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:
http://www.uark.edu/misc/xtimber/index.html

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


I have posted this comment thread and the picture of the manzanita tree
on the ents website at http://www.nativetreesociety.org/wnts/galleries/sedona/sedona_canyon.htm