How convert canopy point to surface area?

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cjusto
Posts: 2
Joined: Thu Apr 30, 2020 3:05 pm

How convert canopy point to surface area?

Post by cjusto » Thu Apr 30, 2020 3:13 pm

Can you explain to me how convert a canopy point (i-Tree Canopy) to surface area in (km2)?
Thanks!
Jason.Henning
i-Tree Team
Posts: 224
Joined: Fri Dec 21, 2012 7:45 am

Re: How convert canopy point to surface area?

Post by Jason.Henning » Thu Apr 30, 2020 6:15 pm

Thanks for the question.
The tool is not converting individual points to area but it is converting the percentages. If 25% of your sample points are classified as tree canopy then the sampling assumption is that 25% of the area is tree canopy. If the total area within your boundary of interest is 200km² then .25*200km² = 50km² of tree canopy.
This same conversion works for any of the covertypes and if you apply it to each covertype and sum those areas you will get the total area within your boundary of interest.
This is a linear transformation and which is why the percent cover and area can both be reported on the same graphs in the i-Tree Canopy reports.
-Jason
A member of the i-Tree Team
farkasal
Posts: 6
Joined: Thu May 28, 2020 1:30 pm

Re: How convert canopy point to surface area?

Post by farkasal » Wed Aug 12, 2020 9:22 am

Hi Jason,

I had the same question about how i-Tree Canopy calculates Area per land cover class. I assumed the same, that it would just take a percentage of the area of the boundary, but the sum of all the areas calculated is more than double that of the actual area being surveyed (448 km2 calculated by Canopy vs 212 km2 actual, n=3300). Does this have to do with sample size? Or maybe an incorrect estimate of the area within the uploaded boundary?
Erika.Teach
Posts: 23
Joined: Fri Feb 12, 2016 2:59 pm

Re: How convert canopy point to surface area?

Post by Erika.Teach » Wed Aug 12, 2020 11:15 am

Hello, Jason is working on other projects today. Will you please send us a copy of the Canopy project you are working with as well as the files you uploaded to define the area in Canopy, the shape file. Send those to info@itree.org

Thank you, Erika
farkasal
Posts: 6
Joined: Thu May 28, 2020 1:30 pm

Re: How convert canopy point to surface area?

Post by farkasal » Thu Aug 13, 2020 9:49 am

Hi Erika!

I've sent off an email with the requested files to info@itreetools.org.
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