There are many types of changes in an ecosystem--the changes in the plants and animals in response to different seasons. Changes in plant and animal populations due to food supply and weather. There are slow changes that take place over hundreds of years. There are natural changes that happen suddenly--such as fires, floods, diseases and climate change. There are usually good and bad aspects of natural changes that in the end, balance out. Some changes in an ecosystem are human-caused and like natural changes, not all are bad. It is the responsibility of each of us to be careful with the environment--not to harm it as we make changes.

2 DISCS INSIDE.

Includes 1 DVD and 1 CD-ROM.