Elasticity of Ecosystems

Posted by Rosemary Drisdelle Jan 16, 2008

In the article What is an Ecosystem, I mention the idea of equilibrium: in theory, ecosystems remain the same for long periods of time because the amount of energy being added by the sun compensates for the energy lost in the lives and deaths of living things. Everything in the ecosystem depends on everything else and all needs are met.

There must be considerable change allowed, however—quite a bit of elasticity—because there are significant natural fluctuations in climate that don’t bring down ecosystems. An unusually cool summer would be a good example (less energy being added). Some plants won’t do as well at cooler temperatures, therefore some other species don’t have as much food and they don’t do as well either. Some species that don’t normally do well in cooler years thrive briefly because the competition is less. But as long as the cool weather doesn’t continue year after year, the normal balance returns.

This is greatly oversimplified of course, but it does suggest that something quite significant has to happen to destroy an ecosystem: the loss of a keystone species perhaps, extreme destruction of habitat, or a long-lasting change in weather patterns.

It’s discouraging to think that humans are causing all three of these things simultaneously in ecosystems all over the world. By the time we learn not to do it, what will be left?