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| Ecological Stability |
Ecological Stability
Ecosystem
or ecological stability refers to capability of a natural ecosystem to apply self-regulating
mechanisms so as to return to a steady state after an outside disturbance.
Ecosystem stability meant there is a balance between production and consumption
of each element in the ecosystem. The number of each species in a mature
ecosystem generally remains constant.
The
self regulatory mechanisms are also called homeostatic mechanisms .These are mainly
negative and positive feedback mechanisms. For example. If the population of
insects in a small ecosystem area increases greatly due to favorable climate,
then food supply falls short of demand due to increased competition. Eventually
some insects’ die of starvation and slowly the ecosystem returns to its
original size.
Negative
feedback occurs when the result of a process influences the operation of the
process in such a way as to reduce changes. Negative feedback tends to make a
system self-regulating. It can act as a stabilizing force and reduce the effect
of fluctuations. Negative feedback loops where just the right amount of
correction is applied in most timely manner can be very stable, accurate and
responsive. Negative feedback controls the rate of a process to avoid
accumulation of the product. Negative feedback is widely observed in
biogeochemical processes of nature as well as in economics and social behavior.
In contrast, positive feedback is a feedback in which the system responds so as
to increase the magnitude of any particular perturbation, resulting in the
amplification of the original signal instead of stabilization. Any system where
there is positive feedback together with gain greater than one will result in
an out of control, runaway situation. Both positive and negative feedbacks
require a feedback loop to operate. The relative stability is achieved in a
system through negative and positive feedback mechanisms by pulling the system
in either direction. It must be noted that in nature biogeochemical processes
achieve equilibrium, either transiently or hypothetically. They are at the most
in a near-equilibrium, either transiently or hypothetically. They are at the
most in a near-equilibrium state. This self-regulatory process is often
referred to as homeostasis in biological sciences.
Some
of the important characteristics of a stable ecosystem are-
(i)
They are in dynamic equilibrium.
(ii)
These are mature ecosystems i.e. they have attained the stage
of climax community.
(iii)
These ecosystems have high inertia i.e. resistance to change.
(iv)
Stable ecosystems have high resilience i.e. ability to
ecosystem to return to normal state after a disturbance or the ability to
recover from change.
(v)
Sometimes ecosystems attain stability by succession i.e.
replacement of one species by another species.
(vi)
These ecosystems have high species diversity.
(vii)
As a result they have diversity of food web. This increases
the resilience of the system to outside invasions of exotic organisms and
reduces the fluctuations in the population within a given ecosystem.
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