Attributing Physical Sense for Quantitative Expression of Ecological Resilience

(is in continuation of what was discussed in class:

planetary boundary hypothesis,  & adaptive cycle theory)

Life on the Earth is subtended by the whole gamut of processes, which we generalize as ecological. 

Let us visualize life on the Earth to be suspended as shown below.

Assuming the spring indicates the above said processes

 

          

 

 In mechanics, students study something called law of elasticity. It states that the extension of a spring is in direct proportion with the load applied to it. Materials obey this law as long as the load does not exceed their respective elastic limit. Stress at which materials start to deform irreversibly is called yield point. Number of yield points acting, creates what is called yield surface. Yield surface is usually considered as five dimensional.

Applying this concept to the Earth; it is only logical to presume that as long as anthropogenic pressure is within the yield point of a given ecosystem, it stands the possibility to revert back to original state.

The 5D structure to study the yield surface of an ecosystem can be considered to be comprised of:

1.    A plane comprising location (x,y,z) - A 3d location can be visualized as a proxel (process element), something akin to pixel, which is more familiar. This includes all primary bio-physical parameters sensed there in and their dynamics.

2.    Time (of observation)

3.    Socio-ecological factors. (Social component comes to picture only when man is a part of the system under study. Say, if we are studying a pond ecosystem deep inside the Western Ghats/ African or Amazonian forest, untouched by modern man, this dimension reduces itself to ecological. These are scenarios, where man can still be considered as a natural animal.

Whilst, if we are studying Ashtamudi/ Victoria/ Chad lakes, those which are extensively and destructively interfered by modern man the social arm dominates the ecological arm.               

The problems for the class are:

A.    Attempt to arrive at the components that can define the yield criterion for a given case. Let us take the more familiar Ashtamudi lake.

B.    Explain the behavior of basic metaphors (ball, basin, key variable, threshold) vis-à-vis yield criterion of Ashtamudi lake.

Yield criterion concerns the limit of elasticity under combination of stresses.

You would find that although it is always not possible to ascribe a cause and effect to all the components, it still does make sense to move forward from established concepts of physics in reaching a holistic picture and more importantly a quantitative estimate for ecological resilience.   

We shall discuss further in the class.