ABSTRACT
An ecosystem is any group of plants, animals, or nonliving things interacting within their external environment. Typically, ecologists study individual organisms; populations of organisms; communities of organisms; or the ecosystem as a whole. Barry Commoner, in his book The Closing Circle, identifies four "laws of ecology" that are based on widely accepted norms in the science of ecology. The first law of ecology is that everything is connected to everything else. The second law of ecology is that everything must go somewhere. The third law of ecology is that nature knows best. The fourth law of ecology is that there is no such thing as a free lunch. While Commoner's four laws of ecology provide a useful orientation for our study of humankind's interaction with its environment, there are two additional components of our relationship with nature that need to be expounded on: the notion of sustainability and steady states and the common pool nature of natural resources.
