Tulip Tree Heights   Will Blozan
  Nov 10, 2004 15:52 PST 

Yo, Dale and Tom,

I am totally confident that the tallest hardwoods are in second-growth or
younger stands of natural origin. ...I measured a grove in the Smokies last
weekend that will have a Rucker well over 130'. Two species of trees reach
160' (all hardwood) and the canopy dominants will easily average over 150'.
I took some core samples to age the stand. Guess what? 66 years at BH. I
know of 170' trees ~the same age (tuliptree). I think that 50-60% of the top
10 height records for the Smokies are in second-growth hardwoods.

My question is where are the 180' tuliptrees? If a 70 year old tree can
reach 170', why can't 180' be reached by 120 years? Or 300 years? Or 600
years?

I have no Earthly idea!

Will
Lower Big Creek update   Will Blozan
  Nov 13, 2004 12:14 PST 
Hello ENTS, NPS staff, et al,

Last weekend Tom Remaley of the GRSM and I revisited some tall trees to
remeasure them and monitor annual growth. ...

What really blows me away is the sustained growth rates of these trees, and
the fact that most of Big Creek, which today has forests to 170' tall, was
essentially denuded of trees at the establishment of the GRSM-NP in the
mid-1930's. I wonder what the early park managers thought as they gazed upon
the denuded and entirely cleared slopes of lower Big Creek. Did they have
any idea of the potential for such phenomenal growth? It must have been
depressing at the time! Well, now the forests can lay claim to many eastern
height records and perhaps the tallest temperate deciduous forests in the
east, if not globally. Average canopy heights will rival or exceeded even
the finest old-growth stands, and these forests will serve as an excellent
study in growth rates (height and volume) and the formation of canopy
architecture both on an individual tree and a forest and landscape level.

Study of these forests will also help us figure out and challenge the ideas
of a maximum canopy height for many species. For example, tuliptree is
well-known to exceed 170'; with over 20 trees in lower Big Creek alone
exceeding this height (probably over 100 can be found on just the first 5 or
6 drainages off lower Big Creek). But of all the 170'+ tuliptrees thus far
identified (~50 park-wide?), only 3 exceed 175', and none exceed 178'. Some
of these trees are less than 70 years old. Since no other tuliptrees in
old-growth forests can top the second-growth forest heights, have the young
trees just peaked, or is there a biological or genetic limit? The height
ceiling for tuliptree is sharp and consistent across the entire park
regardless of forest disturbance history. Does this indicate an intact
genetic base, or the opposite? What makes a 70 year old vigorous tree stop
growing up when all its neighbors are just as tall? Maybe they have not
stopped, but there is no height difference in tuliptree forests 130 years
old and 70 years old on similar sites. I think I need to get up in the trees
and examine the tops in addition to selecting trees to monitor annually.
Also, with enough aerial core samples at various heights, I could
reconstruct height and diameter (volume) gain over many years, and determine
how long a tree (or forest) has been 150' tall (or whatever height chosen)
or greater. Such knowledge would influence management in many ways, both
economically and biologically. Grant money anyone???

...

Big Branch

Tuliptree            9'0" X 163.1'      ~70 years old

Tuliptree            5'10" X 151'      Cored: 65 years at BH


Unnamed creek

Tuliptree            5'10" X 153'       Cored: 66 years at BH, in crown
contact with tallest sycamore, may be taller.



Will
Re: Lower Big Creek update   Edward Frank
  Nov 14, 2004 18:39 PST 

Will,

Congratulations on another excellent trip report. You and Jess are setting
the standards for trip reporting. I like your idea of multiple cores at
various heights to document the history of growth for a tree/stand of
trees. One thing that struck me is that there are a number of tree height
champions that have died in the past few years - The Yonaguska hemlock,
among them. If there are any similar big trees downed in the area of
interest, they could be more easily cored to see if the process would give
you the information you anticipate. There would not be any concerns about
the numbers of cores you took or any adverse effects on the tree. The same
could be done for a variety of species - perhaps even tried on some long
dead chestnut snags. I can't make grant money suddenly appear, but a
demonstration of the technique on a downed tree could not hurt. I am
looking forward to seeing some photo's from your trip.

Ed
Re: Tulip tree height   Lee E. Frelich
  Nov 16, 2004 06:19 PST 

Will:

The theory that likely explains the tulip tree heights is as follows:

1. By age 70 (probably by age 40 or 50) the tree crowns have run into each
other, so that each tree cannot expand its crown and produce more leaf area.
2. Therefore they cannot produce an increasing amount of wood.
3. The wood that is produced is spread over a taller and taller trunk that
is also bigger in circumference each year, forcing the rings to get narrower.
4. The narrower rings mean two things:
         a. the tree will become unstable if it grows taller, since it
can't increase the dbh of its trunk very fast.
         b. Since only the outer rings conduct water at a high rate, water
cannot be pumped up the tree fast enough through these narrow rings to
support continued height growth, and in the absence of the mechanisms that
redwoods have for getting water to very high branches, height growth stops.

If this theory is true then we can predict that the trees will put on
another spurt of height growth when the stand undergoes self thinning and
transition to an uneven-aged stand, in which case successful trees will be
able to expand their crowns into gaps caused by the death of a neighboring
trees, and more crown area means more wood, and wider rings that can
support more height, mechanically and physiologically. The same theory also
allows us to predict that trees are shorter in northern climates and at
higher elevations.

FYI a theory is a set of ideas that tries to explain why observed
conditions are as they are. There is not a dichotomy between theory and
fact as is commonly supposed. A theory is accepted if it has support (i.e.
if its predictions are observed in the real world) and not accepted if it
doesn't have that type of support. A fact is simply an observation, such as
the tree is 170 feet tall. Grant proposals that devise a reasonable
theory, show what its predictions are, and then show that it is feasible to
test those predictions unequivocally in the field, are the ones that get
funded by agencies such as National Science Foundation. We could probably
get this type of grant funded.

Lee
RE: Tulip tree height   Will Blozan
  Nov 16, 2004 18:33 PST 

Lee,

Thanks for the ideas to think about. Here some questions and observations:

1) Tuliptrees on Baxter Creek which are likely 120-140 years old (I have not
cored any yet) have the same height as the 70 year old forests, but there
are no visual clues that I can identify (yet) that suggest that the trees
have been either a) growing more slowly, or b) at 170' for 50-70 years. The
upper crowns do not look to me as old as the theory would suggest. Aerial
core samples from examples of trees spanning all age ranges would help solve
the puzzle- structurally, spatially and temporally.

2) There are numerous examples of older, huge tuliptrees growing in
uneven-aged forests that have no greater height than the 70 year old trees.
Undoubtedly they were released from crown competition which allowed them to bulk up and put on girth. But still, they are not taller than the young
ones.

3) Perhaps some of the older trees have developed a different (i.e. craggy)
architecture after once having been a "straight and narrow" tree. Drastic
differences in age from one portion of the tree to another adjacent portion
would support this thought. For example, a 400 year old "base structure"
could be supporting a canopy only 50 years "old". New sprouts from storm
damages constantly recreate crown- especially in tuliptree. I have seen
sourwood and blackgum trunks differ in age by over 50 years within only a
few inches. This is because the "base structure", often very slow growing
and old in these two species, will send up a new terminal shoot when
conditions favor a new spurt of height growth. They essentially "hang out"-
presumably storing energy for the day they get the light gap or other
stimulus to grow upwards. They then can regenerate an entirely new canopy of
young growth characteristics supported by an ancient "base structure". The
lower old limbs are then subordinated and shed. (Trees are sooo COOL!)

4) As a tuliptree gains in girth it will also lose in flexibility. This puts
the weakest portion of the tree- the young top canopy, in the full brunt of
wind and weather, and all that on an unyielding "base" of huge, static wood.
To me, this change in architecture as the tree ages will result in more
frequent and sever storm damages as the tree cannot absorb wind loading
forces in a flexible trunk. I think (my theory anyway) that this leads to a
"stag headed" canopy architecture and may in fact limit height growth as
well.

I would be glad to talk with you further about designing a project to study
these ideas.

Will
RE: Tulip tree height   wad-@comcast.net
  Nov 16, 2004 19:02 PST 
Is there any chance the younger tall trees are regrowth from old stumps left behind from the clearcutting? I have noticed extremely fast regeneration on cut trees. For instance, I had a twenty foot white ash on the property where I work that was attacked by borers and then snapped in half in a wind. I then cut the tree to the ground in spring, and now there is over five feet of new growth on that stump in one season. This, as compared to a seedling ash I have that put on less than a foot in the same time period. Could this be happening on a larger scale with the tulip poplars? Say a 2-300 yr old tree was felled in the 30's, is it possible that the rapid growth is the root system trying to balance out the canopy? 

Scott Wade
RE: Tulip tree height    Will Blozan
  Nov 16, 2004 19:18 PST 
Scott,

Some of these 70 year old forests are growing in converted landscapes, i.e.
not just cut and left to grow. They were converted to pasture or other open
uses and have since "grown in". Stone spring houses can still be found with
140'+ trees growing on top of them. Old fences and other structures
suggesting a field are commonly found. I feel much of the super forests are
not from sprout origin, and the well-formed root crowns and perfectly
straight, well-spaced single stems further support this. The older Baxter
Creek grove was probably cleared once and left to grow from what was there
and seeded in. However, stump sprouts are not evident.

Regardless, 177' is the maximum after many years of searching (unless Jess
and Mike found something in Big Creek on Sunday that is a new record). This
maximum holds true over all age and disturbance classes (in the Smokies at
least). Jess, correct me if I am wrong, but is only one tuliptree known
outside of the Smokies that reaches or exceeds 170'? I know you list one in
SC (GA), and Mike may have one I don't recall in Kilmer.

Will
Re: RE: Tulip tree height (Jess and Mike read this)   Jess Riddle
  Nov 17, 2004 11:28 PST 

As far as I know, the 170.2' tree at Tamassee Knob is the only tuliptree
outside of the Smokies over 170'. What's more, I think only four sites
outside of the park, Wadakoe Mountain, central Brevard Belt, Lilly Cornett
Woods (sp?), and Joyce Kilmer, have tuliptrees confirmed over 160'. The
cove with the 170' tree at Tamassee does have two others over 165', and an
adjacent has a tree that will almost certainly exceed 170' and may reach
175'. I'll confirm that in the next couple of months. No spectacular
finds from upper Chestnut Branch or Kilby Branch last weekend in the Big
Creek watershed. I'll try to get a post out in the next few days.

Jess Riddle
RE: Tulip tree height   Lee E. Frelich
  Nov 18, 2004 06:26 PST 

Will:

These are good alternatives hypotheses for explaining maximum
height. However, I still believe that there is an absolute hydraulic limit
for each species. If there wasn't, then some trees that by chance did not
experience storm breakage would easily soar past 177 feet. The storm
breakage hypothesis (your #4) probably limits many individuals to shorter
heights than hydraulics alone would allow, so it is still a limiting
mechanism for many trees.

Regarding your hypothesis #2, I only meant to imply that more crown area
when neighboring trees died allowed the trees to go from 170 to 177 feet,
since several other mechanisms including the hydraulic limit and the
mechanisms you point out are coming into play for trees that tall.

It seems likely that several mechanisms influence the maximum height of
trees with similar genetics that are growing on similar sites. Perhaps
several of these mechanisms each influence height by a few feet, and
perhaps they can reinforce or counteract each other depending on the
situation for each tree.

Lee