2.06 Homeostasis: Balance in the Community

Ready for a break? How about we stop here under the shade of this tree? This is so peaceful. Just look at that field of dandelions. Aaaaahhhhh! Harmony and balance . I can feel it, can you feel it?

Remember that there are cycles in nature, the water cycle for example. In this activity you'll find that there are also systems of checks and balances in nature that maintain the number of organisms that inhabit an area and that determine how quickly an ecosystem changes.

In this activity you will: identify common limiting factors in an ecosystem. describe the conditions under which primary and secondary succession take place.

Balance. It is all about balance.

In nature there is always a striving for balance. Living things will inhabit an area if their needs are being met. Organisms need a certain balance of food, water, and sometimes a specific temperature range to survive. This natural balance is called homeostasis. Conditions for ecological homeostasis must be met for the organisms to live and survive in a particular habitat or ecosystem.

Take a look at the United States map below. Do more people live in Alaska or Texas? You are correct if you said Texas.

• People prefer to live in Texas because the climate is better for humans.

Now think about polar bears.

• Polar bears thrive in the icy environment of Alaska but wouldn't do too well in Texas.

What is it about the polar bear that enables it to live in Alaska? Click on the image of the polar bear to find out.

Things like the amount of food, water, and temperature are called limiting factors. Limiting factors are anything (biotic or abiotic) that controls (or limits) the number and kinds of organisms living in a given area. The harsh, cold climate and the lack of food in Alaska limit the number of humans that live there, while the heat of Texas limits polar bears from moving in to that state!

So just remember - limiting factors limit kinds and numbers. You'll need this information as we head down the trail a bit farther.

Click on the BioVenture tab to continue the Extreme Eco Challenge.