Ed,
Thanks for helping flesh out these ideas. When I submitted my thoughts, I
had three concepts floating around in my head, two of them dealing with HRI and
one with PRI. The one I settled on for HRI was that of the tallest member of
the ten tallest species regardless of the time frame in which the trees were
measured as opposed to reporting the index computed as of a specific date in
the past, presumably representing all standing trees. To date, we haven't
thought much about factoring into the index the time element, but maybe we
should get serious about incorporating time.
In truth, for sites covering a lot of ground, we will generally have
measured some of the constituent index members recently and others not for a
year or two or longer. So some of the trees composing a currently reported
index may not be standing when we submit the index to a list. This raises
questions on what information we intend the index to actually convey. Do we
intend the index to be a snap shot of a site at a specified point in time? Time
plays a critical part and prevents most of our indices from actaully
representing snap shots.
Medium-sized sites may be covered in a season and really small areas in
just a few days. In fact, we may make only a single visit to a site and report
the index based on that visit, but from my experience, one visit seldom does
justice to a site. We all know that, but our knowledge doesn't always get
transmitted in our reporting. Somehow the effort expended needs to get
communicated as well as the overall time period a reported index represents. At
least we need to be thinking in that direction.
I admit that do like the idea of an index giving us a more or less
current snapshot of a site. But, more importantly, I want to know what a site
is capable of growing over an extended period of time. The historical pattern
of an index is informative about how a site deals with disturbances, growth
rates, etc. as an index goes up one year and down the next. I'm inclined to
think the historical index, by whatever name, is the best measure of what a
site can produce over time and should serve as the base or denominator of
possibly several kinds of ratios. The question is how complicated do we want to
make the indexing process and toward what objectives.
I like your notation/nomenclature better than mine. I think you are on to
something with a date suffix. How about extending it to include a date range
for the constituent trees. The years of the newest and oldest measurements
would be used to show the range to which the index is applicable. For example,
MTSF's index is based on measurements from 2004 to 2008. The full notation
would be: RHI10:2004-2008 or RI:2004-2008 for short in case of the index .
This form would reveal indices in need of updating.
While we're discussing the Rucker index, we need to tackle to the topic
of site size with more determination. The area of MTSF that produces the 136+
index covers at most 1,500 acres, and if I drew the boundaries carefully, that
size would likely be between 1,100 and 1,200 acres. For larger sites, I
particularly like the idea of an overall site index combined with several
sub-site indices.
Bob
-------------- Original message --------------
From: "Edward Frank" <[EMAIL PROTECTED]>
Bob,
I assume the question was partially directed at me as well as the rest of the
ENTS members. I like the concept you are presenting here. One index, your
Historical Rucker Index, HRI, is the Rucker Index including the tallest trees
of the tallest ten species ever measured at a site. Your Present Rucker Index
PRI, includes only the heights of tree as they exist at the present time. I
like the ratio you propose comparing the two indexes. I really don't care for
your nomenclature.
When you say Historical Rucker Index, I think of it as meaning the RI at some
discrete point in the past. In general I have always considered the basic
Rucker Index to represent the average of the largest trees recorded at the
site, and their maximum height, whether or not they were still at their maximum
height, or whether or not they were still standing. Others may have
interpreted this value differently. I would recommend that the standard Rucker
Index be defined in this way explicitly, then the term "Historical" would not
need be used. This would clarify the meaning of the value and avoid future
confusion
For your PRI, you are talking about the index of the contemporaneous trees
growing at the site at this particular time - the present. What strikes me is
that if you call "Present" then it practically begs to ask what date does
present mean? If someone would look back from fifty years in the future, then
they would want to know the date of the "Present" in the index. Still, though
have wracked my brain, I can think of no word or letter more appropriate for
the 'snapshot in time' idea you have proposed.
In May 2006
http://www.nativetreesociety.org/measure/rucker/to_rucker_or_not_to_rucker.htm
We had a discussion about the nomenclature of the various Rucker Index. I
proposed a structure that I thought would be good for the long-term for how the
information should be ordered. The idea was to avoid confusion as we added
more and more variations of the Rucker Index to the repertoire. I would like
to encourage the adaptation of this idea of a Present Rucker Index to that
format. It isn't that I proposed this structure, it is because I think a
uniform naming pattern will make things easier to deal with over time.
The structure I proposed was of the format for example: RHI10-xx where:
1) Type of Index (R = Rucker)
2) Parameter of Index (H = Height,) code letters for other types of
indexes like girth, crown spread, etc would go here.
3) Number of trees in the Index (10, 05, 20, etc)
4) Other Information (for example the 15th iteration would be
represented as I15)
In the case of the basic rucker height index with 10 trees, the notation could
be simplified to just RI, if another type of index was used, or if the basic
height index was used in conjunction with another parameter, then the full
notation would be required.
For your Present Rucker Height Index, the full notation I would suggest would
be RHI10-P2008. This would mean Rucker- Height Index - 10 tree - Present -
2008. In the discussion there is no reason it could not be simplified to RI-P.
In the tables I would suggest the full notation.
In your ratio, the RI (HRI in your notation) would always be greater than the
RI-P (PRI) in your notation. This ratio may be informative about the current
versus maximum heights on a site. Over a long period of time you may also
compare the RI-P from different times and see how these values changed over
that period of time. That is one reason why the RI-P should have a date also
in tables or compilations. The format for dates should be just the year- I
don't see time resolution beyond that being practical or useful.
Ed Frank
Join me in the Eastern Native Tree Society at http://www.nativetreesociety.org
and in the Primal Forests - Ancient Trees Community at:
http://primalforests.ning.com/
----- Original Message -----
From: [EMAIL PROTECTED]
To: [email protected]
Sent: Friday, October 03, 2008 6:35 PM
Subject: [ENTS] PRI, HRI, and PRI/HRI
ENTS,
Today John Knuerr and I tracked down the champion white ash in Trout Brook
and remeasured it. Its prior height as determined by John Eichholz a couple of
years ago was 151.5 feet, tops in the Northeast. However, the top sprig appears
dead. We got 149.3 feet after multiple measurement attempts. There is still a
lot of understory that blocks vision, so we can't absolutely rule out a higher
point. We'll return in about a month when the crown will be more visible.
However, at present, the tree drops out as the tallest of its species for MTSF
and in its place is the other 150-footer on the south side of Clark Ridge.
This brings me to a point. Trees can die and drop out of the RHI for a
site. Other trees can come into the list. Still other trees can gain or lose
height and still remain in the list. What this inevitable change of the index
means is that we can lose sight of the potential of the site to grow tall
trees, which is partly what we are attempting to measure with the RHI or RI for
short. We are, of course, also taking instantaneous shots of the forest,
capturing status at a moment in time. The following tables show the historical
and present indices of MTSF. When I report a site index in the future, I
will include its historical Rucker Index HRI along with its present RI, called
a PRI (present Rucker Index) for properties where the more detailed level of
reporting is warranted. That would generally be the case for properties that
are visited frequently like MTSF. I would hope Dale will do the same for Cook
Forest , Tom Diggins for Zoar Valley, and Will for the GSMNP.
One way we might implement the concept is to show the two indices in ratio
form: PRI/HRI. For MTSF that form would yield 136.1/136.8. Thoughts, anyone?
Bob
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