## Relative tree calculations

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hdelaconcha
Posts: 50
Joined: Mon Jul 11, 2016 8:10 pm

### Relative tree calculations

I read the explanation of how you calculated this information but can you share the exact number of emsions per car (g/mi) and the miles per car you used for it? just for comparison purposes, thanks.

Also I am proposing doing a complete inventory of Merida´s Publics Parks and was wondering in estimating crown condition is enough to get reasonable good results as against using Crown conditions and crown measurements (N/S+E/W+top+bottom) since I am concern that the amount of trees is considerable and I am looking to get the minimum best data for the calculation. In other words how much does crown measurement increases precision of the data, in your experiencie, to determine if it is worth going through it.

Gracias
Horacio de la Concha
AGRINET SA de CV
Cuernavaca MEXICO
hdelaconcha@agrinet.com.mx
Jason.Henning
i-Tree Team
Posts: 146
Joined: Fri Dec 21, 2012 7:45 am

### Re: Relative tree calculations

Hi Horacio,
Here are the methods behind converting the carbon sequestration to vehicle miles.
1. Convert amount of carbon sequestration (metric tons) to lbs by multiplying by 1,000*2.204
2. Divide amount of carbon sequestration (lbs; calculated in step 1) by the total average C emissions per vehicle (lbs)
To calculate total average C emissions per vehicle (lbs)
• a. Divide grams of CO2 emitted/gallon of gasoline (8887) by the average miles traveled per gallon of fuel consumed for all light duty vehicles (21.4 mpg) to get the grams of CO2 emitted per mile
• b. Convert CO2 emitted (grams/mile; calculated in step 2a) to lbs/mile by dividing by 1,000*2.204
• c. Multiply CO2 emitted (lbs/mile; calculated in step 2b) by the average vehicle miles traveled per vehicle for all light duty vehicles (11,318 miles) to get the total average CO2 emissions per vehicle
• d. Convert total average CO2 emissions per vehicle (lbs) to total average C emissions per vehicle (lbs) by dividing by 44/12
References:
8887 grams of CO2 emitted/gallon of gasoline (step 2a) - http://www.epa.gov/oms/climate/regulati ... 10012a.pdf
21.4 (step 2b) - http://www.fhwa.dot.gov/policyinformati ... 11/vm1.cfm
11,318 (step 2c) - http://www.fhwa.dot.gov/policyinformat ... 1/vm1.cfm
Jason.Henning
i-Tree Team
Posts: 146
Joined: Fri Dec 21, 2012 7:45 am

### Re: Relative tree calculations

As to your crown parameter questions, the crown widths (N/S and E/W) as well base and top heights do directly impact the accuracy of the carbon, air pollution, and stormwater results. Those models are directly driven by the estimates of leaf surface area. i-Tree Eco estimates leaf surface area by determining the volume of the tree crowns based on those height and width measurements. Then it determines the leaf surface area within that volume using species specific LAI estimates. Without those measurements the models will use species specific estimates of tree height and crown widths based on DBH. Those estimates should be relatively accurate on average but they could be highly inaccurate for an individual tree with an atypical crown or anywhere your tree crowns deviate from typical conditions.
For more information on which measured variables impact which outputs please see this document, http://www.itreetools.org/resources/man ... ations.pdf
hdelaconcha
Posts: 50
Joined: Mon Jul 11, 2016 8:10 pm

### Re: Relative tree calculations

Thanks for the answer, nice format by the way. I also want to tell you about another presentation I will be doing and finally I got the Merida Report Printed and officially given to the public. I tried to attach the info as a JPEG, but couldn´t how do you do that.
Thanks
Horacio de la Concha
AGRINET SA de CV
Cuernavaca MEXICO
hdelaconcha@agrinet.com.mx