TOPIC: PRI, HRI, and PRI/HRI
http://groups.google.com/group/entstrees/browse_thread/thread/22c204d0e0f584f9?hl=en
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== 1 of 1 ==
Date: Fri, Oct 3 2008 3:35 pm
From: dbhguru@comcast.net


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.
Historical Index

 

Historical Index
Height	Species	Circumference	ENTS Points	DOM
169.4	WP	10.4	1832.2	7/1/2007
151.5	WA	6.2	582.4	11/20/2004
138	SM	11.4	1793.4	10/18/2002
133.5	NRO	9.3	1154.6	11/25/2004
131.8	BNH	4.3	243.7	4/24/2006
131	HM	10.7	1499.8	9/21/2003
130.5	AB	8.4	920.8	4/9/2006
128	RM	6.6	557.6	4/15/2006
127.7	BTA	3.5	156.4	10/24/2002
126.9	ABW	5.5	383.9	4/26/2006
136.8	Rucker Index
Present Index
Height	Species	Circumference	ENTS Points	DOM
169.4	WP	10.5	1867.6	9/7/2008
150.1	WA	6.2	577.0	4/30/2006
134.4	SM	5	336.0	10/23/2006
133.5	NRO	9.3	1154.6	11/25/2004
131.8	BNH	4.3	243.7	4/24/2006
130.5	AB	8.4	920.8	4/9/2006
130.3	HM	11.1	1605.4	11/26/2006
128	RM	6.6	557.6	4/15/2006
126.9	ABW	5.5	383.9	4/26/2006
126	BTA	3.5	154.4	4/27/2006
136.1	Rucker Index

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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TOPIC: PRI, HRI, and PRI/HRI
http://groups.google.com/group/entstrees/browse_thread/thread/22c204d0e0f584f9?hl=en
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== 1 of 1 ==
Date: Sat, Oct 4 2008 11:53 am
From: "Edward Frank"


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/

==============================================================================
TOPIC: PRI, HRI, and PRI/HRI
http://groups.google.com/group/entstrees/browse_thread/thread/22c204d0e0f584f9?hl=en
==============================================================================

== 1 of 2 ==
Date: Sun, Oct 5 2008 9:26 am
From: dbhguru@comcast.net


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

== 2 of 2 ==
Date: Sun, Oct 5 2008 10:11 am
From: "Edward Frank"


Bob,

As for time, I we could consider just using the date of the most recent updating measurements or additions to demarcate the date. This includes the assumption that the other trees on the list are still standing or haven't gotten shorter since they were measured - not a bad assumption generally. But settling on a single date for the update rather than a range, there would facilitate analysis and comparison between sites. I don't have a problem really with listing the range of time for the measurements as you suggested, but for plotting things the date of the most recent update on the list would be the appropriate one to use.

As for site size,yes we can break larger sites down into smaller subsites. GSMNP can be broken down into drainage basins, with the rank of the drainage basin basically determining the size. I would be curious to see what those size can out to be. A site should be broke down only if there is some way to define the area in terms of topography, or ecology. I am not a big fan of just drawing lines to create artificial boundaries (topography is the closest I feel comfortable with in this respect.). Sometimes breaking a site down into smaller segments would be simply arbitrary and I don't know what that really gain us us toward understanding. Perhaps just listing the acreage included in the site or subsite for the Rucker Index would be sufficient.

There was the idea Jess expressed about looking at the size versus RI concept. I really liked it, but mine was the only reply. Perhaps we can get Jess to expand on his idea and my questions.

Ed