Allometric equations

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Giacomo
Posts: 5
Joined: Thu Oct 24, 2019 7:11 am

Allometric equations

Post by Giacomo » Thu Oct 24, 2019 7:15 am

Where i can find the allometric equations that i-Tree use about the tree growth?
Jason.Henning
i-Tree Team
Posts: 181
Joined: Fri Dec 21, 2012 7:45 am

Re: Allometric equations

Post by Jason.Henning » Thu Oct 24, 2019 1:19 pm

Hello Giacomo,
This may depend on which of the i-Tree Tools you are using. If you are using i-Tree Eco please see the section of this paper, http://www.itreetools.org/eco/resources ... ethods.pdf, titled "UFORE-C: Carbon Storage and Annual Sequestration". i-Tree is not using species specific growth rates but rather general rates for species classified as fast, moderate, or slow growing. These three base rates are then adjusted up or down depending on measurements like the crown light exposure, annual frost free length, and current tree size relative to maximum.
Hope that information is helpful.
-Jason
A member of the i-Tree Team
Giacomo
Posts: 5
Joined: Thu Oct 24, 2019 7:11 am

Re: Allometric equations

Post by Giacomo » Mon Oct 28, 2019 6:49 am

Jason.Henning wrote:
Thu Oct 24, 2019 1:19 pm
Hello Giacomo,
This may depend on which of the i-Tree Tools you are using. If you are using i-Tree Eco please see the section of this paper, http://www.itreetools.org/eco/resources ... ethods.pdf, titled "UFORE-C: Carbon Storage and Annual Sequestration". i-Tree is not using species specific growth rates but rather general rates for species classified as fast, moderate, or slow growing. These three base rates are then adjusted up or down depending on measurements like the crown light exposure, annual frost free length, and current tree size relative to maximum.
Hope that information is helpful.
-Jason
Hi Jason, that was really helpful.
I I would like to ask one more thing, on the paper they talk about this: "The multiple equations used for individual species were combined together to produce one predictive equation for a wide range of diameters for individual species. The process of combining the individual formulas (with limited diameter ranges) into one, more general species formula, produced results that were typically within 2% of the original estimates for total carbon storage of the urban forest (i.e., the estimates using the multiple equations). Formulas were combined to prevent disjointed sequestration estimates that can occur when calculations switch between individual biomass equations"; but there's no reference about where i can find the equations that were created about every species.
Jason.Henning
i-Tree Team
Posts: 181
Joined: Fri Dec 21, 2012 7:45 am

Re: Allometric equations

Post by Jason.Henning » Mon Oct 28, 2019 8:48 am

Hello Giacomo,
That paper references this document,
Nowak, D.J. 1994b. Atmospheric carbon dioxide reduction by Chicago’s urban forest. In: McPherson, E.G.; Nowak, D.J.; Rowntree, R.A., eds. Chicago's urban forest ecosystem: results of the Chicago Urban Forest Climate Project. Gen. Tech. Rep. NE-186. Radnor, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station: 83-94.
Which can be found through the US Forest Service archives, https://www.fs.usda.gov/treesearch/ or directly here, https://www.nrs.fs.fed.us/pubs/gtr/gtr_ne186.pdf. In chapter 6, page 85, please see table 1 which lists the biomass equations and provides references for each one. You will have to track down those references for the actual equations but many of them are also available in the US Forest Service, "Treesearch" archives.
Thanks,
Jason
A member of the i-Tree Team
Giacomo
Posts: 5
Joined: Thu Oct 24, 2019 7:11 am

Re: Allometric equations

Post by Giacomo » Mon Oct 28, 2019 9:00 am

Jason.Henning wrote:
Mon Oct 28, 2019 8:48 am
Hello Giacomo,
That paper references this document,
Nowak, D.J. 1994b. Atmospheric carbon dioxide reduction by Chicago’s urban forest. In: McPherson, E.G.; Nowak, D.J.; Rowntree, R.A., eds. Chicago's urban forest ecosystem: results of the Chicago Urban Forest Climate Project. Gen. Tech. Rep. NE-186. Radnor, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station: 83-94.
Which can be found through the US Forest Service archives, https://www.fs.usda.gov/treesearch/ or directly here, https://www.nrs.fs.fed.us/pubs/gtr/gtr_ne186.pdf. In chapter 6, page 85, please see table 1 which lists the biomass equations and provides references for each one. You will have to track down those references for the actual equations but many of them are also available in the US Forest Service, "Treesearch" archives.
Thanks,
Jason
Thank you so much, Jason.
I have a last question, on my study fild i have a bit of coppice tree, i can't understand how to add it to itree-eco6, because i just have the DBH of the biggest stem but every trees has like 10+ stem more or less of the same dimension; i need to add them alone like a single tree even if they are the same plant? or there's a way to make i tree-eco knowing that they are coppice tree?
Thank you again for the help, u are really kind.
Jason.Henning
i-Tree Team
Posts: 181
Joined: Fri Dec 21, 2012 7:45 am

Re: Allometric equations

Post by Jason.Henning » Mon Oct 28, 2019 10:31 am

Hello Giacomo,
Copice is not a common practice here in the US so i-Tree doesn't have a defined way to handle those trees. However, for multi-stem trees you can enter up to the 6 largest stems as DBH1 to DBH6. Alternatively, you could calculate the dbh of a tree that would have the same basal area as all stems combined. The formula for this is: combined DBH = square root (sum (DBHi^2)). Where DBHi will be your dbh values for each of the stems. This calculation is actually what i-Tree does when you enter multiple stems. You should get identical results with either approach for trees with up to 6 stems.
Thanks,
Jason
A member of the i-Tree Team
Giacomo
Posts: 5
Joined: Thu Oct 24, 2019 7:11 am

Re: Allometric equations

Post by Giacomo » Mon Oct 28, 2019 11:40 am

Tnx a lot
Giacomo
Posts: 5
Joined: Thu Oct 24, 2019 7:11 am

Re: Allometric equations

Post by Giacomo » Thu Nov 07, 2019 4:35 am

Jason.Henning wrote:
Mon Oct 28, 2019 10:31 am
Hello Giacomo,
Copice is not a common practice here in the US so i-Tree doesn't have a defined way to handle those trees. However, for multi-stem trees you can enter up to the 6 largest stems as DBH1 to DBH6. Alternatively, you could calculate the dbh of a tree that would have the same basal area as all stems combined. The formula for this is: combined DBH = square root (sum (DBHi^2)). Where DBHi will be your dbh values for each of the stems. This calculation is actually what i-Tree does when you enter multiple stems. You should get identical results with either approach for trees with up to 6 stems.
Thanks,
Jason
Hello Jason, i follow your suggestion but i have some problem whit the Corylus avellana, because, in me study case, they have too much stems and is almost impossible to measure their DHB; do you have any advice? or i just exclude them? (the url is a photo similar to my trees).
https://it.wikipedia.org/wiki/Corylus_a ... struik.jpg
Thanks,
Giacomo
dellings
i-Tree Team
Posts: 26
Joined: Thu Aug 21, 2008 2:12 pm

Re: Allometric equations

Post by dellings » Thu Nov 07, 2019 9:44 am

Giacomo,

Given a bunch of stems, you can estimate the combined DBH by performing the following steps:

1. Take several measurements of the total width of all the stems from various sides.
2. Average the measurements from #1 to obtain the Average Width.
3. Compute the combined DBH using DBH = Sqrt[(1 - % missing) * (Average Width)^2)] where % missing is your best estimate of the amount of area missing from a circle with a diameter of the Average Width determined in step 2.

Another option would be to compute the average DBH from measuring a few stems and then extrapolate the average based upon the total number of stems via:
1. Compute average stem DBH via avg_dbh = Sqrt[Sum(DBHi^2) / n] where n is the number of stems measured and i is each individual stem from 1 to n.
2. Compute the combined DBH using DBH = sqrt[avg_dbh^2 * m] where m is the total number of stems

Neither of these methods are as accurate as having measured every stem, but they should at least get you close to the desired value.
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