26, 2004 18:26 PDT
I was wondering if anyone read the new article in Nature about
redwood height maximums. I don't get the journal, so I could
only read the online general consumption article, which was very
interesting. It predicted the physical height ceiling of a
redwood at around 420 feet before it would become theoretically
unable to support any more growth due to water deficits. I was
wondering what model of tree hydraulics they were basing this
on? I don't even know if all of the mechanisms of water
transport have been decisively figured out yet, I thought it was
still debatable and not fully understood, but I may not be
operating off of the most recent information available. Hell,
the information I have I only barely understand. BVP, if you're
reading this, maybe you could shed some light? Anyone?
Redwoods in Nature
28, 2004 06:51 PDT
Yes, I work closely with both George and Steve in redwood
research. The paper comes at the limits to tree height from a
physiological perspective. The beauty of the work is that four,
completely independant methods were used to estimate a potential
limit to redwood tree height at Rockefeller Forest - the world's
Delta 13 concentrations in foliage, size/mass ratios of foliage,
photosynthetic density per mass of foliage, and predawn and
midday moisture stress levels were all used to predict a maximum
possible height. All four methods resulted in values between 122
and 130 m.
A tree will almost certainly encounter some difficulty before
achieving this. The tallest tree currently has had at least six
episodes of dieback and regrowth.
Keep in mind this is a potential maximum for one site during one
climatic period. Also, this research does not address any
potential genetic limitation to growth.
I hope this helps...
Redwoods in Nature
28, 2004 09:34 PDT
How much is known about the rates of growth for different West
conifers? How does Douglas fir compare to redwood for the first 100
years? The first 250, 500, 1000? I'm presently stuck on trying
understanding growth rates, relative and absolute, for white
seeing high absolute volume growth in the Mohawk pines that are
100 to 150-year age class, which I think surprises some of our
friends. What is this period of growth like for the West Coast
Given their great longevity, has anyone plotted graphs of volume
accumulation over a 1,000 years or more?
For those trees that get repeatedly pruned back, is there any
evidence that they return to their previous heights at faster or
rates than that which originally got then to a particular
On a slightly different theme, silviculturists often develop
notions of growth rates for species over time. In addition, the
producers in southern New England see diameter changes much more
than they see height changes when trees are in the 80-foot and
height class. I have often observed that a 130-foot white pine
looks basically the same to them as a 155-footer. They just
that extra 25 feet. However, they would all readily see a
difference at the 50 to 75-foot levels.
I'm inclined to wonder if the difference in
visual impact of an
additional 25 feet of height acquired at an early stage of life
white pines as opposed to the addition achieved at a much later
shapes one's perceptions about how fast the trees are growing.
growth obviously look shorter at greater distances to all of us,
has to learn to compensate. Our buddy Will Blozan is one of the
I've seen at doing that for eastern trees. I can do it too, but
require a longer period of site eye calibration than Will does.
I realize that I'm straying into uncharted
territory here, but I'm
trying to understand the differences in perception about the
some of us see in the eastern white pines versus that perceived
vast majority of the wood producers who visit pine stands with
course, Ents have the benefit of constant reinforcement from
measurements, but assessing growth is the business of wood
would have thought that the majority would be able to accurately
height, diameter, and total volume for young and old pines
not judging their talents at sizing up the number of logs in the
trunk. All do that well, but their talents don't extend to the
tree. How do you find the estimating eye of wood producers to be
there on the West Coast for the whole tree estimation?