Documentation for Species Value Assignment

If you have questions, comments, and suggestions specific to one or more of the components of the i-Tree Software Suite, this is the place for them! Again, please check the i-Tree website and the FAQs before posting. Relevant topics include UFORE, STRATUM, and the utilities such as MCTI or Storm Damage Assessment Protocol.

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rgthurau
Posts: 17
Joined: Fri Jun 20, 2008 10:08 am
Location: Denver, CO
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Documentation for Species Value Assignment

Post by rgthurau » Wed Aug 13, 2008 2:04 pm

Hello,
Can iTree give a reference to the methods for determining the "Species Value Assignments" given for certain species? I'm just looking to back up some of these values with some science.

For example: Carya species use the values of Green Ash for the calculations.

Thanks

RT
smaco
i-Tree Team
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Joined: Wed Dec 06, 2006 1:40 pm

Post by smaco » Wed Aug 13, 2008 4:48 pm

Hi RT,
Unfortunately, there isn’t a lot of science involved here but, rather, informed judgment. For each climate zone there are approximately 20 or so trees modeled for growth and benefits; all other trees are matched to these using Species Value Assignments. The matching is already completed for a large selection of trees (see Appendix D) in each climate zone using the same strategy that is outlined in section 2.4.2 of the User’s Manual--taking into consideration mature size, tree type, form, and family and genus relationships. However, it would behoove any user to take a hard look at this list and modify the Species Value Assignments based on local knowledge, especially where mature tree size may differ within a climate zone. Ultimately, the Species Value Assignments are your responsibility for every species listed in your inventory.

I hope this helps. --Scott
a member of the i-Tree Team
Rennaker
Posts: 5
Joined: Tue Aug 12, 2008 5:26 pm

Post by Rennaker » Thu Aug 14, 2008 5:28 pm

Hi,
If I understand correctly, all tree species should have their SpCode = to the corresponding SppValue Assignement? Or does the Species Code field work when preforming STRATUM?
Thanks
azelaya
i-Tree Team
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Joined: Fri Jun 27, 2008 10:50 am

Species value assignment clarification

Post by azelaya » Fri Aug 15, 2008 12:19 pm

Hello,

I think that you understand how it works but see if this helps clarify the picture.

As mentioned in a previous reply to RT, each STRATUM region has approximately 200 trees that are most likely to be found in that region. However, those 200 trees do not all have individual benefits and growth calculations available. So, the species value assignment is used as a mechanism to assign benefit and growth values to those trees that do not have actual data available. Therefore, the species value SppValue Assignment relationship would be the value that actually drives the STRATUM benefit and growth outputs. However, the species code is needed to create the relationship with the allied species used in the Spp Value Assignment.

Here is a hypothetical example of how one may decide to change the SppValue Assignment for an individual tree to reflect local conditions. The Midwest region has Sweetgum tree listed with a SppValue assignment as (BDL) Broadleaf large tree. However, if I am in the upper Midwest using STRATUM, I may decide to change the SppValue assignment for that tree to Broad leaf medium (BDM) as this tree may not grow as large as in southern parts of the Midwest region. So, the species code would stay the same in STRATUM but changing the species value assignment could be used to capture local knowledge and refine outputs.

Al
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rgthurau
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Joined: Fri Jun 20, 2008 10:08 am
Location: Denver, CO
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Re: Documentation for Species Value Assignment

Post by rgthurau » Fri Feb 21, 2014 6:41 pm

Hello,
Looking back at my question posted waaaay back in 2008 (has it been that long!?) I'm curious if there have been any serious changes to the way specific species contribute to ecosystem service values provided by trees in the Streets inventory?

From the Manual v5.0 annual benefits reported are: Energy, Stormwater, Air Quality, Carbon Dioxide, Carbon Stored, and Aesthetic/other.

How many of these values would be the same (or different) if my inventory was species specific as opposed to calling all trees a single species?
Also, I assume tree size is always an important factor for values, but can you inform me if that assumption is incorrect for any of the above values?
Do any other factors contribute to a tree's impact on reported values (i.e. condition)?

Thank you.

Rich
Jason.Henning
i-Tree Team
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Re: Documentation for Species Value Assignment

Post by Jason.Henning » Wed Feb 26, 2014 11:31 am

Hi Rich,

There haven't been any major updates to the methodology used in i-Tree Streets. To get a better idea where the benefit numbers come from you could check out the "Community Tree Guide" associated with the climate zone you are using in Streets (click on "i-Tree Streets Reference City Community Tree Guide", at this link http://www.itreetools.org/resources/archives.php). There you will see that there are about 20 species measured and i-Tree Streets matches any species that are not on the list to the most similar species using the species table (http://www.itreetools.org/streets/resou ... 0Codes.xls) along with any modifications you make to the table within Streets. So the benefits do indeed differ by species. How exactly those differences show up depends on which species were measured to create the model (see those tree guides) and which species you measured in your inventory. In short species and tree size impact all of the benefits you mentioned within i-Tree Streets. Tree species and size are the only factors that influence the estimated ecosystem services within i-Tree Streets.

The condition measurements only affect the replacement value estimates. You can see this forum post from more information on that topic, http://forums.itreetools.org/viewtopic. ... tion#p1797.

Jason Henning
----------------------------
i-Tree Support
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