Rules for Co-champion Status

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Rules for Co-champion Status

Post by dbhguru » Fri Nov 28, 2014 11:14 am


One of the last issues Don and I are dealing with in the AF Measuring Guidelines Work Group is co-champion status and how it is determined. This was the subject of our last telephone conference call with American Forests, and they are looking for us to propose a replacement system for the old rule that says if a certified candidate is within 5 points of the champion, it is a co-champion. This old rule applies across the size spectrum of trees. However, some folks advocate a percentage system, e.g. if a candidate is within 5% of the champion, it become, or could become, a co-champion.

There are strengths and weaknesses to both these simple approaches. From my perspective, neither takes into consideration differences in equipment accuracy, the efficacy of different measurement methods (e.g. sine versus tangent), small tree versus large tree measuring challenges, and simple tree shapes versus complex ones. We can't factor in just plain sloppiness, inexperience,or dishonesty, but we can consider the first set of factors that could lead to differences for the same tree assuming equally experienced and conscientious measurers.

Here is our latest thinking, copied from an email that I originally sent to Don, but I'm guessing that he would like to hear the thoughts of the rest of you as he sorts through the elements from the sandy beaches of Kauai, where I believe he is now. Also, I expect the new National Cadre members would like to see this topic aired fully and get input from all sources and points of view. I'll first present what I sent to Don and then explain the two formulas afterward.



1. If at least one of the trees was measured by an older method the following formula applies

Co-Champion Point Spread = 2 + 0.03 x Champion Tree Points

-- or expressed in percentage form --

Co-Champion Point Spread = 2 + 3% of Champion Tree Points

Application of the formula:

a. Current champion was measured by old methods and contender by preferred methods.

If contender has less points than the champion, but is within the spread returned by the above formula, it is a co-champion. It it exceeds the current champion in points, it becomes the sole champion.

b. If Current champion was measured by preferred methods and contender by older methods.

Contender must exceed the champion by at least the spread returned by the above formula to be a co-champion, and then consider only a provisional co-champion.

c. Both trees were measured by older methods.

The contender must exceed the champion by the spread returned by the above formula to be considered a co-champion. It would be listed first, but marked as provisional. The reason for this seemingly odd rule is that we're trying to wean the states off old methods, and we don't want to continue cluttering the National Register with suspect measurements.

2. If both trees were measured by a preferred methods, the following champion applies

Co-Champion Point Spread = 2 + 0.01 x Champion Tree Points

-- or --

Co-Champion Point Spread = 2 + 1% of Champion Tree Points

Application of the formula:

If the contender is within the spread returned by the above formula, it is a co-champion. Which ever tree earns the most points is listed first.

Rationale for above formulas

The first formula covers situations where at least one of the trees was measured by the older more error-prone methods, and the second formula applies to situations where both trees were measured by our preferred methods.

With this explanation in mind, for very small trees, say under 40 feet in height, where the top is easily identified and is cross-triangulated and the extensions of the crown clearly identified along the drip line, measurement errors made will likely not differ appreciably between sine and tangent methods. However, for short trees, the accuracy of the equipment may become a significant factor, especially if the measurer doesn't search for the point of display changeover. For example, lasers with different accuracy ratings such as +/- 3 feet, +/- 1.5 feet, +/- 1.0 foot, +/- 0.5 feet , etc. generate error possibilities for the sine and tangent-based methods that can represent a significant percentage of tree height. Imagine a 3-foot height error on a 30-foot tall tree. That's a 10% error. Keep in mind that there is no assumption made as to who is doing the measuring, i.e. the measurer is not necessarily a Cadre member, so we can't expect compensation/adjustments for all the factors listed above. But this error component is just height. What about the other dimensions?

If the drip line is delineated for a small tree, differences between experienced measurers won't vary that much, but could by a sufficient amount to generate one point on the champion tree formula, i.e. average crown spread difference of of 4 feet, generating one point. Differences in circumference measurements are likely to be well under an inch - a half inch at most.

Putting all these considerations together, I rationalized a two-point spread at the low end of the tree size spectrum, regardless of equipment and methods. However, the error pattern diverges as tree size increases. In the formulas above, I add 3% of the champion's big tree points for older measurement methods and 1% for the preferred methods. I'm not going to admit where I pulled those numbers, except to say that they are based on my personal experience. They may differ from that of the rest of you. So, I'd be most appreciative if those of you who do lots of measuring and are experienced in the main measuring techniques would come forward with your proposed constants and factors. Remember, the equation form is:

Co-Champion Point Spread = Constant + Factor x Current Champion's Points

How do you vote on Constant and Factor for old methods and for the preferred methods?

I recognize that we could build a database of measurements specifically to tease apart the impacts of equipment, method, tree size, and tree shape and refine the two formulas, but judging by past experience, that would take a long time. I mean a long time! Since the 5-point and 5-percent rules are arbitrary, for the immediate future, I have no problem with substituting the present rules with those reflecting our collective experience. We just need to come to an agreement as to where that collective experience points.

Happy After Thanksgiving Everyone,

Robert T. Leverett
Co-founder, Native Native Tree Society
Co-founder and President
Friends of Mohawk Trail State Forest
Co-founder, National Cadre

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Re: Rules for Co-champion Status

Post by mdvaden » Fri Nov 28, 2014 5:43 pm

The co-champion thing crossed my mind again this week after reviewing co-champion Coast Redwoods, and then Oregon's champion Sitka Spruce.


On my page, I list one found a few years ago as an "off-the-record" co-champion, because Ascending the Giants ignored getting around a huge buttress root, and measured above it, about 4 feet too high. Something a plumb bob would easily have bridged.

Although they had a laser, they don't use it to shoot from trunk to branch tips for gauging crown spread. Instead, they wander the ground guessing if they are under the tip. I found trying that it's easy to be off 15 at least.

One of their group said spread did not matter much and that height was the most important with circumference.

That's where we differ a lot. I place equal emphasis on every measurement if possible. I scratch my head why someone might not care as much if crown spread were off a few points, but be diligent about height right down to each point or foot.

I find height and circumference easier than crown spread.
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Re: Rules for Co-champion Status

Post by Don » Sat Nov 29, 2014 1:00 am

There’s a lot to address in your post, but my first stab is to support you in your sense that the accuracy of all measurements are important, in our context. Towards the crown spread measurement end, I’ve long been a proponent of the GRS Densitometer…as described in part, below in

"The GRS Densitometer contains a mirror, sighting marks (guides), and leveling vials allowing the user to project a vertical line-of-sight either up into the canopy or down to the ground. The field technician can simply look through the GRS Densitometer, level the two bubble vials, align the sighting marks, and then tally the feature(s) covering the sighting mark (intersection of cross-hairs or dot). Depending on the type of survey you are performing, you can record the various characteristics of the vegetation and/or landscape feature(s) that cover or intersect the sample point location."

For specifics in purchase, go to:

For a better sense of what it looks like, go to: ... sp?id=6512

With one spirit level establishing horizontal, and the other establishing vertical, you can walk to the crown’s edge, and after a "little back and forth-ing", rather accurately determine the crown’s edge…in conjunction with a laser rangefinder, “crown radii” can be rather quickly obtained, if using the “spoke method”.
Don Bertolette - President/Moderator, WNTS BBS
Restoration Forester (Retired)
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