comparing 30yr to 50yr forecast outputs

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kselmkibi
Posts: 1
Joined: Tue Jun 11, 2019 9:03 am

comparing 30yr to 50yr forecast outputs

Post by kselmkibi » Tue Jun 11, 2019 10:06 am

basically, i ran the forecast for the same set of 700 trees at the defafult of 30 years, and then again at 50 years.
and the results were different - not drastically different, to be fair - but the difference nonetheless calls for examination:

the 30 year analysis said the total lea area acreage will be 5.0 at the 30 year mark.
the 50 year analysis predicted that the total leaf area would be 4.9 at the 30 year mark.

I understand that this is relatively small, i'd just like to understand why.

also, i would like to understand why runoff avoided is not part of the forecast outputs.
Has anyone attempted their own runoff avoided calculations based on the leaf area forecast? what was your approach to that?
Jason.Henning
i-Tree Team
Posts: 172
Joined: Fri Dec 21, 2012 7:45 am

Re: comparing 30yr to 50yr forecast outputs

Post by Jason.Henning » Wed Jun 12, 2019 8:21 am

I was able to replicate that discrepancy due to different project lengths and agree that appears to a bug rather than a rounding error. I have submitted it as an issue through our internal system and our development team will take a look at it.
Adding avoided runoff to the Forecast projections is on our work list. We actually have an internal prototype that will do that estimation, it is a matter of getting programmer time to implement it. The internal prototype parses avoided runoff based on estimated canopy cover rather than leaf surface area. Canopy cover can capture how much ground surface is covered by trees which helps account for things like improved infiltration and ground water storage. Leaf surface are,a on the other hand, is a more direct metric of accounting to leaf level storage. I think both approaches can be justified.
A member of the i-Tree Team
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