Transfer of energy through an ecosystem can be described as food chains, food webs, and food pyramids. Populations of organisms may fluctuate in response to the availability of resources. Population fluctuation of one type of organism may result in corresponding changes in the populations of other organisms. Ecosystems may change over observable spans of time. Change is a natural process within ecosystems.
Human activities can accelerate the process of change.
Humans are a part of the environment and rely upon it. Human activities, both conscious and inadvertent, affect the quality of natural resources. Humans need to exercise judgment, care, and planning in our use and management of the environment.