a tree relative to that above ground is usually cited as about 20%. I use 15%, preferring to err on the conservative side. We don't get species specific with respect to root carbon. Jut a gross add-on.

5. So, how would we compare carbon both accumulated to a point in time and annual growth rate for a species? We can profile the growth of say a white pine that reaches a specified set of dimensions and show when it gained the most carbon. Of course, to be complete, you must factor in decay rates and they vary greatly. However, I've done a mountain of these comparisons and have it down pretty well, and am willing to share the methodology.

If you want I will begin by sharing predictive species volume-biomass models with you. Let me know if you'd like me to do this?

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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MikeK
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Re: Catching up on several topics

Post by MikeK » Tue Nov 29, 2022 2:51 pm

I'm certainly interested in reading whatever you want to share. I'm an engineer, no calculation can scare me. I've been combing through a number of studies on this site - particularly the OLDLIST and concurrent studies. I'm in the process of reading through most of the NY reports, and although most leave me with questions, I don't want to respond and revive all of these old threads, so I'll curb my enthusiasm the best I can.

I had been pondering what could be done with all the data that has been collected by this group - and of course this seems like it could be inline with that (carbon sequestration). I also thought of some other things such as height/girth/age limitation of species based on ecoregion. That seems like it could fit well into speciation distribution, and thus carbon modelling.

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