What is carrying capacity?
 
 
 
Carrying capacity:
 
The population that can be supported indefinitely by an ecosystem without destroying that ecosystem
 


 
Talking Points
 
 
 
  • Not an absolute number
     
  • Depends on available resources and per capita consumption
     
  • Not "caring" capacity


 
Narrative
 
 
 
The carrying capacity is the size of a population that can live indefinitely using the resources available where that population lives. For example, consider an island onto which is dropped a colony of rabbits. As long as there is an adequate supply of food and water, the rabbits will not only survive but they will reproduce and the colony will get larger. The rabbit population can continue to grow as long as food and water are adequate. However, if at some point, there are more rabbits that there is food to feed them, then the rabbit population will start to decline.

This limit is called the carrying capacity. Carrying capacity is not a fixed number; it depends upon factors such as how much each rabbit eats, how fast the food grows, and how well the natural systems of the island can handle the waste produced by the rabbits. Obviously, in a drought year less food would grow and the island would support fewer rabbits. In good years, the island would support more rabbits.

The earth is our island. We have an advantage over the rabbits in that we have developed technology to grow, process, and store food so that we can survive the bad years. We have also developed technologies for handling wastes that we create. However, there is still a carrying capacity that the earth can support. That carrying capacity is a function of the number of people, the amount of resources each person consumes and the ability of the earth to process all the wastes produced. Sustainability is about finding the balance point among population, consumption, and waste assimilation.
 
 
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Copyright © 1998 Maureen Hart. All rights reserved.