Sedona Canyon, Arizona

Is This Old-Growth?   Don Bertolette
  Sep 19, 2004  

Attaching an image from my most recent outing...perhaps it will serve as a point from which to launch a discussion on just what constitutes old-growth, and what makes a bush a bush (not intended to launch a political  discussion!) and a tree a tree.  The foreground is a manzanita (Arctostaphylos spp), the background the redrocks of Sedona, and predictably enough, me on middle ground. I am comfortable suggesting that this manzanita is pre-Euroamerican settlement in origin.

I suggest that there is an analogy of this manzanita (and an oak of similar stature and "soil" bank) to the more famous Bristlecones of the White Mountains of Eastern Central California (attaining 3-4,000 years). Surely they're old-growth? In my view, they belong to their own category, an old-growth tree/forest that have attained their status from the "economy" of their growth habit...they have adapted to conditions that are extraordinary in their extremes - cold, minimal soil nutrients, incredible levels of ultra-violet rays (10-14,000 feet, precious little atmosphere filtering out the sun's rays), heat.

This probably opens up the bush/tree question, as there are those who propose that the common creosote bush is among the oldest continuous lifeforms (posited to create concentric "rings" as they allelopathically force their growth outwards).

Back to manzanita, I have not yet seen one with a singular bole high enough to have a dbh, but numerous examples yield trunk diameters of a foot or more. This specimen here is growing in precious little soil and able to survive on very little moisture. Taken during the second week in September, the temps were in the low 80's. Not unusual for the area to rise into the 90's, occasionally in the 100's.

-Don Bertolette,  Sun, 19 Sep 2004

RE: Is This Old-Growth?   Robert Leverett
  Sep 21, 2004 07:39 PDT 


   Your make very important points. As I know you would agree, the definitions we adopt for OG usually incorporate science, politics, economics, and aesthetics. While our intent may be to restrict the criteria to science, I think the exigencies of the situation usually dictate otherwise. I'm struck by the practicality of Lee Frelich's definition that for him old growth is whatever the resident authority says it is. Lee then works within the context of that definition to explore the natural processes that shape the forest environment - toward a rapidly or slowly evolving system.

   Perhaps you should become the resident authority under the auspices of WNTS. WNTS could become a repository for ideas, models, and debate. One can hardly not be struck by the difference between environments that cycle forests every 100 to 200 years as in flood plains to rock and ice environemnts that can allow gnarled bristlecone pines to linger on for 5,000 years. Allowing for a 150 year cycle on a flood plain, one cycle of the bristle cones equals 33 cycles of the flood plain environment. Of course each environment has many cycles that play out beyond the obvious seasonal ones, but sometimes it helps to consider how old growth environments differ from one another as well as consider the points of similarity.   


RE: WNTS: Are These OG Forest   Edward Frank
  Sep 21, 2004 10:17 PDT 


Don presents a simple question about whether these manzanita are trees and whether or not they constitute and old-growth forest. Behind this simple question lies a variety of hidden questions:

1) Are these short manzanita considered to be a tree? The hidden question is whether or not height is a dominant factor in determining whether something is a tree or not. I don’t know. Is there some structural or physiological difference between a tree and other types of vascular plants? Does something become tree solely based upon height? I know there are species of oak that are maybe a meter in height, are these trees or not? Other members of the oak family reach large size, so does it make sense that some are trees and others are not? Does it really make any difference?

The Oklahoma Biological Survey defines the terms as follows: “There are approximately 2,400 plant species in Oklahoma (Taylor and Taylor 1994) and about 330 are trees, shrubs, or woody vines. For the purpose of this document, a woody plant is defined as a plant that retains some living woody material at or above ground level through the non-growing season (several species of small cacti fit this definition, but are not recognized trees or shrubs). Categorizing a woody plant as "tree", "shrub", or "vine" is often difficult and can appear arbitrary. Distinguishing between a tree and a shrub can be particularly difficult. That is why it is not unusual to see descriptions such as "small tree or large shrub." In this treatment we have adopted the following definitions: a tree is a woody plant that is at least 10 cm (4 in ) in diameter at 1.4 m (4.5 ft) above ground level; a shrub is less than 10 cm in diameter at 1.4 m above the ground and usually has multiple stems or is clonal; a woody vine does not stand upright without support but climbs on other vegetation or sprawls on the ground.” So as far as the OBS is concerned the main difference between trees and shrubs are their height. For the purposes of the WNTS and ENTS I would lump both trees and shrubs together as a single category as the separation between the two groups is arbtrary. Therefore this manzanita (Arctostaphylos spp) is a “tree.”

2) Does this population of trees, including both manzanita and (oaks?) Constitute a forest? Don says, “In my view, they belong to their own category, an old-growth tree/forest that have attained their status from the "economy" of their growth habit...they have adapted to conditions that are extroardinary in their extremes...” I have been looking at definition for various forest types.

Bob Leverett (Feb 10) wrote, “.. you raise some interesting points. The most intriguing to me concerns how we actually define forests/forest types especially today when so much human-created disturbance has taken place that impacts what we can do. How might we define a floodplain forest of say the Connecticut River at the latitude of Hatfield, Massachusetts, given the massive ecological changes that have taken place from the surrounding farms over many years? ...The answer to the question of what we include in a definition probably depends on one's profession. If so, what might be the differences in the requirements of a definition as seen from the perspectives of the forester, forest ecologist, plant ecologist, wildlife biologist, and conservation biologist? Who would emphasize what as hard and fast requirements of a definition. Like everyone else on the list, I've read plenty of definitions of forest types/associations that are oriented to species composition. Some hint at structural features, but usually only in a very general way.”

Lee Frelich (Feb 10) wrote; “Minnesota Department of Natural Resources recently switched to natural community-based definition for forest and other vegetation. They used ordinations including trees, shrubs and understory plants to separate communities within each region of the state. The ordinations were based on thousands of plots where all trees and plants were identified by Natural Heritage Ecologists. Those plots that fell together in clusters in multi-dimensional ordination space defined a natural community, and the characteristics of those plots were used in the descriptions that have now been published (but its not on the web yet).”

So clearly we can define this plant community as a distinct entity. Is it a forest? It seems to me what we define as a forest or not a forest depends on the density of trees in an area. In the eastern US trees often grow like weeds. The density of trees in an eastern forests is high. This is partially related to the age and species present, but if talking about mature forests a major factor is the availability of water. In drier climates there are savannah forests with more widely spaced trees intermingled with grasses. A good example of this type of forest is the cross-timbers area of Texas, Oklahoma, Kansas, and Arkansas. You can see examples of this type of growth on the University of Arkansas cross-timbers website:

It seems reasonable to say that what is a forest and what is not depends on the environmental conditions. There is a spectrum between dense tree population in wet areas, to more open savannah forests. Therefore under the extreme conditions found in the arid areas of the southwest and western United States, a sparsely populated community of woody plants should be considered a “forest.”

There is little debate about whether these representative trees are old or not. Their “forest” for the most part is relatively undisturbed by human activities- they haven’t been timbered or cultivated. So these forests should meet even the most strict definitions of an “old growth forest” if you accept the first two propositions that these are trees and constitute a forest.  An important side issue is how do you measure these trees, since many of them do not reach breast height? At what point should their circumference be measured? As for height, I would think the “pole method” would be most appropriate.

Ed Frank
RE: Ancient Forests of the Northeast    Edward Frank
   Sep 26, 2004 18:25 PDT 


Your comment about differences of opinion over what to include as old growth is interesting as it comes in a time when I am again struggling on how to deal with the concept of old growth as I work on a website. You seemed to like Lee's pragmatic definition "For Lee's purposes, it is whatever the group he is working with says it is."

That works fine if you are dealing with people with a vested interest in one definition or another. For people like myself who are exploring the concept of old growth forest it is pretty useless. Some definition or boundary is needed in order to compare what we see to the definition. A classification system allows you to make comparisons. It allows you to disagree with the boundaries. It allows you to form alternative classifications.

I have read that the Inuit people have about a zillion different names for snow. I believe that by giving these variations of snow different names and different definitions, it allows them to think about the idea of snow in an entirely different level than those of us who simply call all of the white stuff snow.

I guess after having read a large amount of material on the subject a workable definition for me and from my perspective is still unformulated. I would tend to a relatively broad definition - I am an inclusionist by nature. I feel that too restrictive of a definition limits your conceptualization of issues and processes. By having a limited definition, perhaps you think you are making a stricter definition and weeding out the gray areas, but what you really are doing is leaving out transitional phases which may be your key to understanding. I have a broad definition of what are karst areas and processes as well, so a broad inclusive definition of old growth fits in well.

Ed Frank

Robert Leverett wrote:

       Bruce and I differed on what to include as old growth. I applied a
more conservative criteria than did Bruce. He prevailed, though, and
probably for the right reasons, given the readership at which we were
aiming. All in all, the partnership was a solid one. We worked well
together and it is appropriate that Bruce's name is listed first. He did
a heck of a job.

RE: Ancient Forests of the Northeast/Old Growth    Edward Frank
   Sep 26, 2004 18:37 PDT 

Bob and other ENTS,

This is my introduction on Old Growth from the ENTS website. Some of you
may have seen it, but it seemed to fit with the last post.

The Minnesota Department of Natural Resources  defines old growth as follows: "Old-growth forests are natural forests that have developed over a long period of time, generally at least 120 years (DNR definition and consistent with definitions for the eastern United States), without experiencing severe, stand-replacing disturbance--a fire, windstorm, or logging. Old-growth forests may be dominated by species such as sugar maple, white spruce, or white cedar that are capable of reproducing under a shaded canopy. These old-growth forests can persist indefinitely.  Old-growth forest may also be dominated by species such as red pine, white pine, or red oak that do not reproduce as well under shade and that require disturbance to open the canopy. These old-growth forests will eventually be replaced by the more shade tolerant tree species in the absence of disturbance."  

The attempt to define old growth is a mire of different viewpoints, perspectives, motivations, terminology. At this time I don't think a simple all-encompassing definition exists as the characteristics of an old growth forest varies from locality to locality and from forest type to forest type. Maurice Schwartz found ninety-eight separate definitions of old growth with an internet search. The above definition has problems itself. Some forest types are dominated by trees with a lifespan of less than 120 years. These forests otherwise may have all of the characteristics of old growth but are excluded by the time criteria stated above. The definition is also ambiguous with respect to how much disturbance is severe disturbance. Regulators want a strict definition that can be applied without compromise, dynamicists want a definition based upon processes that are taking place in the evolution of the forest, environmentalists want a more encompassing definition to include areas peripheral to the oldest forest which are essential to maintaining ecosystem integrity, lumbering interests want a limited definition that says that very little forest is old growth because of potential public opposition to timbering old growth forest.


Re: Ancient Forests of the Northeast   Don Bertolette
  Sep 26, 2004 19:21 PDT 
An often quoted "Forestry is not Rocket Science, it's much more complex than that", comes to mind.  When Bob first started, it seemed possible to come up with a definition for the piece of New England he was looking at. As his horizons expanded, the complexity of defining "old-growth" expanded "LOGarithmically"!

Even regional definitions become complex (geographic boundaries, ecosystem boundaries, or?).  I'm not sure I'm correctly citing (jump in here, Lee) the paper that is coming to mind (a terrible thing to waste!), but the role of disturbance timing and disturbance severity threshold are critical to "old-growth succesional pathways".


Frelich, L.E. & P.B. Reich. 1995b.   Neighborhood effects, disturbance, and succession in forests of the western Great Lakes Region. Ecoscience 2:148-158.

for additional thoughts on what needs to be considered in "defining old-growth".  A rather comprehensive treatment can also be found at


H. Gyde Lund

Forest Information Services


I think you might have been looking for convergence, but it has not yet been known to happen...;>}


RE: Ancient Forests of the Northeast
  Sep 27, 2004 07:10 PDT 


This appears to be the PA Bureau of Forestry's stance on the question...


RE: Ancient Forests of the Northeast   Edward Frank
  Sep 27, 2004 11:50 PDT 


Thanks for the link. One passage in particular stands out in the description.

"Finally, it is also important to include representatives of different ecosystems in old growth, not only the typical hemlock-white pine or hemlock-beech associations of the well-known Cook Forest and Heart's Content. It is for those reasons that places are included in this tour such as Bear Meadows (a large ancient bog) and Cranberry Swamp, giving visitors a broader vision of the varied components of the entire macro-system. While it is true sometimes that "we can't see the forest for the trees," it is just as true that we should not confuse the forest with the trees. In other words, while we speak of old-growth forests in terms of the major tree species found there, old-growth is really a term describing entire ecosystems. The other plants and animals who live within the tree-defined
framework are vital to the whole."

Re: Ancient Forests of the Northeast   Don Bertolette
  Sep 27, 2004 18:43 PDT 


I too have found that "old-growth" is a better adjective for forest, forested ecosystem, than it is a direct object...

Re: Ancient Forests of the Northeast   Lee E. Frelich
  Sep 30, 2004 06:14 PDT 

Don, and Ed:

There is not and never will be a biological definition of old growth. Since old growth is a human construct, it is what people say it is, and that varies among political jurisdictions.

However, if you want a simple inclusive definition for outlining forests on the ground for preservation, then use primary forests (forests that have not been logged). There is still some subjectivity here, since in some regions all forests had at least some selective cutting, and you still have to come up with a subjective criterion for amount of human disturbance that disqualifies a stand from the category of primary forest. Also, primary forest includes a stands dominated by young early successional forest, old early successional forest, young late successional forest, and old late successional forest (the latter is what most people are stuck on when they discuss old growth).

See the discussion in chapter 5 of my book and in this paper:

Frelich and Reich, 2003, Perspectives on development of definitions and values related to old-growth forests. Environmental Reviews 11: s9-s22.

I have a pdf of the paper I can send to anyone who is interested.

RE: Old Growth Definitions   Edward Frank
  Oct 01, 2004 19:33 PDT 


I read your paper and it is very well done. I do understand what you are saying in the paper. My quandary is that I would like to have a page or section on the websites dealing with the concept of "Old Growth." This
phrase is always being tossed around by this group or that agency and is in the consciousness of the general public. A person who comes across a patch of old trees while hiking will wonder if it is some of the "Old Growth" he has heard about and what that means. If someone finds our websites through an Internet search of "old growth," will we have an explanation presented there that will be satisfactory to them? Will we have an explanation that is comprehensible to them? Will the explanation presented turn on a light
bulb in there head - and say "aH! Ha! I understand". I have read much of the stuff on the web defining the term. It is indeed a political question, it most assuredly depends on tree types involved, climate, and an entire horde of considerations couching any proposed definition. I want to have definition on a web page that is easily understandable to start with, then go into greater detail of how under various circumstances other factors must also be considered.

I do like your explanation of "Primary Forest" in the paper and that may indeed be the way to go for the website. I will need to think about things for awhile, figure out what good concepts are in each of the various "definitions" and come up with something. I am particularly intrigued by the definition from the PA DNR that talks about old growth as an ecological system that may include bog settings and other non-forest or perhaps I should say non-typical forest settings. I think that the dwarfed trees and other desert plants scattered about arid southwestern terrains should be considered as "old growth system" if not actually a forest.

Anyway thanks for sending the pdf file.

Ed Frank
RE: Old Growth Definitions   Ernie Ostuno
  Oct 01, 2004 20:15 PDT 

I always wondered about forests that were affected by natural disturbance. A case in point: Say there is an area of old growth that is struck by a windstorm and suffers an extensive blowdown. Is the acreage that was affected no longer considered "old growth" even though it is still part of the larger ecosystem that does include some surrounding old growth? Another case: What if the percentage of trees lost was 25,
50 or 75 percent? Is the area that suffered 25 percent loss of trees still considered old growth while the area that lost 75 percent no longer considered old growth?

I don't know if you've seen this before, but it's a dissertation by one of the Marc Abram's grad students at Penn State concerning some recent work on dendroecological studies of forest disturbance histories:


RE: Old Growth Definitions   Lee Frelich
  Oct 02, 2004 16:28 PDT 


The old-growth forest that blows down, whether 25%, 50%, or all of it, is still primary forest and has the potential to recover to a developmental stage with large old trees. Since all forests are created by disturbance, this is part of the natural cycle. The most important function of reserved old-growth forests is to see how they respond to and recover from disturbance.

Regarding what to call partially disturbed forests (and all old-growth stands repeatedly experience partial disturbance and recovery from it), there are a number of terms such as mature-sapling mosaic, young forest with mature remnants, multi-aged pole forests, etc. The threshold for calling a blowdown a stand initiation event is subjective, some people say 75% and others 90% blow down.

These disturbance dynamics are why I think we should be talking about primary forest rather than old growth (which is just one stage of a cycle), although old growth is so well established in peoples minds that we have to continue to deal with it.


RE: Old Growth Definitions   Gary A. Beluzo
  Oct 03, 2004 06:37 PDT 


Clearly stated. I agree wholeheartedly with the language, the challenge is to refocus the debate over natural forests to "primary" rather than "old growth", which is simply a snapshot in the life of the primary (and autopoietic) forest. The danger in continuing to focus on "old growth forests" is that as these forests undergo natural disturbance policymakers could legally (and quite logically) take them out of protection. I am still very interested in coming up with a scale of "naturalness" to apply to forests so that in New England and elsewhere folks can catalog forest lands that have had some degree of anthropogenic disturbance on a continuum.

How do we refocus the policymakers?

RE: Old Growth Definitions   Edward Frank
  Oct 03, 2004 23:16 PDT 

Lee, Gary, Ernie, Bob, and other ENTS,

The concept of primary forest is a fine concept and should be used for regulatory purposes. What I see as a challenge is how to apply the concept in a manner that it appeals to the general public? People are impressed by individual or groups of BIG trees or an individual or grove of OLD trees. I do not think they are for the most part impressed or even more than peripherally cognizant of the dynamic processes of forest renewal. Intellectually I can appreciate these processes, but I do not get the same emotional charge for young primary forest as I do for big trees or old trees. Can the average person even tell the difference between a forest that is a primary forest being regrown after a blowdown from one that is being regrown from a clearcut? Sure many of you can, if you study forests or are particularly familiar with the characteristics of forest processes, the differences are apparent, but members of that group are in the minority. The majority of the public, even those who are outdoors people, hikers, hunters, etc., are oblivious to the differences. Even within ENTS, most of the posts focus on the few big trees in a stand and little on the forest structure as a whole. Big trees or old trees are where most of the interests lie. If the general public does not appreciate the concept of a "young" primary forest regrowing after a blowdown or fire event, can it be expected that the regulatory or administrative facets of government will give them much heed?

I was up to Kinzua Bridge State Park, PA today. A year and a couple months ago at the park, a historic railroad bridge 201 feet high, across a stream valley, was blown down by what the weather service determined was a tornado. A large number of trees were flattened along with the bridge.  They lined up like match sticks all pointing the same was along the valley walls. It struck me as I visited the park soon after the storm that visitors were impressed by the destruction of the bridge, but also talked about the way the trees had been downed. A year later there was little talk about the downed trees. Brush had sprouted to cover much of the damage. In a couple years the missing trees will not even be considered.  The point is after a blowdown or fire in a Primary forest of old or big trees, people will be interested in the destruction immediately afterward, and they may bemoan the loss of the old forest, but There will be little if any emotional attachment for the young forest replacing the old one. It may be primary forest, but is there a drive to protect it? Or even give it special management considerations?

Ed Frank
RE: Old Growth Definitions   Lee E. Frelich
  Oct 04, 2004 05:49 PDT 


Most tree populations in the northeastern U.S. that have not been logged go back 3000-5000 years. That usually interests most people, especially when you tell them that the young post-disturbance forest is carrying on a 5000 year heritage.

RE: Old Growth Definitions   John Knuerr
  Oct 04, 2004 05:24 PDT 

J. Baird Callicott, a philosophy professor, wrote an essay entitled "The Land Aesthetic", in which he tries to capture Aldo Leopold's thoughts on how we come to appreciate the landscape.

In brief:

- he begins by pointing out that the Western appreciation of natural beauty does not flow naturally from nature itself; is not directly oriented to nature on nature's own terms; nor is it well informed by the ecological and evolutionary dynamics. it is superficial and narcissistic; in a word, it is trivial.  He describes Leopold's land aesthetic as an appreciation that begins simply with our ability to perceive what is pretty. To develop a land aesthetic requires a willingness to learn things about the land that deepens our knowledge which in turn informs our senses.  

I'm pretty sure that all of us on this list have experienced this process personally.  The challenges you point out are not limited to the issue of forest appreciation. The greater issue is the overall dumbing down that is occurring in our culture and the fact that most people are more and more cut-off from significant experiences of the natural world around them. And, the expectation is that the natural world will give them wow-experiences that they can immediately consume (sound-byte mentality).  So, I'm thinking if we can give them an immersion experience in the forest that includes a cognitive component on forest dynamics, we might have a shot? The language we use doesn't need to be complex. It could be in the form of a story (... imagine your standing in this spot 140 years ago...  what would you see?) that engages them and educates them.

Any thoughts?

RE: Old Growth Definitions   Robert Leverett
  Oct 04, 2004 05:47 PDT 


You've adroitly opened a whole new area of exploration for us on the list that we've heretofore hardly touched upon. I have a deep stack of Wild Earth Journals with musings on the meaning of wilderness, wilderness experience, and a string of hot debates between J. Baird Callicott and Dave Foreman. The two started out amiable enough but grew ever more strident with one another. Both have substantial egos, BTW, but I think that overall Callicott wins in the size of ego department.  He often seems to know better what significant thinkers of the past were thinking than did the thinkers themselves. I guess I better dust off my copies of Wild Earth.

   What we are aiming toward is an exploration of the complex mix of science, ethics, aesthetics, politics, recreation, etc. in attempting to discern the purposes and roles of wilderness and its old growth surrogate. I'm sure my buddy Don Bertolette will have lots to say on the subject. Anyway, thanks, for broaching the topic. A great one.