Tallest three eastern sites compared

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Will Blozan
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Tallest three eastern sites compared

Post by Will Blozan » Sun Feb 12, 2012 3:03 pm

NTS,

I know I have other things to do but in the course of entering new data I had some thoughts about Rucker indices and the Tree Dimension Index (TDI) system. These ideas are not new but the numbers below are up-to-date so we have some real numbers to look at. Jess Riddle also proposed looking at the number of record trees per site which I have also done. This is inherently reflected in the TDI scale but just raw numbers tell a clear story.

Most of my work with NTS has coincidentally been in the super-tree sites of Great Smoky Mountains National Park (GRSM- NC&TN), Congaree National Park (CONG-SC), and Savage Gulf State Park (SVGF-TN). Thus, I was interested in looking at the current Rucker 10 and Rucker 5 indices as well as TDI height indices for all three sites.

I know, some will instantly respond with the disparity of the sizes of the parks in question. GRSM is vastly larger than SVGF with CONG similar to SVGF. This is not reflected in the numbers below but there are still vastly smaller areas of GRSM that totally smoke the entire park RI for both CONG and SVGF. This can be explored in more detail later.

Also, the numbers used below are maximum current and historical heights as obtained by laser only. The Boogerman Pine's original tape-drag is not included and some trees in both GRSM and CONG are now dead. These are compared to max known to NTS. A value of 1.00 in the TDI scale means it is the tallest specimen known of the species.

With this in mind here are the current Rucker Index and TDI series for all three parks. There is a comparison of the top 10 and top 5 trees in each park, # height records (HTR) in the top 10 and 5, and concludes with a percentage of the eastern max Rucker 10 index which is 171.45. Taking it out to the R20 would be interesting; GRSM is still 158.9!

Comparison of top three tall eastern tree sites
R10 R5 TDI10 TDI5 HTR 10 HTR 5 Percent of east R10
GRSM 169.42 178.54 0.988 1.00 9 5 98.82%
SVGF 154.88 161.14 0.953 0.953 2 2 90.34%
CONG 151.46 160.36 0.980 0.989 8 4 88.34%

For what it is worth, here is something to chew on. I would think that the TDI10 may be a good way to compare widely different sites in a more equatable way. It eliminates the height variance over latitude and if compared using regional maxima this wouold further reveal the superlative sites relative to others in completely different geographic regions. Mohawk Trail would likely compare on par with the Smokies.

Is there a way we can scale these ratios into a superlative index?

Will

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Tyler
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Re: Tallest three eastern sites compared

Post by Tyler » Mon Feb 13, 2012 10:46 am

Will,

I like the idea of using the TDI10 to compare different sites. I'm all for comparing the sites in as many different ways as possible. It's interesting that in the top three sites in the east, extremes of topography can be seen. At CONG one of the flattest sites, SVGF with rugged mountains, and GRSM having the tallest mountains in the east.

I wonder how the sites would compare with the Rucker Girth Indices plugged in instead of the height?

Tyler

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bbeduhn
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Re: Tallest three eastern sites compared

Post by bbeduhn » Tue Feb 14, 2012 12:33 pm

I agree about using TDI as a comparison. One question is where to draw the borders on the regional level. Should it be by state/political borders or by natural borders (mountain ranges, rivers, etc.)? Is there enough data for some regions to establish maximum heights? The more the merrier with comparisons and data. I like to get creative with stats. Baseball has a ridiculous number of comparison points now with Sabermetrics. Our forests can certainly use more stats, though perhaps not so many as baseball now utilizes.

As for scaling into a superlative index, the Smokies would have to be broken up into its own regions, some examples, Cataloochee, Cosby, Deep Creek. The numbers Will has given work well. It breaks them down to a decimal figure, the closer to 1 the more superlative. The question remains on how to delineate the regions or simply follow latitude. I assume natural divisions would work better than political or latitudinal divisions.

I'm sure there are more columns to be added to what Will has so far but I like what I see so far.
Brian

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edfrank
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Re: Tallest three eastern sites compared

Post by edfrank » Mon Feb 20, 2012 1:46 am

Brian,

We have talked about how to define borders before. There really isn't a single best way to do it. Everything is pretty dependent on what you are trying to compare among the sites. It probably needs to be done on a case by case basis. For example if we include PA as part of the northeast, Say the tallest walnut would be in western PA, near the Ohio border, while the tallest walnut in Oho was in the eastern part of the state near the PA line. Would it be better to have an arbitrary division of Northeast versus Midwest, or should it have the flexibility to say these sites should be considered as part of the same region?

Arguments can be made for ecological boundaries based upon forest type, or for political boundaries because of their clearly defined ad understood boundaries, but I would suggest whatever division or definition is best or most appropriate for the comparison you are making. I have argued in the past in favor of ecological forest type designations that are fudged to the closest political boundaries, but since have been persuaded to change my mind to a case by case, comparison by comparison basis.

We have been having this discussion of what is a site in regards to the structure of the NTS database import fucntion. I like the idea of sites with subsites within those sites defined by whatever criteria the measurer decides is best. This follows the numerical concept of sets and subsets. A subsite could encompass the entire site, in which case they would be the same. Others have suggested different designations. (I mostly agree with my own opinion, but can be convinced to change my mind with better information and better ideas.)

The idea of superlative works well if by superlative you mean height. There are other criteria that might make a site superlative aside from just height - age of trees, complexity of the ecosystem, how intact the forest might be, species composition, unique growth patterns, or some aesthetic criteria. In many of these cases it is not easy to assign a value for a superlative comparison. I talked about some of these ideas in the Forest Aesthetics discussions available on the website.

Ed
"I love science and it pains me to think that so many are terrified of the subject or feel that choosing science means you cannot also choose compassion, or the arts, or be awe by nature. Science is not meant to cure us of mystery, but to reinvent and revigorate it." by Robert M. Sapolsky

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Will Blozan
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Re: Tallest three eastern sites compared

Post by Will Blozan » Mon Feb 20, 2012 8:05 am

Tyler wrote:Will,

I like the idea of using the TDI10 to compare different sites. I'm all for comparing the sites in as many different ways as possible. It's interesting that in the top three sites in the east, extremes of topography can be seen. At CONG one of the flattest sites, SVGF with rugged mountains, and GRSM having the tallest mountains in the east.

I wonder how the sites would compare with the Rucker Girth Indices plugged in instead of the height?

Tyler
Tyler,

You bring up a good point since hidden in your question is perhaps one potential "flaw" of the TDI index. First, just my comments on the RG10 for each site; the ten largest tree species based on trunk girth. Both GRSM and CONG would score quite high since each park contains the largest known specimen of several species. SVGF would not score very high as the trees are superlatively tall, not large. I don't have enough data or time to look into this right now so I am just guessing.

Here is the problem; with enough looking- all three parks could potentially tie at 100 based solely on TDI girth values. Remember, the TDI system "levels the playing field" so that the diminutive (but supelative) gum bumelia in CONG would out-point the huge cherrybark oak (not sure- just an example). Thus, should the RG index should be made of the top ten largest individuals for the species or for the site? Same for height, volume, or whatever metric is used.

Of course it should be for the maximum on the site, not TDI value but as you have probably figured out by now- this number would very likely not be the highest score possible. What does this tell us?

Will

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edfrank
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Re: Tallest three eastern sites compared

Post by edfrank » Mon Feb 20, 2012 10:24 am

Will, Tyler,

For comparisons you should be comparing the largest examples of whatever parameter you are measuring. So for heights the GRSM would be tops, with girth there would almost assuredly be different trees from the sites that you are comparing as the fattest aren't necessarily the tallest. The girth index would be based upon the fattest trees. For TDI composite you would compare those trees with the largest TDI's.

Comparing for individual TDI parameters such as the TDI height or the TDI girth values is an interesting applicaton. TDI measures the size of an individual with biggest for that species. In looking at just one TDI parameter the value should be the largest example of each of the ten largest species for that parameter. If three parks would tie for the highest score, I don't really see any problem with that. I don't see this as very likely, but why could they all not be the best for the species they include? It is different way to define or compare what is or is not superlative, but it seems to be a valid concept to me and not a flaw at all.

I never have liked the idea of creating a value for a single species based upon the largest ten individuals for that species. It basically is just an average that better reflects the amount of and depth of measurement that has been done more so than being a good reflection of the size of that species. With the Rucker Index even if you have not actually found the single tallest individual, you are close and the result is a reasonable assessment of the overall height structure.

Ed
"I love science and it pains me to think that so many are terrified of the subject or feel that choosing science means you cannot also choose compassion, or the arts, or be awe by nature. Science is not meant to cure us of mystery, but to reinvent and revigorate it." by Robert M. Sapolsky

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Will Blozan
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Re: Tallest three eastern sites compared

Post by Will Blozan » Sun Sep 29, 2013 4:16 pm

NTS,

Just wondering if Don Bertolette has seen this exchange yet... as it was a topic of discussion not long ago. Be nice to revive it as well.

Will

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Jess Riddle
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Re: Tallest three eastern sites compared

Post by Jess Riddle » Sat Oct 05, 2013 9:00 pm

Will, All;

This is great to see. The up to date numbers are nice, and the comparison is very interesting. Not surprising, but still interesting. These numbers seem like a great launching point for a discussion of how to describe sites.

To put the comparison of ranking systems another way, we are simply talking about absolute height versus relative height. The Rucker Index averages the absolute heights of the tallest species. TDI, when reduced to only the height component, is simply relative height. As Will points out, state height records are a special case of relative height. They take the state height record as the standard and express height on a binary scale; a tree is either the record or it isn’t.

Relative height definitely offers some advantages for comparing sites in very different environments. The standard could be also defined by many criteria beyond ecoregion or political boundaries. For instance, we could compare sites with forests of different ages. Some fantastic sites may be languishing in obscurity, because the absolute height of the trees are not yet as great as those of more mature sites. We are limited only by the variety of sites we have collected data on.

As Ed has implied, unless I’m mis-interpreting his comments, many of the decisions about how to choose categories and groups for analysis should be dictated by our goals. Looking at sites within the context of the eco-region where they occur might be most appropriate for a scientific analysis, while using political boundaries would be better suited for a report to managers. Similarly, only the tallest species would be included if we were considering impression of height a site creates (not quite the right phrase), while all species would be included for other goals. If we do sum comparisons using all species, the sum of heights might have more intuitive appeal than the average.

I hope this discussion continues as I’m sure others have more good ideas about how to numerically describe tall tree sites.

Jess

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Will Blozan
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Re: Tallest three eastern sites compared

Post by Will Blozan » Sun Oct 06, 2013 7:11 am

Jess,

Many thanks for your input here. "Languishing in obscurity" is a classic phrase that often sums up my posts here...

Anyway, the limitless potential of the TDI concept is overwhelming and defining the best application certainly is a must. This is no small task and illustrates the need for more and more accurate NTS generated tree data- of ALL species. At the most basic level, I really think it has the power to transform champion tree lists into a more realistic product that includes all tree forms unbiased (not multi-stemmed though).

Your comment about forests that have not reached potential yet is a great one. If we can affix age of origin to the stand (or tree?) then we have a great metric with which to measure potential. Chasteen Creek, Barkers Creek, and other sites immediately pop into mind as superlatives coming of age so to speak. I think Burnt Mountain would be the 100 on the scale for a young site based on what I have seen...

Will

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Don
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Re: Tallest three eastern sites compared

Post by Don » Sun Oct 06, 2013 10:52 am

Will-
Relative to comparisons, I think you're on to something, and I'll be re-reading the thread to further comprehend the 'subtleties and nuances'...
Regarding the AF system of comparisons, it's something I suspect would be possible in the future. Currently the data supporting the National Registry wouldn't have a standard level of accuracy for comparison. As AF "ups the accuracy level", TDI could be helpful...those who've commented in the past with regard to other superlative features of the trees under comparison are only as valuable as the standards of data are the same.
I'm guessing, without having fully thought this out, that the width of the array of size champions that AF collects is broader than the TDI could reasonably include?
-Don
Will Blozan wrote:NTS,

Just wondering if Don Bertolette has seen this exchange yet... as it was a topic of discussion not long ago. Be nice to revive it as well.

Will
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