Climax Forest

Climax Forest / Sub-Climax

== 2 of 2 ==
Date: Fri, Feb 8 2008 11:15 pm
From: "Edward Frank"

Gary,

That is a god question that I am sure someone here can answer. I have been reading definitions of climax forest and related terms. I have appended them below. In general I would say that most swamps are ephemeral in nature. they may be long lasting in terms of human life span, but on an ecosystem scale they are not permanent. Isolated swamps tend to slowly fill in with debris, soil, organic matter,and eventually turn to peat bogs, then to dry land. River based swamps often dry as the river changes their channel, and they slowly fill in. River Channel -> Oxbow Lakes -> Swamps -> dry land. Others in some coastal settings are maintained by tidal processes, but these also fill in as the sediment are moved around.. I am not sure that what you were told is totally true. Theoretically the swamp would eventually fill in, so by definition the cypress swamps would be sub-climax. Some of the swamps beside a major river system like the Mississippi River are stable over long periods of time. The question is how long does the environment need to be stable for it to be considered a stable system and thus a climax forest? That is one of the problems with the climax forest concept, as the environmental conditions change, the vegetation changes as well, and there is not necessarily one path of succession that the vegetation may take. Still a long term stable cypress swamp could be considered a climax system.

Ed Frank

--------------------------------------------------------

Climax Forest: Definition: A plant community dominated by trees representing the culminating stage of natural succession for that specific locality and environment. A climax community is a relatively stable and undisturbed plant community that has evolved through stages and adapted to its environment. A climax species is a plant species that will remain essentially unchanged in terms of species composition for as long as the site remains undisturbed

Climax vegetation is the vegetation which establishes itself on a given site for given climatic conditions in the absence of anthropic action after a long time (it is the asymptotic or quasi-equilibrium state of the local ecosystem). Tropical evergreen forest is an example of climax vegetation, as are temperate forests, tundras, savannahs, grassland etc. These major vegetation types are broadly governed by the latitude of the region in which they occur. Within these regions variants exist, dependent upon altitude, geographical location and environment, local prevailing micro-climate and soil or rock type. Thus, in temperate regions, beech forests tend to populate chalky soils and oak forests tend to prefer clays and mountain, heath, cliff, estuarine or shore-line areas will have their own variations. An ecosystem which has reached its climax is more resilient to perturbations (climatic or anthropic) than an artificial plantation.

Climax community: also described as a climatic climax community, is an ecological term for a biological community of plants and animals which, through the process of ecological succession - the development of vegetation in an area over time - has reached a steady state. This equilibrium occurs because the climax community is composed of species best adapted to average conditions in that area. The term is sometimes also applied in soil development.

Problem with Climax Concept: Ultimately, even if succession tends towards a steady state, the time required to achieve this state is unrealistically long; in most cases, external disturbances and environmental change occur so frequently that the realization of a climax community is unlikely, and therefore it has come to be regarded as a less useful concept. Long-term vegetation dynamics are now more often characterized as resulting from the action of stochastic factors. (A stochastic process is one whose behavior is non-deterministic in that a state does not fully determine its next state)

The climax community continues to propagate itself and tends to remain relatively unchanged overtime. Disruptive events like fires, hurricanes, blights, or human influence may temporarily cause new and different communities to form (ie. fields, pine forests, swamps), but over time these eventually succeed back to the climax community.

Bog succession

Another example of plant succession occurs as shallow ponds gradually fill in with soil washed in from the surrounding terrain and organic matter produced by underwater plants.

As we walk from the edge of a poorly-drained, boggy pond back into the forest, we pass through a series of zones that recreate in space the plant succession that has been occurring in time.

a.. From the swamp loosestrife and other plants at the waters edge past
b.. sphagnum moss and pitcher plants, then
c.. blueberries and poison sumac, followed by
d.. black spruce and American larch and, finally,
e.. swamp maples and white pines

one passes concentric zones, each representing a later stage of plant succession as the soil has become firmer and dryer and the shade denser.

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

== 2 of 7 ==
Date: Sat, Feb 9 2008 6:05 am
From: dbhguru@comcast.net

Ed, Gary,

I would especially like to hear Neil Pederson's views of the climax-subclimax nature of bald cypress swamps, and naturally, those of Lee, the two Dons, Gary Beluzo, etc. We shouldn't forget Tom Diggins and absolutely not BVP.
Sometimes I think we forget about a process that takes place in research, i.e. that of creating artificial definitions, first for convenience, but then becoming stuck with them as a whole new generation spends its time trying to prove or disprove what was just a convenient starting point in sudying a complex process in nature. If the natural processes that lead to the establishment of bald cypress swamps are sufficiently repetitive as to keep ample cypress in the southern swamp ecosystem, why would we regard the bald cypress stage as subclimax and the stage (to change also) that follows as climax. Maybe we're too hung up on seral stages. If the operative part is stability in the absence of disturbance, but disturbances always happen, sometimes sooner and sometimes later, why create a definitional requirement that excludes what clearly will happen.
I guess that frequency of disturbance and length of time in a stage would naturally drive our terminology bias toward whichever stage lasts longest as the climax phase. But the term climax seems to generate more confusion than clarity. I realize that many ecologists dropped it from their scientific vocabulary, post E. Lucy Braun, but it has a life of its own like the term old growth.
I hope others will weigh in and share their current thoughts about the validity of the climax concept. Should it only apply when one stage lasts appreciably longer than others? How many cycles of different length can we impose on a landscape seen at different spatial and temporal scales until simple concepts like the canonical definition of climax become too simplistic and ultimately misleading?

Bob

== 3 of 7 ==
Date: Sat, Feb 9 2008 6:42 am
From: "Joseph Zorzin"

Bob, the concept of climax forest is useful only in the sense that it gives us a sense of the where "forest succession" will lead without those inevitable disturbances. Sometimes those disturbances might not occur for a long time, so knowing that the stand will reach a relative "stasis" is useful.

Understanding the stages of forest succession including the climax is critical in good forest management- a forester must understand these concepts in order to predict how the forest will respond after a "treatment". In fact, without understanding these concepts, a forester won't even know what sort of treatment should be carried out.

Joe

== 4 of 7 ==
Date: Sat, Feb 9 2008 7:14 am
From: dbhguru@comcast.net

Joe,

Yes, I do understand the human time scale implications of the climax concept and what that portends for human generated changes. It is a very interesting subject short or long term.

Bob

== 5 of 7 ==
Date: Sat, Feb 9 2008 7:34 am
From: "Joseph Zorzin"

It was of course Henry David Thoreau who first described forest succession.

== 6 of 7 ==
Date: Sat, Feb 9 2008 8:08 am
From: doncbragg@netscape.net

ENTS & Gary--

Without getting into the Clementsian versus Gleasonian versus other thoughts on the structuring, patterning, and dynamics of vegetation, I'm not sure how much I'd read into the notion that baldcypress is sub-climax.? In part, this depends on context--baldcypress habitat generally comes in several different forms.? It can be found along the wetter channels of small streams or in small pockets of low ground in a larger bottomland system.? These sites tend to be too wet for most other species to do well, and so scattered baldcypress will appear and reach the canopy.? However, if the stream channel shifts, or the pond silts in, or the wet spot is too small to permit the relatively shade-intolerant cypress to replace itself given the types of canopy gaps that can form, baldcypress will disappear from that location in a generation.? In this context, it is early successional.? In a larger habitat (e.g., a gradually filling oxbow lake), it may be the only species that can persist on the site for perhaps thousands of years.? Eventually, though, as the land builds and the wetness recedes, more shade-tolerant hardwoods will invade the site, and as the old giant cypress fade away, they are not replaced.? Think of the site we visited at Sky Lake--underneath the old giants, there was hardly a cypress sapling to be found.? Plenty of water tupelo, though, which were able to survive the shade.

The x-factor in this story is, of course, disturbance (natural or human).? These degrading cypress stands can be perturbed and, under the right circumstances, permit the cypress to replace themselves.? The extreme age that cypress can live to, coupled with its ability to withstand certain?key disturbance events like wind or flooding,?will in many cases allow it to remain (even though in reduced numbers) in many areas until the site is adequately opened for cypress regeneration.? Short of a fundamental change to the disturbance regime (e.g., the shifting of a river completely out of a bottomland, the ending of large-scale hurricanes along the coastlines), it is hard to image some areas not being "true" climax sites (whatever that means).

Part of the problem with concepts like climax or sub-climax is that they assume an equilibrium environment, which we now recognize is rare, even on the scale of a few hundred or few thousand years.? Very long-lived trees have the ability to transcend things like shifts in climate, maturation of soils, changes in hydrology, alterations to disturbance regimes, etc.

Anyhow, to make a long story short, under certain types of definitions, I think it is possible to view baldcypress stands as subclimax (or climax, or early successional), but without context and definitions of the terms (what is a "perpetual subclimax"?), this description is not particularly useful.

Don

~~~~~~~~~~~~~~~~~~~~~~~~~~~
Don C. Bragg, Ph.D.
Research Forester
USDA Forest Service
Southern Research Station
DonCBragg@netscape.net
~~~~~~~~~~~~~~~~~~~~~~~~~~~

== 7 of 7 ==
Date: Sat, Feb 9 2008 2:38 pm
From: Lee Frelich

Bob:

The official definition of climax is that the species composition remains
stable for more than one tree generation (i.e. the species replace
themselves) in the absence of exogenous disturbance (in other words in the
absence of disturbance other than tree deaths due to old age). This comes
directly from Clements' paper about 1936 and is still a valid concept that
I used in my book.

There is really no time scale or spatial scale attached, nor does the
concept exclude mid-tolerant and intolerant species of trees. Balsam fir is
very shade tolerant but lives about 40 years and replaces itself until
budworm or a fire removes it. This fir forest shows that short-lived
species can form climaxes. In old-growth northern hardwoods and hemlock,
regeneration of mid-tolerant species such as yellow birch, green ash, black
ash, basswood and red oak occurs within treefall gaps resulting from death
of very large old trees (and forming very big gaps), thus the forest can
regenerate in the same composition over time and qualify as a climax.

Intolerant paper birch can form a climax on rocky bluffs where reproduction
of the same species can take place over time.

As for the successional status of species--we haven't come up with an
intelligent way to classify that yet. Its a constant headache. Maybe I will
think about it and write a paper about it some time if I can solve the
problem. Most tree species can be early, mid or late successional under
different circumstances. There is probably a set of ecological rules that
explains successional status, but no one has discovered it yet.

Lee

==============================================================================
TOPIC: Old growth baldcypress....perpetual sub-climax?
http://groups.google.com/group/entstrees/browse_thread/thread/2a748ef124c7c963?hl=en
==============================================================================

== 1 of 2 ==
Date: Sun, Feb 10 2008 10:47 am
From: neil

Bob,

My Dynamics of Ecosystems just spent almost a month reading a few
somewhat classic papers on "what is an ecosystem?", "what is
succession?", "what is climax?" and related topics. We ran the gamut
over the course of the 20th century over a few subjects, including how
the idea of an ecosystem changed through time. My background colors my
view: as an undergrad and MS student, I am the product direct
descendants of Howard T. Odum. I have worked with & for folks very much
in the middle of the traditional forest ecology/disturbance ecology
school of Cooper-Heinselman-Lorimer-Abrams-Frelich. Since then I have
branched out, no pun intended, into the world of paleoecology &
climatology and think about things at different time and spatial scales.
Have you read Sprugel's "Disturbance, Equilibrium, and Environmental
Variability: What is `Natural' Vegetation in a Changing Environment?"
paper? It blew my mind about a decade ago. I'm still trying to put it
back together.

I recall older papers deriving different seral stages, types of
subclimax, etc. Longleaf pine was seen as a fire-subclimax, which, in
its day, fit in very well with the whole notion to reduce forest fires.

Right now I'm one who shies away from climax-subclimax terms. I
understand the term climax and the reasons why we use such terms
[including succession and ecosystem]. I've seen so many repeating
patterns that make me go, "oh yeah, in northern New England and New
York, it'll come back to beech-birch-maple" or "yeah, when longleaf pine
ecosystems do not burn, they change to a mixed-hardwood, broadleaf
species-dominated forest." But, when marking timber in northern Vermont
and conducting FIA surveys for the USFS in New England, I've seen so
many exceptions to traditional succession that it challenges what was
learned in school. And, then when one moves to the mixed-mesophytic
forest, well, things do not seem as straight-forward as in other
regions. Lee, which paper of yours talked about different trajectories
following disturbance? That was an important paper to me.

When it comes to ecosystems like baldcypress swamps, I think about
landtype/ecotype influencing forest composition and development. Outside
of areas like this where site conditions constrict species composition,
usage of the term climax is difficult for me. Sprugel's description of
The Big Woods in MN being a drier oak woodland 300+ yrs ago nailed that
for me. Climate can move and pivot an ecosystem on a geologic dime.

It is funny, however, that when I think about ecosystem concepts in
terms of the flow of energy, matter & ecosystem metabolism (ala
Hutchinson, Lindeman [1942] & H.T. Odum) instead of forest composition,
despite what Tansley wrote, Clements terms climax & even 'superogranism'
makes a decent bit of sense to me; the 'organism' 'evolves' to capture &
concentrate as much energy as possible at that time. And yet, I find
myself more of a Gleasonite. I see what he is saying. [BTW, I recently
re-read Lindeman's classic 1942 paper "THE TROPHIC-DYNAMIC ASPECT OF
ECOLOGY" and found Figure 3 in that paper to be wonderfully
forward-thinking regarding ecosystem succession and productivity through
time. I wish he had the data some of our scientists have now].

So, sorry, more muddy waters from me [you should see my student's faces
sometimes!]. Despite what I think, I use many of these terms (though not
climax) because it helps communicate with others and helps us determine
where anthropogenic disturbance has moved an ecosystem so far beyond a
historical threshold that we may want to 'restore' the ecosystem
[restore, another loaded term]. I think about the term old-growth in a
very similar way. What I try to do with my research is describe a
particular ecosystem, what past events & conditions may have lead it to
its present state and what factors might influence its future with the
few methods and tools I use while avoiding some terms - it is what it is
based on the data.

In class I come back to this parable when talking about ecosystems
saying we can only understand so much and must interact with others so
that we can better understand ecosystems:
http://www.wordinfo.info/words/index/info/view_unit/1/?letter=B&spage=3

neil

== 2 of 2 ==
Date: Sun, Feb 10 2008 11:32 am
From: "Joseph Zorzin"

----- Original Message -----
From: "neil" <mockernut@gmail.com>

(snipped)

> Right now I'm one who shies away from climax-subclimax terms. I
> understand the term climax and the reasons why we use such terms
> [including succession and ecosystem]. I've seen so many repeating
> patterns that make me go, "oh yeah, in northern New England and New
> York, it'll come back to beech-birch-maple" or "yeah, when longleaf pine
> ecosystems do not burn, they change to a mixed-hardwood, broadleaf
> species-dominated forest." But, when marking timber in northern Vermont
> and conducting FIA surveys for the USFS in New England, I've seen so
> many exceptions to traditional succession that it challenges what was
> learned in school.

(snipped)

Every forest is different- but, the basic rules seem to hold- though we
don't always find what we'd expect - often because past land use and abuse
often results in certain species not being available (close by) to fill
their respective succession roles. We can generally expect shade tolerant
species to succeed less shade tolerant species. It seldom if ever happens
the other way around.

In New England, the landscape is so complex- with some of the most complex
geology and soils on this planet, with slopes facing every direction and
infinitely variable drainage conditions- with so many species present- it's
amazing that most of the time, I've found- it's fairly easy to see what
happened and to predict what will happen if no forestry activity will occur
or if an array of forestry practices occur.

Joe

Home