The Next Step For MTSF/ Study Plans   dbhg-@comcast.net
  Apr 17, 2004 14:51 PDT 

ENTS:

   ...

    Let's take my forest icon - MTSF. Its Rucker index presently stands at 134.5 based upon the maximum heights of the 10 tallest species. We often cite that statistic when comparing Mohawk to Cook Forest, Zoar Valley, and other exemplary sites. However, what does the 134.5 really tell us? Do we have a few exceptional specimens in Mohawk growing among a far more ordinary distribution of trees? To answer this question, we need to extend our base of measured trees.

    If we do a Rucker index by species and then average the 10 species indices, we get 126.1 for Mohawk as compared to 134.5 for the maximums. The average is 94% of the maximum. The range runs from 91% to 97% of the maximums - except for one species, American beech, which is 85%. The index of 126.1 is based on 100 trees instead of 10. But can we now picture the canopy of the Mohawk forest? No, because we included only 10 species in our indices.

   If we increase the number of participating species from 10 to 13, we drop the index of the maximums to 129.6 and the index for the averages to 121.6. Why 13? Well, that is based on the limitations of our current database. We should extend the count to 14 to include all the commonly distributed species. Were we to do that and were we to extend our searches, we'd end up with an index of about 120. Were we to take the process to include the top 16 species, we'd likely get about 118. So going from 10 to 16 species and including the top 10 of each species would drop the index from 134.5 to about 118. Do we now have a complete picture? Far from it.

    Even the extension of the sample base from 10 trees to 160 trees leaves important questions unanswered. Do most of the superlative Mohawk trees grow in a limited region? Even more restrictive, do they grow in a contiguous area? Is there a ceiling to floor range for the canopy within the areas that aren't too young or that represent marginal growing conditions? Can we, for example, expect to see a canopy that commonly makes it to a particular height threshold (say 100 feet) in just about any place we might look where growing conditions are reasonably favorable? These questions and others have to be answered if we're to gain a truly complete picture of the Mohawk forest in terms of vertical structure.

    So from our existing database, where can we go to provide a more realistic picture? The following statistics provide us with a starting point.

    1. Rucker Index based on maximums for 10 tallest species: 134.5
    2. Rucker Index based on averages for 10 tallest species: 129.6
    3. Rucker Index based on maximums for 13 tallest species: 126.1
    4. Rucker Index based on averages for 13 tallest species: 121.6
    5. Rucker Index based on averages for 14 tallest species: 120.0
    6. Rucker Index based on average for single tallest species: 159.5
    7. Rucker Index based on average for single shortest species: 99.3
    8. Number of species reaching 150 feet and over: 1
    9. Number of species reaching 140 feet and over: 2
    10. Number of species reaching 130 feet and over: 6
    11. Number of species reaching 120 feet and over: 11
    12. Number of species reaching 100 feet and over: 20
    13. Tallest single tree: 164.2
    14. Number of trees measured to over 160 feet: 5
    15. Number of trees measured to over 150 feet: 60
    16. Number of trees measured to over 140 feet: 162
    17. Area encompassing very high growth potential: 600 acres
    18. Area encompassing high growth potential: 1200 acres
    19. Age range of tall trees: 80 to 350 years
    20. Common age range for tallest trees: 120 to 200 years

   So what kind of a picture do the above statistics paint? Do they suggest pockets of super trees? Do they tell us what percentage of the canopy surpasses 80 feet, 90 feet, 100 feet in height, etc.? By region? By terrain type? By aspect? By elevation? Overall? Do they tell us what the forest of the future might look like? No they don't. To get a complete picture of the vertical structure of Mohawk's forest, we still have a long, long way to go. It would help immensely to have a cumulative height distribution for a site. What % of the canopy surpasses 80 feet, 90 feet, 100 feet, etc. This kind of distribution along with a picture of the contribution made of each species and all the current maximums is where we're headed next with MTSF.

   So, are we mesmerized by the sport statistics that we have fun teasing each other with? Hardly.

Bob
RE: Rethinking the ENTS role   dbhg-@comcast.net
  Apr 17, 2004 19:37 PDT 

Ed:
...

Certainly everybody should not be doing what we're doing in Mohawk. Broad approaches integrated with highly concentrated, site-specific areas will provide us with many worthy problems to work on.

   One reason we're saturation measuring Mohawk is so that we'll eventually have enough data to back off and see what general predictors work best to capture the detail and allow us to predict averages and ranges. We're finally getting a large enough database to do that.

 ...

Bob
RE: Rethinking the ENTS role   dbhg-@comcast.net
  Apr 19, 2004 04:25 PDT 

Joe:
...

We're getting ready to put in about a dozen plots in MTSF to monitor growth rates and absolute volume accumulation as functions of species, and a large array of site variables over time. Susan Benoit and I briefed Jim Damaio last Wednesday and he gave us the full go ahead. We were looking at the first location yesterday. My hope is to get the Forest Stewards Guild involved with us to help us design the plots and provide input on the data to gather.

Bob
RE: Rethinking the ENTS role   Robert Leverett
  Apr 19, 2004 06:30 PDT 

Joe:

A few more thoughts on the growth monitoring experiments at MTSF. What
we're looking to do is to establish baseline data for natural
regeneration on a selection of sites that we believe support unusually
high growth rates. Yesterday, we measured a white ash on Totem Brook
that was no more than 70 years old (65 would have been a minimum age).
It was 119.3 feet tall by my calculations and had a breast high diameter
of 23 inches. Its point of major branching was at 80.5 feet above its
base. What would this tree have achieved at say 50 years of age? What
might it achieve in 100 years? How well is it doing for the location,
i.e. what do we think the maximum site potential is for ash?

After leaving the Totem Brook site, Howard Stoner and I went to the
Elders Grove and took a start of growing season set of measurements for
the huge Saheda Pine. We got a number of different results from various
locations that establish a minimum height for the tree of 162 feet and a
maximum of 164. Most of our measurements were at the high side of this
range. I settled on a measurement that gave us 163.6 feet and while I
believe this height to be a little on the high side, by June, it will be
less so. Incidentally, this tree was measured in 1994 at 160.1 feet via
transit. Will Blozan climbed it in 1998 and we taped one of its growth
sprigs to 158.3 feet as a conservative measure based on where the plumb
line touched the ground relative to the root mass. That measure could
have easily been 158.6 or 158.7 feet, if not more. Assuming Will got the
highest leader of the many he had to choose from, then the most probable
height for the tree is about 162.5 feet. If we assume there was a leader
at 159.3 and the tree is now 162.5 feet, then the average annual growth
rate would be 7.7 inches per year. Given what has been occurring for
other trees, this is not unreasonable, though it still seems slightly
high.
    If we go back to the 1994 measurement of 160.1 feet and allow for
Howard's 164.2 feet as the best measurement, we get an average growth of
5.5 inches per year, which seems more likely for the Saheda Pine. So
what is its height? We're going to have to do a lot more measuring to
include possibly use of a transit again. Saheda is giving us a real
challenge and we've got a very narrow window of time to get good
measurements. For me, that's next weekend's challenge.
     Saheda is 43.2 inches in diameter at breast height. It is arrow
straight - one spectacular pine. People who visit Saheda fall in love
with that great tree. What would most rank and file wood products
industry people see in the tree? Boxes, flooring, lawn furniture,
toothpicks, paper? I'd hope not, but fear that might be the case. Where
do most foresters fit into the picture? Well, certainly some would see
the above, but by no means all. I'm pleased to say that the ones I've
taken there have approached this great tree with reverence.
     What did Saheda look like at ages 50, 100, 150,and now at
approaching 175? Enquiring ENTS minds want to know. After we gather data
on the youngest of the Mohawk pines and all ages up to the Saheda, we
may be able to say. That's where we are headed.

Bob
RE: Rethinking the ENTS role   Robert Leverett
  Apr 19, 2004 07:18 PDT 

Lee:

   In the case of MTSF, in addition to the old growth, we are fortunate
to have second growth stands from very young to very mature available
for us to study and none of the areas have received the periodic
massacring that private lands so commonly have to endure. Several of the
Mohawk stands of interest have gotten a kind of second wind and are
growing rapidly both radially and vertically. I'm unsure of whether this
is climate-induced or part of a natural pattern. The rapid radial growth
of the northern red oaks in the Shunpike area of Clark Ridge that Neil
Pederson verified is an example of this second wind. The oaks are
growing radially now faster than they were at half their age. They are
presently between 100 and 130 years old.

   It is pretty obvious to me that there is lots left for us to learn in
western Mass about the growth patterns of our trees over a span of fully
150 years. The local notion that most species of trees are pretty well
done by the time they reach diameters of 12 to 16 inches strikes me as
at the least strange given what I routinely see.

   Trees may not maintain acceptable economic growth for 200 years, but
the idea that they're ready for plucking at between 40 and 60 years just
doesn't jive with what I see in the high growth areas of a good three
dozen sites in central and western MA. I have to conclude that many, if
not most, foresters work with highly degraded forestscapes and just
haven't come to fully realize it. Well, that IS what all the high
grading discussions point toward.

   If we can make a contribution toward opening eyes, I for one, believe
that the great land stewards of the past will smile down on us.

   BTW, what are common misconceptions that you encounter from wood
producers about forest growth? Would you bed willing to share some of
the common misconceptions and comment on how widespread they are?

Bob
The next step for MTSF   Bob Leverett
  4/16/2004 &  4/19/2004
Private Emails 

The attached Excel spreadsheet takes the Rucker indexing to the next level by computing the index on each species and then an overall. At present, this incorporates 128 trees in Mohawk. The single index for 13 species is 129.6. The composite index is 121.6. Both will drop with the addition of the white birch, but we need to add the white birch to paint a better picture of the MTSF canopy potential.

..............................

   My full dataset for MTSF currently includes 712 trees. I'll soon send
another spreadsheet in a form more appropriate to web posting. I usually
send a "limited edition" to a small group of you who are more apt to think
about it and make suggestions for improvement.

 
RE: The next step for MTSF    dbhg-@comcast.net
   Apr 19, 2004 19:27 PDT 

Ed:

...

   There are a number of separate populations of pines being sampled in Mohawk that vary in age from 100 to 175 years. Stands that are growing exceptionally fast can reach significant heights and still have small diameters. The Pocumtuck Pines are in this class. We can divide the Pocumtuck Pines into six sets with each pine belonging to 3 sets. We have the set of older pines and the set of younger pines. We have the set of pines that receive more light and the set that receive less light. We have the set that receive the most water and the set that receives the least. The pines that are the oldest, receive the most light, and receive the most water are both the largest and slightly the tallest. The pines that are the youngest, receive the least light and water are the smallest and shortest. Some pines fall into each combination of age, light, and water. Of course other factors such as injury and disease enter the picture to slow growth, but discounting those factors, competition with neighbors enters the picture to allow some slender pines to gain great height.

Bob
RE: The next step for MTSF    dbhg-@comcast.net
   Apr 20, 2004 04:16 PDT 

Ed:

   There are probably 200 pines in what we call the Pocumtuck area. The dense clusters of white pine there create an almost uniform canopy in places with trees varying in height on the order of 12 feet and circumference of 3 feet for the same moisture and soil condition and moderate changes in light exposure and ages varying between 5 and 10 years. Variations in age and height each run between 7 and 9%, while variations in circumference run between 35 and 40%. In the older Elders grove, the age range varies by about 9 to 11%, height by 12 to 14%, and circumference by 25 to 30%. This is the first crack at testing stand limits. More to come.

Bob
Range of WP dimensions    Robert Leverett
   Apr 20, 2004 09:12 PDT 

Lee, Ed, Colby, et al.:

   Based on current data, what might we expect from a 125 to 135-year
old white pine stand in MTSF in terms of the range of tree dimensions?
Do we have enough data to compute the ranges? Yes.

    Circumference: 6.5 - 10.5 feet
    Height:         135 - 155 feet
    H/D Ratio:       40 - 75

    Circumferences can vary by almost 40% for living trees.
    Heights can vary by about 13% for living trees.
    Age variation is 7%.

   How will these numbers change with added aging, say 40 years? What
would the broadest range of height to diameter ratios likely be
throughout the life of the stand?

   How do these ratios compare with white pines in the Connecticut River
Valley? Holding age constant, the Valley ratios will be a little less,
reflecting less height for the same diameters. Calculating exactly how
much less requires more data though. That will be one of the objectives
of this summer, i.e. broaden the base of white pine data across a large
area of southern and central New England.

Bob
Placing height measurements in perspective   John Eichholz
  Apr 29, 2004 21:37 PDT 

Bob, Howard:

material deleted....
Using several sets of instruments can improve our prediction of tree
height. When we want to know the absolute height of a specific tall
tree, we can use many methods to cross reference and hone in on the
height. However, I believe the evidence exists that the height
measurement has a natural variation due to rangefinder variability and
human factors.

Some of the large scale sampling we will be doing at MTSF will likely be
simplified by classing trees into 5' height ranges anyway. We may be
measuring large numbers or all of the trees in a limited area of high
growth. This will readily tell us the maximum height and cbh, and the
average. Grouping trees into height classes allows us to also know the
modal or most common height. We locate the 5' height range that has the
most trees, comparing that to the top height attained and the high to
low range. We don't know what kind of distributions we will find,
(except they will be unusually tall). Comparing old stands of trees to
young ones nearby will happen first, to see how trees evolve in height
and mass. Later we can compare stand to stand, species to species and
correlate that with differences in site. Then we might be ready to
compare with sites outside MTSF. Or, maybe we could make a Rucker index
of the modal values.

Looking at the length of some of the bibliographies that appear on this
list you would think this has been done before. That may be true, but I
think it is safe to say it has not been done at MTSF until now!

John
RE: Placing height measurements in perspective   John Eichholz
  Apr 30, 2004 06:10 PDT 
Ed:

Yes, and I am particularly interested in the relationship between the
modal value and the maximum. The traditional Rucker index , relying on
the single tallest individual of 10 species, is quick and easy to
determine, relative to the modal index. The modal index I think might
represent more accurately the volume potential of a site. It would
reflect the average canopy height, not its ceiling. How well would the
distribution of tree heights reflect the age diversity of the site?
Also, how would modal values/ height distributions by species vary with
the prevalence of that species on the site?

If I am interpreting correctly, the Reineke stand density index (SDI)
draws conclusions about diameter distributions, saying that basal area
of any site can be converted to a basal area/tree count at 10" diameter,
enabling stocking rates of sites of different ages to be compared. Has
this been debunked? Can we do something similar with heights? Will
sites with a high SDI also have high heights? Will sites with a high
"height index" continue volume growth for a longer time than shorter
sites? How about sites with a high SDI?

I am probably way over my head when it comes to traditional forest
mensuration methods. On the other hand, it makes sense to me that we
have a recent technological advantage in being able to quickly and
accurately measure heights, especially in hardwoods. Are any of the
foresters out there aware of height measures similar to the SDI?

John
RE: Placing height measurements in perspective   Robert Leverett
  Apr 30, 2004 10:13 PDT 

John:

With respect to existing indices, I expect that the only way we're
going to find out what works and what doesn't for the natural stands of
100 years in age and older is to gather the data ourselves and then
develop a variety of statistical distributions, even if we stumble a few
times in the process. We've got Lee Frelich on board to keep us going in
the right direction. He won't let us stray too far from a scientifically
defensible direction.

Maybe there are stand-based growth relationships that could be dug out
of books and applied directly to the habitats and species mixes we're
studying. However, the rates, averages, and indexes developed for timber
management purposes have built in biases that make them of questionable
applicability for our purposes - if we're looking to achieve high levels
of accuracy. I'm reminded of what Karl Davies discovered about the
development of volume-based growth models from a woefully inadequate
database. Inadequate or not, the FS routinely applies it.

     Several things we may assume about the silvicultural data reflected
in the tables that wood producers use that were developed using data
from the past.

    1. Much of the data were gathered in relatively even-aged stands
and/or in highly controlled environments. It is unclear how much data
have been gathered from the kinds of places we study, e.g. extensive
boulder fields with forests of all ages.

    2. Whole tree volume was unimportant.

    3. Where used, whole tree height determinations using clinometer and
baseline for volume determinations would have been off, sometimes by
significant amounts, but an average of 5% to 7% is probable.

    4. Volumes for logs based on standard lengths and diameters assumed
circular cross-sections. I think that Bob Van Pelt has discussed in the
past the size errors that can result from invalid assumptions of
circularity. I think some wood producers attempt to get around the
problem by using calipers to try to arrive at an average diameter.
However, this method still has problems. As an example, if the
cross-sectional area of a tree is elliptical with the major axis being
25% greater than the minor axis, then averaging the lengths of the two
axes and computing the area of the circle based on the resulting average
yields a circle with an area about 1.2% greater than the area of the
ellipse. However, as we have also seen, assumptions of ellipticity are
risky. My guess is that deviations from circularity generally produce
area errors of 3% or less. Maybe someone out there has a feel for this.
I expect BVP and Lee Frelich do.

In terms of our own volume calculations, I'm unsure if we need to
worry about departure from circularity, unless visual inspection of a
tree suggests radical departure. At the least, we should get several
sets of calipers.


Bob
How Many Left?   dbhg-@comcast.net
  May 02, 2004 07:58 PDT 

Dale:

material deleted...
   I'd also like to get down to Fairmont Park and try to pick up where Will left off. We need to give southern Pennsylvania some serious attention.

   I plan to visit Claremont NH, hopefully, this month, and if not, in June. We need a lot more data from that splendid site. It is by far our most under-sampled of the great northeastern white pine sites. If Will is correct about the number of 150s at the Claremont Site, and he probably is, it would be insightful to be able to get a census of them.

   Dale, those few of us who are involved in the heavy measurement need to concentrate on the top 4 or 5 white pine sites - unless we can recruit more researchers. Yesterday, I spent all afternoon on just 9 white pines, trying to get sufficiently accurate data so that future measurements will reflect actual growth. That requires locating a spot from which to measure each tree, settling on a height from eye-level to base, which should not change from year to year, and then concentrating on determining crown growth. 

That means photographing the crown from the same spot after each year's new growth has been achieved. Measurements and photographs can be compared year to year to arrive at a reasonable growth determination, thereby eliminating variations that fall within the range of equipment accuracy tolerances. In other words, if variations in readings resulting from one's own aptitudes in combination with the range associated with the accuracy limits of one's equipment can easily overpower an expected new year's growth, (+/- 1.5 feet versus 0.5 to 1.0 feet), then it would take several years before we could arrive at an acceptable calculation of annual growth. 

Well, this aging body of mine doesn't have unlimited time. Gotta make hay, while there's still energy to thrash it. So the challenge open to us to fine tune our annual measurements is very labor intensive using our present equipment. So the number of trees we choose to annually measure must be limited.

   For the bigger picture, we need to focus our attention on a sampling plan that will capture data useful to not only record the past record of growth, but also to predict maximum potential without requiring an army of measurers with its attendant loss in quality control. So far, the problem has proven almost intractable.

Bob
Re: How Many Left?   John Eichholz
  May 02, 2004 19:15 PDT 

Bob:

I think you are right about the photos. Regardless of whether we are
off by a foot or two on the initial, or subsequent measurements, by
comparing with dated photos we have a visual confirmation of height
change. Not only that, we can effectively restrict subsequent error
mainly to clinometer error from height change measurements when we are
comparing various branch nodes, once we agree on a baseline height of a
given node. Angle error should be much more controllable using tripods
than rangefinder error, especially since we are then interested in the
angle difference between nodes, not the absolute angle. The photos will
serve as a durable record of where we measured in the past, and how the
crown is evolving.

By the way, white pines in my yard are just beginning to elongate. The
growing tips are about 1" long now (May 1, 2004).

John
Re: How Many Left?   dbhg-@comcast.net
  May 03, 2004 03:13 PDT 

John:

   Identifying the measurement and photographing spot for each sample tree is going to be fun. Whew! But if we want to track annual growth and know what is happening to each sample tree then I think you and I are in agreement that we have no choice. I seriously doubt anything like this has been tried before.

Bob
RE: How Many Left?   Robert Leverett
  May 03, 2004 08:12 PDT 

Dale:

material deleted...
   Maybe, by July, we'll have the methodology down better on our
impending annual tree-growth monitoring experiments. As previously
described, we're looking at a system of baseline measurements and
photographic images of the crown. For the accuracy range of our
equipment, accurately interpreting annual growth for individual trees
where the amount of new growth falls well within the error range of the
measuring procedure we use, is problematic. We need to take our
measuring methodology to the next level to compensate for the accuracy
limits of our equipment. The many measurements we've taken of the Jake
Swamp tree from a variety of locations by equally qualified measurers
under varying light conditions, shows us that we can repeatedly get
numbers ranging from 162.5 to 165.5 feet. Some of this range is
attributable to hitting different twigs from different locations. Some
is attributable to changes is lighting. Some is attributable to
differences in the accuracy of the individual lasers and clinometers
being used. Some is associated with the experience of the measurer.
These 4 sources of difference create a complex mix. Averages based on
large sample sizes might work fine, but are too labor intensive to apply
to dozens of trees.

   We need to set the exact measurement location for each sample tree
and then establish a baseline measurement for the height below eye
level. This below eye-level component will not change from year to year.
Then we need to agree on what is the highest twig and establish a
baseline measurement of the height of that twig above eye level. We need
to document photographically the twig. Subsequent annual measurements
would concentrate on the new growth as shown in the photographs.

   In terms of numbers of the 150s, most did not exist in MTSF 2 or 3
years ago. Mohawk has grown into its 150s and the number of 140s makes
Mohawk a candidate for 100+ 150s in the next 5 to 8 years, barring
disturbance. In 10 years, we could be looking at upwards of 150 150s. If
I'm still around at that time, I doubt that I'll know them all by name.

  One final point, we have a very simple way now to quickly get
accurate counts of pines in a known area and project the counts to an
acre or hectare. More on this later.

Bob
RE: Placing height measurements in perspective   Ed Frank
  May 05, 2004 

John,

You will need large numbers of samples in order to get a reasonable
distribution using even a 5 foot height range. What numbers of tree
height measurements do you anticipate will be needed from a particular
area to calculate a valid modal distribution for a particular species?
How many species do you want to try sample in a given area?

Given that the present height data used to compute Rucker indexes for a
site were preferentially selected for height, I don't see any real
relationship between the modal values and rucker indexes that would be
valid between different sites or plots. Am I missing something? Do you
think sites with similar rucker indexes will have a like distribution of
modal values?

One key question is that Rucker indexes may contain tall species that
may be in limited numbers in a particular stand, how are you going to
deal with rucker indexes which contain species for which you can't
calculate a modal value (average canopy height)? I would just like to
have you expand on the ideas you are expressing and see where it leads.

To continue this line of questions, if you are comparing the modal
distribution of tree heights between plots of different ages, how are
you going to differentiate between the height variation caused by the
age differences and those caused by other undetermined factors related
to growth?

I am certainly not opposed to collecting field data for the sake of
collecting it and documentation of a site. But can you tell me and
others on this list concisely what you believe the modal distribution
study will tell us better than the current Rucker index that will
justify the massive increased effort required to collect this data and
do this type of study? Or is it just to see what would it show? I am
not being critical just looking for some elaboration.

Ed Frank
Re: Placing height measurements in perspective    Colby Rucker
   May 06, 2004 04:17 PDT 

Ed,

I have similar concerns. Constructing a height index for a given tract from
the ten tallest examples of their species is valid, because the elements are
not selected arbitrarily. However, as the plot becomes smaller, and/or the
heights are derived disproportionately, the bottom line becomes more
questionable.

Constructing an index for some habitat niche can also be flawed, since it is
based on pre-conceived boundaries, and the tallest examples may occur at
interfaces corresponding to the arbitrary boundaries. Constructing indexes
from adjusted numbers (five feet, etc.) blurs the essential nuances of
height advantage for any species. Absolute accuracy of the equipment is
less important than the consistency of the individual.

While our height indexes have proven useful in comparing the height
capability of sites all over the east, often demonstrating regional factors,
they tell less about the individual site. Using the maximum heights for all
the tree species on a site, and arranging them in perhaps six different
height groups can give a good picture of forest structure by niche
availability for the site. Our ENTS web page gives examples for Cook,
Corcoran, Belt, and Chase. Constructing a forest structure profile would
seem to be the most logical next step for Mohawk.

Once an overall profile is constructed, additional trees can be measured in
a given niche to identify the role of species existing in habitats which
offer less than optimum opportunities for those species. In that way, a
study of forest structure can be progressively refined while using numbers
derived from investigation, not assumption, as much as possible.

Colby
RE: Placing height measurements in perspective    Lee E. Frelich
   May 06, 2004 05:59 PDT 

John, Ed et al:

Tree heights in old stands are difficult to characterize because trees of
all sizes are part of the canopy, including small saplings in gaps, because
the canopy has an irregular surface (this is my alternative to viewing the
canopy as having holes caused by gaps).

Therefore, tree height (and dbh as well) can be characterized in these ways:

1. Height distribution, which is a histogram with approximately 10 size
classes showing all canopy trees, including gap trees.

2. Top heights. These could be the height of the top 10 or 20 trees in a
stand or in an area of certain size (perhaps per acre or per 10 acres) by
either dbh or height for a given species.

3. Qualified average heights or qualified median heights. These could be
the average or median of all large trees in a certain crown class such
dominants, or dominants and codominants combined. Or it could be a random
sample of 10 or 20 such trees. Again a stand or a standard area would have
to be chosen (e.g. 1 acre or 10 acres).

We have a silviculturist from Germany in our department whose Ph.D.
specialty was in quantifying structure of complex old growth stands. I
will see what he has to say on the topic.

Lee
Lots'a talk    Robert Leverett
   May 06, 2004 08:15 PDT 

Ed, Colby, John:

      Good discussions. Please keep the critical analysis coming.

      In thinking about what everyone has said, it occurs to me that the
Rucker index in all its forms continues to hold its value to us mainly
because it gives us a picture of what is actually at a site. It isn't
relying on extrapolations from fixed plots to predict growth averages of
maximums. We hunt down the maximums and record what they are and where
we find them. No guesswork. By going several levels deep on each species
we eventually reach a point where we can profile a dozen or more species
quite accurately in terms of site or sub-site potential. Site boundaries
are problematic as Colby points out. Score a point for him. But we can
still do well. However, explaining the site potential satisfactorily in
terms of a host of independent variables is a whole different kettle of
fish. That's the real job. Over the next several seasons, we'll see how
successfully we can do it at MTSF.

       A daunting challenge for those of us who spend a lot of time at
particular sites is getting out of our heads and onto paper what we
know, or at least think we know, about site potential. Quoting a few
statistics in our e-mails exchanges can make it appear that we're
relying too much on a few select measurements. For example, the original
Rucker index is based on only 10 numbers. However, a lot of territory
was covered and a lot of measurements taken to get to those 10 numbers.
What pictures remain locked in our heads that aren't communicated by the
display of 10 numbers and an average? Lots of pictures. Our personal
knowledge bases incorporate countless observations taken over years of
searching and in all seasons that give each of us a set of mental maps.
So the real databases are in our heads and those databases are far more
extensive than what we're able to translate into a few lists and display
in a few spreadsheets. So, the ENTS faithful are challenged to find ever
better was to approximate simply on paper what we have in our heads.
Eventually, we would get there by sheer weight of effort, but that
process is hopelessly inefficient, and in the interim, we can appear to
be putting too much stock in a single statistic or index, especially
when communicated in these informal e-mail discussions.

       The real reward of all this is that we're the ones doing the
research into the growth potential of our big tree/tall tree sites. We
can now profile hemlock growth fairly accurately over most of MTSF
courtesy of all the roaming around we've done using our shotgun approach
to measuring, but that obviously isn't good enough for rigorous
scientific research. So we have to look for more conventional
replicatable designs that others can apply to arrive at the same general
level of understanding as we have. Otherwise, "it ain't science". But
developing the methods and measurement protocols goes beyond my level of
expertise. That's why Lee Frelich has come to our rescue. Darn, it's
turning out to be hard work. Still, I shouldn't complain. The difficulty
of the task keeps us at the top of the food chain, i.e. we're the ones
with the knowledge, even at this incomplete level of understanding.
Hmmm, that was quite a statement. Is it really true? Yes, it certainly
is.

       What has been enlightening to me over the past 12 years has been
my growing awareness of the gaps in our understanding of the maximum
growth potential, and even growth patterns, of important tree species
within a region, given our opportunities to observe those species for
almost 400 years. What could we have possibly missed, given such a long
time to observe/study a species like Pinus strobus? Well, suppose we ask
the question: "What is the growth potential of the white pine in the
Deerfield River watershed of western Massachusetts?". Suppose we ask
that question of all potentially interested parties living/working in
western Massachusetts. What would the range of answers be? What would
UMASS forestry academics say? What would the Mass Bureau of Forestry
say? What would independent foresters say? What would loggers say? What
would tree farmers say? What would arboculturists say? What would
ecologists and botanists say? What would naturalists say? People in all
these fields would have observed the species in question countless
times. But what would they have learned from their observations? That
white pines grow fast, reach large size, and may live for 250 to 400
years? The forestry academics would likely turn to information sources
and quote aggregate timber volumes produced, i.e. board foot totals.
Members of other groups would speak anecdotally of the growth increments
they have seen ("I saw pines in so-and-so's lot growing regularly at 30
inches a year."). Some would quote from Forest Service data, based on
broadly derived numbers. Some would describe individual trees they had
seen or heard about, maybe even using information we provide through our
list or website. Some would recount tales of big trees elsewhere - more
anecdotal stuff. Some would claim that the question was scientifically
unimportant. Some would assure us that the answers lie in existing
silvicultural literature, but wouldn't have the sources handy. Yes, and
some might make wise cracks about tree-hugging and then lapse into
mind-numbing rants on other subjects, assuring us that the answers to
our questions are known, but are totally irrelevant. But would any from
the groups draw a clear picture for us of what the white pine does
across the range of growing habitats that exist in the Deerfield
watershed for the full life of the species? Given the vast importance of
the white pine, historically and presently, you'd think so. Well, I've
asked the question of members from all the groups listed above. I have
yet to find a single individual from any of the groups that has a clear
idea of what the white pine is doing within the region cited. Many have
bits and pieces, glimpses, but none have a coherent picture of the
whole, certainly not for the full life span of the species. So that has
become an ENTS mission.

      Tomorrow, several of us will walk MTSF with State Forester James
DiMaio and show him our tagged trees, identify where we want to put in
study plots, discuss the data set we want to develop, and discuss with
him our overall study objectives and the outputs. He is taking the study
very seriously. He is giving us a special research permit and he has
made it clear that he looks forward to the seeing the information we
gather and learning of our conclusions. I guess we really have stumbled
on a gap in our knowledge of white pine growth potential in the
Deerfield River watershed of western Massachusetts and southern Vermont.
Score big points for ENTS.

Bob


Robert T. Leverett
Cofounder, Eastern Native Tree Society
Experimental design    Edward Frank
   May 06, 2004 10:47 PDT 

Bob,

Most of the comments have been concerning experimental design aspects of
the ideas expressed by John. I am not trying to discourage the effort, I
am trying to make sure everything is well thought out.

When you design an experiment there are several questions that must be
addressed.

1) What are you trying to determine? What questions are you trying to answer?
2) What data is needed to answer these questions?
3) How can this data be collected?
4) How is the data going to analyzed?
5) How are you going to compare the information between localities?

Specifics of experimental design.

1) How can we collect this information in a practical manner? What is the
best way to do it?
How are you physically going to do it?
2) What is the minimum amount of data that needs to be collected?
3) What is the optimum amount of data to provide the most information? and
when is additional information simply overkill?
4) In a field situation, how do we define the boundaries of what data we
are collecting and what area we are gathering information from? What do we
need to collect and what is not needed?
5) Are the boundaries to be random, arbitrary, or defined by a particular
parameter?
6) How do establishing these boundaries affect what information is gathered?
7) How is the data collected going to be quantified? Are the assumptions
and methodology used to quantify the data valid? Are they arbitrary or
something that is physically measured?
8) Do the quantified numbers actually mean something?
9) Are there hidden assumptions or biases in the process of generating
these numbers?
10) Are there aspects of the site that are important to answering the posed
question that are not easily quantified and how are you going to deal with
them>
11) Are you going to include descriptive, non-quantitative analysis of the
site or aspects of the site? To what extent are these going to be used?
12) How does this methodology improve on existing methodologies? What does
doing it this way tell you that doing it some other way does not?
13) If this method is more costly in terms of labor or material costs, does
it improve on another methodology enough to make it worth the increased
costs?

When you have gathered this information, you must figure out how you are
going to analyze it.

1) What hidden assumptions have you made when collecting the information?
2) How has the data collection process affected the information gathered?
3) How are the various aspects of the data collected going to be compared
and integrated within a single site?   
4) What factors are independent and what are interdependent?
3) How are you going to compare the information gathered from one area to
other areas? This is the most critical point. If you can not compare the
data o anything else what is it going to tell you?

From experience I have found that if I can not articulate the answers to
these questions, I have not thought through the entire process enough. It
is critical that you clearly define what question you are trying to answer.
However just one aspect of these questions can not be considered alone.
All of these are interrelated. The questions you are asking must be
clearly defined, the results must answer the questions you are asking, and
the experimental design must gather the data needed. The worst thing is to
gather lots of data and find you have left out some key factor from the
data set, or that the analysis process can't answer the questions ask.
Interrelated in the operative word.

Ed
RE: Experimental design    Robert Leverett
   May 06, 2004 13:07 PDT 

Ed:

   I don't interpret your comments as discouraging what we're doing in
any way. You are serving a most useful function. Please keep it up. I
often take it for granted that you realize I agree with you and take off
from there. I usually start with what you and Colby say as the givens
and then strike out to explore some of the fuzzy areas. Also, I'm
continually trying to ascertain if what I'm doing is really contributing
that much useful information. In some cases I'm just restating what
we're doing for members who are fairly new to the list and haven't had
the time to explore the extensive research library that you've created
on the website. These discussions we're having are very valuable to
elucidate every aspect of our research to include that which is
rigorous and that which is "seat of the pants" - my specialty. But oh
my, has it been fun.

   What's coming up will more along the line of your design. In fact,
what you've created will be my checklist.

Bob
Re: Lots'a talk    Fores-@aol.com
   May 06, 2004 16:46 PDT 
Bob:

I wish you good luck on your venture.

It is an unfortunate aspect of the forestry profession that as foresters, we
typically deal with the harvest of most trees long before they ever reach the
age and proportions that are the essence of MTSF.

I believe that it is really important to have the opportunity to acknowledge
and document the biological record such a patch of woods will produce as a
result of your efforts.

The serious science you are applying to information gathering and
quantification, especially the science related to size, age and height measurements, will
set a new bar for forest appreciation (in the virtual sense) and I predict
that it will only be a matter of time before the academic community will make
MTSF a stop on their field trips into the woods with students.

Russ Richardson
How Many Left?    Edward Frank
   May 06, 2004 17:54 PDT 

John and Bob,

This photo documentation is an interesting idea. Will you be using a film
camera or digital? Digital is ideal for this purpose because you can
immediately see if you gotten a good picture. One variable between
pictures taken a year apart is the focal length of the lens. In 35 mm most
people are using zoom lenses. If the photos were taken with a fixed focal
length lens from the same spot then the pictures could be superimposed and
compared directly. With digital cameras with built in zoom lenses, the
equivalent might be to zoom out to the maximum optical zoom length.

It is a silly question but Do the branches grow longer between points or
only at the tips? Could you determine the elevation difference of two
points on a single shoot, say one at a branching point and one at the tip?
If so then you would in effect be measuring that length between them. (the
assumption would be that the tip is directly above the branch- not really
true but ...) If photos from subsequent years included the same branch
point and tip the amount of growth could be measured directly using the
initial photo and length measurement as a scale. This would eliminate any
other measurement variables, so long as the same focal length was used, the
image was scaled the same, and it was taken from the same spot.
Additional measurements would not really be necessary except for
confirmation purposes.

Ed Frank
Digital Tips    John Knuerr
   May 07, 2004 03:22 PDT 


I don't have a good telephoto lens for my digital so I will be using the
500mm lens on my old Olympus OM-1. I'm planning on shooting a measuring
tape against a white background from several different yardage distances.
These slides can then be placed over the slides of the tree tips. This, of
course, assumes the same focal length used for each shot and the same
accurate yardage distances.
The differences in camera/lens angle to target is still a variable we need
to address.
Re: How Many Left?   John Eichholz
  May 08, 2004 08:17 PDT 

Ed, Bob,

Lots of good discussion here. In reply to the photography thread, I will
have to use a film camera, as that is what I have. I will be using a
135mm lens and ASA400 color print film. I can scan these and make a file
out of it. I would imagine taking the photos from the same spot each
year, unless the tree top grew out of sight. I would be looking for a
particular branch of the tree to remeasure.

As for the branch question, I think the tree is made out of actual wood,
and can't grow any longer once it forms, only wider with the addition of
new growth. A particular branching point should stay at the same "place"
in space as the tree grows, unless it bends.

Then, the measurements taken the next growing season include the new top
and the location of the last year's top. The photograph would serve as a
reminder of where last year's tip was. I guess you could use the picture
to scale the growth. You run into the same problem as measuring with
instruments, that being to compensate for the angle of the new growth
from your line of sight. Over time, the photographic record will
describe how the tree grows, but the height measurements will still only
be as accurate as the instruments we use. After several years, we can
use the photos and records to say how the tree grows on average, and to
compare which years it grew best. Unlike tree rings, the evidence
accumulates in plain view, if we take the time to collect it.

I'm still not sure what use all this data will be, but we are working on
it. Your notes on experimental design are very helpful and in the spirit
of collaboration. Not all elements of the experiment will address all
the points, but we should be sure to address the relevant points as well
as we can. The height and growth records will be accurate, repeatable
and verifiable, so they will be useful as scientific data.

The bigger question, "what are we trying to determine" I think has been
addressed by Bob in the proposal in general terms. The DCR interest in
the work speaks to its value. It is up to us to come up with an
experimental design that will have some relevance to the question. Then,
the protocol for collecting the data should fullfill the design goals. I
think the hard part is goint to be the experimental design.

John
Re: How Many Left?   greentreedoctor
  May 08, 2004 09:37 PDT 
A particular branching point should stay at the same "place" in space as the tree grows, unless it bends.

John:

Just a few things you've likely already considered. The tallest branch may not be the primary "leader".   The larger and more central leader may be less likely to bend due to loading, fatigue, ect. You may want to pass on a multi-stemmed or double-topped tree. You may want to avoid self-correcting branches and trees (tropism).   You may not want to choose the tallest tree in a given stand. It's better to let fellows share the load (if lightning, ice, wind or drought, takes out your top, your experiment may end prematurely). If it's possible to include a background or periphery target (mountain, tree, ect), your findings may prove for useful.

Good luck.   We all look forward to the photos.

Randy