GHG Planting Calculator

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prateek13pat
Posts: 3
Joined: Wed Aug 08, 2018 3:32 pm

GHG Planting Calculator

Post by prateek13pat » Wed Aug 08, 2018 3:40 pm

Hello!

I have a question about the impact of location on carbon sequestration rates. Keeping everything else the same, I just changed the location for an American Elm tree in the GHG Planting Calculator and came up with the following lifetime sequestration numbers in lbs of CO2:

San Francisco CA 45,750.80
San Diego CA 36,869.60
Denver CO 5,770.80
Chicago IL 5,770.80
Oklahoma City OK 12,550.70
Austin TX 19,728.10
Seattle WA 19,728.10
Dallas TX 19,728.10
Washington DC 12,550.70
New York NY 12,550.70
Portland OR 12,550.70

Does changing location affect growth rate? I couldn't find an answer by reading David Nowak and Daniel Crane's papers. Is there a way to understand the back-end calculation here? Thanks.
Jason.Henning
i-Tree Team
Posts: 142
Joined: Fri Dec 21, 2012 7:45 am

Re: GHG Planting Calculator

Post by Jason.Henning » Thu Aug 09, 2018 10:38 am

Thanks for your question. The methods in the GHG Planting Calculator are actually adapted from i-Tree Streets which is a region based empirical model. Essentially, the tool "maps" the entered trees onto trees that were measured in the same climate/growth zone and assumes that these trees would sequester comparable amounts of carbon. It is not necessarily using traditional tree growth models. The methods underlying i-Tree Streets were originally put together by Greg McPherson and others in a series of Community Tree Guides. These Community Tree Guide are collected under the i-Tree Streets heading in our "Methods and Files" section, http://www.itreetools.org/resources/archives.php. The specific carbon methods were originally put forth in this publication, https://www.fs.fed.us/psw/publications/ ... gtr171.pdf. Lastly, you may want to view this "Climate Zone" map, http://www.itreetools.org/streets/image ... _zones.jpg, which shows how different cities may be assigned to different climate zones and therefore be assigned different growth and sequestration rates.

-Jason
prateek13pat
Posts: 3
Joined: Wed Aug 08, 2018 3:32 pm

Re: GHG Planting Calculator

Post by prateek13pat » Thu Aug 09, 2018 1:28 pm

This is all very helpful, Jason - thanks a lot!
prateek13pat
Posts: 3
Joined: Wed Aug 08, 2018 3:32 pm

Re: GHG Planting Calculator

Post by prateek13pat » Fri Aug 24, 2018 9:25 pm

Jason, I perused through the Community Tree Guidelines (Greg McPherson's publication) and the methodology for estimating CO2 sequestration. The method classifies US into three tree growth zones, however the map you directed me to (used by iTree Streets) has 16 zones. I did some tinkering myself for different species in multiple zones, and there surely appear to be more than three sequestration values for any species just by varying the location, as I'd posted in my original comment. Were the number of tree growth curves for each type of species increased from 3 (north, central, south in the Community Guidelines) increased to 16? If so, where can I find those?

Thanks, Prateek
Jason.Henning
i-Tree Team
Posts: 142
Joined: Fri Dec 21, 2012 7:45 am

Re: GHG Planting Calculator

Post by Jason.Henning » Mon Aug 27, 2018 10:26 am

Hi Prateek,
There are 16 Community Tree Guides, 1 for each of the 16 climate zones on that map. You can find those in the Archives I linked to above, http://www.itreetools.org/resources/archives.php. You will need to expand the "i-Tree Streets & STRATUM Resources" section there and then scroll down to the "i-Tree Streets Reference City Community Tree Guides" section. Alternatively, you can find them directly from the Forest Service, here https://www.fs.fed.us/psw/topics/urban_ ... ides.shtml. The appendices of those documents generally describe the specific methodology.
These models are empirical in nature and are not classical growth curves. For each of the 16 locations the trees in a reference city were measured intensively. The Planting Calculator takes the species and diameter entered by the user and finds a "best match" in the reference city data and uses a lookup table to find the carbon stored in that tree. It then uses generalized growth for fast, medium, or slow growing species and adjusts them based on local growing degree days, tree condition, and the light available to the tree. Following that it will return to the lookup tables to find the new tree carbon storage. Taking the difference of the pre- and post- growth carbon numbers gives the total carbon sequestered.
The Forest Service recently published all of the underlying tree data from those community tree guides here, https://www.fs.usda.gov/treesearch/pubs/52933.
If you want to see the actual look-up tables you will need to install the i-Tree Suite of tools on your PC. Then the lookup tables for each of the 16 zones will be titled ResourceUnit.xls and in a separate folder at this location on your PC, C:\Program Files (x86)\i-Tree\STREETS\Data\ResourceUnit.
I hope you can find what your looking for in one of those documents or locations.
Thanks,
Jason
ywjong
Posts: 1
Joined: Thu Sep 27, 2018 12:13 pm

Re: GHG Planting Calculator

Post by ywjong » Thu Sep 27, 2018 12:21 pm

Hi, I am new to i-tree tools too and I am a student who wishes to use the i-tree planting to quantify carbon benefits of urban tree planting.

However, I do get a bit confused by the results the calculator showed me (all parameters used were equal for the five trees, time scale used is 40 years):

Image

Given that crepe myrtle is a moderate sized shrub/small tree, it seems unlikely that crepe myrtle can sequester almost as much carbon as willow oak and even more carbon than other large trees such as Southern Magnolia and Northern Red Oak. I would like to ask was there any assumptions or limitations from the carbon calculator that I missed? Any guide on this will be appreciated!
Erika.Teach
Posts: 4
Joined: Fri Feb 12, 2016 2:59 pm

Re: GHG Planting Calculator

Post by Erika.Teach » Mon Oct 08, 2018 2:16 pm

Hello,

Thank you for bringing this to our attention.
We are currently in the process of determining possible causes for these results.
When that is resolved we will post an update.

Erika
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