1) We often measure species diversity by plant species, i.e.,
Redwoods, Sphagnum spp. However, my view of the ecosystem that I
think is more successful is the understanding that animals, etc. are
part of the ecosystem and play their role in the ecosystem whole. A
question I have is why do we as humans not include the animal kingdom
as a significant part of the ecosystem?
Much of the United States land area (2/3rds) has a natural tendency
to shift to simplicity, if disturbance were removed (I call this
conscience decision to remove disturbance the tool of rest). We often
associate this disturbance as being fire and perhaps, technology applied
by humans. However, living organisms are also a way of causing
disturbance in the ecosystem.
Did you watch Dances With Wolves and the scene with the passing herd
of bison? This was only a small herd, about a thousand, that created
the swath in the landscape. At one time, there was 60 million bison
on the continent, by some conservative estimates. Early European
settlers wrote of finding a high knoll to stay on while bison passed
them for five days!
The United States land area had huge populations of bison, elk (prairie
elk which were supposed to be double the numbers of bison), antelope,
deer, and other species several thousand years ago that would amaze us in
terms of complexity. In association with these herds were predators,
wolves, bear, cougar, humans.
There had developed, over time, immense complexity, variation, and
volume of species (plants included). We replaced these migrating
herds with equivalent numbers of stationary herds of cattle, sheep,
goats, and even elk, bision, antelope and deer (look at the tragedy
of Yellowstone Park).
Many of the National Parks and Monuments in the Southwest are
becoming deserts today, created by our belief that animals are not
part of the ecosystem. Areas of once thriving grasslands and perennial
streams are becoming areas of blowing sand, parched soil, dry stream
beds and simplicity of species. Humans are creating simplicity due to
the paradigms that the animal kingdom is foreign to the ecosystem.
2) The role time plays in diversity. We measure time as a function
of our lifespan. The Redwood trees live 1500 years plus. That's
longer than Europeans have been in America, by three times. Redwoods
wear out, die of old age, and fall down creating a incredible change
in the relationship of light on the forest floor. New diversity
springs from this passing of the old tree. As I have stood as a
midget in the Redwood forests, I have thought about being a midget in
time as well.
"We see the world as we are, not as it is". I am often reminded of
that thought when pondering about the ecosystem.
> To: email@example.com
> Cc: firstname.lastname@example.org, email@example.com
> Date: Sun, 17 Nov 1996 18:06:25 PST
> Subject: the more diversity the better?
> From: firstname.lastname@example.org (James V. Worstell)
> Are there any ecologists on this list who can discuss "positive feedback
> switches"? Many plant species change their environment to make it more
> suitable for themselves and in so doing decrease diversity--Coastal
> redwoods being a primary example cited by many. An extreme example:
> Sphagnum spp create "monocultural" bogs from ponds--almost eliminating
> diversity and helping more of their species survive. Many ecologists
> see stability as associated with lack of diversity. Where ecosystems
> are regularly disturbed, diversity is usually far higher, according to
> the studies of Reice and others. Extreme diversity and disturbed,
> chaotic physical conditions go hand in hand in nature. Many (or can we
> say most?) species fight such extreme diversity by creating a stable
> environment more conducive to their kind. Diversity increases as
> stability decreases.
> While decrying the pesticide-laced Illinois cornfield or Mississippi
> cotton field, one need not make the inferential leap to "the more
> diversity, the better."
> If these species had listservs they'd probably not say "diversity is bad"