Difference between Exponential Growth and Logistic Growth
Difference between Exponential Growth and Logistic Growth
Exponential Growth vs. Logistic Growth
The difference between exponential growth and logistic
growth can be seen in terms of the growth of the population. Population growth
is defined as an increase in the size of a population over a specific time
period. The growth rate is calculated using two factors – the number
of people and the unit of time. This rate is influenced by the rate at
which birth takes place every year (also known as the birth rate). It is also
influenced by the rate at which living beings die (also known as the death
rate).
The size of the population does not rise indefinitely
because of the limitation of certain factors. These factors are water and
nutrients, space and light as well as the existence of competitors. The
explanation for population growth can be done using 2 growth models – exponential growth and logistic growth.
Exponential growth and logistic growth are terms that
are used in relation to population. The former is the kind of growth that is
present when the rate of growth is proportional to the amounts that exist. It
is the same for the latter; however, logistic growth considers other
major factors. These are competition and limited resources.
Exponential growth requires specific ideal conditions.
These conditions vary to a great extent. In logistic growth, the growth rate is
quick at the beginning then it begins to slow down later on. This happens when
a number of organisms are in competition for limited space. As the
population comes to a state of equilibrium, then the growth rate is equal to
zero. Also if there is no interruption, then the population remains
stationary. A population has the potential to grow exponentially when it has
access to different and unlimited resources. Logistic growth starts rapidly
while exponential growth is the opposite. It begins at a slow rate then the
rate speeds up when the population rises.
What makes Exponential Growth Different from Logistic Growth?
Exponential growth and Logistic growth models help in
explaining the growth of the population. Exponential growth is a growth in
population wherein the number of individuals increases. This happens even when
the rate of growth does not change. As a result, it creates an explosion in the
population. Logistic growth entails exponential growth in population along with
a growth rate that is in a constant state. As the population comes to its
carrying capacity, the growth rate then decreases significantly. This happens
due to the availability of limited resources for each and every entity.
Exponential Growth
In exponential growth, the sole determining factor for the
growth rate of a specific population is the rate of birth. The factor which
limits this growth is the availability of resources. When plotting the number
of entities against time, the result shows a curve with a J-shaped
characteristic. This is exponential growth.
Based on this curve, the beginning of the growth is slow and
it speeds up as the size of the population grows. When looking at reality,
as the population increases in size, then the food supply, as well as space,
becomes more and more limited. That is why this model of growth is known to be
more idealistic than the logistic growth model.
The most important aspect of exponential growth is the
number of entities that come into each generation (otherwise known as the
growth rate). It rapidly increases as the population increases in size too.
When this happens, then the outcomes can be very dramatic.
Logistic Growth
In logistic growth, carrying capacity is taken into account.
Carrying capacity is defined as the size in which a specific population
ultimately reaches stabilization. When this happens, the population’s growth
rate fluctuates. It either goes a bit above or a bit below the carrying
capacity. The logistic growth model is more realistic than the exponential
growth model. Therefore it is applicable to more kinds of populations that
exist on this planet.
When plotting a graph for logistic growth, you will notice
that it forms an S-shaped curve. When there are only a few entities, the
population will increase in size slowly. Then as the number of entities
increases, the population grows in size more rapidly. As a final step, when
there are already many entities in the population, the growth then slows down
once again. This is because of the limitation of resources and space. In
logistic growth, a specific population will keep on growing until it comes to
the carrying capacity. This is the maximum quantity of entities that can be
supported by the environment.
Common Differences between exponential growth and
logistic growth
Both exponential growth and logistic growth are terms that
describe models. These models are used to explain population growth
effectively. Both models refer to the population but in different ways.
One major difference is that exponential growth starts slow and then picks up as
the population increases while logistic growth starts rapidly, then slows down
after reaching the carrying capacity.
·
The exponential growth model shows a characteristic
curve that is J-shaped while the logistic grown model shows a characteristic
curve that is S-shaped.
·
The exponential growth model is applicable to
any population which doesn’t have a limit for growth. The logistic growth model
is applicable to any population which comes to a carrying capacity.
·
The exponential growth model typically results
in an explosion of the population. The logistic growth model results in a
relatively constant rate of population growth. This happens when the growth
rate of the population arrives at its carrying capacity.
·
Exponential growth is ideal for populations that
have unlimited resources and space – such as bacterial cultures. Logistic
growth is more realistic and can be applied to different populations which exist
on the planet.
·
The exponential growth model doesn’t have any
upper limit. The logistic growth model has an upper limit, which is the
carrying capacity.
·
Exponential growth happens when the rate of
growth is in proportion to the existing amounts. This is also true for logistic
growth but the difference is, it also includes competition and resources which
are limited.
