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Post by duane » Sun Dec 19, 2010 9:09 am

This article on biodiversity, is the first in a series by Ian Sutton.

Understanding the situation:
Have you ever wondered why bio-diversity in the Environment is so important?

It all comes down to the complexity of feedback loops, all interacting with each other.

In order for equilibrium, (perfect balance), to be maintained in a system there must be an equal flow of energy both entering the system and leaving the system. This creates cycles, or feedback loops, within the system.

When there is excess available energy entering a cycle the balance moves away from equilibrium. Once that excess energy is consumed, the cycle begins moving back towards equilibrium, releasing the energy it had absorbed in the previous stage of the cycle. This energy is then made available for other feedback loops to absorb and move away from equilibrium, and intern passing the energy on when they return to equilibrium.

The greater the number of feedback loops interacting with each other, the less energy is available to any one loop. This safeguards against any one cycle absorbing to much of the available energy and moving to far away from equilibrium.

WHAT THE: One simple example of a feedback loop system is the food web. The predator prey relationships. This is the cycle of solar energy that is converted into chemical energy by the plants and some microbes. The food web facilitates the flow of this energy throughout the entire biota.
If a wallaby population increases in number it can be due to the influence of several feedback loops. If it is a good year for rain the extra vegetation provides a higher calorie intake of energy. The response of the cycle to this increase in available energy is to increase in population and move away from the existing equilibrium. Alternatively it could be a sudden decline in predators, this equates to an energy input to the wallabies, again responding by increasing in population.

In situation one the growth of the population of wallabies will slow and then cease when the population of the predators increase, in response to their increase in available energy. Alternatively, if there is no predator in the system, the wallaby population increase will slow and then cease only once the available food source declines and there is not sufficient energy input to continue the population growth. A steep incline is always followed by a steep decline.

A food chain is a connection of feedback loops.

From each successive feedback loop energy moves up the food chain. A food web is a network of feedback loops all mediating each other. As bio-diversity decreases, strands of the food web are cut. As the complexity of the food web decreases the buffering effect is decreased and individual feedback loops can now absorb much larger inputs of energy.
If there is low bio-diversity resulting in grasshoppers having no predators, and a good season for rain increases their food availability, the resulting population increase would not be mediated since their predators are not present to consume some of the increased available energy. The plague would only begin to decrease in population when the energy the vegetation is providing, decreases through over grazing. However this feedback loop does not kick in until after the damage is done and can often lead to desertification and extinction.

The greater the number of relationships an organism has, the more safeguards are in place. If an organism has many predators and one becomes extinct, the resulting available energy would be shared by all related feedback loops allowing all the populations to increase only a small amount. The population of the prey will still be maintained by the other existing predators, as all population then adjust towards the new equilibrium.

The food chain is also layered into trophic levels. Each level is influential in balancing the levels below and above them. The highest trophic level is the top predators. Top predators tend to be opportunist hunters who have a wide range of prey. Like all living organism, energy efficiency is the name of the game, so they hunt whatever is easiest to catch. If any of their prey has a spike in population, they become the easiest to find. The top predators act as a secondary feedback loop to correct any energy imbalances in the trophic layers below them. Very important function!

The Environment is a network of relationships and the greater the bio-diversity, the more complex the network becomes and the more balanced the system becomes.

Diversity mediates the populations of all living things and as diversity decreases the fluctuation in populations increase. Pest and disease are the results of a decrease in bio- diversity while pestilence and plague are the results of the loss of bio-diversity.

Australia is losing bio-diversity at an alarming rate and once the level of diversity reaches critical point; the stage is set for a mass extinction. Combine this with climate changed predictions of more extreme weather patterns creating prolonged droughts and then destructive flooding rains and the near future does not look bright for our flora and fauna.

We need to protect all remaining diversity if we are going to have any chance of restoring a balance to the environment. Keep in mind if the mass extinction occurs we won’t see a balance return until new diversity evolves. That is only a split second in geological time but will seem forever in human time.

Written by
Ian Sutton

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