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TOPIC: Another Idea - Rucker Index Depth
http://groups.google.com/group/entstrees/browse_thread/thread/a0d6b4bf723ebeb9?hl=en
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== 1 of 1 ==
Date: Fri, Jan 25 2008 9:38 pm
From: "Edward Frank"
ENTS,
If you have been with the group for awhile you know I do not feel
favorably toward the multiple iterations of the Rucker Index. This
approach mentioned by Colby Rucker in a post http://www.nativetreesociety.org/threads/top_ten_stuff.htm
strikes me as a better way to look at species depth, along with the
previous idea of 3D Tree Profiles
Here is what Colby wrote in Part:
With a decent number of sites on the list, it's interesting to see
how
specific areas rank, and speculate on why. For starters, I looked at
the #
10 tree for each site, and noticed that CCW & MTSF were not only
taller than
the sites ranked lower, but taller than a couple above. This goes to
that
"deep depth" factor - lots of species over 100 feet.
Belt Woods is quite the opposite. Although the visual impact is
rather
overwhelming, the tall-tree diversity is very low, with the #10 tree
being
at the bottom of the list. If the list were based on just five
species, the
list would be quite different: Sevier 158.1, Congaree 152.7, Belt
145.8,
Tamassee 145.8, Cook 141.9, Cohutta 140.0, Mohawk 139.8, Kelly
138.0, Chase
137.6, IceGlen 136.2, L.Pinnacle 130.0, Long Cane 129.7, Monroe
129.0, Grren
Lake 126.5, Beall 126.1, Corcoran 124.8.
If we take the average of the smaller five (trees #6 through # 10),
we see
that "deep depth" factor again. Sevier 142.1, Congaree
131.3, Tamassee
125.9, Kelly 124.1, Chase 121.4, Mohawk 119.7, Long Cane 118.7, Cook
118.2,
Belt 116.2, LPinnacle 115.8, Corcoran 114.7, IceGlen 114.2, Beall
113.8,
Cohutta 109.8, GreenL 109.5, Monroe 105.4.
In the above list, Mohawk & Chase improved their rankings, as
did Long Cane,
LPinnacle, IceGlen and Corcoran, suggesting considerable diversity
in the
upper canopy. Although we are aware that the loss of a single
outstanding
tree could change the numbers, that single tree does represent, as
best as
we can determine, the potential of that species at this time, so
it's
reasonable. If the lost tree is the last of its kind, it suggests
that the
forest structure has changed, and there's no longer a niche for that
species.
The looking at different portions of an extended Rucker Index
strikes me as a viable approach.
Ed Frank
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