Defining Forest Types   
  Feb 09, 2004   
This thread started as a post by Joe Zorzin questioning the merits of a floodplain restoration program being implemented in Massachusetts.   Joe Zorzin, Feb 09, 2004 02:33 PST "Bottoms Up."  Later posts diverged into the question of defining forest types.

Defining forest types   Robert Leverett
  Feb 10, 2004 07:41 PST 


   Apart from the political ramifications of the particular government
program being discussed, 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
decades. In restoration, are we attempting to define what is there now
and expand it or appeal to what we think was there in the past? For the
narrow strips that exist between field and river, would we just include
the most prevalent tree species and a shrub or two or would we include a
detailed accounting of the canopy, understory, shrub, and herb layers,
limited though they might be? Would we include the animal species
typically associated with the floodplain for the particular region?
Would we include the main disturbance features of the floodplain and the
terrain characteristics that they produce? Would we describe and define
the forest on both spatial and temporal scales, including the details of
succession? In other words, is the forest not only the species
composition we see from a snapshot perspective, but everything that is
encompassed from a series of snapshots stretching over decades that
capture the dynamics of the floodplain environment - and the
introduction of invasives? The long term snapshot sequence would include
not only the fact of annual flooding, but how that flooding occurs, such
as an occasional large flood.

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. For
example, I would guess that the life of a tip up mound in a flood plain
forest would be considerably shorter than that of a mountain forest.
However, I don't think I've ever heard a discussion of the life of
tip-up mounds as a component of a forest definition. Should it be?

What is being alluded to here is the depth of our understanding we
seek of a forested environment when we categorize, classify, and define.
In terms of animal habitat, we often seek to artificially create
structural features associated with old growth forests within managed
forests. But within a managed forest, these creative endeavors can only
be taken so far. We've obviously settled on tradeoffs.

Let no one downplay the importance of this approach to our
understanding, classifying, and defining. I once heard David Suzuki
interview a government forester in Canada who looked out over a
landscape of nothing but stumps from a vast clearcut and called it a
forest. I was flabbergasted,. It was evident to me that the industrial
forester, in government garb, placed absolutely no importance on all the
forest features mentioned above. He defined a forest solely in terms of
tree species and made no distinction between a planted forest and a
naturally evolved one - at least in terms of the importance of retaining
feaatures of the latter. He had his definitions pretty straight in his

It is apparent that some of us might settle for nature taking its
course in reclaiming farmlands, while others see human intervention as
necessary. How far do we want to take the process of restoration and for
what purposes? How far do we need to go in defining our terms?

Robert T. Leverett
Cofounder, Eastern Native Tree Society
Re: Defining forest types   Lee E. Frelich
  Feb 10, 2004 08:28 PST 


Minnesota Department of Natural Resources recently switched to a 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).

RE: Defining forest types   Gary A. Beluzo
  Feb 10, 2004 08:55 PST 

I think that by constructing a "historical transect" for the site one
could attempt to deduce what forest type would be there now without the
impact of humans. The literature must suggest what should be growing on
a particular site given geography, climate, soils, moisture regimes,
terrain shape index, etc. So, presumably we can determine what should be
there without human influence, of course what is there now may be the
appropriate tree association WITH human influence.

RE: Defining forest types   Robert Leverett
  Feb 10, 2004 09:18 PST 


Will this approach to defining communities in Minnesota drive public
forestry and act as a barrier to habitat destruction? I am still struck
by the road blocks that Lynn Rogers ran into within the forestry world
when he was advocating for the preservation of residual old growth white
pine in Minnesota as important bear habitat. From your past posts, I
understand that public forestry in Minnesota has come a long way. I
suspect that Minnesota is light years ahead of Massachusetts, but still
bureaucracies have a way of proclaiming noble objectives in writing
while falling far short of meeting those objectives in actual practice.
Just wondering.

Re: Defining forest types    greentreedoctor
   Feb 10, 2004 10:18 PST 
...may be the appropriate tree association WITH human influence.

I remember decades ago when a Maine diary farmer (the deer hunter I spoke of earlier) let a back field grow. After years of tall grass, thorns and nettles took over. It could be painful to pass through, but this still was the best access to a favorite brook at the bottom of the hill. Several years later I thought the field would now be grown up and I could attend to my long-neglected aquatic friends-I was mistaken. Though I grew up dodging alders and negotiating tree tops, juvenile broadleaf trees had grown so close together that access was "impossible".   I did try to approach the brook from the highway, but was unable to find the brook. Not that it had dried up in one of our infamous Yankee dry summers, but what the loggers hadn't cut out, the beaver had flooded.   

Knowing the history of such matters, it will likely not be during my lifetime that this brook and field returns to normal. Only in my limited description can my son imagine what this brook was once like. A brook that you could easily step across once yielded brook trout almost a foot long.      The Baldwin, fed by an ever-faithful spring at the bottom of a cow pasture, stayed clear and cold throughout the summer. Large hemlock and spruce made walking easy and allowed easy access to every part of the brook. Each deep embankment held it's own trophy that only the most patient of fisherman could entice. A ridge followed the brook on one side, with a pathway on the crest over 150 years old. Though it had not been maintained in 40 years, it still revealed the original trail. There were no beaver dams on the Baldwin; not as long as anyone can remember. Because there was little standing water, you didn't need to bathe in creosol & tar to keep from being eaten alive by mosquitoes and black flies. Most fishermen ignored this deep forest jewel. Either the fish must be too be small, or the trophies won't bite. For years a handful of us boys spent the summer days catching as many brookies as we wanted. We remembered to gently release our catch and only keep the pan-size. It seemed the supply was unending.   Cane poles, green pickerel line, stick stringers and oversized black hooks; no stocking, fishing licenses or game wardens required.

If I don't sound like a forester it's because I'm not one. But I do know the difference between what we once had and what is now left. Many of northern Maine's brooks can no longer support a cold water fish nursery.   So, until things change up there, I'll stick to Dixieland trout.         

RE: Defining forest types   Lee E. Frelich
  Feb 10, 2004 11:00 PST 


They are actually training the DNR staff foresters to use the new community
classification key. That means they will know what type each forest is, not
that they will attain the same balance of forest types that we might like.

Regarding white pine, it is making somewhat of a comeback at this point in
MN. The DNR has planted many acres, and natural regeneration is being
encouraged. That's good since white pine is one of the species that has
such a wide tolerance for climatic conditions, whether they get warmer or
colder in the future.

Re: Defining forest types   BRUCE ALLEN
  Feb 10, 2004 11:17 PST 


If you are trying to restore a floodplain forest, the definition would include trees, shrubs, vines, herbs, and all the other biotic components of a forest. You start by restoring processes - hydrologic regime, disturbance regime, and the suite of species appropriate to the site. You can't plant all the species, so efforts have focused on the heavy seeded tree species -oaks and hickories, while vines, shrubs, and herbs are largely ignored. I guess you have to subscribe to the "build it and they will come" philosophy.

I would look at the best remaining examples to base definition. I have tended to ignore the animal species, but they playing a controlling role in species composition in many forested ecosystems (deer in Penn., Moose in northern New Hampshire, and hogs in the Congaree).

Re: Defining forest types   The Darbyshires
  Feb 10, 2004 22:54 PST 

A similar approach has been used in the western forests for many years. We
call them "plant associations". I believe this approach is most common in
Washington, Oregon, Idaho, Montana and northern California. In Idaho and
Montana they tend to refer to them as "habitat types". These associations
can be useful for identifying less common and more common associations and
this can be used to help protect the less common associations from human
disturbance. They can also be useful for predicting natural regeneration
success, fire regime/fire return interval, post-harvest levels of snags and
woody debris, the occurrence of frost pockets, etc.

Back in my earlier years in the woods, I worked on one of the crews
collecting plot data on the Mt Hood National Forest that was used for the
development of the true fir plant associations on the Mt. Hood and
Willamette National Forests. We did a very complete inventory of the
vascular plants, snags, and woody debris on the plots and also dug a soil
pit and described the soil texture, rock content, parent material, and color
for each soil horizon.