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.