The pine hardwood forest is the biotic expression of the environment
(climatic, edatopic, physiographic, physiognomic elements) occurring there.
There are elements that both influence the distribution of the pine (eg.
Loblolly pine, and the hickory).

Pines are 'schleromorphic', 'meso-megphanerophytes', and have evergreen
sclerophyllous needles. This feature of pines makes them highly adapted to a
wide range of environments, but not to environments with infrequent stand
initiating events like wildfire and windthrow. A stand of pines therefore,
except in the most xeric sites, is often not a indicator of a climax forest
ecosystem. There are exceptions and these exceptions are common in the west
where Ponderosa pine, white bark pine et cetera occur. The presence of
stands of trees dominated by Ponderosa pine or white pine in the interior
rainforests, may indicate a young seral stage forest, usually a cohort of
trees established by wildfire. White pine seeds are viable after they are
released onto the forest floor for over 100 years, as is ceonothus, a
nitrogen fixing shrub. White pine will germinant where there are no living
white pine after a wildfire or a clearcut is created.

In many forested environments, and thus ecosystems, pine is not regarded as
a climax species, since it is relatively short-lived. Pine also require high
light levels, and in many species have semi-serotinous cones which means
that pines often require a disturbance to regenerate, enough light and heat
must occur at the forest floor to facilitate the release of seed and for
germinants to establish. Thus in white pine for instance the strategy is for
rapid height and radicle growth shortly after germination. A white pine
seedling is remarkably in how much the radicle can extend the first season
of life.

However many hardwood seedlings do not have this strategy, and for instance
some hickories have very high shade tolerances, and do not rely on a
wildfire disturbance to leave a gap in the forest to regenerate.

The issue about complexity is that in a climax forest the abundance and
diversity of species is usually very large in comparison to the young seral
stage associated with a pioneer forest. There is every reason to believe
that there is some 'randomness' in nature, in how some events initiate, but
at the same time, there are many antecedent events and environmental
elements (constants) which have a high probability of occurring at the
microsite where a seedling is established. For instance lightening induced
wildfires are not actually and purely stochastic. There are antecendent
environmental conditions that must take place before a wildfire can occur.
In the Arctic there are no lightening and thunder storms. The troposphere in
the Arctic  is too cold to induce convection type storms with enough energy.
However in the tropics not only are lightening storms frequent, but some
storms reach hurricane intensities. For some physical reasons a hurricane
can only occur when the temperature at the sea surface reaches more than 80
Degrees fahrenheit, which is not possible in the high Arctic.

So the randomness that appears in the environment is perhaps more illusory,
than real. The fact that hurricanes frequently strike Florida (I have seen
the results where entire beaches of been denuded of sand by their forces)
indicates that the temporal scale is frequent enough to allow species which
are not shade tolerant to establish as dominant and leading species in areas
where there is perhaps a low frequency of wildfires. So the presence of
shade intolerant and relatively short lived pine may actually be referred to
as a climax ecosystem where frequent storms blow stands of trees down, and
where there is frequent wildfire. An old-growth pine forest would perhaps be
160-200 years old. The fact that wildfires are frequent enough to allow pine
to dominate is evidence enough that there may be other factors which
influence the distribution and abundance of pine. One of these is the
edaphic quality of the environment. Pines are psammophytes, and prosper well
on sandy soils. However in pre-columbian times the frequency of wildfire,
and storms, would be much less of an impact than the short term frequency of
human induced disturbances such as farming, grazing, and timbering. In the
timbering disturbances where all the trees which are commercial are
clearcut, the frequency is very frequent, the frequency may be only 40
years. Thus there would not be enough time every for more shade tolerant
species to become a dominant in the understory, or upper canopy of a pine
forest.

So the continuum in nature which we could call the pine-hardwood phase
begins it's journey after a stand initiating event like wildfire, and it
progresses toward a closed canopy forest with few species of small flowering
plants associated with the first 5 or so years (this pioneer stage is
relatively rich in some functional groups). In the Ray's patch there is a
meadow which is either anthropogenic, or it is an edaphic, or it is a seral
stage, and it is this patch that confers some important diversity to the
'whole patch' not just the species in the closed canopy stand of pine and
hardwoods.

Along the temporal continuum of pioneer stage to climax stage there is a
middle region which is relatively sparse in species diversity. This stage
occurs during the maturity of the pine from the beginning of the closed
canopy to the onset of the death of individual dominant and sub-dominant
trees. In the density over age relationship most stands are limited by
density, with the smaller intermediates and suppressed trees dying out
first, leaving the co-dominants and dominants to carry the flag.

Eventually the smaller seedlings and saplings begin to release during after
individual tree death of the pines occurs in the mid-seral forest. These
species are the Yews, Hemlocks, and Cedars where conifers are common, and a
range of hardwoods which are tolerant of some shade in the hardwood forests.
As the stand ages the large dominants in the canopy begin to die too. And
this when the onset of 'climax' or 'old growth' conditions begins. This
stage is denoted by largish gaps in the canopy in which more or less shade
tolerant species are released from 'light restricting' environments as
induced by the closed canopy of the light demanding pine. All kinds of
insects, fungi and birds have now begun to live on the old pine. The pine
simply becomes a host to hundreds of epiphytes, insects. These species do
not even occur in the young seral stand. These species often are established
in the pine only were there are remnants of the old climax forest, patches
and individual trees that were spared by the wind, the fire that swept
through perhaps 150 years ago. There are perhaps as many as 400 species
which are dependent on the old stands of pine...

For instance near riparian areas the pileated woodpecker has to have a
hollow or rotten living or dead tree in order to nest. It needs a tree with
a diameter larger than 31 centimeters at breast height to make a cavity in
to nest and raise it's young. With only one exception the piciformes, all
depend on a closed canopy forest with some old trees for nesting. Since the
pileated woodpecker is a primary excavator many species of cavity nesting
birds and animals are dependent on the pileated woodpecker. At one time the
pileated woodpecker was nearly made extinct in the eastern parts of North
America because lumbering had removed the vast majority of large old trees.
In addition during the time of Thoreau there was extensive hunting of the
Pileated woodpecker (Henry David Thoreau never saw a live Pileated
Woodpecker, In Bent). The demise of the pileated woodpecker would cause a
cascading series of local extinctions in birds...

The flicker is the only piciforme that will nest in an open canopy
forest...so it is more adapted to using snags and rotten trees in wildfires,
but it is also prone to more nest predation. This is the reason why the red
headed woodpecker nests in the closed canopy forest: because it does not
want to nest in the open, near an agricultural area where there are species
of european starlings. Starlings do not inhabit closed canopy forests....and
while there vast numbers of starlings in grain growing and food growing
regions, there are none in the extensive adjacent closed canopy forests in
the Interior (general statement).

So anyway there is a brief description of the 'continuum' that is
undisrupted and necessary for the ecology of many species of forest
dependent species. You can have climax meadow ecosystems in an oak forest,
and there are variations on this but the point is that all the phases are
integral to the whole ecosystem. Thus the contention that climax is dead is
rather unwarranted since the idea that should be expressed and fleshed out
is what is a natural and necessary distribution of the various seral stages?
If wildfires were excluded in Eastern forests, then the meadow phase would
be vastly reduced, and even the 'climax stage' or 'phase' would be reduced
for the 'meadow' variant of the oak forest habitat or oak-hardwood biome.

Saying that climax is dead is not appropriate for other reasons. One of the
reasons is for ecosystem health reasons. Diversity and complexity confer
great resilience to stresses caused by rapid environmental changes.

chao

john





----- Original Message -----
From: Ray Lanier <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, October 30, 2001 1:13 PM
Subject: Re: Ethical implications of environmental change


> Hello Steven,
>
> Thanks for the summary and for the reference; I'll follow up.
>
> A couple of more questions.
>
> 1.  When one considers the particular time horizon applicable to a
> particular problem, is it possible the "climax" might be an applicable
term?
> For example, looking at a human life span would it be unreasonable to
> consider a particular phase in an ecosystem evolution as "climax" while
that
> would be totally inappropriate in evolutionary time?  I'm thinking of my
> little "patch" :-) of pine-hardwood hammock.  I've been watching it for 25

> years now; while I see much change in some specifics -  new growth of
> wildflowers in a little clearing associated with a large number of
butterfly
> species.  But, the totallity is still pine-hardwood.  However, I well know
> that geological time has brought with it many radical changes that I can
see
> in road cuts, etc.
>
> The major changes that I have seen over my life-time have been human
> induced.  Of course, I know that there is also a long-run evolutionary
> change.  The relationship is sort of like amplitude modulation of radio
> signals; a high frequency as a carrier of the audio signal.  An important
> problem for us is to figure out how to distinguish between the two and
what
> might the "appropriate" relationship (if there is such as "appropriate").
> Do you folks think so?
>
> 2.  We talk about the fact that humans are a part of nature.  And I agree.
> But, there has been a major change in the human over time, physically,
etc.,
> but also culturally.  Humans have always used nature but at such a low
level
> that there was little impact over time.  Now, however, we with substantial
> increased #s, have developed tools that enable us to drastically impact
> nature.
>
> Wasn't it Einstein who said something like "humans have learned to use
> nature but have not developed mentally enough to use it intelligently" (I
> know that's not the quote but it gives the sense).
>
> I think I understand and agree with much that is said here about change &
> humans in nature.  Most folks of my persuasion that I know agree.  But,
> where we differ from much that is said here, is directly about the *way*
> humans interact in nature; the changes in the way and in the potential for
> humans to over-ride nature's evolution process.  The questions that arise
> relate to how do we determine the limits, if any, that we should impose on
> ourselves; how do we determine what is "acceptable" change - how do we
> define it, and many related questions that we seem not to be addressing.
>
> Enough for now.  Thanks folks for your ideas, comments.
>
> Ray