==============================================================================
TOPIC: Tree Half-Life
http://groups.google.com/group/entstrees/browse_thread/thread/7e39a7f7fdac107f?hl=en 
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== 1 of 2 ==
Date: Wed, Feb 6 2008 7:40 pm
From: "Edward Frank"


ENTS,

A few years ago Colby Rucker posted these comments as part of a longer post:

Most of the trees were dead or decadent. I expect the sour gums to reach
250, a few northern reds may see 165, chestnut oak 200, and scarlet oak 120.
More importantly, a list of maximums can be misleading. Maybe it's better
to consider a sort of "half life" as in radioactivity. The last ca. 200
year-old black oak in my woods has fallen, and the rest are perhaps 100.

From a silvicultural standpoint, a few lingering shells don't reflect the
average lifespan of a species before a significant number of them start
falling over, dying back, or rotting up the center. On less stressful
sites, as in the mountains, that stage will be delayed.

So, it's difficult for anyone to state the lifespan of any species without
going into a lot of detail regarding regional differences, habitat
influences, and survival percentages. I suppose it's like people; a few
live past 100, but hard work will break you down by half that.

We have been talking about various ways to characterize the lifespans of various tree species, how to define old-growth, etc. I am not sure how to work the concept out, but it sounds like an idea that could be used. How about some ideas people?

Ed Frank

== 2 of 2 ==
Date: Thurs, Feb 7 2008 12:33 am
From: "Edward Frank"


ENTS,

I really like this conceptually. it also fits to some degree with ideas presented by Doug Bidlack on Putting Big Trees in perspective, where he suggested developing a mean height for a tree species.

The problem remaining with any age criteria is how do you effectively, and non-invasively determine the ages for each tree in stand or forest? You really can't at this point, so statistical evaluation methods are hard to implement. Basically my interpretation might be if you took the ages of all the trees of a species in the sample forest over some minimum age - say 100 years - then you could determine what the median age was for the entire population. This would mean that a single extremely old tree would not shift the median any more than a tree than another tree above the median age. It would not necessarily need to be a median, but another value such as where was the break for the 20th upper percentile forage.

As applied to heights, first you could look at the size distribution for a species on a site. Say White Pines at Cook Forest , PA. Dale has an excellent Data set. trees in the 140 foot range are basically too numerous to measure. But if you set the minimum height for this group at 150 feet, then you could calculate what the median height was for all white pine trees greater than 150 feet in height. This might be a better and more representative value of a typical "tall" height than the maximum height of the single tallest tree in the plot. the tallest tree is often much higher than most other trees in the plot as it represents the peak of an ever steepening curve on the height distribution plot. It may even be an anomalous outlier height with respect to the rest of the trees in the plot. This would not be the case of a typical tall value determined by this median or percentile process.

I have not thought this out in detail, or even if it is a useful number to generate, but I still like the concept. I think the median or percentile approach is better suited to looking at these typical values than would a simple numerical average of heights.

Ed Frank

==============================================================================
TOPIC: Tree Half-Life
http://groups.google.com/group/entstrees/browse_thread/thread/7e39a7f7fdac107f?hl=en
==============================================================================

== 1 of 3 ==
Date: Thurs, Feb 7 2008 6:01 am
From: "Lee E. Frelich"


Ed:

Technically, the concept of half life only works if the mortality rate is
constant over time, which leads to a negative exponential survival curve.
The statistical properties of a negative exponential are such that: (1) The
mean age at death would be the reciprocal of the annual mortality rate
(i.e. if 1% died every year, then the mean age at death would be 100
years), (2) 63% of all trees would die at ages younger than the mean age at
death (to carry the mathematical example I started further, with a 1%
annual mortality rate, 63% of all trees would die prior to age 100, (3)
some trees would live 2, 3, or even 4 times the average age at death (thus
balancing out the large number that died relatively young).

Trees have much more variability in age at death than people (whose age at
death clusters tightly around the mean, leading to a unimodal distribution
of age at death), but they don't quite approach the half-life/negative
exponential model. They are somewhere in between. Mortality rates for
trees are not constant with age, but are higher for younger and older
trees, so the half life model cannot be applied.

The concept of canopy turnover rate in forests is closely related to the
half-life concept. If gap formation rates in a forest are 1% per year on
average, then the average canopy residence time is 100 years, and since
trees of many ages are killed to form gaps when disturbances such as
windstorms occur, the fact that mortality for individual trees does not
follow the half-life model does not preclude that model from applying at
the scale of the stand or landscape. In fact it does apply in boreal
forests due to fires that create constant rates of canopy turnover as long
as the climate stays the same, and in hemlock and sugar maple forests
(between major disturbances such as derechos), where canopy turnover has
been shown to range from 150-200 years in several case studies.

Lee

== 2 of 3 ==
Date: Thurs, Feb 7 2008 6:24 am
From: "Joseph Zorzin"


Wow, I've been a forester for 35 years and I didn't know what Lee just said. Makes perfect sense though.

That gave me a vision of how the numbers might look in a managed stand with the goal to manage actively for old growth...... hmmmmmm...... let's see, plot the statistics every 5 years, showing periodic dips, then the numbers go to a higher level than after the previous cycle, ever upward- a job for many generations. Such a human influenced "super old growth" just might be quite an exceptional work of art- though not autopoietic, unless the people doing this work are themselves autopoietic! (trying to hook Gary Beluzo into a metaphysical discussion <G>)

If the emphasis was to periodically thin very lightly, always leaving the healthiest trees (those that look like they'll live the longest)- I wonder just how large the average tree size and or age can go?

Joe

== 3 of 3 ==
Date: Thurs, Feb 7 2008 12:14 pm
From: DON BERTOLETTE



Gary-
We agree...I can think of a half dozen species (Bristlecone Pine, Foxtail Pine, Western Juniper, Whitebark Pine, Brewer's Spruce, Lodgepole Pine, Mountain Hemlock) growing at or above treeline in the western US that face extremes in temperature, UV exposure, and winds yet live 500 to 4,000 years. They'd be old-growth ecosystems in my book...'economy' comes to mind.
-Don

==============================================================================
TOPIC: Tree Half-Life
http://groups.google.com/group/entstrees/browse_thread/thread/7e39a7f7fdac107f?hl=en
==============================================================================

== 1 of 2 ==
Date: Thurs, Feb 7 2008 2:59 pm
From: "Edward Frank"


Lee,

Excellent response. I was thinking of this as a method to characterize the "status" be it age or height, of a specific subset of the total population of the tree species at a site. The use of a percentile or median model rather than a numerical average would offset the scatter, and the stretch, found at the upper end of a plot of size or age distribution. The problem still remains of how to define the lower cut-off point for defining these sub-sets so that the sub-set will represent a meaningful category. Since the percentile result would be to a large degree related to the lower limit of the category, then there needs to be a good rationale for setting this limit. I can't figure out how this would work. I don't see any good process for setting this lower limit that could be applied with consistency to different populations. So I thought I would put the basic idea out there to see what every else thought or to see if they had any additional ideas.

Ed

== 2 of 2 ==
Date: Thurs, Feb 7 2008 8:18 pm
From: Beth Koebel


Don,


"(Bristlecone Pine, Foxtail Pine, Western Juniper,
Whitebark Pine, Brewer's Spruce, Lodgepole Pine,
Mountain Hemlock) growing at or above treeline..."

I thought the treeline was defined as the elevation
where the trees grow below and not above. Am I wrong?
Or is there exceptions?

Beth

==============================================================================
TOPIC: Tree Half-Life
http://groups.google.com/group/entstrees/browse_thread/thread/7e39a7f7fdac107f?hl=en
==============================================================================

== 1 of 11 ==
Date: Fri, Feb 8 2008 4:01 am
From: neil



Hi All - Ed thanks for this thread. It is very interesting.

It seems to me that what is being asked is what influences tree
mortality or, put it another way, tree longevity. Lee notes that while
there is generally a 1% turnover in the canopy or tree mortality, that
there is a lot of variation in when a tree dies in a population. So, the
notion is interesting and complex: generally there is a constant rate of
tree mortality in the forest, but being able to predict when a tree [or
a group of trees or a significant proportion of that population] might
die [or how long they live] over time is tricky.

Episodic is the thought that comes to my mind when thinking about this.
Previous studies by Lee, Craig Lorimer, Marc Abrams, Dave Orwig, etc.
show episodic forest recruitment, especially for the oldest & dominant
canopy trees. What this suggests, in a sense, is that there are pulses
of recruitment of a species [or two species], mortality of many of the
individuals recruited and then some lingering individuals from that
cohort that persist in the forest due to various factors [genetics,
luck, etc]. There are some decent examples of this on the web:
http://www.geocities.com/renzomotta/agestru.jpg and
http://www.fs.fed.us/rm/landscapes/Locations/Manitou/tree_ring.GIF

Researchers working in less complex ecosystems have some data
supporting episodic nature of tree mortality. Ricardo Villalba indicated
how mortality [and recruitment] fluctuated with climate variations in
border forests of Argentina. Stephen T. Jackson and Steve Gray looked at
the age structure of pinyon pine at a northern range limit and showed
how one individual persisted through a megadrought roughly 600 yrs ago
and is likely the founding member of the current population. I believe
that while pinyon is undergoing another dieback out west, but I would
bet not all individuals are dead [unless, of course, it is something
like an invasive disease knocking out the population]; someone please
correct this if wrong. Southern pine beetle does not kill all
individuals in a forest when it rips across the landscape.

Sorry, a bit of a tangent there, but the episodic nature of tree
longevity and mortality seems to be a common theme. I think it might
apply to eastern/closed-canopied forests. Tony D'Amato has data
indicating how a significant number of sweet birch trees [black birch
for northerners] can live past 250 yrs if they 'make it' more than
150-200 yrs in western MA. Though eastern forests are different than
those in semi-arid regions, the processes are essentially the same:
gathering of light, nutrients & water while resisting disturbance
events. The higher biodiversity in eastern forests might set up
conditions so that some individuals of some species versus other species
will persist during extreme climatic or disturbance events.

There has been reference to stress in this thread. Edmund Schulman's
'longevity under adversity' article regarding bristlecone pine and other
species at mountain treelines speaks to the general rule of thumb of
live fast, die young. Merrill Kaufman indicated similar patterns in
lodgepole pine back in the 1990s. Others have noted this pattern since
then, including Tom Melvin's work with Scots pine in northern Europe in
the early 2000s. He found that the oldest individuals in a typical
dendro collection grew slower while younger than younger individuals. I
found this same pattern with white & chestnut oak in the eastern US.
There is something about stress that confers longevity in the biological
world. And, it seems to apply to trees.

Bryan Black, Jim Colbert & I have just had a manuscript accepted in
Ecoscience that quantifies this relationship. Bryan analyzed the growth
patterns of a large sample of eastern hemlock, ponderosa pine,
Douglas-fir and white oak and found there are different trajectories in
growth when the oldest and youngest trees in a species were the same
age; when the oldest white oaks sampled were 50 or 100 yrs old, they
grew slower than when the youngest white oaks were 50 or 100 yrs old. We
tested the pattern again on smaller collections of tulip-poplar, white
oak and chestnut oak where the core samples contained the pith. Again,
we saw the same results. In fact, the phenomenon was more pronounced for
white oak. Bryan further tested this on about 5-6 European species and
found the same pattern. Across all species tested, longevity seems to be
related to initial growth rates; the slower a tree grows, the longer it
might live. We are excited about these findings [hence the long email,
apologies].

There seems to be a lot of evolutionary and management implications as a
result of this phenomenon, though they are just hypothetical
implications at this time. The Black et al. paper will not be in print
until September. If anyone is interested in reading a pre-print of this
article, please contact Bryan - bryan.black@oregonstate.edu - or myself
at my work address - neil.pederson@eku.edu.

Does this help or just muddy the waters?

neil

== 2 of 11 ==
Date: Fri, Feb 8 2008 6:22 am
From: dbhguru@comcast.net


Neil,

Your very extremely lucid submission does clear some waters, but muddies others. For foresters looking to growth super trees in just a few years, the old-growth like nature of the resulting forest would appear to be illusory. The idea of near old-growth needs to be rethought. Maybe the aim needs to be to achieve a diverse, super forest rather than mimicing old growth forest attributes. The slow growing black birches form a much larger population than any of us heretofore imagined. I see them in many areas where people don't think much about what they are seeing. Mount Tom, the Holyoke Range, many areas of the Berkshires are loaded with 150 to 200 and sometimes older black birch. I'm sure youthful mortality was very high in places I see the residuals. But the number of advanced age black birch in western Massachusetts is impressive.

Bob

== 3 of 11 ==
Date: Fri, Feb 8 2008 6:48 am
From: "Neil Pederson"


Bob,

Wow - you said:

"For foresters looking to growth super trees in just a few years, the
old-growth like nature of the resulting forest would appear to be illusory.
The idea of near old-growth needs to be rethought. Maybe the aim needs to be
to achieve a diverse, super forest rather than mimicing old growth forest
attributes. The slow growing black birches form a much larger population
than any of us heretofore imagined."

That is EXACTLY one of the hypothetical implications we stuck into the end
of the paper.

Wow!

neil

== 4 of 11 ==
Date: Fri, Feb 8 2008 6:51 am
From: ForestRuss@aol.com


Bob:

I think that there might have been something in American chestnut that
stifled the spread of black birch but I also think that in many areas the hundreds
or thousands of black birch trees per acre became established in the gaps
created by the death of chestnut. It is so common in Massachusetts, Vermont,
northern CT and in many other places that I think ring counts on many cut
stumps would show an explosion of numbers between 1910 and 1920.

A strange factoid about black birch is that prior to the Civil War black
birch bark was stripped from trees and boiled for the "wintergreen" essence in
the bark and by the middle 1800s black birch populations had become so depleted
that there was concern about it being driven to extinction. When
artificial wintergreen essence was developed in the 1850s the demand for black birch
oil dropped off and the species recovered.

When I find the reference to the black birch/wintergreen oil business again I
will forward the actual publication where I read that historical account.

In WV black birch has almost no commercial value in spite of having almost
no nectria canker (a very common NE problem), growing very tall and reaching a
high quality uncommon to anything one is likely to encounter in New
England....and black birch normally responds to any kind of release unlike most
forest trees...instead of growing faster, it dies!

Russ


== 5 of 11 ==
Date: Fri, Feb 8 2008 7:25 am
From: "Joseph Zorzin"



----- Original Message -----
From: dbhguru@comcast.net
To: entstrees@googlegroups.com
Sent: Friday, February 08, 2008 9:22 AM
Subject: [ENTS] Re: Tree Half-Life


Neil,

Your very extremely lucid submission does clear some waters, but muddies others. For foresters looking to growth super trees in just a few years, the old-growth like nature of the resulting forest would appear to be illusory.

The "foresters" wanting to grow super trees will never allow those trees to reach anything like an old growth stage as they continually try to shorten the rotation cycle. They would love to grow a tree the size of a telephone pole in only several years- then mow them down and start over again.

The idea of near old-growth needs to be rethought. Maybe the aim needs to be to achieve a diverse, super forest rather than mimicing old growth forest attributes.

The near old-growth "uberforest" managing by an "uberforester" can be diverse in species and size, rich in timber values, rich in ecosystem values and have significant old growth forest attributes- such as snags, hollow/rotten trees, plenty of rotting logs on the ground, "legacy trees", little or no sign of skid roads. It wouldn't be the goal to develop a forest of just veneer quality red oak, cherry and hard maple- though such trees may make up much of the stand- other trees of low value species will also be retained for biodiversity. Some crooked or forked trees will be left for artistic reasons. Though such an near old-growth uberforest may not appeal to the old growth purist - don't compare it to a true old growth- compare it to the tens of millions of acres of wasted, high graded, neglected forest.


The slow growing black birches form a much larger population than any of us heretofore imagined. I see them in many areas where people don't think much about what they are seeing. Mount Tom, the Holyoke Range, many areas of the Berkshires are loaded with 150 to 200 and sometimes older black birch. I'm sure youthful mortality was very high in places I see the residuals. But the number of advanced age black birch in western Massachusetts is impressive.

Many were left after high grading- black birch in western Mass. is an "associate" of red oak- if you see little red oak near those birches, you know the place has been whacked. Unfortunately, some of the best black birch were probably cut- leaving crooked, forked, damaged trees- which can still manage to survive.

Joe


Bob

== 6 of 11 ==
Date: Fri, Feb 8 2008 7:43 am
From: "Lee E. Frelich"


Ed:

I would use quartiles, quintiles, or deciles, because if you do that people
perceive the cut off points as being objective, even though as you pointed
out, there is no way to justify a given cut off point.

Lee

== 7 of 11 ==
Date: Fri, Feb 8 2008 8:01 am
From: ForestRuss@aol.com


Joe:

Good post!

Russ

== 8 of 11 ==
Date: Fri, Feb 8 2008 10:29 am
From: "Edward Frank"


Lee,

I guess I don't want to fool someone into thinking it means something, I actually want something that does.

Ed

The most beautiful thing we can experience is the mysterious. It is the source of all true art and all science. He to whom this emotion is a stranger, who can no longer pause to wonder and stand rapt in awe, is as good as dead: his eyes are closed."
- Albert Einstein

== 9 of 11 ==
Date: Fri, Feb 8 2008 11:01 am
From: DON BERTOLETTE



Neil-
With regard to the snippet below:, from your previous post:


Bryan Black, Jim Colbert & I have just had a manuscript accepted in Ecoscience that quantifies this relationship. Bryan analyzed the growth patterns of a large sample of eastern hemlock, ponderosa pine, Douglas-fir and white oak and found there are different trajectories in growth when the oldest and youngest trees in a species were the same age; when the oldest white oaks sampled were 50 or 100 yrs old, they grew slower than when the youngest white oaks were 50 or 100 yrs old. We tested the pattern again on smaller collections of tulip-poplar, white oak and chestnut oak where the core samples contained the pith. Again, we saw the same results. In fact, the phenomenon was more pronounced for white oak. Bryan further tested this on about 5-6 European species and found the same pattern. Across all species tested, longevity seems to be related to initial growth rates; the slower a tree grows, the longer it might live. We are excited about these findings [hence the long email, apologies].I began wondering if it wasn't what's below ground that affords the 'lifeblood' of the tree growing in adversity, rather than all the sexy photosynthesis/transpiration/respiration? Could it be simply (I know, nothing is that simple) that advanced root system growth affords the stability needed by a tree living in such spartan conditions?
-Don

== 10 of 11 ==
Date: Fri, Feb 8 2008 11:25 am
From: DON BERTOLETTE



Beth-
A reasonable question. My years in many of the western wilderness areas (in particular, those rising above treeline) brings to mind the word 'krumholtz' which refers to alpine and subalpine species growing at or near treeline. Treeline, if measured exactly in any given area wouldn't necessarily hold rigidly to a topographic contour line, but would vary with microsite differences. Those trees venturing above the "mean treeline" would be outliers, out on the tails, where microsite environmental conditions permitted them. These would be the gnarly, twisted, dwarf or elfin (partially referring to origin of word krumholtz) trees that truly live in adversity.

While I've grown old and fat in the time since my tours of western wildernesses, the world at treeline remains strong in my memory. I treasure the times that I am able to visit there..."adversity" happens at lower elevations here in Alaska! 

== 11 of 11 ==
Date: Fri, Feb 8 2008 2:06 pm
From: "Neil Pederson"


Don,

Oh certainly, it could be the underground system that allows trees to
maintain life 'on the rocks'. I recall seedling studies where individuals
put more effort/energy/investment belowground when treated with drier
conditions [if I'm recalling correctly]. So, sure, why not... if large trees
'behave' like small trees. Of course, you always have more stem storage of
water in larger trees. There might be other differences.

But, the whole tree still needs to persist [conduct photosynthesis,
maintain itself...] in shade, drought, etc....

neil

==============================================================================
TOPIC: Tree Half-Life
http://groups.google.com/group/entstrees/browse_thread/thread/7e39a7f7fdac107f?hl=en
==============================================================================

== 1 of 5 ==
Date: Fri, Feb 8 2008 3:19 pm
From: "Edward Frank"


Lee,

I think we can agree that some trees live longer in a similar setting than others. So if you made a plot of the age distribution of the trees of different species the amount of "curvature" for different species would be different. The plot would not be linear, but it would not be geometric, as you say, but somewhere in between. Could the shape of this curve be expressed as some exponential value between 1 and 2? [There are fewer trees at the higher end of age, so even if the rate of death is higher per age category, the actual number of trees that die at a particular age could likely be lower - maybe this means the curve flattens out a little, but it would still trend upward I think]

Could a death curve shape be defined for each different species in a particular setting? In a mixed forest, this would mean the the canopy residence time for each species would be different?

In your post you comment that there is a higher mortality rate for younger trees, and a higher mortality rate for older trees - doesn't that imply that there is some middle range in which mortality rate is the lowest? How could that point be determined? it would also I think be different for different species - would it be higher for trees that tended to be longer lived than it would be for trees that are shorter lived?

Certainly fire, wind and other natural devastation events would keep interrupting this process in many areas, but the sequence could proceed to pretty far along in some areas by pure chance. Sort of like the Climax forest concept - the forest might not actually achieve this ideal because of disturbance, but it would reflect the end game the process is pointing toward.

I understand what you are saying about the canopy residence time on a large could follow the half life model if there is regular pattern of fire or other disturbance.

If you were plotting tree heights, there is some value, in the white pine example at Cook in the 130 to 140 foot range, where a plot of the heights of all the trees in sequence would almost be flat. At greater heights there would tend to be progressively steeper upward plot as the change in heights between individual trees became greater as the number of trees reaching a greater height decreased. What shape would you think this plot would be? It also would be different for different species as different species have different degrees of variability in height. The base of a set of tall trees could be defined as the point where the slope of this plot line reached a certain value.

Ed

"The philosophers have only interpreted the world in various ways; the point is to change it."- Karl Marx

== 2 of 5 ==
Date: Fri, Feb 8 2008 3:58 pm
From: Beth Koebel


Don,

Thank you for your explanation. Having lived
most(98%) of my life at about 500 feet above sea level
or lower it is easy for me to think in black and white
(a tree line that trees don't grow above) instead of
gray (the tree line being an average elevation).

Beth

Only two things are infinite, the universe and human stupidity, and I'm not sure about the former....Albert Einstein

== 3 of 5 ==
Date: Fri, Feb 8 2008 5:53 pm
From: dbhguru@comcast.net


Beth,

Treeline is even more complicated than that. In central and northern Wyoming, timber line averages between 9,000 and 10,000 feet. At the same latitude in New England, the treeline is between 4,000 and 5,000 feet. I'm unsure where it is in northern Oregon and southern Washington. I suspect it is between 5,500 and 7,500 feet. But major weather patterns act longitudinally as well as latitudinally. Ernie can speak authoritatively to that. I'm sure Lee can as well. And as Don points out microclimates abound on a single mountain. There's a big difference between the treeline on northern versus southern sides, but areas of protection out of the wind will have a higher treeline regardless of side.

As an aficionado of statistics, I've long been aware of how we often simplify concepts, activities, states of nature, etc. that use some measure of central tendency as an absolute. I used to think that the normal body temperature was exactly 98.6 degrees and that was true for everyone. I've since learned differently. I wonder how many numbers we think of as absolute measures that are in fact approximations or broad averages? One I can think of right of the bat is the relationship between air temperature and altitude.

Bob

== 4 of 5 ==
Date: Fri, Feb 8 2008 6:18 pm
From: Gary Smith


ENTS,

To add a little something to the northern/southern side issue, about
15 years ago I visited a bristlecone pine grove in the White Mountains
close to Bishop, CA. I also recall a town called Lone Pine near there.
I'm thinking the grove may be called the Patriarch Grove, but it was
long ago and I may be mistaken.

Anyway, this was at roughly 10k ft of altitude, maybe a little. I
distinctly recall that the bristlecones on one side (I'm thinking the
northern face) seemed lusher and in better shape than the ones on the
other side, which must have been a southern face. I always figured
that the northern side probably retained moisture better, being that
it faced away from the sun, and this was the reason that the
bristlecones appeared healthier.

If you ever get out to the Yosemite area of California, do go out of
your way to visit a bristlecone grove. They are something.

gs

== 5 of 5 ==
Date: Fri, Feb 8 2008 9:21 pm
From: James Parton


Gary,

Along with visiting the Sequoias & Redwoods, I have always wanted to
visit a Bristlecone grove. It would be awe-inspiring to visit some of
the oldest trees on earth!

http://www.pbs.org/wgbh/nova/methuselah/explore.html 


James Parton.

==============================================================================
TOPIC: Tree Half-Life
http://groups.google.com/group/entstrees/browse_thread/thread/7e39a7f7fdac107f?hl=en
==============================================================================

== 1 of 7 ==
Date: Sat, Feb 9 2008 4:56 am
From: Gary Smith


James,

Thanks for providing that link. Methuselah Grove and the Discovery
Trail, that is exactly where I went! I spent several hours up there
that day, and was really worn out from the altitude when I got back to
my car.

On that same trip, I saw the giant sequoias. Awesome.

gs

== 2 of 7 ==
Date: Sat, Feb 9 2008 6:32 am
From: "Joseph Zorzin"


Ed, most of your questions have been answered by forestry researchers, a long time ago. There has been a great deal of good forestry research, unfortunately, very little of it ever gets applied.

All sorts of variables- such as age, height, volume, value, basal area have been plotted vs. each other for all species and types of stands. This research is the raw material for practicing foresters, if they care to practice forestry rather than just "feed the mills".

We study all that in forestry school, then forget most of it- but then we develop an intuitive sense of these relationships.

Joe

== 3 of 7 ==
Date: Sat, Feb 9 2008 7:07 am
From: "Edward Frank"


Joe,

I don't doubt that these questions have already been answered, I just don't know what the answers are..

ed

"The philosophers have only interpreted the world in various ways; the point is to change it."- Karl Marx

== 4 of 7 ==
Date: Sat, Feb 9 2008 7:11 am
From: "Joseph Zorzin"


Well, as I pointed out- I've long ago forgotten them. <G> I started looking for them but forestry books generally bore me. <G>

Joe

== 5 of 7 ==
Date: Sat, Feb 9 2008 7:31 am
From: "Edward Frank"


Joe,

Lots of information that has been collected can be used in different ways to answer different questions. I am thinking in terms of defining maturity in a stand in a non-arbitrary as a starting point for some other processes. Some of the information I am not so sure actually has been worked out in detail, because some of the height variations are pretty subtle and many of the older height measurements are pretty crappy. People have been dong forestry for a long time , but always the answers and questions must be considered with respect to the understanding of other aspects of the ecosystems and processes involved. I know in the 1950's there were elaborate schemes to explain mountain building, then with plate tectonics everything changed. Today many of the approaches are ecosystem and process based, while older studies were often directed toward production and perhaps timber sustainability.

So at times may ask stupid questions. I don't have a coherent forestry education or background. I also figured out in classes in college, that as I was one of the brighter students, if I did not understand something, many of the other people didn't understand it either, and they were just afraid to ask for clarification. So I would ask questions until I understood.

Ed

"The philosophers have only interpreted the world in various ways; the point is to change it."- Karl Marx

== 6 of 7 ==
Date: Sat, Feb 9 2008 3:09 pm
From: Lee Frelich


Ed:

People want trees to follow certain attractive mathematical distributions,
but the trees don't have to (and this is one reason the world is so full of
ecologists who used to be mathematicians, who puff themselves up with their
curve fitting but don't really understand trees).

Yes, even under uniform environmental conditions all the species would have
a mortality function (by age or size class) with different curvature, with
different low points, and this would lead to survivorship curves with
somewhat different shapes, and different tree maximum sizes and ages, and
different canopy residence times. The only way to determine the shapes of
the mortality curves is to map a lot of trees and then wait 20 years and
determine their status, and plot the data on percent of trees in each size
class that died. A graduate student and I are working on that based on
about 30,000 trees mapped on 70 acres in 1988-1989, which were just
re-tallied by the student. This study is taking place in the hemlock, sugar
maple, yellow birch and basswood forests of Sylvania Wilderness, Upper
Michigan, and the U-shaped mortality function seems to be upheld. This
means that people can stop complaining about the paper Lorimer and I
published in 1984, where critics (i.e. Rubin et al from Syacuse University
in a recent paper) have claimed that we made up the mortality functions (we
did, but we turned out to be right, its that spiritual thing that
ecologists like me have, which allows us to understand things about the
forest that mathematicians can't see).

The curved mortality function leads to a rotated sigmoid (like a slightly
flattened 'S' rotated on its side) size distribution of trees in the forest
(steeply descending for young small trees, almost flat in the mid sizes and
ages, and with a strong down turn in older trees).

Lee

PS. I just heard the crowns of trees outside my window crashing into each
other, and checked the weather forecast and discovered an arctic front just
arrived, with winds gusting to 40 mph and predicted wind chills of -40 by
morning. My morning walk tomorrow will be a cold one, although it appears
that Minneapolis will escape the blizzard warning that Fargo and Upper
Michigan have, where winds will gust to 60 mph tonight. No wonder the
hemlock woolly adelgid hasn't made it to the Porkies and Sylvania in Upper MI.

== 7 of 7 ==
Date: Sat, Feb 9 2008 3:11 pm
From: Lee Frelich


Bob:

Not only does the weather vary by aspect and change tree line, but soil
type boundaries also affect it. In some places the weather would allow tree
to grow further up the mountain, but the soils ends and becomes mostly
rock, thus limiting tree line.

Lee

==============================================================================
TOPIC: Weather questions for Lee
http://groups.google.com/group/entstrees/browse_thread/thread/ff8830abe783fad4?hl=en
==============================================================================

== 1 of 1 ==
Date: Sat, Feb 9 2008 4:01 pm
From: dbhguru@comcast.net


Lee,

I haven't read yet of any unusually low temperatures in the upper Mid-west. I've heard you quote some low wind chills, but not absolute temperatures. Is this turning out to be a milder than normal winter for Minnesota - at least absolute temperature wise?

With respect to you explanation of trees not following theoretical curves, I say bully for the trees. I remember that our friend Al Gordon got miffed at armchair mathematicians who sat in front of computer screens and developed exotic curves for tree growth without having ever seen live trees of the modeled species.

Bob

==============================================================================
TOPIC: Tree Half-Life
http://groups.google.com/group/entstrees/browse_thread/thread/7e39a7f7fdac107f?hl=en
==============================================================================

== 1 of 4 ==
Date: Sat, Feb 9 2008 4:07 pm
From: dbhguru@comcast.net


Lee,

Interesting that you added soil to the mix. Mount Monadnock in southern New Hampshire has developed alpine vegetation on its now rocky, mosrly bare summit. a fire around 1806, if I remember correctly, burned off the vegetation and the soil eroded away. Alpine plants are filling in crevices. Monadnock is 3165 feet in altitude, but rises close to 2,000 feet above the surrounding countryside. Its denuded summit has a pretty rough climate.

Bob

-

== 2 of 4 ==
Date: Sat, Feb 9 2008 11:38 pm
From: "Edward Frank"


Lee,

It sounds like an interesting project to reexamine that forest after 24 years of time. I don't think I am a frustrated mathematician. I tend to see the world as a series of processes that change over time. The comments I make about graphs are because these just form in my head as I think about different factors, I guess as a tool to organize my thoughts. I don't see the equations just graphs, maps, 3d objects, and like movies that I can run back and forth through time. (My mother always asks me how I know something when I answer an obscure question on Jeopardy. I tell her I don't know the answer just appears in my head - these graphs just appear in my head.)

Yes your rotated sigmoid matches what I envision. I was thinking a graph in which on the x-axis each tree would be one unit apart and on the y-axis would be height. You graph would be number of trees per height unit. It is just presenting the data set in different terms. My graph would be flat at the beginning (your steep), rising at the middle section (your flat), and then flattening out some at the other end (yours heading downward again). I do understand that these "graphs" simply serve as a baseline concept for examining what you are actually seeing in the field and only represent a part of what is going on.

Ed


"The philosophers have only interpreted the world in various ways; the point is to change it."- Karl Marx

== 3 of 4 ==
Date: Sun, Feb 10 2008 12:03 am
From: DON BERTOLETTE



Bob-
After reading about treeline comments, I'm reminded of the trees growing singly or in small groups, as seen from a fishing boat along the Flaming Gorge canyon walls...just enough soil and water getting sequestered in crevasses to sustain the tree(s). I would imagine tight growth rings there!
-Don

== 4 of 4 ==
Date: Sun, Feb 10 2008 12:37 am
From: "Edward Frank"


Lee,

It is too bad that there is not a direct linear relationship between tree age and height. Because you could do a mortality per height graph that also would be u-shaped - similar in shape to the mortality in time graph. Only the mortality with height graph could be done at a single time by measuring the heights of all the trees in the height range of interest. at a site. No need to wait twenty years to se what had died off. (You could skip chunks of the tiny trees as you know they are going to plot steeply downward..)

Ed

"The philosophers have only interpreted the world in various ways; the point is to change it."- Karl Marx

==============================================================================
TOPIC: Tree Half-Life
http://groups.google.com/group/entstrees/browse_thread/thread/7e39a7f7fdac107f?hl=en
==============================================================================

== 1 of 2 ==
Date: Sun, Feb 10 2008 4:07 am
From: dbhguru@comcast.net


Don,

Yes, very tight growth rings. I also remember our walk up that side canyon near Ogden and the assortment of spruce and fir we saw. I remember us eating all of Dale's delicious peaches and his excellent homemade ice cream. How delightful that was. now Dale and Celeste live in potato country (Pocatello, Idaho). Wouldn't be the same though, pigging out on taters instead of peaches and ice cream.
It would be soooper doooper if you could come to the gathering at Black Mountain, NC April 18-20. Is there even a remote chance?

Bob

== 2 of 2 ==
Date: Sun, Feb 10 2008 11:05 am
From: neil



ENTS,

A set of data coming down the research pipeline suggests that size, not
age, is an important factor of tree longevity. A lot of this work comes
from this lab: http://www.geos.ed.ac.uk/abs/research/forestsci/homepage.htm 

Related: 20 yr data sets and tree mortality, a nice paper recently came out:

* van Mantgem, P. J., and N. L. Stephenson. 2007. Apparent
climatically-induced increase of tree mortality rates in a
temperate forest. Ecology Letters 10:909-916.
< http://www.werc.usgs.gov/seki/pdfs/van%20Mantgem%20&%20Stephenson%202007.pdf  >[Journal
Article]

I see there is a new paper co-authored by Stephenson linking mortality
with prior growth of a tree. It appears that we may need to know the
long-term trends in growth and a tree's response to past events to be
able to predict mortality. These papers can be downloaded here:
http://www.werc.usgs.gov/seki/stephenson.asp 

neil