What are the parameters behind the tree type codes?

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Joined: Mon Jul 15, 2013 6:03 pm

What are the parameters behind the tree type codes?

Post by leremita » Mon Jul 15, 2013 6:59 pm

Are height and width determining factors for the tree size categories: small, medium and large? And what are the sizes (in feet) of each category? Small is 25' or less?

And do you keep the same tree type throughout the climate zones, or can it change? For instance a tree at the coast may be bigger because of moisture, and shorter in the desert?

I noticed that some plants are given the category of "palm" even though they are not palms. Is that just because that's the best reference plant?
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What are the parameters behind the tree type codes?

Post by azelaya » Wed Jul 17, 2013 10:54 am

The parameters for this type of information can be found in the Community Tree Guides which provide the background methodology of the Streets model.

For example, page 36 of the Southern California Tree Guide has a chart with basic canopy width, height and leaf surface area that are used for representative small, medium and larger trees in that climate zone. The USFS Community Tree Guides can be accessed from the Resources - Archives page http://www.itreetools.org/resources/archives.php under the i-Tree Streets Reference City Tree Guides tab

SMALL TREE - 23 ft tall, 28 ft spread, 628 sq. ft
MEDIUM TREE - 24 ft tall, 28 ft spread, LSA = 1,438 sq. ft.
LARGE TREE - 36 ft tall, 39 ft spread, LSA = 2,496 sq. ft.

This is a regional model so there are limitations as you mentioned as growth in different areas of the zone can vary. It is possible for users, fine tune the species value assignments to make the model more localized by opening the Input - Species option in Streets and changing assigned species values to be more representative of their local tree characteristics.

There are typically only 20-30 trees modeled in each climate zone http://www.itreetools.org/streets/resou ... ov2011.pdf and those modeled trees are then used as representative trees for other common street trees in a climate zone to determine estimated ecosystem services and structural values. yes, there are instances where palms may be assigned to non-palms as the determined as that was the best reference plant by the original researchers.
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