(a)


With a smooth
exponential growth,
steady state is
achieved with
little or no
overshoot and
cutback.......




(b)


..... By increasing
the rate of growth,
higher overshoot
and cutback are
probable....




(c)


..... And with
extreme growth
rates, the
overshoot and
cutback can be
severe.







 FIGURE 2.


z
0
a-
<

-J
4

a-
0
1.


z
0
h-
<
_J
a-

0
a-.
o
1-.


Growth Patterns and Carrying Capacity.


natural animal populations have built-in control
mechanisms that sense overcrowding conditions and
limit populations automatically. Some, however,
do not, and with these we witness another common
phenomenon known as overshoot and die back. If
the resource is limited it can only support a
particular population. Anything more than that
will cause a die back until the carrying capacity
is again reached as shown in Fig. 2b and 2c.

 The overshoot and die back can be harmful to
the entire population depending on the degree of
overshoot: the steeper the growth, the greater
the overshoot and the harder the die back.

 The carrying capacity of an environment de-
pends on all its energy sources. Just as one
can raise the carrying capacity of an aquarium
full of fish by adding a subsidy of fish food,
man can increase the carrying capacity of his en-
vironment with subsidies of fossil fuel technol-
ogy based on outside resources. Urban develop-
ment is based on two types of energy sources,
those found locally and those imported.

 During the early stages of development in
Lee County, life was mainly based on local re-
sources. As development proceeded from rural
settlements to high energy urban cities, more and
more imported resources were used. The limited
carrying capacity based on local resources was in-
creased by employing complex technology based on
fossil fuels from outside to sustain additional
levels of human habitation. The "green revolu-
tion" in agriculture, tertiary sewage treatment,
solid waste disposal in land fill operations,
aqueducts and pipelines for water are all exam-
ples of methods devised to increase the carrying
capacity of an area by technology based on im-
ported energy.