Crown Size Influence

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

Crown Size Influence

Post by hdelaconcha » Wed May 09, 2018 9:57 am

I have to do a complete inventory of some streets in PUEBLA, Mexico, and because of limitations I cannot use i-Tree STREETS. So I will use I-Tree ECO instead with each street as a strata (like a park), I will be measuirng trees in the sidewalk but mostly in the ridge (middle of the street) which is only 2-3 m wide, however for obvious reasons I will not be measuring Crown Size specially since N/S and E/W lengths are very risky. I just want to have an idea of the order of magnitud of difference in precision that I can have if I measure Crown Size, is it a 5%, 10, 15% difference?
Thanks
Horacio de la Concha
AGRINET SA de CV
Cuernavaca MEXICO
hdelaconcha@agrinet.com.mx
Jason.Henning
i-Tree Team
Posts: 132
Joined: Fri Dec 21, 2012 7:45 am

Re: Crown Size Influence

Post by Jason.Henning » Fri May 11, 2018 9:05 am

Hi Horacio,
I have never looked at the exact situation you describe but you may want to run a test where you enter a variety of crown diameters for a couple species and see how the results you are interested in change. Also, you may want to review this document which indicates which results are based-on the crown width measurements, https://www.itreetools.org/resources/ma ... ations.pdf.
In general, the crown width measurements are used to calculate the crown volume of each tree. That volume is then used to estimate the total leaf surface area of the tree. The leaf surface area is then used in models to interact with the hourly pollution, rainfall, and weather data to estimate the avoided runoff and air pollution removal as well as structural numbers like the crown cover. Since the widths are part of the volume equation they are first converted to an area which means that any errors will be squared and then multiplied by some function of the height. Given the complexity of the hourly modeling it is difficult to gauge the exact impacts but hopefully this gives you a way to consider how those errors may impact your results.
Thanks,
Jason
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