Encyclopedia of Environmental Science and Engineering, Volume I and II

ECOSYSTEM THEORY 265

are not prepared to house or employ them (the

tragedy here is that industrialized agriculture can

result in increased food per acre but it can also

widen the gap between rich and poor so that there

are increasing numbers of people unable to buy

the food!).

6) While we generally think of production and decom-

position as being balanced on the biosphere as

a whole, the truth is that this balance has never

been exact but has fluctuated from time to time in

geological history. Through the long haul of evo-

lutional history production has slightly exceeded

decomposition so that a highly oxygenic atmo-

sphere has replaced the original reducing atmo-

sphere of the earth. Man, of course, is tending to

reverse this trend by increasing, decomposition

(burning of fuels, etc.) at the expense of produc-

tion. The most immediate problem is created by

the increase in atmospheric CO 2 since relatively

small changes in concentration can have large

effects on the heat budget of the earth.

7) Ecological studies indicate that diversity is directly

correlated with stability and perhaps inversely

correlated with productivity, at least in many situ-

ations. It could well be that the preservation of

diversity in the ecosystem is important for man

since variety may be a necessity, not just the spice

of life!

8) At the population level it is now clear that the

growth form of the human population will not

conform to the simple sigmoid or logistic model

since there will always be a long time lag in the

effects of crowding, pollution and overexploita-

tion of resources. Growth will not “automatically”

level off as do populations of yeasts in a confined

vessel where individuals are immediately affected

by their waste products. Instead, the human popu-

lation will clearly overshoot some vital resource,

unless man can “anticipate” the effects of over-

population and reduce growth rates before the

deleterious effects of crowding are actually felt.

Intelligent reasoning behavior seems now to be

Protista

Monera

Ciliophora

Sarcodina

Porifer

a

Ingestion

Coelenterata

Chaetognatha

Echinodermata

Chordata

MolluscaArthropoda

Annelida

Absorption

Te n

toculata

Aschelminthes

MesozoaPlatyhelminthes

Photosynth

esis

HyphochytridiomycoidPlasmodiophoremycoid

Sporozoa

Zoo

ma

stig

ina

Cn

ido

spo

rid

Myao ia

myc

ota

Acr

asio

myc

ota

Lab

yrin

thyl

omy

cota

Plantae Fungi Animalia

Cya Bacteria

nop

hyt

a

Euglenophyta

Chr

ysophyt

a

Pyrrophyta

Zygomycota

Basidiomycota

Ascomycota

OomycotaCh

ytr

iid

om

cy

ato

Trocheophyta

Bryophyta

CharophytaPhoeophyta

RhodophytaChlorophyta

FIGURE 2 A five-kingdom system based on three levels of organization—the

procaryotic (kingdom Monera), apearyotic unicelluar (kingdom Protista), and eucary-

otic multicelluar and multinucleate. On each level there is divergence in relation to

three principal modes of nutrition—the photosynthetic, absorptive, and ingestive. Many

ecology and microbiology texts list four kingdoms by combining the “lower Protista”

(i.e., Monera) with the higher “Protista” to form “Protista.” Evolutionary relations are

much simplified, particularly in the Protista. Only major animal phyla are entered,

and phyla of the bacteria are omitted. The Coelenterata comprise the Cnidaria and

Ctenophora; the Tentaculata comprise the Bryozoa, Brachiopoda, and Phoronida, and in

some treatments the Batoprocta. (From Whittaker, 1969.)

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