Definition Old Growth   James Parton
  Aug 29, 2007 08:47 PDT 


What age on the average does a tree have to be to be considered an
old-growth tree in our eastern forests? This figure seems to vary
according to what book you read or what Internet site you visit. Some
have 200 years, some 150 and others 120 years. I have always used 150 as
a rule of thumb. I wonder what the US Forest Service recognizes?

James Parton
RE: Definition_Old Growth   DON BERTOLETTE
  Aug 29, 2007 15:10 PDT 

I think you'll find as many definitions as we have ENTS used to be thought that a "one-size-fits-all" definition existed.
I think most of us would agree that some of the variables to be considered would be: 1)species, 2)geography (topography/latitude/longitude), 2)reference conditions (human history), and 3) regional disturbance cycle (natural history).
All other things being equal, the second criteria is most often employed by the USFS, as well as a fair number of the 'scientifically inclined'.
At issue is whether you're seeking an inclusive or exclusive definition...scientists may often use an exclusive definition, usually characterized with tighter constraints, whereas a lay person may not particularly care that a mostly intact, otherwise old-growth forest had high value walnut old-growth taken out one winter when walnut prices had soared, making them worth the hassle of winter logging.
This may not be the answer you were seeking, did you have specific trees/forests in mind?  For the record, I have come to accept the concept of old-growth ecosystems, but am seldom found referring to old-growth trees ("no tree can be an island unto itself", if I might paraphrase).
RE: Definition_Old Growth   Edward Frank
  Aug 29, 2007 16:08 PDT 


What is old growth is a complicated issue that does not have a ingle
answer. That is why different sites have different definitions. We
have a entire section devoted to it on our website, Personally I ike
the introduction to the section on the index page: (Of
course since I wrote it I may be slightly biased)   Some of the more
recent debates also appear in this thread: No
single numeric definition can be used that can be applied to all
forests, because the nature, ecology, and age structures of forests vary
so dramatically. Trying to to apply a single number will always result
in a wrong baseline for a large minority of the forests being
considered. So really your question can not be fairly answered.

Ed Frank
FW: Definition_Old Growth   Will Blozan
  Aug 29, 2007 16:49 PDT 

This is a difficult question as some species will not live that long. I have
heard a rough equation of 1/2 the maximum known life expectancy.

Besides, a tree can't be "old-growth". The term applies to a forested
ecosystem- some trees will be seedlings, some "ancient". I do not support an
age determined definition of old-growth.

RE: Definition Old Growth   Edward Frank
  Aug 29, 2007 20:31 PDT 
Will, Everyone,

I really hate this definition, because that means every time a
dendrochronologist extends the maximum age for a species they are
wiping out hundreds of acres of what were formerly old-growth forest and
chagrining them to just forest.

This definition means the greatest destroyers of old-growth forest are
our friendly neighborhood dendrochronologists. How dare they push back
the maximum ages for all those tree species.....

The definition is based upon the fallacy that half the maximum age that
a species is capable of reaching under special circumstances is somehow
related to how long a tree species will survive on average under normal
conditions in a typical forest settings if otherwise left undisturbed by
fires, other large scale natural disturbances, or human activity. There
isn't any reason to believe that the two number are related at all.
Indeed many of the oldest tree specimens are often those that are
stunted and growing in very harsh atypical conditions. Maximum ages for
these specimens may be several times greater than typical natural
lifespans in normal forest settings.

To my mind the 50% maximum age figure is completely arbitrary and can
not be justified at all.

Ed Frank
RE: FW: Definition Old Growth   James Parton
  Aug 29, 2007 21:01 PDT 


Thank you for your replies & insights on my question concerning "
Definition_Old Growth ". I realized that there would be some varying on
this because of climate, location, forest type, etc. For example 150
years old would seem to be an old tree for most of us but would be a
youngster for a Bristlecone Pine. Your replies indicate that it is more
than just a number that indicates old growth. I will ponder on your

James Parton
Re: Definition Old Growth
  Aug 29, 2007 22:26 PDT 

    Nature does not recognize a state that we label old growth either for individual trees, tree species, or forest ecosystems. The designation is entirely artificial and human contrived. It is often useful to identify our oldest forests, and all of us use it, but we need to keep its artificiality in mind.

    In terms of trees, I suppose we could call an old tree growing in a designated old growth forest and old growth tree. However, such a designation to an old pasture tree seems inappropriate - regardless of age if the tree started growing from a pasture condition. As a general rule of thumb, 150 years has been used for trees and forests mainly stemming from the assumption that most eastern species can live to an average age of 300 years and 150 is half of that. Lesser ages are often used by people trying to save a tree or forest. Something over 150 years seems appropriate, maybe compromise at 175, if (and only if)an age is required.

    I'll now pass the talking stick to whoever wants to agree, disagree, or amplify.

RE: FW: Definition Old Growth
  Aug 30, 2007 06:17 PDT 

   You are correct, the so-called 50% rule is arbitrary and should be retired once an for all. Among definitions, it lives in infamy and has been sorely abused over the years by resource managers who seek to minimze old growth acreages, where the old growth designation imparts protections, so that control over the timber resource is not lost. I think the defintion was originally applied in a much more limited way, sort of a test case for old growth red spruce stands. But since its inception, it has been "idiotified" to coin a word.

RE: Definition_Old Growth   James Parton
  Aug 30, 2007 06:44 PDT 


While it seems to be more difficult to do with trees, it seems human to
me to wanna label something as " young, mature or old ". Whether
difficult, artificial or inaccurate the title " old growth " adds a
distinction to a tree or forest, like an older person above 70, it's
earned. I know this is not very scientific, but.....

Re: Definition Old Growth   Gary A. Beluzo
  Aug 30, 2007 07:09 PDT 

James, et al

My thinking has been strongly influenced by Lynn Margulis who says
that "natural systems" are those that are AUTOPOIETIC (ie. self-
regulated and self-directed). In other words, an AUTOPOIETIC FOREST
is one that is not being MANaged by humans but rather EMERGENT
processes that result from the integration of all biotic and abiotic
components of the forest. There are of course both internal and
external disturbances that will influence the trajectory of both the
autopoietic and managed forest but the key difference is in the
influence by many species rather than the control by one. Humans
have a tendency to simplified ecosystems so my definition of an old
growth system would be a "forested system that has been autopoietic
for some minimum time period. Autopoietic systems tend to have more

Folks like the 150-200 year criterion because it is easy to measure
(i.e. incremental core) but there are at least several problems with

1) Different forest types are composed of different trees that have
different longevities
2) After a major natural disturbance there may be NO trees left
standing that are 150+ years old- do we rule this system out? If so,
ALL of our old growth forests are but temporal snapshots of ever
changing systems and if the Old Growth trees are gone then presumably
the site would lose legal protection (and its visual appeal to some!)
3) Managed systems that have been allowed to return to an
autopoietic state after say 150 to over 1000 years of continuous
human disturbance do NOT necessarily show the original species or
processes we call these systems "old growth"?

I guess it depends on whether you are interested in OLD TREES
(regardless of past history) or NATURAL SYSTEMS (regardless of
present tree ages). More to come...

Gary Beluzo
RE: FW: Definition_Old Growth   Lee E. Frelich
  Aug 30, 2007 07:15 PDT 


I agree with Ed that using any criterion related to maximum age is silly.

Most of the definitions I have seen used by scientists have been based on
patterns of stand development.

However, my definition is that old growth is whatever the local people say
it is. Other concepts such as primary forest are more useful.

Re: FW: Definition_Old Growth   neil
  Aug 30, 2007 10:15 PDT 

well someone has to do it. better us then them.

let us not forget Dr. Charlie Cogbill urging us to consider a
process-based definition. for example, what is a forest that has never
been logged gets cut down in the 'prime of its life' [1/2 max age -
haha] by a great midwestern windstorm? is it not still a special place
on Earth even though many of the trees at that site will be younger than
ancient aspen for much of a century? are the natural processes still in
place even though old does not apply to tree age? [it seems the answer
is a general yes, right, unless you subscribe to Bill McKibben's 'End of
Nature' hypothesis that there is little, if anything natural, in the world]

RE: FW: Definition_Old Growth   Zachary Stewart
  Aug 30, 2007 11:09 PDT 

Really, in my opinion, I think the loggers are going to try to find
a way to log old-growth forests no matter what the age, and they
would like to see old-growth defined as liberally as possible...
I think 200-250 years is a good rule of thumb, but I am no expert
at these kinds of things.

- Zac
RE: FW: Definition Old Growth   Edward Frank
  Aug 30, 2007 12:09 PDT 


That is a terrible rule of thumb. That is approaching the maximum age
known for most species of trees know from the east and would mean that
for many forests currently defined as old growth, they would no longer
meet that definition. The big problem with that criteria is that few
forests in the east are pristine. The longest lived species in most
stands may be white pines and hemlocks. The timbering history in the
eastern United States is one of selective cut after selective cut in the
early 1800's through early 1900's. White pines were the first ones cut.
Oaks were cut. Hemlocks were
stripped of their bark. Hemlocks are currently dying on a massive scale
from Hemlock Wooly adelgid.

If you look at what are left after these selective cuts you have forest
that have all the characteristics of old growth forest, minus the
longest lived species because of human disturbance 100 to 150+ years
ago. If you want to save anything resembling old-growth forest for
future research or for future generations you must work with what you
have, This is what we have in the eastern United States for the most
part. Only a handful of eastern trees are known to reach ages over 300
years. The oldest documented basswood is less than 200 years old, most
maples, oaks, birches, are in the mid 200's or less for the oldest known
specimens.   Using your rule of thumb virtually no old growth would meet
your definition in the eastern United States. Certainly none dominated
by anything but pine or hemlock. It is worse than a terrible rule of
thumb or definition.

Ed Frank
Re: Definition Old Growth   Gary A. Beluzo
  Aug 30, 2007 12:23 PDT 

So do we simply want a collection of OLD TREES (ala Cathedral Pines
in CT) or do we also want the structure and function of a dynamically
adapted ecosystem (i.e. autopoietic forest) that not only provides
the infrastructure for current old trees but also future old trees?   
This seems to be the crux of the issue.

If we want not just the trees but also the forest then silviculture
to develop old growth characteristics will simply not do,
particularly since all human managed ecosystems are vast
simiplications of the natural thing. I've read in several articles
that whereas the 20th century was the time of reductionistic science
(e.g. traditional physics), that the 21st century will be the time of
systems science (ecology). New language, methods, and tools will
needed in order to understand (and restore?) complex natural systems.


RE: FW: Definition_Old Growth
  Aug 30, 2007 12:39 PDT 


Speaking for Live Oak trees, no one knows! The largest and
oldest were cut down for warships. The oldest I can date from my small
project is around 300 years. We don't know for sure how long a Live Oak
can live live? A tree is a magnificent thing I wish they could talk.
They have helped mankind survive these years and how do we thank them,
clearcutting, genetic engineering, forest manipulation, etc. Who speaks
for the trees? Sorry about the rambling, Old growth is in the eye of the


Re: Definition Old Growth   DON BERTOLETTE
  Aug 30, 2007 13:55 PDT 


If I've read your post below correctly, Margulis' definition is consistent with that of Oliver and Larson's (Forest Stand Dynamics) "True Old-growth Forest", with an added time dimension?

RE: FW: Definition Old Growth   DON BERTOLETTE
  Aug 30, 2007 14:03 PDT 


Goes to show what "rules of thumb" are worth...

RE: FW: Definition_Old Growth   Zachary Stewart
  Aug 30, 2007 14:25 PDT 

Sorry... like I said I am far from expert on these things :(
I guess it would depend on the type and structure of the forest...
didn't mean to cause a problem... I need to shut up and let the experts
discuss things like this! (But the loggers I'm sure like the idea of
200-250 years... let's hope nobody in high authority read my post!)

- Zac
Re: FW: Definition_Old Growth   DON BERTOLETTE
  Aug 30, 2007 14:30 PDT 

Neil/et al-
While not entirely conceived as a process based definition, I think Oliver and Larson (Forest Stand Dynamics) came close with their definition of "True Old-growth".  As I recall, it considered the import of disturbance, as it would be the stand that evolved from the first cohort responding to a major disturbance.  Unsaid, implied, at least in my read, is that the second generation has had enough time to permit Charlie's "processes" to initiate/take place.
Re: FW: Definition_Old Growth   William Morse
  Aug 30, 2007 14:32 PDT 

Hello Group,

Here in NY, the State Environmental Quality Review Act (SEQRA) defines
mature forests as groups of trees 100 years and older, but no
definition of "old growth" is provided. I've never heard the FWS say
'boo' about protecting one tree. However, the state does consider
trees older than 100 yrs old a "significant resource".

Travis Morse
RE: Definition Old Growth   Edward Frank
  Aug 30, 2007 14:39 PDT 


I want both. While a young autopoietic has value, say one that has
recently been restarted in the cycle by a natural event, there is value
in old trees as well, even of they are individuals.

To further elaborate, An Autopoietic forest without old trees is like a
cup of hot chocolate without the chocolate, it is hot, but it is still
just a cup of water.


RE: FW: Definition_Old Growth   Edward Frank
  Aug 30, 2007 14:47 PDT 


No Zac, don't shut up. I want to hear your opinions even if I do
disagree with them. People who are not experts bring valuable
observations to the table that are not taken itno account by the
experts. If I did not want to hear your opinions I would simply ignore
them not argue with them. Post every idea you have even if it is
totally strange and off the wall. That is what this forum is for.
Please continue to post. If all I wanted to hear were expert opinions I
would just look things up in books. I argue with Lee and others all the
time, in such cases they are the experts and I am the novice butting
heads. I am a geologist, not even a forester, but I have learned on
this forum by posting and arguing and reading and going out in the
field. Just because an expert says something doesn't make it right -
there is a good chance it is, but then again you never know... So keep
posting - I want to hear what you have to say. The same goes for all
the others who have recently joined ENTS or who are lurking in the
background. Post your observations, opinions and questions, that is why
we have this forum..

Ed Frank
Re: Definition_Old Growth   Gary A. Beluzo
  Aug 30, 2007 16:59 PDT 

I'll need to take Oliver and Larson's book out and read the section =20
of OG again...but basically most of us on the list I think agree that =20=

it is a PROCESS rather than a PRODUCT.   I personally don't think =20
that ages should be involved as long as the site is autopoietic. =20
But, as Lee Frelich says, Old Growth is whatever the locals want to =20
call it, it is a political device.

Re: Definition_Old Growth   Ron Gonzalez
  Aug 31, 2007 06:57 PDT 

Hi Ents,

I'm no expert -- !! But I have really learned a lot from lurking in this
forum. I just love the forests, and you've helped me deepen my
appreciation for them. Thank you all.

I was on a group backpack a couple of weekends ago, through the Pigeon
Lake Wilderness in the west-central Adirondacks, just east of Big Moose
Lake, west of Raquette Lake. We were walking along, and I (as usual) had
my head up in the air, checking out the crowns of what seemed like mile
after mile of mature red spruce, with large white pine around the several
lakes we passed. I was oohing and aahing a lot, as red spruce is a special
favorite of mine, and I've never seen so many mature spruces along a
trail. The moss covering the ground was several inches thick everywhere,
with mats of creeping snowberry in profusion. I started yammering on about
how beautiful all this old growth was...

Then someone asked me, 'what is old growth?' -- and I really couldn't
answer! I thought about it a few minutes, and blurted out something like,
'there's a lot of controversy about its definition, but I think the term
is used to describe a forest and its ecosystem that are still very close
to what it would have been before the Europeans came.' Was I totally wrong
-- or somewhat close to tight? Or just 'politically correct'?

I should have clarified that the term I really meant to use was 'primary
growth' or 'first-growth' -- i.e. never logged or intentionally cleared by
people. I suppose I use the term 'old growth' to include forest that was
selectively logged so lightly that it's been able to recover to a
condition where it would take an expert to tell that that logging ever
happened (McMartin writes about this being the case in areas of the
southern Adirondacks).

So let me put it this way: You're walking along through forest you suspect
may have never been logged, but you don't know for sure, and someone asks
you "This is so beautiful -- Is this 'old growth'?" What do you tell them?

- Ron Gonzalez
Re: Definition_Old Growth   Gary A. Beluzo
  Aug 31, 2007 07:41 PDT 


On occasion I have said "Autopoietic (Primary) Forest is what the
area IS and Old Growth Forest is what the public SEES."

Re: Definition_Old Growth   DON BERTOLETTE
  Aug 31, 2007 08:51 PDT 

When I used the phrase "time dimension", I was referring to that period of time the "processes" take to go through a cohort generation responding to the disturbance, and into the cohort that follows it.
I wholeheartedly agree with you that the simplistic formula of 0.5 times Maximum attainable age is a rule of thumb and who knows where the thumb has been.
As to 'old-growth' being a political phrase, I'm afraid that has evolved as you say, but darn it, it's time we took it back!
RE: Definition Old Growth   DON BERTOLETTE
  Aug 31, 2007 10:00 PDT 


Of course I'm thinking of western trees here, but when I went out from Kentucky on an Old-growth Forest Inventory detail (with USFS then) to N. California, we visited a stand of Shasta Redfir that were uniformly over 40 inches dbh and across a broad landscape. They weren't an old-growth ecosystem. For several reasons.  They were the cohort that responded to a volcanic event occurring just over 300 years ago.  So they didn't meet the O & L definition.  There was very little diversity (actually depauparate, and more to my point, lacking horizontal heterogeneity). There was very little diversity structurally (lacking vertical heterogeneity).  All items I feel need to be considered in O-G definition.

Re: RE: FW: Definition_Old Growth   Thomas Diggins
  Aug 31, 2007 11:35 PDT 

I definitely agree that "old growth" is a process-based state of
ecological development and function (a 2003 Frelich and Reich paper
[Environmental Reviews, 11: S9 - S22] gives a nice discussion of this
point). However, readers should also check out my Zoar Valley paper in
the latest ENTS Bulletin to see some data on tree ages in a very
minimally disturbed northeastern old-growth forest. It is, of course,
not an exhaustive age study, but we generated core-based age estimates
for a lot of trees representing quite a few important canopy species.
Coring old broadleaf trees is pretty frustrating though; you get a a
lot of hollow centers.

Back to Don and Gary and Question for Lee
  Sep 01, 2007 13:07 PDT 
Don, Gary, etc.

   The problem I see with the second generation definition of Oliver and Larson is that it always assumes recalibration from a stand leveling disturbance, or old field clearing, etc. In areas of the mixed and central mesophytic forests, that time can, at least historically, could be a millennia of longer. In the interim, short and even long term processes proceed through many cycles. The result gave rise to the now disavowed climax forest, but there was some justification for the notion, at least in the mixed and central mesopytic forest regions. It is unclear to me if the results can be considered identical. I doubt that they are. I wonder what Lee Frelich has to say.

    This is where input from Bill Martin would be valuable. He's an expert on the mixed mesophytic.

Re: Back to Don and Gary and Question for Lee   Lee Frelich
  Sep 04, 2007 17:20 PDT 

The climax is a legitimate concept that I used in my book Forest dynamics
and disturbance regimes. When defined as Clements did in his paper in the
late 1930s, that the species can replace themselves in the absence of stand
leveling disturbance (without all the extras that others added later to
discredit Clements), it works just fine. Maple and hemlock forests have
commonly been stable for 2000-3000 years by this definition.

Re: Back to Lee again   Lee Frelich
  Sep 05, 2007 19:35 PDT 

Constant biomass and density of trees, constancy in shape of diameter


At 06:26 AM 9/5/2007, you wrote:

     Good points. For the benefit of others on the lsit, could you mention
the missing elements that caused ecologists to reject the idea oa climax
forest? Thanks.
Re: Back to Lee again
  Sep 06, 2007 03:54 PDT 

     From your answer, I presume that the concept of a climax forest was perverted to mean that the forest was thought to retain the same biomass and density of trees and shape of the distribution of tree diameters for century after century as well as retaining the same species. A question that comes to mind, perhaps requiring conjecture on your part, which you my not wish to do, who wanted to discredit Clements and for what reasons?