Required inputs for calculating leaf surface area

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pete.stewart
Posts: 7
Joined: Tue Apr 03, 2018 1:19 pm

Required inputs for calculating leaf surface area

Post by pete.stewart » Wed Nov 14, 2018 8:11 am

I'm wondering what are the required set of measurements (and also the optimal ones) for calculating leaf surface area.
I'm wanting to use Eco to help me make calculations of the Importance Value of ash trees in series of parks, and trying to settle on a relatively quick data collection protocol.
Are species and dbh by themselves enough for a rough estimate? To improve the estimate should I also measure height, spread, and other variables? Thanks!
azelaya
i-Tree Team
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Joined: Fri Jun 27, 2008 10:50 am

Re: Required inputs for calculating leaf surface area

Post by azelaya » Wed Nov 14, 2018 11:14 am

The following information is extracted from the Use of DIrect Measures by i-Tree Eco v6 document which describes how tree measurements are used for various estimates https://www.itreetools.org/eco/resource ... nships.pdf

DERIVED VARIABLES
• Leaf area is estimated using:
o Species – to identify shade coefficient
o Total height – to estimate height of the crown
o Crown base height – to estimate height of the crown
o Crown width – to identify crown width dimension
o Percent crown missing – to modify base leaf area for actual amount present

In short, your leaf area estimates will be improved by providing more canopy measurements which are used by the model to estimate crown volume and adjust for missing areas, etc. Otherwise, the model is estimating these which may be more inaccurate especially at the individual tree level. There is not a known factor to describe the accuacy difference, but you could always try running a measured tree with and without canopy measurements to compare estimates and get an idea of differences in estimates.
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pete.stewart
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Joined: Tue Apr 03, 2018 1:19 pm

Re: Required inputs for calculating leaf surface area

Post by pete.stewart » Thu Nov 15, 2018 9:59 am

Thanks ! That's really helpful.
Am I getting this correct: If I don't enter data for 'Percent Crown Missing', Eco will use 13% as a default for all species? (From the 'Eco Guide to Data Limitations' pdf)
azelaya
i-Tree Team
Posts: 372
Joined: Fri Jun 27, 2008 10:50 am

Re: Required inputs for calculating leaf surface area

Post by azelaya » Thu Nov 15, 2018 11:10 am

Yes. your understanding is correct as a default of 13% will be applied as the Percent crown missing to all trees if you decided not to collect the "Crown" measurments.

You may have noticed in Eco that there are (4) measurements that are required if you toggle on the "Crown Size" option in project configuration.
Height to live top
Height to crown base
Canopy width: East-to-West & North-to-South (2 measurements)
Percent crown missing

Basically, these are all associated and you will need to provide all or nothing with this particular data option.
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Hanyu
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Joined: Sat Apr 30, 2022 12:32 am

Re: Required inputs for calculating leaf surface area

Post by Hanyu » Sat Apr 30, 2022 12:37 am

Hi, I would like to learn some more information regarding this topic.
In MyTree, when we try to describe our tree at the begining, we are only asked to enter the species and the dbh. However, according to the manuscript, numbers such as height is also required. Does this mean there is a calculation to get the height using the given species and dbh. Otherwise, how does the system know the height without us entering the numbers.

Thanks.
azelaya wrote:
Thu Nov 15, 2018 11:10 am
Yes. your understanding is correct as a default of 13% will be applied as the Percent crown missing to all trees if you decided not to collect the "Crown" measurments.

You may have noticed in Eco that there are (4) measurements that are required if you toggle on the "Crown Size" option in project configuration.
Height to live top
Height to crown base
Canopy width: East-to-West & North-to-South (2 measurements)
Percent crown missing

Basically, these are all associated and you will need to provide all or nothing with this particular data option.
Jason.Henning
i-Tree Team
Posts: 290
Joined: Fri Dec 21, 2012 7:45 am

Re: Required inputs for calculating leaf surface area

Post by Jason.Henning » Mon May 02, 2022 8:02 am

Hi Hanyu,
I am guessing the original post was referring to i-Tree Eco where users have the option to submit the height and other crown metrics to get the most accurate estimates. MyTree is a greatly simplified tool that allows for ecosystem service estimates based on a minimum set of tree measurements. There are allometric equations that are used to estimate the crown width and tree height base on the tree's species and diameter. Other assumptions are made about average dieback and percent crown missing. If you would like to use the complete set of crown related measures you should use i-Tree Eco. For more details about the underlying methods and equations please see Understand i-Tree and the publications referenced in that document.
Thanks,
Jason
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Hanyu
Posts: 3
Joined: Sat Apr 30, 2022 12:32 am

Re: Required inputs for calculating leaf surface area

Post by Hanyu » Wed May 11, 2022 11:09 am

Thank you so much for your reply. I wonder if there's annwhere we can see the equetions for MyTree where it calculates the crown width and tree height base on the tree's species and diameter.
Jason.Henning wrote:
Mon May 02, 2022 8:02 am
Hi Hanyu,
I am guessing the original post was referring to i-Tree Eco where users have the option to submit the height and other crown metrics to get the most accurate estimates. MyTree is a greatly simplified tool that allows for ecosystem service estimates based on a minimum set of tree measurements. There are allometric equations that are used to estimate the crown width and tree height base on the tree's species and diameter. Other assumptions are made about average dieback and percent crown missing. If you would like to use the complete set of crown related measures you should use i-Tree Eco. For more details about the underlying methods and equations please see Understand i-Tree and the publications referenced in that document.
Thanks,
Jason
Jason.Henning
i-Tree Team
Posts: 290
Joined: Fri Dec 21, 2012 7:45 am

Re: Required inputs for calculating leaf surface area

Post by Jason.Henning » Thu May 12, 2022 3:43 pm

Most of the dbh to crown width models are derived from this publication, https://www.fs.usda.gov/treesearch/pubs/60534. For additional details about the dbh to height to models you can email info@itreetools.org for a spreadsheet of equations by species.
Thanks,
Jason
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Hanyu
Posts: 3
Joined: Sat Apr 30, 2022 12:32 am

Re: Required inputs for calculating leaf surface area

Post by Hanyu » Fri May 13, 2022 2:55 am

Thank you so much. These are really useful information.
Jason.Henning wrote:
Thu May 12, 2022 3:43 pm
Most of the dbh to crown width models are derived from this publication, https://www.fs.usda.gov/treesearch/pubs/60534. For additional details about the dbh to height to models you can email info@itreetools.org for a spreadsheet of equations by species.
Thanks,
Jason
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